genetics Flashcards
phenotype
the gens that are expressed physically
evolution
the change in allele frequency of a population overtime
gene pool
the total number of alleles with a population
multiple alleles
Multiple alleles occur with genes that have more than two different alleles, through an individual will only have two of the alleles in its genotype.
bottleneck effect
when populations decrease in numbers due to catastrophic event or human action
lethal alleles
A lethal allele occurs when a mutation results in an allele that produces a non-functional version of an essential protein. This results in the organism dying.
genotype
genetic make-up of an individual
haploid
one set of chromosomes
genetic drift
loss or change in the frequency of an allele in a small population due to chance alone
dominant
An allele that if present is always expressed phenotypically
founder effect
when a small group of a population colonize an isolated area, changing allele frequency.
trait
genetic feature
co-dominance
Co-dominance inheritance occurs when both alleles are equally dominant and both alleles are present in the heterozygous genotype they are both expressed in the phenotype
incomplete dominance
Incomplete dominance in heritance occurs when neither allele ‘dominates’ the other and both alleles are present in the heterozygous genotype, they produce a blended phenotype.
independent assortment
each pair of homologous chromosomes are sorted independently of the other pairs during meiosis which greatly increases genetic variation
homozygous
having the same alleles
test cross
mating involving an unknown genotype with the homozygous recessive
diploid
two sets of chromosomes
heterozygous
having different forms of an allele
chiasmata
the points on chromatids where the homologous chromosomes cross
chromosome segregation
the separation of alleles during meiosis so that each gamete carries only one allele
zygote
a diploid cell formed by the fusion of two haploid cells
meiosis
cell division that produces sex cells- haploid from diploid
natural selection
the selection of individuals based on their fitness to survive and then breed
alleles
an alternative form of a gene
centromere
responsible for the separation of chromosomes
recombinant
the gametes produced as a result of crossing over
chromatids
the two strands of a replicated chromosome
crossing over
the exchange of genetic codes between homologous chromosomes during meiosis
gametes
sex cells (sperm and eggs)
somatic cell
all body cells minus sex cells
inheritance
when genetic information is passed down from one generation to the next
recessive
if present the gene is only expressed phenotypically when homozygous
homologous pair
pairs of chromosomes having the same genes
chromosomes
thread like structure within a cell nucleus made of DNA that contains genes
mutation
alternation of the sequence of bases on the DNA. This produces new genetic information and maybe new phenotypes
DNA
makes up chromosomes and codes for proteins. Double helix like structure
gene
a sequence of DNA that codes for a specific protein or RNA molecule
mutagen
an agent that causes change in DNA, such as chemicals or radiation
genetic variation
the differences in the DNA sequence between individuals of the same species
fertilization
the fusion of gametes to create life
