Genetics Flashcards
Father of Genetics
Gregor Mendel
- Austrian monk
- experimented with peas
Why Peas?
- many offspring
- easy to grow
- short generation time
- many varieties
- each plant is hermaphrodidic
Law of Segregation
- each parent has 2 units that it could possibly pass on for each trait
- two units split up as pollen and eggs
Nondisjunction
failure of separation of chromosomes during meiosis
Law of Independent Assortment
each trait is inherited independently from every other trait
*just because a pea is green does not mean it will be round
Gene
segment of DNA that codes for a specific protein trait
Allele
- component of a gene
- organisms typically have 2 for each
Dominant Allele
- can overshadow another
- designated with CAPITAL letter
Recessive Allele
- can be overshadowed
- designated with LOWER CASE letter
Homozygous
- having some form of allele for a gene
- BB = homozygous dominant
- bb = homozygous recessive
Heterozygous
- having the opposite form of alleles for a gene
- Bb
Genotype
- specific combination of alleles for a gene
- BB, bb, Bb
Phenotype
- the physical expression of a genotype
- skin color, eye color, hair color
Hybrid
an individual who is the result of crossing two sexually reproducing parents
Generation Vocabulary
P= parent
F1= first filial
F2- second filial
Punnett Squares
visual representation for the probability of allele inheritance in offspring
Monohybrid Cross
tracing the inheritance of one gene
*4 squares
Monohybrid Cross Ratios
geno 1:2:1
pheno 3:1
Dihybrid Cross Ratio
9:3:3:1
Dihybrid Cross
- 16 possible genotypes
- 4 possible phenotypes
Incomplete Dominance
- two different alleles combine to create an intermediate phenotype of a given trait
- red flowers + white flowers = pink flowers
Codominant Traits
- traits occur when both alleles are expressed in one heterozygous individual
- human blood type
Polygenic Traits
- interactions of many genes are responsible for a single trait
- skin color
Epistasis
- interaction of one gene with another will alter the phenotype outcome
- albanism