Honors Biology Unit 5 Final Exam

Purpose of meiosis: to reduce the chromosome number from diploid to haploid and to generate genetic diversity among the producers

How many? 4 genetically distinct haploid cells

Which stages are diploid vs haploid? Prophase I and Metaphase I are diploid, then at the end of Anaphase I through Meiosis II, the cell is haploid

Major Events: Crossing over and synapse happens in Prophase I, Independent Assortment happens in Metaphase I and Nondisjunction can happen in Anaphase I and Anaphase II.

 Genetic Variability: Independent assortment, crossing over/synapse, and random fertilization

Difference between homologous and non-homologous chromosomes: Homologous chromosomes  are paired chromosomes with identical gene sequences, one from each parent, while non-homologous chromosomes have different genes and are not paired

Tetrad: a ground of 4 chromatids

Chiasma: where the homologous chromosomes are paired when crossing over

Centromere: what shapes the number of chromosomes and is in the middle where the sister chromatids join

Karyotype: a visual representation of an organism’s complete set of chromosomes, including their number, size, and shape

Nondisjunction:  the failure of chromosomes to separate. This happens in Anaphase I and Anaphase II

Chromosome deletion, duplication, inversion or translocation can disrupt normal gene function and lead to various genetic disorders.

True-breeder: a homozygous recessive individual

Hybrid: the offspring of two different parents

P generation: two individuals that are mated to foresee or analyze the genotypes of their offspring

F1 Generation: resulting offspring from the P0 generation

F2 Generation: the result of two F1 plants that were crossed or self-pollinated

Difference between incomplete and codominance? Incomplete dominance is the blending and mixing of alleles, creating a new phenotype, where as incomplete dominance is where you can see both allele present in the heterozygote

Test-Cross: the mating between an individual of unknown genotype and a true-breeding individual

Law of Independent Assortment: alleles of different genes assort independently during gamete formation

Pedigree Rules: if there is a 50/50 ratio between men and women that are affected, then the disorder is autosomal; if most of the males in the pedigree are affected, then the disorder is X-linked. If one of the parents have the disorder and it doesn’t skip generations then the disorder is dominant.

Pleiotropy: when one gene influences many characteristics/symptoms

Polygenic Inheritance: A single phenotypic character results from the additive effects of two or more genes.

Linked Genes: when two gene loci are close together, there is reduced chance for crossing over to occur between the two loci, which means they are linked. When the chi square problems donot follow normal mednelian outcomes is when the genes are linked.