Inheritance Flashcards
Define gene
The base sequence of DNA that codes for the amino acid sequence in a polypeptide or functional RNA
Define allele
Form of a gene
Define gene loci
Fixed position on a particular DNA molecule/ chromosome
Define genotype
Genetic constitution of organism
Define phenotype
The expression of the genetic constitution and its interaction with the environment.
Define homozygous
Having 2 copies of the same allele of a gene
Define heterozygous
Having 2 different alleles of a gene
Define dominant
Expressed in both the homozygous and heterozygots
Expressed in both the homozygous and heterozygote
Define recessive
Only expressed in the homozygote, and not in the heterozygote.
Define haploid
Gametes have one allele of each gene
Define diploid
Cells with two alleles of each gene
Define monohybrid cross
Inheritance of 2 characteristics
Define pedigree analysis
Family tree of patterns and inheritance
Define text cross/back cross
Cross with the homozygous recessive individual to determine the genotype of the individual
Define codominance
Alleles which are both expressed in the heterozygote.
Define multiple alleles
Many alleles of a particular gene within the population.
Define sex linkage
Where the gene is carried on the x-chromosome
Define autosomal linkage
Where the 2 genes are carried on the same chromosome
Define epistasis
Where 2 genes are on different chromosomes but interact in a biochemical pathway to produce phenotypes
Define the Chi-squared test/ goodness of fit
A way of comparing results (observed) to predicted (expected) results to decide whether linkage is occuring
Describe monohybrid crosses
- looks at one characteristic
-shows what the offspring genotypes and phenotypes could be - first generation is known as f1
-crossing this first generation together would produce the second generation which would be known as f2
Q- i am a black mouse, how could you deduce my phenotype? I could be BB or Bb
-mate with brown mouse, whose genotype you know must be bb
-look at ratios of black:brown mice in offspring
-if all offspring are black the parent was BB
-if around half were black parent was Bb
Why are numbers in a monohybrid cross never exact?
As fertilisation is random and sample sizes have to be very large to get close to the ratios
