Genetics Flashcards
allele
different forms of a gene due to slightly different order of bases. eg brown eyes & blue eyes
allele frequency
is a measure of the relative frequency of an allele on a genetic locus in a population
asexual reproduction
reproduction only involving. Does not produce genetic variation
Co - Dominance
heterozygous individuals have a phenotype the shows the phenotype of both parents
complete dominance
a form of dominance in heterozygous conditions where in the allele that is regarded as dominant completely mask the effect of the allele that is received
crossing over
occurs during meiosis, when the homologous chromosomes line up at the equator, sometimes they tangle, snap & exchange genetic variation\information
Diploid
a cell or an organism, consisting of two sets of chromosomes, usually one set from the mother and another set from the father
evolution
is the change in the characteristics of a species over several generations & relies on the processes of natural selection
fertilisation
a process in sexual reproduction the involves the union of male (sperm) and female (ovum) gametes (each with a single set of haploids chromosomes) to produce a diploid zygote
Fi (first generation)
the parental generation of the first set of parents crossed
founder effect
is the loss of genetic variation that occurs when a new population is established by a very small number of individual
gamete
sex cell of an organism eg sperm, egg, pollen, or ova
gametic cells
sex cells. eg egg, cells that have half the chromosomes number. if a mutation occur in one of these cells & that cell results in a zygote, all cells in the offspring will have the mutation
gene
a length of DNA that holds the instructions for a characteristics
gene pool
refers to the total number of genes of every individual in a population
genetic diversity
the total number of characteristic in the genetic make up of a species
genetic drift
is then change in the frequency of an existing gene variant (allele) in a population due to the random change alone and not natural selection.
genotype
the genetic make up of an organism
haploid
when a cell has half the usual number of chromosomes
heterozygous
different forms of the allele are present in the genotype eg Gg Hh
Homozygous
Same from of the allele present in the genotype
incomplete dominance
heterozygous individuals have a phenotype the is intermediate between the two homozygous phenotype
lethal alleles
alleles that produce a gene product the kills of the offspring
linked genes
genes that are located close together on the same chromosome that tend to be inherited together
Unlinked genes
Genes that are located further apart on the on the same chromosome and tend to be separated during crossing over
meiosis
type of cell division the produces gametes
Multiple alleles
When 3 or more alternative forms of a gene the occupy the same locus
mutation
a permanent change in the DNA base sequence creating a new allele
Natural selection
individuals with more advantages traits are more likely to survive and reproduce and increasing these advantages alleles in the population over generations
Phenotype
the physical appearance of an organism
Population bottle neck
the population bottle neck produces a decrease in the gene pool of the population because many alleles, or gene variants, that were present in the original population are lost
pure breeding
group of identical individuals that only produce one type of gamete due to the fact they are homozygous
segregation
the process that occurs during meiosis where pairs of alleles are separated when the homologous chromosomes splits
sexual reproduction
reproduction involving two parents, produces genetic variation
somatic cells
body cells - eg skin cells, if a mutation occurs in these cells it will not be passed on to the next offspring
test cross
a genetic cross between homozygous recessive individuals & a corresponding suspected heterozygous to determine the genotype of the latter
