B17 Inherited change Flashcards
What is a gene
A sequence of bases on a DNA molecules that codes for a protein which results in a characteristic
What is an allele
A different version of a gene
What is the definition of genotype
The genetic constitution of an organism
What is the definition of phenotype
The expression of the genotype and its interaction with the environment
Dominant allele
An allele whose characteristic is always expressed even if there is 1
Recessive allele
An allele that is only observed in the phenotype if 2 copies are present
Co dominant alleles
When both types of alleles are expressed in the phenotype
Locus definition
A fixed position of a gene on a chromosome
Homozygote
An organism carrying 2 copies of the same allele
Heterozygote
An organism carrying 2 copies of different alleles
Monohybrid inheritance
Inheritance of a characteristic controlled by 1 single gene
Genetic diagram for monohybrid inheritance of 2 homozygous parents for dominant and recessive
Check online lol
What is the F1 generation/ offspring
The first set of offspring
F2 offspring
I think it’s crossing over the F1 offspring
Ratio of heterozygous dihybrid cross
9:3:3:1
Ratio of heterozygous dihybrid cross
9:3:3:1
What makes a sex linked characteristic
Allele coding for a characteristic is located on a sex chromosome
Is Y smaller than X
Yes
Why do males more often get recessive linked diseases
Males are XY
Females are XX
So males only require 1 recessive allele for it to be expressed whilst females require 2
Autosome definition
Any chromosome that is not a sex chromosome
Where are autosomal genes located
On the autosomes
Why are genes on the same autosome said to be linked
They will not be separated by independent segregation, only can be split up by crossing over.
The closer together the 2 genes are on the autosome the more closely they are to be linked because
Crossing over is less likely to split them up
Why won’t you obtain expected phenotypic ratio for autosomally linked genes?
The gametes produced will be limited to the pair that are linked. Therefore a higher proportion of offspring will have their parents genotypes
What is epistasis
When the allele of 1 gene masks the expression of an allele of a different gene
Dihybrid cross with a recessive epistastic allele ratio
9:4:3
Dihybrid cross with a dominant epistastic allele ratio
12:3:1
What is the null hypothesis
That there’s no significant difference between the observed and expected values
If X^2 is larger than the critical value then
There is a significant difference
So we reject the null hypothesis
If X^2 is smaller than the critical value
There is no significant difference
We can accept the null hypothesis
Why is Chi Squared used
Categorical data
Autosomal linkage exam question when u compare values
Z individual produced mainly GN and gn gametes.
Crossing over produces few Gn or gN gametes.
So less Ggnn or ggNn individuals
Why don’t the X and Y chromosome form the typical bivalent as other chromosomes do
Y and X are different sizes so the chromatids are unable to line up and form the bivalent shape
