Bio Definitions Flashcards
Genotype
The genetic constitution of an organism
Phenotype
Observable characteristics determined by its genotype and its interactions with the environment
Co dominant
Both alleles are expressed and contribute to phenotype
Dominant
Allel is always expressed and contributes to phenotype
Recessive
Alleles that is only expressed if homozygous then will contribute to phenotype
Sex linkage
A genes whose locus is on the X chromosome
Monohybrid
A genetic inheritance cross of a characteristic determined by one gene
Assumes 3:1 ratio
Dihybrid cross
A genetic inheritance cross for a characteristic determined by 2 genes
Assumes 9:3:3:1 ratio
Chi squared test
To see if difference between observed and expected value are significantly different in categorical data
Gene pool
All the genes / alleles in a population
Loci/locus
Position of allele on chromosome
Diploid
Pair of homologous chromosomes
Haploid
One set of chromosomes
What does Hardy Weinberg predict?
Frequency of alleles of a particular gene will stay constant over many generations providing no mutation, large populations, migration, selection, random mating
Why named model organism is good for studying
genetics
Small size so simple nutrient medium so less cost
Reproduce quickly so many generations can be studied
Large number of eggs so improved reliability
why would recessive sex-linked
diseases/phenotypes be more
common in XY than XX
XX need 2 recessive alleles
Why may a genetic cross
give different phenotypic
ratios to what is expected?
Epistasis
Random fusion of gametes
Small sample size
Evidence for allele being recessive?
Parents are heterozygous, and therefore carriers of recessive allele, can both pass recessive allele to child making them affected/recessive
phenotype as homozygous
Evidence for X linked disease/trait being recessive
Mum passes on X chromosome with recessive chromosome to son
Evidence for allele not being on X chromosome?
Look for homozygous recessive daughter and dad with dominant allele on X chromosomes
Look for homozygous recessive mother and dominant phenotypes son
Autosomal linkage
Genes are on the same homologous pair of chromosomes (not the sex chomosomes)
Epistasis
When one gene affects the expression of another gene within the phenotype
Allele
Different versions of genes
