Compendium Review, Section I - Major Topic II - Genetics
Chapter 18 – Patterns of Chromosome Inheritance
18.1 Chromosomes and the Cell Cycle
Chromosomes occur in pairs in body cells.
A karyotype is a visual display of a person’s chrmosomes.
A normal human karyotype shows 22 homologous pairs of autosomes and one pair of sex chromosomes.
Normal sex chromosomes in males: XY
Nomal sex chromosomes in felmales: XX
The cell cycle occurs continuously and has four stages: G1, S, G2, and M
In G1, a cell doubles organelles and accumulates materials for DNA synthesis.
In S, DNA replication occurs
In G2, a cell synthesizes proteins needed for cell division
Apoptosis also occurs during the cell cycle.
18.2 Mitosis
Mitosis is duplication division that assures that all body cells have the diploid number and the same kinds of chromosomes as the cell that divides. The phases of mitosis are prophase, metaphase, anaphase, and telophase.
o Prophase: Chromosomes attach to spindle fibers.
o Metaphase: Chromosomes align at the equator
o Anaphase: Chromatids separate, becoming chromosomes that move toward the poles
o Telophase: Nuclear envelopes form around chromosomes; cytokinesis begins. Cytokinesis is the division of cytoplasm and organelles following mitosis. The proper workings of the cell cycle and mitosis are critical to growth and tissue repair.
18.3 Meiosis
Meiosis involves two cell division: meosis I and meiosis II.
Meiosis I – Homologous chromosomes pair and then separate
Meiosis II – Sister chromatids separate, resulting in four cells with the haploid number of chrmosomes that move into daughter nuclei.
18.4 Comparison of Meiosis and Mitosis
In prophase I, homologous chromosomes pair; there is no pairing in mitosis.
In metaphase I, homologous duplicated chromosomes align at equator.
In anaphase I, homologous chrmosomes separate.
Spermatogenesis and Oogenesis
o Spermatogensis In males, produces four viable sperm.
o Oogenesis In females, produces one egg and two or three polar bodies. Oogenesis goes to completion if the sperm fertilizes the developing egg.
18.5 Chromosome Inheritance
Meiosis is a part of gametogenesis and contributes to genetic diversity
Changes in Chromosome Number
Non disjunction changes the chromosome number in gametes, resulting in trisomy or monosomy.
Autosomal symddromes include trisomy and Down syndrome.
Changes in Sex Chromosome Number
Nondisjunction during oogenesis or spermatogenesis can result in gametes that have too few or too many X or Y chrmosomes.
Syndromes include Turner, Klinefelter, poly-X, and Jacobs.
Changes in Chromosome Structure
Chromosomal mutations can produce chromosomes with deleted, duplicated, inverted, or translocated segments.
These resul.t in various syndromes such as Williams and cri du chat and Alagille and certain cancers.
Chapter 21 – DNA Biology and Technology
21.1 DNA and RNA Structure and Function
DNA is the genetic material found in the chromosomes. It replicates, stores information, and mutates for genetic variability.
Structure of DNA
Double helix composed of two polynucleotide strands. Each nucleotide is composed of a doxyribose sugar, a phosphate, and a nitrogen-containing base (A, T, C, G).
The base A is bonded to T, and G is bonded to C.
Replication of DNA
DNA strands unzip, and a new complementary strand forms opposite each old strand, resulting in two identical DNA molecules.
The Structure and Function of RNA
RNA is a single-stranded nucleic acid in which the base U (uracil) occurs instead of T (thymine).
The three forms of RNA are rRNA, mRNA, and tRNA
21.2 Gene Expression
Gene expression leads to the formation of a product, usually a protein. Proteins differ by the sequence of their amino acids. Gene expression requires transcription and translation.
Transcription – occurs in the nucleus. The DNA triplet code is passed to an mRNA that contains codons. Introns are removed from mRNA during mRNA processing.
Translation – occurs in the cytoplasm at the ribosomes. tRNA molecules bind to their amino acids, and then their anticodons pair with mRNA codons.
The Regulation of Gene Expression
Regulation of gene expression occurs at four levels in a human cell:
Transcription Control – In the nucleus; the degree to which a gene is transcribed into mRNA determines the amount of gene product.
Posttranscriptional Control – In the nucleus; involves mRNA processing and how fast mRNA leaves the nucleus.
Translational Control – In the cytoplasm; affects when translation begins and how long it continues.
Posttranslational Control – In the cytoplasm; occurs after protein synthesis.
21.3 Genomics
A Person’s Genome Can be Modified
Gene therapies can treat various medical conditions.
The human genome has now been sequenced via the 13-year-long Human Genome Project.
Genomes of other organisms have also been sequenced.
The Personal Genome Project is underway, which would allow individuals to have their own personal genome sequenced.
Functional and Comparative Genomics
Functional genomics is the study of how the 25,000 genes in a human genome function
Comparative genomics is a way to determine how species have evolved and how genes and noncoding regions of the genome function.
Proteomics and Bioinformatics are New Endeavors
Proteomics is the study of the structure, function, and interaction of cellular proteins. Bioinformatics is the application of computer technologies to the study of the genome.
21.4 DNA Technology
Recombinant DNA contains DNA from two different sources. The foreign gene and vector DNA are cut by the same restriction enzyme and then the foreign gene is sealed into vector
Chapter 19 – Cancer
19.1 Cancer Cells
Certain characteristics are common to cancer cells. Cancer cells:
Are not normal cells and do not contribute to normal body function.
Do not undergo apoptosis – they enter the cell cycle an unlimited number of times.
Form tumors and do not need growth factors to signal them to divide.
Gradually become abnormal – carcinogenesis is comprised of initiation, promotion, and progression.
Undergo angiogenesis (the growth of blood vessels to support them) and can spread throughout the body (metastasis)
Cancer is a Genetic Disease
Cells become increasingly abnormal due to mutation in proto-oncogenes and tumor-suppressor genes.
In normal cells: the cell cycle functions normally.
Proto-oncogenes promote cell cycle activity and restrain apoptosis. Proto-oncogenes can mutate into oncogenes
Tumor-suppressor genes restrain the cell cycle and promote apoptosis.
In cancer cells: the cell cycle is accelerated and occurs repeatedly.
· Oncogenes cause an unrestrained cell cycle and prevent apoptosis.
· Mutated tumor-suppressor genes cause an unrestrained cell cycle and prevent apoptosis.
18.1 Chromosomes and the Cell Cycle
Chromosomes occur in pairs in body cells.
A karyotype is a visual display of a person’s chrmosomes.
A normal human karyotype shows 22 homologous pairs of autosomes and one pair of sex chromosomes.
Normal sex chromosomes in males: XY
Nomal sex chromosomes in felmales: XX
The cell cycle occurs continuously and has four stages: G1, S, G2, and M
In G1, a cell doubles organelles and accumulates materials for DNA synthesis.
In S, DNA replication occurs
In G2, a cell synthesizes proteins needed for cell division
Apoptosis also occurs during the cell cycle.
18.2 Mitosis
Mitosis is duplication division that assures that all body cells have the diploid number and the same kinds of chromosomes as the cell that divides. The phases of mitosis are prophase, metaphase, anaphase, and telophase.
o Prophase: Chromosomes attach to spindle fibers.
o Metaphase: Chromosomes align at the equator
o Anaphase: Chromatids separate, becoming chromosomes that move toward the poles
o Telophase: Nuclear envelopes form around chromosomes; cytokinesis begins. Cytokinesis is the division of cytoplasm and organelles following mitosis. The proper workings of the cell cycle and mitosis are critical to growth and tissue repair.
18.3 Meiosis
Meiosis involves two cell division: meosis I and meiosis II.
Meiosis I – Homologous chromosomes pair and then separate
Meiosis II – Sister chromatids separate, resulting in four cells with the haploid number of chrmosomes that move into daughter nuclei.
18.4 Comparison of Meiosis and Mitosis
In prophase I, homologous chromosomes pair; there is no pairing in mitosis.
In metaphase I, homologous duplicated chromosomes align at equator.
In anaphase I, homologous chrmosomes separate.
Spermatogenesis and Oogenesis
o Spermatogensis In males, produces four viable sperm.
o Oogenesis In females, produces one egg and two or three polar bodies. Oogenesis goes to completion if the sperm fertilizes the developing egg.
18.5 Chromosome Inheritance
Meiosis is a part of gametogenesis and contributes to genetic diversity
Changes in Chromosome Number
Non disjunction changes the chromosome number in gametes, resulting in trisomy or monosomy.
Autosomal symddromes include trisomy and Down syndrome.
Changes in Sex Chromosome Number
Nondisjunction during oogenesis or spermatogenesis can result in gametes that have too few or too many X or Y chrmosomes.
Syndromes include Turner, Klinefelter, poly-X, and Jacobs.
Changes in Chromosome Structure
Chromosomal mutations can produce chromosomes with deleted, duplicated, inverted, or translocated segments.
These resul.t in various syndromes such as Williams and cri du chat and Alagille and certain cancers.
Chapter 21 – DNA Biology and Technology
21.1 DNA and RNA Structure and Function
DNA is the genetic material found in the chromosomes. It replicates, stores information, and mutates for genetic variability.
Structure of DNA
Double helix composed of two polynucleotide strands. Each nucleotide is composed of a doxyribose sugar, a phosphate, and a nitrogen-containing base (A, T, C, G).
The base A is bonded to T, and G is bonded to C.
Replication of DNA
DNA strands unzip, and a new complementary strand forms opposite each old strand, resulting in two identical DNA molecules.
The Structure and Function of RNA
RNA is a single-stranded nucleic acid in which the base U (uracil) occurs instead of T (thymine).
The three forms of RNA are rRNA, mRNA, and tRNA
21.2 Gene Expression
Gene expression leads to the formation of a product, usually a protein. Proteins differ by the sequence of their amino acids. Gene expression requires transcription and translation.
Transcription – occurs in the nucleus. The DNA triplet code is passed to an mRNA that contains codons. Introns are removed from mRNA during mRNA processing.
Translation – occurs in the cytoplasm at the ribosomes. tRNA molecules bind to their amino acids, and then their anticodons pair with mRNA codons.
The Regulation of Gene Expression
Regulation of gene expression occurs at four levels in a human cell:
Transcription Control – In the nucleus; the degree to which a gene is transcribed into mRNA determines the amount of gene product.
Posttranscriptional Control – In the nucleus; involves mRNA processing and how fast mRNA leaves the nucleus.
Translational Control – In the cytoplasm; affects when translation begins and how long it continues.
Posttranslational Control – In the cytoplasm; occurs after protein synthesis.
21.3 Genomics
A Person’s Genome Can be Modified
Gene therapies can treat various medical conditions.
The human genome has now been sequenced via the 13-year-long Human Genome Project.
Genomes of other organisms have also been sequenced.
The Personal Genome Project is underway, which would allow individuals to have their own personal genome sequenced.
Functional and Comparative Genomics
Functional genomics is the study of how the 25,000 genes in a human genome function
Comparative genomics is a way to determine how species have evolved and how genes and noncoding regions of the genome function.
Proteomics and Bioinformatics are New Endeavors
Proteomics is the study of the structure, function, and interaction of cellular proteins. Bioinformatics is the application of computer technologies to the study of the genome.
21.4 DNA Technology
Recombinant DNA contains DNA from two different sources. The foreign gene and vector DNA are cut by the same restriction enzyme and then the foreign gene is sealed into vector
Chapter 19 – Cancer
19.1 Cancer Cells
Certain characteristics are common to cancer cells. Cancer cells:
Are not normal cells and do not contribute to normal body function.
Do not undergo apoptosis – they enter the cell cycle an unlimited number of times.
Form tumors and do not need growth factors to signal them to divide.
Gradually become abnormal – carcinogenesis is comprised of initiation, promotion, and progression.
Undergo angiogenesis (the growth of blood vessels to support them) and can spread throughout the body (metastasis)
Cancer is a Genetic Disease
Cells become increasingly abnormal due to mutation in proto-oncogenes and tumor-suppressor genes.
In normal cells: the cell cycle functions normally.
Proto-oncogenes promote cell cycle activity and restrain apoptosis. Proto-oncogenes can mutate into oncogenes
Tumor-suppressor genes restrain the cell cycle and promote apoptosis.
In cancer cells: the cell cycle is accelerated and occurs repeatedly.
· Oncogenes cause an unrestrained cell cycle and prevent apoptosis.
· Mutated tumor-suppressor genes cause an unrestrained cell cycle and prevent apoptosis.
19.2 Causes and Prevention of Cancer
Development of cancer is determined by a person’s genetic profile, plus exposure to environmental carcinogens.
Cancers that run in families are most likely due to the inheritance of mutated genes (like breast cancer).
Certain environmental factors are carcinogens (like UV, tobacco, radiation).
Industrial chemicals (like pesticides and herbicides) are carcinogenic.
Certain viruses (like hepatitis B and C and HPV) cause specific cancers.
19.3 Diagnosis of Cancer
The earlier a cancer is diagnosed, the more likely it can be effectively treated. Tests for cancer include:
Pap test for cervical cancer
Mammogram for breast cancer
Tumor marker test – blood tests that detect tumor antigens/antibodies
Tests for genetic mutations of oncogenes and tumor-suppressor genes
Biopsy and imaging – used to confirm the diagnosis of cancer
19.4 Treatment of Cancer
Surgery, radiation and chemotherapy are traditional methods of treating cancer. Other methods include:
Chemotherapy involving bone marrow transplants
Immunotherapy
P53 gene therapy
Other therapies, such as inhibitory drugs for angiogenesis and metastasis, which are being investigated.
Chapter 20 – Patterns of Genetic Inheritance
20.1 Genotype and Phenotype
Genotype refers to the alleles of the individual, and phenotype refers to the physical characteristics associated with the alleles
Homozygous dominant individuals have the dominant phenotype
Homozygous recessive individuals have the recessive phenotype
Heterozygous individuals have the dominant phenotype
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