Chapter 18 - Patterns of Chromosome Inheritance
Sub-Topics:
Chromosomes and the Cell Cycle
Mitosis
Meiosis
Comparison of Meiosis and Mitosis
Chromosome Inheritance
Chromosomes and the Cell Cycle -There are 46 chromosomes that occur in pairs of 23. These chromosomes make up the human DNA. Only one pair of chromosomes decides the gender of the person while the other twenty-two pairs are autosomes, or non-sex chromosomes. For the sex of the individual they must have two X chromosomes and for the sex to be male the individual must both an X and a Y chromosome, for the Y chromosome develops testes.
Karyotype- Mitosis, the duplication and division of cells, maintains that every cell has 46 chromosomes. Each chromosomes sister chromatids are duplicated chromosomes because they contain the same genes. Each chromatid contains a DNA double helix which controls the heredity of the individual. A centromere, containing the chromatids, holds the chromatids together until a particular phase of mitosis when it breaks. After which the two sister chromatids become separate chromosomes.
The Cell Cycle- The cell cycle is the process in which the cell grows, replicates DNA, mitosis, and Cytokinesis occur to prepare for the division of the cell. Interphase is the state in which most of the time is spent in the cell cycle; it makes up 90% of the cell cycle. During Interphase the cell grows, reproduces DNA, and the final preparation for division are made. Different types of cells take different amounts of time in Interphase. After Interphase the cell goes into mitosis, or nuclear division. Mitosis is made up of four stages; Prophase, Metaphase, Anaphase, and Telophase. After mitosis the cell begins Cytokinesis, in which the cytoplasm is divided and the cell cycle is completed. A process called apoptosis occurs when cells are dividing when they shouldn’t.
Mitosis - Mitosis is the duplication and division of cells. The dividing cell, the parent cell, becomes two other cells, the daughter cells. During mitosis the sister chromatids split at the centromere and each daughter cell receives the same number of chromosomes as the parent cell making them identical to the parent. During mitosis is the important duplication of the centrosome. The centrosome is a microtubule center of the cell. The four phases of mitosis are; Prophase, centrosomes duplicate and chromatin is condensing, Metaphase, duplicated centromeres align and spindle fibers attach to sister chromatids, Anaphase, sister chromatids part becoming daughter chromosomes and move toward spindle poles, and Telophase, daughter cells become nuclear envelops, nucleoli reappear, and chromosomes become chromatin. During Cytokinesis, the last step of the cell cycle, the cell divides completely and forms two cells.
The Importance of the Cell Cycle and Mitosis - Without the cell cycle, including mitosis, people would be without certain normality’s. Normality’s such as proper growth, reparation of an injury, and proper healing.
Meiosis – is the reduction division. DNA replication is followed by meiosis I when homologous chromosomes pair and the separate. During Meiosis II the sister chromatids become chromosomes that move into daughter nuclei. In humans the daughter cells mature into gametes that fuse during fertilization which restores the diploid number of chromosomes in the zygote.
Stages of Meiosis -Meiosis is a part of sexual production. Both meiosis I and meiosis II have the same four stages of nuclear division as did mitosis.
· Prophase I synapses occurs the spindle appears while the nuclear envelop fragments and the nucleolus disappears. During this phase crossing over occurs in which the exchange of genetic material happens.
· Metaphase I – the homologous pairs align independently at the equator to combine into a possible 8,388,608 different combinations of maternal or paternal patterns.
· The significance of Meiosis is for one to keep the chromosome number consistent from generation to generation. An easier way to keep the chromosomes consistent is to reproduce asexually.
Chromosome Inheritance – an individual receives 22 pair of autosomes and two sex chromosomes. Individuals that are born with either to many or too few autosomes or sex chromosomes, most likely due to nondisjunction during meiosis. Normal development depends on the presence of exactly two of each kind of chromosome. Too many chromosomes are tolerated better than a deficiency of chromosomes, and several trisomies are known to occur in humans. Only trisomy 21 has a reasonable chance of survival after birth. The chances of survival are greater when trisomy or monosomy involves the sex chromosomes. Down syndrome also known as trisomy 21 is most common autosomal trisomy. Persons with trisomy 21 or Down syndrome have three copies of chromosome 21 because the egg had two copies instead of one. Down syndrome is characterized by the short stature, and eyelid fold, a flat face, stubby fingers, a side gap between the first and second toes, a large fissure tongue, a round head, a palm crease, and mental retardation. The genes that cause Down syndrome are located on the bottom third of chromosome 21.
Changes in Sex Chromosome Number – is a result of inheriting too many or too few x or y chromosomes. The following are some of these disorders.
· Turners Syndrome – an individual will only have one sex chromosome which is an x. As adult women they are short, with broad chest and folds of skin on the back of the neck. The ovaries, oviducts, and uterus are very small and unmenstrated and their breast do not develop.
· Klinefelter Syndrome – males are born with two x chromosomes and on y chromosome.
· Polies –X females – have more than two X chromosomes and extra Barr bodies in the nucleus. They have no real distinctive characteristics, but they do seem to be tall and thin with some delayed motor and speech skills.
· Jacobs Syndrome- is XYY males and only result from nondisjunction during spermatogenesis. They are taller than average, acne problems, and speech and reading problems.
Changes in Chromosome Structure – are another type of chromosomal mutation. Agents in the environment such as radiation and chemicals can cause chromosome break down, Changes in chromosome structure include deletions, translocations, duplications, and inversions of chromosome segments.
Chapter 19 Cancer
Topics:
Cancer Cells
Causes and Prevention
Diagnosis of Cancer
Treatment of Cancer
Cancer Cells - – Cancer cells have a number of abnormal characteristics that prevent them from functioning it same manner as normal cells. They divide repeatedly and from tumors in the place of origin and in other parts of the body. Cancer is a cellular disease and these cells have and enlarged nuclei and may contain and abnormal number of chromosomes. The chromosomes are abnormal also. Cancer cells fail to undergo apoptosis as other abnormal cells. The tissues that divide more rapidly are more likely to become cancerous. Cancer cells can also divide an unlimited amount of times unlike a normal cell which will divide up to 60 or 70 times. Cancers cells have lost all restraint and they pile up on one another and form tumors. Cancer cells gradually become abnormal through a multistage process.
Initiation: a single cell undergoes a mutation that caused it to begin to divide repeatedly. Promotion: A tumor develops and the tumor cells continue to divide and mutate. Progression: one cell undergoes a mutation that gives it a selective advantage over the other cells. This process is repeated several times and eventually there is a cell that has the ability to invade surrounding tissues. Cancers are classified according t their place of origin. Cancers occur in all parts of the body, but some organs are more susceptible than others. Lung cancer is most common type of cancer. Breast cancer is another very common cancer mostly found in women, but also found in men.
Cause and Prevention of Cancer- There is still a void in the understanding of cancer and how it happens, but much research has shown some success in finding preventative measures that can be taking to lessen the chances of cancer forming.
Heredity- since we inherit two copies of every gene one from each parent then the mutated copy of the cancer gene is passed on.
Environmental Carcinogens- Radiation with it is natural or artificial has an impact on cells as a mutagen.
Organic Chemicals- Tobacco smoke is a know mutagen along with pollutants such as pesticides, metals, dust, or other chemicals.
Viruses- hepatitis c and b, Epstein Barr, and HPV are all linked to cancer
Dietary choices- A diet high in fat and processed foods show a link to cancer. Eating a well balance diet rich in colorful fruits and vegetables helps keep anti cancer fighters on board.
Diagnosing Cancer – The earlier the detection the better. Testing for the molecular fingerprints of a cancer may be in the future. Routine screening and self examination should be done on a regular basis, monthly for breast and testicles. Tumor marker tests are blood test that can be done to check for tumor antigens and antibodies. Genetic testing is possible to detect the likelihood of cancer before it ever becomes a tumor.
Treatments of Cancer-Standard therapies have been around for a long time and new procedures are always being tested.
Surgery can be done alone or in conjunction with other therapies
Radiation Therapy cases chromosomal breakage and cell cycle duration dividing cells such as cancer and are more susceptible to its effects than other cells. Side effects vary greatly depending on which part of the body is targeted.
Chemotherapy treats the entire body unlike radiation that is focused on just the targeted area. Chemotherapy usually mixes medication to prevent the cancer from becoming resistant to the drugs. What chemicals that are used are based on the patient’s type of cancer, age, health, and the ability to handle the drug. Certain cancers respond successfully when treated with chemotherapy. Chemotherapy fails at times because cancer cells become resistant to one or several chemo drugs.
Bone marrow transplants are sometimes done in conjunction with chemotherapy, due to the large populations of dividing cells. The patient’s stem cells are harvested and stored before chemotherapy begins. They are then returned to the patient by injection as needed.
Newer therapies are in clinical trials. One is immunotherapy which is a vaccine called Melacine which contains broken melanoma cells from two different sources. A gene therapy is also being looked at which respect to the p53 expression to trigger apoptosis. When the adenoviruses infect a cell they first produce a protein that inactivates p53. Now the adenovirus can infect and kill only cells that lace a p53 gene which would be the cancer genes. This genetically engineered virus is now in clinical trials.
Chapter 20 Patterns of Genetic Inheritance
Genotype and phenotype refer to the genes for a particular trait, and the phenotype refers to physical characteristics, such as hairline, blood type, color blindness, and even any cellular disorder. During gametognesis the chromosome number is only half, the gamete has 23 chromosomes. Reduction of the chromosomes number occurs when the homologous chromosomes separate as meiosis occurs. The alleles also separate because they are on the chromosome. Therefore the gamete only carries one allele.
Family pedigrees for Genetic Disorders –are when a genetic disorder is Autosomal dominant and individual with the alleles AA of Aa will have the disorder. If the genetic disorder is Autosomal recessive only individuals with the alleles aa will have the disorder.
Autosomal recessive Disorder-
· affected children can have unaffected parents
· Heterozygote’s Aa has an unaffected phenotype.
· Two affected parents will always have affected parents.
· Affected individuals with homozygous unaffected mates will have unaffected children.
· Close relatives who reproduce are more likely to have affected children.
· Both males and females are affected with equal frequency
o Tay-Sachs disease results from a lack of the enzyme hexosaminidase A and the subsequent store of its substrate a glycosphingolipid in lysosomes. Lysosomes build up primarily in the brain and by 4 – 8 months of life symptoms begin ending in paralysis.
o Cystic Fibrosis occurs when chloride ions fail t pass through a plasma membrane channel protein in the cells. This causes a lack of water resulting in very thick mucus in the lungs and pancreatic ducts. Clogged pancreatic ducts prevent digestive enzymes form reaching the small intestine and in the lungs the thick mucus interferes with breathing.
o Phenylketonuria is a metabolic disorder that affects the nervous system development. Individuals lack an enzyme that is needed of the normal metabolism of the amino acid phenylalanine. Patients must be put on a diet low in phenylalanine until full brain development in reached and even then some doctors believe patients should stay on this diet for life.
o Sickle Cell disease is a disorder in which the red blood cells are not biconcave and result in the cell not being passed along eh narrow capillary and they clog the vessels and break down. These patients suffer from poor circulation, anemia, and low resistance to infection.
Autosomal Dominant Disorders
· Affected children will usually have an affected parent
· Heterozygote’s Aa are affected
· Two affected parents can produce an unaffected child.
· Two unaffected parents will not have affected children
· Both males and females are affected with equal frequency.
o Marfan syndrome is caused by a defect in an elastic connective tissue protein called fibrillin. The person often has a dislocated lens, long limbs and fingers, and a caved in chest. The aorta wall is weak and could possibly burst without warning.
o Huntington Disease is a neurological disorder that leads to progressive degeneration of brain cells. The disease is caused by a mutated copy of the gene for a protein call Huntington. Most patients appear normal until middle age then symptoms appear and death will occur in 10 to 15 years. There is no cure for this disease.
Polygenic Inheritance- is traits such as skin color and height that are governed by several sets of alleles. The dominant alleles have a quantitative effect on the phenotype, and these effects are additive. The result is a continuous variation of phenotypes.
Incomplete dominance – occurs when the heterozygote is intermediate between the two homozygote’s. Only one allele codes for a product and the single dose of the product gives the intermediate result.
Codominance occurs when alleles are equally expressed in a heterozygote. Such as when a person inherited both parents blood types.
Multiple Allele Inheritance is a trait that is controlled by multiple alleles; the gene exists in several allelic forms. Each person has only two of the tree possible alleles and both 1A and 1B are dominant over i.
Sex Linked inheritance
Normally both males and females have 23 pairs of chromosomes, 22 are called autosomes, and one pair is the sex chromosomes. The sex chromosomes differ between the sexes. Traits controlled by genes on the sex chromosomes are said to be sex-linked, an allele on an X chromosome is X-linked, and an allele on the Y chromosome is Y-linked. A male always receives an X—linked allele from his mother, from whom he inherited an X chromosome. The Y chromosome form the father does not carry an allele for the trait. Usually a sex linked genetic
Disorder is recessive there for a female must receive two alleles, one from each parent.
Chapter 21: DNA Biology and Technology
DNA and RNA structure and function
DNA is a double helix composed of polynucleotide strands. When DNA replicates, each strand serves as a template for a new strand. RNA is also made off a DNA template. DNA is the genetic material found in a chromosome located in the nucleus of a cell. This genetic material has to be able to do three things, replicate so it can be pasted on to the next generation, store information, and undergo mutations that provide genetic variability. When cells divide each new cell gets and exact copy of DAN During replication the double stranded structure of DNA allows each original strand to serve as a template for the formation of a complementary new strand.
RNA is made up of nucleotides containing the sugar ribose. This sugar accounts for the scientific name of this polynucleotide. The four nucleotides that make up the RNA molecule have the following base: adenine, Uralic, cytosine, and guanine. RNA is single stranded, but the single RNA strand sometimes double backs upon itself. Ribosomal RNA is produced in the nucleolus of a nucleus where a portion of DMA serves as a template for its formation. Messenger RNA is produced into the nucleus where DNA serves as a template for its formation. This type of RNA carries genetic information from DNA to the Ribosome’s in the cytoplasm where protein synthesis occurs. Transfer RNA is produced in the nucleus and a protein DNA also serves as a template for it production. This RNA transfers amino acids to the ribosomes. Each type of tRNA carries only one type of amino acid.
Gene expression – Gene expression results in a protein product. Each protein has sequence of amino acids according to the blueprint provided by the sequence of nucleotides in DNA. First, gene expression is called translation. During transcription a strand of mRNA forms, then it forms a transcript of a gene, so then a sequence of nucleotides in DNA is copied to a sequence of nucleotides in mRNA. Protein synthesis requires the process of translation, which means in this cans a sequence of nucleotides is translated into the sequence of amino acids. This is possible only if the bases in DNA and mRNA code for amino acids. This code is called the genetic code.
Genomics – is the study of genetic information in a particular cell or organism. The twenty first century has made plenty of strides in this field. Things that were never thought to be possible are now possible. Though studies conduct by Universities and private labs both were able to know the order of the 3 billion bases A, T, C, and G in our genome. The genome size is not proportionate to the number of genes and does not correlate to complexity of the organism. Comparing genomes is one way to determine how species have evolved and how genes and noncoding regions of the genome function. Another discovery has been how similar the genomes of all vertebrates are.
Proteomics is the study of the structure, function, and interaction of cellular proteins. Many of our genes are translated into proteins in our cells. The analysis or proteomes is more challenging that the analysis of genomes. Computer modeling of the tree dimensional shape of cellular proteins is an important part of proteomics.
Bioformatics is the application of computer technology to the study of the genome. As a result of bioinformatics, scientists are hopeful of finding cause and effect relationships between various genetic profiles and genetic disorders caused by mutifactorial genes.
Sub-Topics:
Chromosomes and the Cell Cycle
Mitosis
Meiosis
Comparison of Meiosis and Mitosis
Chromosome Inheritance
Chromosomes and the Cell Cycle -There are 46 chromosomes that occur in pairs of 23. These chromosomes make up the human DNA. Only one pair of chromosomes decides the gender of the person while the other twenty-two pairs are autosomes, or non-sex chromosomes. For the sex of the individual they must have two X chromosomes and for the sex to be male the individual must both an X and a Y chromosome, for the Y chromosome develops testes.
Karyotype- Mitosis, the duplication and division of cells, maintains that every cell has 46 chromosomes. Each chromosomes sister chromatids are duplicated chromosomes because they contain the same genes. Each chromatid contains a DNA double helix which controls the heredity of the individual. A centromere, containing the chromatids, holds the chromatids together until a particular phase of mitosis when it breaks. After which the two sister chromatids become separate chromosomes.
The Cell Cycle- The cell cycle is the process in which the cell grows, replicates DNA, mitosis, and Cytokinesis occur to prepare for the division of the cell. Interphase is the state in which most of the time is spent in the cell cycle; it makes up 90% of the cell cycle. During Interphase the cell grows, reproduces DNA, and the final preparation for division are made. Different types of cells take different amounts of time in Interphase. After Interphase the cell goes into mitosis, or nuclear division. Mitosis is made up of four stages; Prophase, Metaphase, Anaphase, and Telophase. After mitosis the cell begins Cytokinesis, in which the cytoplasm is divided and the cell cycle is completed. A process called apoptosis occurs when cells are dividing when they shouldn’t.
Mitosis - Mitosis is the duplication and division of cells. The dividing cell, the parent cell, becomes two other cells, the daughter cells. During mitosis the sister chromatids split at the centromere and each daughter cell receives the same number of chromosomes as the parent cell making them identical to the parent. During mitosis is the important duplication of the centrosome. The centrosome is a microtubule center of the cell. The four phases of mitosis are; Prophase, centrosomes duplicate and chromatin is condensing, Metaphase, duplicated centromeres align and spindle fibers attach to sister chromatids, Anaphase, sister chromatids part becoming daughter chromosomes and move toward spindle poles, and Telophase, daughter cells become nuclear envelops, nucleoli reappear, and chromosomes become chromatin. During Cytokinesis, the last step of the cell cycle, the cell divides completely and forms two cells.
The Importance of the Cell Cycle and Mitosis - Without the cell cycle, including mitosis, people would be without certain normality’s. Normality’s such as proper growth, reparation of an injury, and proper healing.
Meiosis – is the reduction division. DNA replication is followed by meiosis I when homologous chromosomes pair and the separate. During Meiosis II the sister chromatids become chromosomes that move into daughter nuclei. In humans the daughter cells mature into gametes that fuse during fertilization which restores the diploid number of chromosomes in the zygote.
Stages of Meiosis -Meiosis is a part of sexual production. Both meiosis I and meiosis II have the same four stages of nuclear division as did mitosis.
· Prophase I synapses occurs the spindle appears while the nuclear envelop fragments and the nucleolus disappears. During this phase crossing over occurs in which the exchange of genetic material happens.
· Metaphase I – the homologous pairs align independently at the equator to combine into a possible 8,388,608 different combinations of maternal or paternal patterns.
· The significance of Meiosis is for one to keep the chromosome number consistent from generation to generation. An easier way to keep the chromosomes consistent is to reproduce asexually.
Chromosome Inheritance – an individual receives 22 pair of autosomes and two sex chromosomes. Individuals that are born with either to many or too few autosomes or sex chromosomes, most likely due to nondisjunction during meiosis. Normal development depends on the presence of exactly two of each kind of chromosome. Too many chromosomes are tolerated better than a deficiency of chromosomes, and several trisomies are known to occur in humans. Only trisomy 21 has a reasonable chance of survival after birth. The chances of survival are greater when trisomy or monosomy involves the sex chromosomes. Down syndrome also known as trisomy 21 is most common autosomal trisomy. Persons with trisomy 21 or Down syndrome have three copies of chromosome 21 because the egg had two copies instead of one. Down syndrome is characterized by the short stature, and eyelid fold, a flat face, stubby fingers, a side gap between the first and second toes, a large fissure tongue, a round head, a palm crease, and mental retardation. The genes that cause Down syndrome are located on the bottom third of chromosome 21.
Changes in Sex Chromosome Number – is a result of inheriting too many or too few x or y chromosomes. The following are some of these disorders.
· Turners Syndrome – an individual will only have one sex chromosome which is an x. As adult women they are short, with broad chest and folds of skin on the back of the neck. The ovaries, oviducts, and uterus are very small and unmenstrated and their breast do not develop.
· Klinefelter Syndrome – males are born with two x chromosomes and on y chromosome.
· Polies –X females – have more than two X chromosomes and extra Barr bodies in the nucleus. They have no real distinctive characteristics, but they do seem to be tall and thin with some delayed motor and speech skills.
· Jacobs Syndrome- is XYY males and only result from nondisjunction during spermatogenesis. They are taller than average, acne problems, and speech and reading problems.
Changes in Chromosome Structure – are another type of chromosomal mutation. Agents in the environment such as radiation and chemicals can cause chromosome break down, Changes in chromosome structure include deletions, translocations, duplications, and inversions of chromosome segments.
Chapter 19 Cancer
Topics:
Cancer Cells
Causes and Prevention
Diagnosis of Cancer
Treatment of Cancer
Cancer Cells - – Cancer cells have a number of abnormal characteristics that prevent them from functioning it same manner as normal cells. They divide repeatedly and from tumors in the place of origin and in other parts of the body. Cancer is a cellular disease and these cells have and enlarged nuclei and may contain and abnormal number of chromosomes. The chromosomes are abnormal also. Cancer cells fail to undergo apoptosis as other abnormal cells. The tissues that divide more rapidly are more likely to become cancerous. Cancer cells can also divide an unlimited amount of times unlike a normal cell which will divide up to 60 or 70 times. Cancers cells have lost all restraint and they pile up on one another and form tumors. Cancer cells gradually become abnormal through a multistage process.
Initiation: a single cell undergoes a mutation that caused it to begin to divide repeatedly. Promotion: A tumor develops and the tumor cells continue to divide and mutate. Progression: one cell undergoes a mutation that gives it a selective advantage over the other cells. This process is repeated several times and eventually there is a cell that has the ability to invade surrounding tissues. Cancers are classified according t their place of origin. Cancers occur in all parts of the body, but some organs are more susceptible than others. Lung cancer is most common type of cancer. Breast cancer is another very common cancer mostly found in women, but also found in men.
Cause and Prevention of Cancer- There is still a void in the understanding of cancer and how it happens, but much research has shown some success in finding preventative measures that can be taking to lessen the chances of cancer forming.
Heredity- since we inherit two copies of every gene one from each parent then the mutated copy of the cancer gene is passed on.
Environmental Carcinogens- Radiation with it is natural or artificial has an impact on cells as a mutagen.
Organic Chemicals- Tobacco smoke is a know mutagen along with pollutants such as pesticides, metals, dust, or other chemicals.
Viruses- hepatitis c and b, Epstein Barr, and HPV are all linked to cancer
Dietary choices- A diet high in fat and processed foods show a link to cancer. Eating a well balance diet rich in colorful fruits and vegetables helps keep anti cancer fighters on board.
Diagnosing Cancer – The earlier the detection the better. Testing for the molecular fingerprints of a cancer may be in the future. Routine screening and self examination should be done on a regular basis, monthly for breast and testicles. Tumor marker tests are blood test that can be done to check for tumor antigens and antibodies. Genetic testing is possible to detect the likelihood of cancer before it ever becomes a tumor.
Treatments of Cancer-Standard therapies have been around for a long time and new procedures are always being tested.
Surgery can be done alone or in conjunction with other therapies
Radiation Therapy cases chromosomal breakage and cell cycle duration dividing cells such as cancer and are more susceptible to its effects than other cells. Side effects vary greatly depending on which part of the body is targeted.
Chemotherapy treats the entire body unlike radiation that is focused on just the targeted area. Chemotherapy usually mixes medication to prevent the cancer from becoming resistant to the drugs. What chemicals that are used are based on the patient’s type of cancer, age, health, and the ability to handle the drug. Certain cancers respond successfully when treated with chemotherapy. Chemotherapy fails at times because cancer cells become resistant to one or several chemo drugs.
Bone marrow transplants are sometimes done in conjunction with chemotherapy, due to the large populations of dividing cells. The patient’s stem cells are harvested and stored before chemotherapy begins. They are then returned to the patient by injection as needed.
Newer therapies are in clinical trials. One is immunotherapy which is a vaccine called Melacine which contains broken melanoma cells from two different sources. A gene therapy is also being looked at which respect to the p53 expression to trigger apoptosis. When the adenoviruses infect a cell they first produce a protein that inactivates p53. Now the adenovirus can infect and kill only cells that lace a p53 gene which would be the cancer genes. This genetically engineered virus is now in clinical trials.
Chapter 20 Patterns of Genetic Inheritance
Genotype and phenotype refer to the genes for a particular trait, and the phenotype refers to physical characteristics, such as hairline, blood type, color blindness, and even any cellular disorder. During gametognesis the chromosome number is only half, the gamete has 23 chromosomes. Reduction of the chromosomes number occurs when the homologous chromosomes separate as meiosis occurs. The alleles also separate because they are on the chromosome. Therefore the gamete only carries one allele.
Family pedigrees for Genetic Disorders –are when a genetic disorder is Autosomal dominant and individual with the alleles AA of Aa will have the disorder. If the genetic disorder is Autosomal recessive only individuals with the alleles aa will have the disorder.
Autosomal recessive Disorder-
· affected children can have unaffected parents
· Heterozygote’s Aa has an unaffected phenotype.
· Two affected parents will always have affected parents.
· Affected individuals with homozygous unaffected mates will have unaffected children.
· Close relatives who reproduce are more likely to have affected children.
· Both males and females are affected with equal frequency
o Tay-Sachs disease results from a lack of the enzyme hexosaminidase A and the subsequent store of its substrate a glycosphingolipid in lysosomes. Lysosomes build up primarily in the brain and by 4 – 8 months of life symptoms begin ending in paralysis.
o Cystic Fibrosis occurs when chloride ions fail t pass through a plasma membrane channel protein in the cells. This causes a lack of water resulting in very thick mucus in the lungs and pancreatic ducts. Clogged pancreatic ducts prevent digestive enzymes form reaching the small intestine and in the lungs the thick mucus interferes with breathing.
o Phenylketonuria is a metabolic disorder that affects the nervous system development. Individuals lack an enzyme that is needed of the normal metabolism of the amino acid phenylalanine. Patients must be put on a diet low in phenylalanine until full brain development in reached and even then some doctors believe patients should stay on this diet for life.
o Sickle Cell disease is a disorder in which the red blood cells are not biconcave and result in the cell not being passed along eh narrow capillary and they clog the vessels and break down. These patients suffer from poor circulation, anemia, and low resistance to infection.
Autosomal Dominant Disorders
· Affected children will usually have an affected parent
· Heterozygote’s Aa are affected
· Two affected parents can produce an unaffected child.
· Two unaffected parents will not have affected children
· Both males and females are affected with equal frequency.
o Marfan syndrome is caused by a defect in an elastic connective tissue protein called fibrillin. The person often has a dislocated lens, long limbs and fingers, and a caved in chest. The aorta wall is weak and could possibly burst without warning.
o Huntington Disease is a neurological disorder that leads to progressive degeneration of brain cells. The disease is caused by a mutated copy of the gene for a protein call Huntington. Most patients appear normal until middle age then symptoms appear and death will occur in 10 to 15 years. There is no cure for this disease.
Polygenic Inheritance- is traits such as skin color and height that are governed by several sets of alleles. The dominant alleles have a quantitative effect on the phenotype, and these effects are additive. The result is a continuous variation of phenotypes.
Incomplete dominance – occurs when the heterozygote is intermediate between the two homozygote’s. Only one allele codes for a product and the single dose of the product gives the intermediate result.
Codominance occurs when alleles are equally expressed in a heterozygote. Such as when a person inherited both parents blood types.
Multiple Allele Inheritance is a trait that is controlled by multiple alleles; the gene exists in several allelic forms. Each person has only two of the tree possible alleles and both 1A and 1B are dominant over i.
Sex Linked inheritance
Normally both males and females have 23 pairs of chromosomes, 22 are called autosomes, and one pair is the sex chromosomes. The sex chromosomes differ between the sexes. Traits controlled by genes on the sex chromosomes are said to be sex-linked, an allele on an X chromosome is X-linked, and an allele on the Y chromosome is Y-linked. A male always receives an X—linked allele from his mother, from whom he inherited an X chromosome. The Y chromosome form the father does not carry an allele for the trait. Usually a sex linked genetic
Disorder is recessive there for a female must receive two alleles, one from each parent.
Chapter 21: DNA Biology and Technology
DNA and RNA structure and function
DNA is a double helix composed of polynucleotide strands. When DNA replicates, each strand serves as a template for a new strand. RNA is also made off a DNA template. DNA is the genetic material found in a chromosome located in the nucleus of a cell. This genetic material has to be able to do three things, replicate so it can be pasted on to the next generation, store information, and undergo mutations that provide genetic variability. When cells divide each new cell gets and exact copy of DAN During replication the double stranded structure of DNA allows each original strand to serve as a template for the formation of a complementary new strand.
RNA is made up of nucleotides containing the sugar ribose. This sugar accounts for the scientific name of this polynucleotide. The four nucleotides that make up the RNA molecule have the following base: adenine, Uralic, cytosine, and guanine. RNA is single stranded, but the single RNA strand sometimes double backs upon itself. Ribosomal RNA is produced in the nucleolus of a nucleus where a portion of DMA serves as a template for its formation. Messenger RNA is produced into the nucleus where DNA serves as a template for its formation. This type of RNA carries genetic information from DNA to the Ribosome’s in the cytoplasm where protein synthesis occurs. Transfer RNA is produced in the nucleus and a protein DNA also serves as a template for it production. This RNA transfers amino acids to the ribosomes. Each type of tRNA carries only one type of amino acid.
Gene expression – Gene expression results in a protein product. Each protein has sequence of amino acids according to the blueprint provided by the sequence of nucleotides in DNA. First, gene expression is called translation. During transcription a strand of mRNA forms, then it forms a transcript of a gene, so then a sequence of nucleotides in DNA is copied to a sequence of nucleotides in mRNA. Protein synthesis requires the process of translation, which means in this cans a sequence of nucleotides is translated into the sequence of amino acids. This is possible only if the bases in DNA and mRNA code for amino acids. This code is called the genetic code.
Genomics – is the study of genetic information in a particular cell or organism. The twenty first century has made plenty of strides in this field. Things that were never thought to be possible are now possible. Though studies conduct by Universities and private labs both were able to know the order of the 3 billion bases A, T, C, and G in our genome. The genome size is not proportionate to the number of genes and does not correlate to complexity of the organism. Comparing genomes is one way to determine how species have evolved and how genes and noncoding regions of the genome function. Another discovery has been how similar the genomes of all vertebrates are.
Proteomics is the study of the structure, function, and interaction of cellular proteins. Many of our genes are translated into proteins in our cells. The analysis or proteomes is more challenging that the analysis of genomes. Computer modeling of the tree dimensional shape of cellular proteins is an important part of proteomics.
Bioformatics is the application of computer technology to the study of the genome. As a result of bioinformatics, scientists are hopeful of finding cause and effect relationships between various genetic profiles and genetic disorders caused by mutifactorial genes.
Gene Therapy is the insertion of genetic material into human cells for the treatment of a disorder. Both Ex Vivo Gene Therapy and In Vivo Therapy are used. Gene cloning can be done to produce many identical copies of the same gene. Recombinant DNA which contains DNA from two or more different sources allows genes to be cloned. To create recombinant DNA a technician needs a vector by which the gene of interest will be introduced into a host cell, such an s a bacterium. One common vector is plasmid.
Bacteria, plants, and animals are genetically engineered to produce biotechnology products. Organisms that have had a foreign gene inserted into them are called transgenic organisms. Transgenic organisms can produce biotechnology products such as hormones and vaccines. Transgenic bacteria can promote plant health. Transgenic crops can resist pests. Transgenic animal can be given growth hormone to produce larger animals, transplant organs, and pharmaceuticals. All of things can have a positive effect on life, but some scientists are skeptical on the safety of genetically engineering our plants and animals.
Bacteria, plants, and animals are genetically engineered to produce biotechnology products. Organisms that have had a foreign gene inserted into them are called transgenic organisms. Transgenic organisms can produce biotechnology products such as hormones and vaccines. Transgenic bacteria can promote plant health. Transgenic crops can resist pests. Transgenic animal can be given growth hormone to produce larger animals, transplant organs, and pharmaceuticals. All of things can have a positive effect on life, but some scientists are skeptical on the safety of genetically engineering our plants and animals.
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