Exam 4: Genetics and Meiosis Flashcards
Genetics
The scientific study of heredity and variation. We don’t inherit traits, but rather genes.
Mitosis
Asexual reproduction resulting in genetically identical offspring
Meiosis
Sexual reproduction forming gametes. The process by which those gametes become haploid instead of diploid.
Genes
Segments of DNA on chromosomes.
One set of chromosomes is inherited from each parent.
Gametes
Reproductive cells. They are haploid, there are 23, and contain chromosomes 1-22 and a single sex chromosome. Eggs: sex chromosome is X. Sperm: sex chromosome is X or Y. They are the only types of human cells produced by meiosis.
Fertilization
The fusion of two gametes forms a diploid zygote.
Somatic cell
Body cell. Anything in humans that is not a gamete.
Important elements of meiosis
In the first cell division (meiosis I), homologous chromosomes separate, resulting in two haploid daughter cells with replicated chromosomes. In the second cell division (meiosis II), sister chromatids separate, resulting in four haploid daughter cells with replicated chromosomes.
Variation in a population
Prerequisite for evolution. Sexual reproduction contributes to this.
Natural selection
Accumulation of genetic variations favored by the environment
Mutation
Change in the nucleotide sequence of DNA, which creates alternative alleles of a gene.
Genotype
Which alleles an individual has: homozygous (2 of the same alleles), or heterozygous (2 different alleles)
Phenotype
The physical characteristics of an organism
Dominant vs recessive alleles
Dominant designated by capital letter, recessive by lowercase. Otherwise explanation is in the name itself. Saying an allele is dominant doesn’t mean it’s common. It means it masks a recessive allele in heterozygotes.
Law of segregation
Mendel’s reasoning that patterns of inheritance included: individuals have two alleles. And those separate from one another during gamete formation.