Biology Lecture Flashcards

Genetics and Inheritance

  • Practice Problem Solving

    • Focus on solving single and double factor crosses using the methods described in the textbook.
    • Remember the procedure: parents, gametes, and progeny.

  • Mendel's Studies

    • Mendel studied genetics through pea plant experiments, establishing foundational principles of inheritance, including:
    • The Law of Segregation: Alleles segregate during gamete formation.
    • The Law of Independent Assortment: Alleles for different traits segregate independently.

  • Alleles and Inheritance Patterns

    • Codominance: Both alleles expressed simultaneously in the phenotype (e.g., AB blood type).
    • Incomplete Dominance: Blending of traits occurs in the heterozygote (e.g., red and white flowers producing pink offspring).
    • Multiple Alleles: More than two possible alleles exist for a gene (e.g., ABO blood group).
    • Polygenic Inheritance: Traits are controlled by multiple genes, influencing phenotypic variation (e.g., skin color).
    • Pleiotropy: One gene influences multiple, seemingly unrelated traits.

  • Gene Linkage

    • Determining Linkage: By examining inheritance patterns in offspring, we can determine if genes are linked or independently assorting.
    • Autosomal vs. Sex Linkage:
    • Autosomal: Genes located on non-sex chromosomes.
    • Sex-linked: Genes located on sex chromosomes, often affecting probabilities of traits across genders (e.g., color blindness in males).
    • Y Chromosome's Role: The Y chromosome often carries fewer genes and influences male-specific traits.

  • Non-genetic Influences on Phenotype

    • Environmental factors, lifestyle choices, nutrition, and climate can influence phenotypic expression.

Population Genetics

  • Gene and Allele Frequencies

    • Definition: The frequency of a specific allele in a population.
    • Calculation:
    • Allele frequency = (Number of copies of the allele) / (Total number of alleles in the population).
    • Importance: Frequencies allow understanding of genetic variation and evolution within populations.

  • Definitions:

    • Species: A group of organisms capable of interbreeding and producing fertile offspring.
    • Population: A group of individuals of the same species in a given area.
    • Gene Pool: The total genetic diversity found within a population.

  • Genetic Diversity Processes

    • Sources of Genetic Diversity:
    • Mutation, gene flow, and sexual reproduction.
    • Impact of Population Size: Larger populations tend to have greater genetic diversity due to a higher number of alleles.

  • Genetic Drift

    • Definition: Random changes in allele frequencies, more pronounced in small populations.
    • Cases of Genetic Drift:
    • Bottleneck Effect: A sudden decrease in population size.
    • Founder Effect: A few individuals establish a new population.

  • Domestication and Genetic Diversity

    • Domestication often reduces genetic diversity due to selective breeding and loss of wild gene pools.

  • Alternative Species Definitions

    • Morphological, ecological, and phylogenetic species concepts, each having strengths and weaknesses.

  • Population Genetics in Humans

    • Attempts to study human populations have faced criticisms due to misuse, ethical concerns, and human rights issues.

Meiosis and Gametogenesis

  • Determination and Differentiation

    • Determination: The process where cells become committed to a specific fate.
    • Differentiation: The process by which a cell acquires its specific characteristics and functions.

  • Cell Checkpoints

    • Checkpoint: Regulatory pathway mechanisms ensuring proper completion of cell cycle transitions.
    • Proto-oncogenes: Normal genes that can become oncogenes if mutated, potentially leading to cancer.
    • Tumor-suppressor Genes: Genes that protect cells from one step on the path to cancer (e.g., p53).

  • Cancer Definition:

    • Uncontrolled cellular replication leading to tumor formation.

  • Reproductive Cells

    • Definitions:
    • Haploid: A cell containing one complete set of chromosomes.
    • Diploid: A cell containing two complete sets of chromosomes.
    • Gametes: Sex cells (sperm and eggs).
    • Zygote: A fertilized egg formed by the union of sperm and egg.

  • Gamete Production

    • Meiosis Stages:
    • Meiosis I and II: Overview includes prophase, metaphase, anaphase, and telophase stages, ultimately leading to the creation of haploid cells.
    • Purpose: To reduce chromosome number and generate genetic diversity.

  • Nondisjunction

    • Resulting failure in the division of chromosomes can lead to disorders like Down syndrome (trisomy 21).

Gametogenesis and Early Fetal Development

  • Spermatogenesis

    • Production of sperm occurs through meiosis.
    • Generally, 4 functional sperm are produced from each parent cell, and the division is equal.

  • Oogenesis

    • Production of eggs; typically 1 functional egg is produced per parent cell, resulting in unequal divisions due to polar bodies.

  • Fertilization Preventive Mechanisms

    • Cortical Reaction: Prevents polyspermy by creating a barrier to additional sperm entry after fertilization.

  • X and Y Chromosome Genotypes

    • Males: XY genotype
    • Females: XX genotype

Key Genetic Definitions

  • Key Terms:

    • Allele: Variants of a gene.
    • Genome: The complete set of genes or genetic material.
    • Genotype: The genetic makeup of an organism.
    • Phenotype: The observable characteristics or traits of an organism.
    • Homozygous: Having two identical alleles for a gene.
    • Heterozygous: Having two different alleles for a gene.

  • Diploid vs. Haploid Definitions

    • Diploid Cells: Somatic cells containing two sets of chromosomes (2n).
    • Haploid Cells: Gametes containing one set of chromosomes (n).

  • Solving Genetics Problems

    • Identify parental genotypes, calculate possible gametes, and find combinations of gametes to predict offspring outcomes.

  • Mendel's Contributions:

    • Established rules of inheritance through experiments with pea plants, leading to foundational concepts in genetics.

  • Inheritance Patterns

    • Explore the relationships and patterns of alleles affecting phenotypic expression in progeny.

  1. What is the Law of Segregation?

    • a) Alleles for different traits segregate independently.
    • b) Alleles segregate during gamete formation.
    • c) One gene influences multiple traits.
      Correct Answer: b) Alleles segregate during gamete formation.

  2. Which inheritance pattern involves both alleles being expressed simultaneously?

    • a) Incomplete Dominance
    • b) Codominance
    • c) Multiple Alleles
      Correct Answer: b) Codominance

  3. What is the term for a sudden decrease in population size affecting allele frequencies?

    • a) Founder Effect
    • b) Bottleneck Effect
    • c) Genetic Drift
      Correct Answer: b) Bottleneck Effect

  4. What type of cells are haploid?

    • a) Somatic cells
    • b) Gametes
    • c) Zygotes
      Correct Answer: b) Gametes

  5. What is the primary purpose of meiosis?

    • a) To produce identical daughter cells
    • b) To reduce chromosome number and generate genetic diversity
    • c) To replicate DNA
      Correct Answer: b) To reduce chromosome number and generate genetic