Genetics, Populations, Evolution And Ecosystems - Inherited Change Flashcards
What does genotype mean?
The alleles an organism has inherited
Phenotype definition
An organisms characteristics and its interaction with the environment
Dominant definition
An allele that will always be expressed in the phenotype
Recessive meaning
An allele only expressed if no dominant allele is present
What does codominant alleles mean?
When both alleles are equally dominant and expressed in the phenotype
What does multiple alleles mean?
When there are more than two alleles for a single gene
What does sex linkage mean?
When a gene locus is on the X chromosome
Give the blood groups and their potential genotypes
A: I^A I^O or I^A I^A
B: I^B I^O or I^B I^B
AB: I^A I^B
O: I^O I^O
What does the genotype of blood group AB show?
Co-dominance
What do blood groups A and B show?
Multiple alleles
How is sex genetically determined?
determined by the combination of gametes:
XX is female
XY is male
Why do the results from genetic crosses often differ from the predicted results?
Because chance determines which gametes fuse with each other and so it is important to use a large number of organisms in genetic crosses to obtain representative results.
What stats test is used in inheritance and what is it used for?
Chi-squared, used to determine if there’s a significant difference between the predicted offspring frequency (ratio) and the actual observed offspring frequency
When doing chi-squared what do you say if the calculated value of chi squared is less than the critical value?
Having stated the null hypothesis that there is no significant difference between the expected and observed frequency of x
- There is more than 5% probability that the results are due to chance
- Do not reject null hypothesis / accept null hypothesis so there is no significant difference between the observed and expected results
What does epistasis mean?
When one gene influences / masks the expression of another gene
Give an example of a sex linked genetic disorder, what its caused by and what it leads to/
Hemophilia specifically X linked, caused by a recessive allele with an altered sequence of DNA nucleotide bases that codes for a faulty protein so the individual cannot produce a functional protein required in the clotting process.
Give an example where epistasis occurs and what each of the genes do as well as their alleles
In Mice where several genes determine the coat colour:
- Gene A controls if the hairs are banded
A= hairs with black bands
a = fully black hairs
-Gene B controls coat color
B = hairs are coloured
b = hairs are white so not coloured
how does codominance affect the inheritance of characteristics?
As both alleles are equally dominant so both are expressed in the phenotype
What is a dihybrid cross?
a genetic cross where where the inheritance of two genes is considered at the same time
Using the dihybrid inheritance example of the peas, give the genes, alleles and their corresponding phenotypes.
-Gene 1 codes of shape
R is dominant for round and r is recessive for wrinkled
-Gene 2 codes for the colour
Y is dominant for yellow and y is recessive for green
What does crossing over in meiosis mean for inheritance?
Results in the new combination of alleles in the gametes and therefor means predicted gametes in the punnet square may differ.
What is autosomal linkage?
When two genes are located on the same chromosome and not on the X and Y chromosome
How does autosomal linkage affect the combination of alleles in gametes?
You can only have both alleles as dominant or both alleles as recessive e.g.
AB and ab
instead of AB Ab aB and ab
