Unit 2 - AOS 2 - Mendel & Inheritance Flashcards
Gene
Specific trait - length of DNA found in a locus both homologous chromosomes
Alleles
One specific form of a gene
Genotype
Alleles for a trait
Gregor Mendel
First person to collect quantitative data to disprove blended inheritance.
- studied pea plants
What was expected with blended inheritance compared to what the results were. (pea plants size)
- offspring were expected to be medium height from a tall and short parent.
- Instead got a mix of tall and short plants
law of segregation
Organisms have two different copies of a trait = one copy from each parent, but which copy gets passes on is completely random.
Complete dominance
Whenever a dominant allele is present in an offspring, the physical trait will be expressed.
AA = Homologous dominant
Aa = Carrier
aa = Homologous recessive
Reasoning behind test crosses
To identify whether a dominant trait is caused by homozygous dominance or heterozygous.
Incomplete dominance
“Neither allele is completely dominant”
Heterozygous = blended appearance
BB = Blue
BY = Green
YY = Yellow
Codominance
“When a single gene has more than one dominant allele”
Both traits are expressed equally
C^R C^R = Red cow
C^R C^W = Roan Cow
C^W C^W = White cow
Sex-linked Disorders
“Inherited conditions found on X chromosome”
Types of crosses
Monohybrid, Dihybrid
Dihybrid crosses
“A cross that shows the possible offspring for two traits”
e.g. split BbRr –> BR, Br, bR, br (FOIL)
Heterozygous x2 = 9:3:3:1
Blood types
Type A = IA i, IA IA
Type B = IB i, IB IB
Type AB = IA IB
Type O = i i
Rhesus factor (RhD)
Red blood cells sometimes have another antigen, a protein known as RhD.
If present your blood is RhD positive.
