Topic 7- Genetics, populations, evolution and ecosystems Flashcards
what is genotype?
alleles that make up an organism
what is a phenotype?
observable characteristics of an organism resulting from the interaction between genotype and the environment
what is a gene?
length of DNA that codes for a particular polypeptide
what is the locus?
position of a gene on a particular DNA molecule
what is an allele?
different form of a gene
homozygous
two alleles the same
heterozygous
two different alleles
dominant allele
allele that expresses itself in the phenotype
recessive allele
allele not expressed
co dominant alleles
both contribute to phenotype
monohydrid inheritance
inheritance of singular gene
law of segregation
in diploid organisms, characteristics are determined by alleles that occur in pairs. Only one of each pair of alleles can be present in a single gamete
dihybrid inheritance
two characteristics determined by two different genes located on different chromosomes are inherited
law of independent assortment
each member of a pair of alleles may combine randomly with either of another pair.
codominance
both alleles expressed in phenotype
multiple alleles
gene may have more than two alleles, but only 2 can be present in an individual
sex linkage
females- XX- same gametes
males- XY- two different gametes
any gene carried by X or Y chromosome is said to be sex-linked
autosomomes
other 22 chromosomes other than sex chromosomes
autosomal linkage
two or more genes carried on the same autosome
all linked genes remain together during meiosis assuming there is no crossing over
do not segregate according to Mendel’s law of independent assortment
epistasis
allele of one gene affects or masks the expression of another in the phenotype
chi-squared test
used to test null hypothesis
is a means of testing whether any deviation between the observed and expected numbers is significant or not
when can the chi-squared test be used?
sample size relatively large
data falls into discrete categories
only raw counts used
degrees of freedom
number of categories — 1
used to find critical value
compare to 0.05 (5%)
gene pool
all the alleles of all the genes of all the individuals in a population at a given time
allele frequency
number of times an allele occurs within the gene pool