bio 161 exam 3

📘 Chapter 10: How Cells Divide

Q: What is the molecular composition of eukaryotic chromosomes?
A: DNA and histone proteins; chromatin is 40% DNA and 60% protein.

Q: What structures organize eukaryotic chromosomes?
A: Nucleosomes (DNA wrapped around histones), centromeres (spindle attachment), and telomeres (chromosome ends).

Q: What part of a condensed chromosome tells you how many chromosomes are present?
A: The number of centromeres.

Q: Chromatin vs. Chromosome?
A: Chromatin = uncondensed (in non-dividing cells); Chromosome = condensed (in dividing cells).

Q: Heterochromatin vs. Euchromatin?
A: Heterochromatin = inactive, tightly packed; Euchromatin = active, loosely packed.

Q: What are Drosophila polytene chromosomes?
A: Giant chromosomes found in fruit fly salivary glands, used in gene mapping.

Q: What is a karyotype and why is it important?
A: A karyotype is a chromosome chart used to detect number abnormalities, sex chromosomes, and genetic diseases.

Q: What are homologous chromosomes?
A: Pairs of chromosomes (one from each parent) with the same genes.

Q: What are the phases of the cell cycle?
A: Interphase (G1, S, G2), M phase (mitosis), and cytokinesis.

Q: What happens during G1, S, G2?
A: G1: cell grows; S: DNA replicates; G2: cell prepares for division.

Q: Why is mitosis important for diploid organisms like humans?
A: It ensures growth, repair, and identical genetic information in cells.

Q: What are the 4 stages of mitosis?
A: Prophase, Metaphase, Anaphase, Telophase.

Q: What does the spindle apparatus do?
A: It moves chromosomes during mitosis.

Q: What’s the purpose of mitosis?
A: Produces genetically identical daughter cells to maintain tissue and function.

Q: How does mitosis differ in plant and animal cells?
A: Animal: cleavage furrow forms; Plant: cell plate forms.

Q: What is cytokinesis?
A: The division of cytoplasm to form two separate daughter cells.

Q: How is the cell cycle controlled?
A: With checkpoints (G1/S, G2/M, spindle) that check DNA and spindle attachment.

Q: What is p53?
A: A tumor suppressor protein that stops the cycle if DNA is damaged.

Q: What are proto-oncogenes?
A: Genes that stimulate cell division; can cause cancer when mutated.

📗 Chapter 11: Sexual Reproduction and Meiosis

Q: Why is meiosis and fertilization essential for sexual reproduction?
A: They create genetic diversity and restore diploid chromosome number.

Q: What cells are formed by meiosis?
A: Haploid gametes: egg and sperm.

Q: Haploid vs Diploid?
A: Haploid (n) = 1 set of chromosomes; Diploid (2n) = 2 sets.

Q: Meiosis vs Mitosis?
A: Meiosis involves 2 divisions, crossing over, and creates 4 genetically unique haploid cells.

Q: Stages of Meiosis I?
A: Prophase I, Metaphase I, Anaphase I, Telophase I.

Q: Stages of Meiosis II?
A: Prophase II, Metaphase II, Anaphase II, Telophase II.

Q: How many cells result from meiosis?
A: Four haploid cells, each genetically different.

Q: How are homologs held in Prophase I?
A: By the synaptonemal complex.

Q: What happens in crossing over?
A: Non-sister chromatids exchange genetic material, increasing variation.

Q: What is Independent Assortment?
A: Chromosomes align randomly during Metaphase I, leading to genetic variation.

Q: How do spindle attachments differ in mitosis vs meiosis?
A: Mitosis: each chromatid attaches to opposite poles; Meiosis I: sister chromatids attach to the same pole.

Q: When does Independent Assortment occur?
A: Metaphase I of meiosis.

Q: Sexual vs Asexual reproduction?
A: Sexual = variation; Asexual = identical offspring.

Q: Pros/cons of sexual reproduction?
A: Advantage: diversity; Disadvantage: energy and need for a mate.

Q: Overall impact of meiosis and sexual reproduction?
A: Produces diversity essential for evolution and survival.

📙 Chapter 12: Patterns of Inheritance

Q: What’s the history behind Mendel’s experiments?
A: Mendel studied pea plants and observed inheritance patterns that led to genetic laws.

Q: Why was Mendel successful?
A: Used large sample sizes, controlled breeding, and quantitative data.

Q: What’s Mendel’s model vs Sutton’s theory?
A: Mendel described gene inheritance; Sutton tied it to chromosome behavior in meiosis.

Q: Define: phenotype, genotype, homozygous, heterozygous, dominant, recessive.
A: Phenotype = traits; Genotype = genes; Homozygous = same alleles; Heterozygous = different; Dominant = expressed; Recessive = hidden.

Q: Monohybrid vs Dihybrid cross?
A: Mono: 1 trait; Di: 2 traits.

Q: What’s the genotypic and phenotypic ratio of a monohybrid F2?
A: Genotype: 1:2:1, Phenotype: 3:1.

Q: What’s the phenotypic ratio of a dihybrid F2?
A: 9:3:3:1.

Q: What’s a test cross?
A: Crossing with a homozygous recessive to find unknown genotype.

Q: Segregation vs Independent Assortment?
A: Segregation = alleles split; Assortment = different genes distribute randomly.

Q: What is incomplete dominance?
A: Intermediate phenotype (e.g., red + white = pink).

Q: What is codominance?
A: Both alleles are expressed (e.g., AB blood type).

Q: What is pleiotropy?
A: One gene affects multiple traits.

Q: What is continuous variation?
A: Traits with many possible phenotypes, like height.

Q: How does the environment affect phenotype?
A: Can change gene expression (e.g., temp affects fur color).

Q: What is epistasis?
A: One gene masks the effect of another (e.g., Labrador coat color).

📕 Chapter 13: Chromosomes, Mapping, and Human Genetics

Q: How do genetic factors affect disease?
A: Pleiotropy, incomplete dominance, environmental factors, etc.

Q: What are inheritance patterns of genetic diseases?
A: Autosomal dominant/recessive, X-linked dominant/recessive, mitochondrial.

Q: What’s a pedigree chart?
A: Diagram showing inheritance across generations.

Q: What do mitochondria and chloroplasts contribute to?
A: Maternal inheritance and cellular energy.

Q: Examples of genetic disorders?
A: Sickle cell anemia, albinism, Down syndrome, etc.

Q: What is nondisjunction?
A: Failure of chromosomes to separate in meiosis.

Q: Disorders caused by nondisjunction?
A: Turner’s (XO), Klinefelter’s (XXY), Down syndrome (trisomy 21), Jacobs (XYY).

Q: What is genetic counseling?
A: Assessing genetic risk in families, often with pedigrees.

Q: What are 2 prenatal screening techniques?
A: Amniocentesis and Chorionic Villus Sampling (CVS).in adaptation and survival.