Lecture 3 Flashcards
Prophase II
Chromosomes recondense
Metaphase II
Individual chromosomes line up on the equatorial plate
Anaphase II
Sister chromatids separate and move toward opposite poles
Telophase II
Chromosomes arrive at the spindle poles and the cytoplasm divides
Crossing Over
Exchange of genetic material between homologous chromosomes that results in shuffling of genes along the chromosome; can result in unequal exchange of genetic material producing chromosomes with deleted or duplicated regions; is independent across the centromere and is proportional to distance
Cohesin
Protein complex that holds the chromatids together and is key to the behavior of chromosomes in mitosis and meiosis
Spermatogenesis
Male gamete production
Oogenesis
Female gamete production
What is unique about meiosis in plants?
Plants alternate between diploid and haploid life stages
Heredity
Passing on of physical or mental characteristics genetically from one generation to another
Heritability
Proportion of total variation between individuals in a given population that is due to genetic variation
MC1R Gene
Encodes the melanocortin 1 receptor; if it has AA variants that reduce receptor efficiency, the pathway shifts to pheomelanin production; if 2 copies are present, pheomelanin is the predominate pigment made which results in red hair
Gene
Locus of DNA that encodes a functional RNA or protein product
Allele
Alternative form of a gene that is located at a specific position on a specific chromosome
Monohybrid Cross
Cross between two parents that differ in a single characteristic
4 Conclusions made from a monohybrid cross
1: One character is encoded by 2 genetic factors
2: Two genetic factors (alleles) separate when gametes are formed
3: The concept of dominant and recessive traits
4: Two alleles separate with equal probability into the gametes
Homozygous
True breeding; alleles are identical (FF, ff)
Heterozygous
Alleles are different (Ff)
Principle of Segregation (Mendel’s First Law)
Each individual diploid organism possesses two alleles for any particular characteristic and only one is passed to offspring
Independent Assortment
Alleles segregate independently when gametes are formed
Dominant
When two different alleles are present in a genotype, but the trait encoded by 1 of them, is the only phenotype observed
Recessive
Both copies of the same allele have to be present for the phenotype to be observed
Chromosomal Theory of Heredity
1902 by Sutton; proved genes are contained on chromosomes
Chromosomal Theory of Heredity
1902 by Sutton; proved genes are contained on chromosomes
Consequences of Meiosis and Genetic Variation
4 cells are produced from each original cell; chromosome number in each new cell is reduced by half (new cells are haploid); newly formed cells from meiosis are genetically different from one another and from the paternal cell; epigenetic modifications are erased and parent specific modifications are established
