Unit 5 Flashcards
Genotype
A combination of alleles an individual has, codes for the phenotype
Phenotype
Physical traits of an individual
Alleles
Different versions of a gene
Heterozygous
Has two different alleles (Ff)
Homozygous
Has two of the same allele
There is homozygous dominant (FF) and homozygous recessive (ff)
True-breeding
Parents produce offspring that all have the same phenotype, this means the parents are homozygous for every trait
Diploid
A cell with two sets of chromosomes
Haploid
A cell with one set of chromosomes
Homologous chromosomes
2 chromosomes in a pair, code for the same type of phenotype
Linked genes
Genes that are close or directly next to each other on the same chromosome and are inherited together
Sex-linked genes
Genes located on a sex chromosome
What are the similarities between mitosis and meiosis
- Nuclear envelope disappears
- DNA coils into chromosomes
- Chromosomes align in the center of the cell
- Fibers separate chromosomes
nuclear envelope reappears - Chromosomes uncoil
- Followed by cytokinesis and the production of daughter cells
What are the differences between mitosis and meiosis
Mitosis:
- Creates 2 daughter cells
- Creates cells that are genetically identical to each other and the parent cell
- Conserves the number of chromosome sets
- Sister chromatid cohesins are cleaved at the end of metaphase
Meiosis:
- Creates 4 daughter cells
- Creates cells that are genetically varied
- Reduces the number of chromosome sets from 2 diploid to 1 haploid
- Cohesins between homologs are cleaved in anaphase 1 and between sister chromatids in anaphase 2
- Has synapsis/crossing over in prophase 1
- During metaphase 1 homologous pairs align at the metaphase plate
- During anaphase 1 homologs are separated
How does meiosis generate genetic diversity
- independent assortment of chromosomes
- crossing over
- random fertilization
What are the advantages of sexual reproduction
Creates genetic variation in offspring
How does the environment affect phenotype
The same genotype can have different phenotypes depending on the environment of the individual
How does the movement of chromosomes during meiosis explain Mendel’s Law of Segregation of alleles
Law - two alleles for a given trait separate from each other giving the gametes only one allele for the trait. This way offspring inherit one allele from each parent
Meiosis - During anaphase, the chromosomes are pulled apart and separated into different gametes
How does the movement of chromosomes during meiosis explain Mendel’s Law of Independent Assortment
Law - Genes separate independently during gamete formation. The allele a gamete receives for one gene doesn’t affect the allele it receives for another gene
Meiosis - During metaphase, the chromosomes randomly line up at the metaphase plate
What is responsible for aneuploidy
The fertilization of gametes in which nondisjunction occurred
What is nondisjunction
A pair of homologs doesn’t separate normally in meiosis resulting in gametes with two of the same chromosome or none
