7: Genetics Flashcards
(21 cards)
Gene definition?
A sequence of bases on a DNA molecule that codes for a protein which results in a characteristic
Allele definition?
A different version of a gene. The order of bases in each allele is slightly different - they code for different versions of the same characteristic
Genotype definition?
The genetic constitution of an organism - the alleles an organism has
Phenotype definition?
The expression of the genetic constitution and its interaction with the environment - an organisms characteristics
Dominant definition?
An allele whose characteristic appears in the phenotype even when there’s only one copy
Recessive definition?
An allele whose characteristic only appears in the phenotype if two copies are present
Codominant definition?
Alleles that are both expressed in the phenotype - neither one is recessive
Locus definition?
The fixed position of a gene on a chromosome
Homozygote definition?
An allele that carries two copies of the same allele
Heterozygote definition?
An organism that carries two different alleles
Carrier definition?
A person carrying an allele which is not expressed in the phenotype but that can be passed on to offspring
Monohybrid inheritance definition?
the inheritance of a characteristic controlled by a single gene
Expected phenotypic ratio in the F1 and F2 generation of a Dihybrid cross of a homozygous recessive x homozygous dominant?
F1 - all heterozygous
F2 - 9:3:3:1
Sex linked characteristic definition?
A characteristic in which the allele coding for it is located on a sex chromosome
X-linked disorders examples?
Haemophilia, colour blindness
Autosome definition?
Any chromosome that isn’t a sex chromosome
What is autosomal linkage?
Genes on the same chromosome are said to be linked as they will stay together during independent segregation of chromosomes, and their alleles will be passed onto offspring together, unless split up by crossing over
Why are genes closer together on the same chromosome said to be more closely linked?
Less likely to be split up during crossing over
What is epistasis?
When the allele of one gene masks the expression of other genes
Chi-squared equation?
x^2 = sum of (O-E)^2 / E
When the x^2 value is larger than or equal to the critical value?
Is a significant difference between the observed and expected result - reject null hypothesis
