7.1 INHERITANCE Flashcards
What is the genotype?
The genetic make up of an organism. All the alleles it contains.
What is the phenotype?
Observable characteristic of an organism, which is a result of the interaction between the environment and genetics.
What is an allele?
A version of a gene. Diploid organisms always have 2 alleles per gene, one from each parent.
What are the types of alleles?
- Dominant
- Recessive
- Co-dominant
What is the F0 generation?
The products of pure breeds (homozygous recessive/dominant)
What is the F1 generation?
The products of F0 x F0 (heterozygous)
What is the F2 generation?
The products of F1 x F1
What are co-dominant alleles?
When both alleles are expressed because they are both dominant.
What is an example of when multiple alleles are present in genetics?
Blood Type (AB/O/A/B)
Which blood groups are co-dominant?
Ia & Ib
Which blood groups are recessive?
O
What is sex linkage?
When certain genes can only be carried on the X or Y chromosomes.
Why do mainly men exhibit X linked diseases?
- X linked diseases are recessive.
- Men have XY and women have XX.
- Men only need one recessive allele to have the disease whereas women need 2.
- Much more likely for men to have the X-linked disease.
If a male has an X linked disease, which parent did he get it from?
The mother has to be a carrier, so he gets it from his mother.
What is an autosome?
All the chromosomes that aren’t sex chromosomes.
What is autosomal linkage?
When multiple genes appear on the same chromosome, so are linked in inheritance.
- Linked genes stay together, and are passed in together.
How does autosomal linkage come about?
The too genes are too close together on the chromosome, so don’t split during crossing over. This means they stay together on their chromosome.
What is epistasis?
When the allele of one gene masks the expression of another allele in the phenotype.
What is recessive epistasis?
When a recessive allele masks another (9:3:4 ratio)
What is dominant epistasis?
When a dominant allele masks another (12:3:1)
What is chi-squared?
A statistical test that shows whether the differences between observed and expected results are significant.
What are the criteria when carrying out chi-squared?
- Big sample size (n>20)
- Only works for discrete data.
- Can only use raw, unprocessed no. counts.
How do you find chi-squared?
x² = the sum of [ (O-E)²/E]
O = observed number E = expected number
