Chapter 12 – The Cell Cycle

Phases and Regulation of the Cell Cycle

The cell cycle is a series of events that cells go through as they grow and divide. It consists of distinct phases and is tightly regulated to ensure proper cell division and function.

• Phases of the Cell Cycle: G1 (cell growth), S (DNA synthesis), G2 (preparation for mitosis), M (mitosis and cytokinesis)

• Mitosis Stages: Prophase, Metaphase, Anaphase, Telophase

• Cytokinesis: Division of the cytoplasm to form two separate daughter cells

• Mitotic Spindle: Structure composed of microtubules and associated proteins that segregate chromosomes during mitosis

• Cell Cycle Control System: Cyclins and cyclin-dependent kinases (CDKs) regulate progression through the cell cycle

• Density-Dependent Inhibition and Anchorage Dependence: Mechanisms that prevent uncontrolled cell division

• Cancer: Results from uncontrolled cell division due to loss of cell cycle regulation

Example: The MPF (Maturation Promoting Factor) is a cyclin-CDK complex that triggers a cell's passage from G2 into M phase.

Know How To

• Identify the purpose and phases of mitosis

• Compare mitosis and cytokinesis

• Recognize checkpoints and explain their role

• Interpret the role of MPF in regulating the cell cycle

• Describe ways cancer cells evade controls on cell division

Chapter 13 – Meiosis and Sexual Life Cycles

Meiosis and Genetic Variation

Meiosis is a specialized type of cell division that reduces the chromosome number by half, producing gametes for sexual reproduction and increasing genetic diversity.

• Diploid vs. Haploid: Diploid cells (2n) have two sets of chromosomes; haploid cells (n) have one set

• Sexual vs. Asexual Reproduction: Sexual reproduction involves meiosis and fertilization; asexual reproduction does not

• Meiosis I and II: Two sequential divisions; Meiosis I separates homologous chromosomes, Meiosis II separates sister chromatids

• Synapsis and Crossing Over: Homologous chromosomes pair and exchange genetic material during prophase I

• Independent Assortment: Random distribution of maternal and paternal chromosomes

• Nondisjunction and Aneuploidy: Errors in chromosome separation can lead to abnormal chromosome numbers

• Life Cycles: Alternation between haploid and diploid stages in fungi, plants, and animals

Example: Crossing over during meiosis increases genetic variation in offspring.

Know How To

• Distinguish between mitosis and meiosis (focus on chromosome behavior)

• Explain how meiosis contributes to genetic variation

• Predict outcomes from nondisjunction events

• Understand terms like homologous chromosomes, sister chromatids

• Interpret a karyotype and infer ploidy level or chromosomal abnormalities

Chapter 14 – Mendelian Genetics

Principles of Inheritance

Mendelian genetics describes how traits are inherited through discrete units called genes, following predictable patterns.

• Mendel's Laws: Law of Segregation and Law of Independent Assortment

• Genotype vs. Phenotype: Genotype is the genetic makeup; phenotype is the observable trait

• Homozygous vs. Heterozygous: Homozygous individuals have identical alleles; heterozygous have different alleles

• Test Crosses: Used to determine genotype of an individual with a dominant phenotype

• Monohybrid and Dihybrid Crosses: Crosses involving one or two traits, respectively

• Probability Rules: Multiplication and addition rules for predicting genetic outcomes

• Non-Mendelian Inheritance: Includes incomplete dominance, codominance, multiple alleles, pleiotropy, epistasis, polygenic traits

Example: Incomplete dominance results in a phenotype that is intermediate between the two parents (e.g., pink flowers from red and white parents).

Know How To

• Solve monohybrid and dihybrid cross problems

• Use Punnett squares and probability to predict genotypic/phenotypic ratios

• Identify inheritance patterns from family pedigrees

• Explain real-life examples like flower color in radishes or height in humans

• Distinguish between dominant, recessive, and codominant traits

Chapter 15 – The Chromosomal Basis of Inheritance

Chromosomes and Genetic Disorders

Chromosomal theory of inheritance links genes to specific locations on chromosomes, explaining patterns of inheritance and genetic disorders.

• Chromosomal Theory of Inheritance: Genes are located on chromosomes

• Linkage and Recombination: Genes close together on a chromosome tend to be inherited together; crossing over can separate linked genes

• X-linked and Y-linked Inheritance: Traits determined by genes on sex chromosomes

• Genetic Mapping: Determining gene location using recombination frequency

• Barr Bodies and X-Inactivation: In females, one X chromosome is inactivated

• Genomic Imprinting: Expression of genes depends on parent of origin

• Chromosome Structure Changes: Deletion, duplication, inversion, translocation

• Non-Mendelian Inheritance: Mitochondrial inheritance

Example: Turner syndrome is caused by monosomy X (missing one X chromosome).

Know How To

• Identify inheritance patterns for sex-linked traits

• Use genetic crosses to infer linkage and recombination

• Predict phenotypes of sex-linked disorders

• Explain consequences of chromosomal alterations (e.g., Down syndrome, Turner syndrome)

• Describe how sex is determined in humans

• Recognize exceptions to Mendelian genetics (e.g., genomic imprinting, maternal inheritance)

Chapter 16 – DNA Structure and Replication

Molecular Basis of Genetic Information

DNA is the hereditary material in all living organisms. Its structure and replication are fundamental to genetic inheritance and cellular function.

• Structure of DNA: Double helix model (Watson & Crick), base-pairing rules (A-T, G-C)

• DNA Replication: Semiconservative model; each new DNA molecule consists of one old and one new strand

• Enzymes Involved: Helicase, primase, DNA polymerase I and III, ligase, topoisomerase

• Leading vs. Lagging Strand: Leading strand synthesized continuously; lagging strand synthesized in Okazaki fragments

• DNA Repair: Proofreading, mismatch repair, excision repair

• Chromatin Structure: DNA packaged with histones into nucleosomes; euchromatin (loosely packed, active) vs. heterochromatin (tightly packed, inactive)

• Epigenetic Regulation: DNA methylation affects gene expression

Example: DNA polymerase adds nucleotides to the 3' end of a growing DNA strand during replication.

Know How To

• Describe the process of DNA replication including all key enzymes

• Differentiate leading and lagging strand synthesis

• Explain how errors are corrected during or after replication

• Understand the structure and role of nucleosomes

• Interpret base-pairing and relate it to DNA's stability and replication

• Relate chromatin packing to gene expression (euchromatin vs. heterochromatin)

Key Equations and Concepts

• Probability in Genetics:

  • Multiplication rule:

  • Addition rule:

• Semiconservative DNA Replication:

  • Each daughter DNA molecule:

Summary Table: Comparison of Mitosis and Meiosis