A&P Biology Lecture 4: Meiosis and Mendelian Genetics

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What are gametes?: Cells that contain half of the chromosomes of somatic cells, specifically eggs and sperm.
What is formed when two gametes fuse?: A zygote.
What type of cell division is meiosis?: Reduction division, resulting in cells with half the parental chromosome number.
What are diploid cells?: Somatic cells that contain two sets of chromosomes.
What are haploid cells?: Gametes that contain one set of chromosomes.
What is the difference between sexual and asexual reproduction?: Sexual reproduction involves meiosis and fusion of gametes, while asexual reproduction involves mitosis.
What occurs during prophase I of meiosis?: DNA condenses into chromosomes, homologous chromosomes bind together, and crossing over occurs.
What is crossing over?: The exchange of DNA segments between homologous chromosomes, creating genetic diversity.
What happens during metaphase I of meiosis?: Homologous chromosomes align along the equatorial plate, with random assortment of maternal and paternal chromosomes.
What is independent assortment?: The random distribution of maternal and paternal chromosomes into gametes during meiosis.
What is the result of meiosis I?: Separation of homologous chromosomes and the formation of two cells.
What happens during anaphase II of meiosis?: Sister chromatids are separated to opposite ends of the cell.
What is heredity?: The passing of traits from parent to offspring.
Who is known as the father of genetics?: Gregor Mendel.
What is a Punnett square used for?: To visualize the possible genetic outcomes from a crossbreeding.
What is a dominant trait?: A trait that masks the expression of another trait.
What is a recessive trait?: A trait that is masked by a dominant trait.
What does homozygous mean?: Having two identical alleles for a trait.
What does heterozygous mean?: Having two different alleles for a trait.
What is an allele?: An alternate form of a gene.
What is the phenotype?: The appearance of an individual based on its alleles.
What is the genotype?: The actual genetic makeup of an individual based on its alleles.
What is Mendel's law of segregation?: During gamete formation, the two alleles for a trait separate into different gametes.
What is Mendel's law of independent assortment?: Genes on different chromosomes are inherited independently of one another.
What is a test cross?: A cross between a homozygous recessive individual and an unknown individual to determine the unknown's genotype.
What is a dihybrid cross?: A test cross that examines the inheritance of two different traits.
What is a monohybrid cross?: A test cross that examines the inheritance of a single trait.
What ratio is expected in the F2 generation from a monohybrid cross?: A phenotypic ratio of 3:1.
What is the expected genotypic ratio from a monohybrid cross?: A genotypic ratio of 1:2:1.
What is a mutation?: A change in the DNA sequence that can lead to different alleles.
What are mutations?: Changes in DNA that can cause proteins to fold differently, affecting their function.
What is hemoglobin's role in the blood?: It is critical for transporting oxygen in blood cells.
How does sickle cell anemia affect hemoglobin?: A mutation in the hemoglobin gene causes it to fold improperly, resulting in sickle-shaped cells.
What is non-Mendelian genetics?: Genetics where traits are linked to multiple genes, leading to continuous variation.
Give an example of a trait that exhibits polygenic inheritance.: Height.
What are autosomes?: 22 pairs of chromosomes associated with non-sexual characteristics.
What are sex chromosomes?: The pair of chromosomes that determine the sex of an individual (XX for females, XY for males).
What is nondisjunction?: The failure of chromosomes to separate properly during meiosis.
What is aneuploidy?: An abnormal number of chromosomes resulting from nondisjunction.
What is trisomy?: A condition where an individual has an extra chromosome.
What is trisomy 21 also known as?: Down Syndrome.
How does maternal age affect the rate of nondisjunction?: The rate increases with maternal age due to the aging of eggs.
What is Klinefelter syndrome?: A condition in males with an extra X chromosome (XXY), leading to sterility and potential developmental impacts.
What is Turner syndrome?: A condition in females with a missing X chromosome (XO), leading to sterility and short stature.
What is hemophilia?: A recessive disorder on the X chromosome that impairs blood clotting.
Why are men more likely to have X-linked disorders?: Men have only one X chromosome, so a single mutated allele will express the disorder.
What is sickle-cell disease caused by?: A defective hemoglobin molecule that leads to misshaped red blood cells.
What advantage do heterozygous individuals for sickle-cell alleles have?: They have enough functioning red blood cells to live a full life and resistance to malaria.
What is the impact of mutations on human populations?: Most mutations are rare and often recessive, not expressed in heterozygous individuals.
How can pedigrees be used in genetics?: To trace the inheritance of traits and determine if they are dominant or recessive.
What happens to individuals with monosomy?: Having one less copy of an autosome is lethal.
What is the significance of chromosome 21 in Down Syndrome?: Individuals have a third copy of chromosome 21, affecting their development.