patterns of inheritence🧬 Flashcards
define homozygous
genotype with two identical alleles
define gene locus
location of gene on chromosome
if a behaviour is naturally performed, what type of behaviour is it and what is its characteristic
type: innate
characteristic: not learned
suggest why the frequency of a trait in a population may decrease
- not selected for
- alleles not passed on
why are physiological problems more common in bred animals
- less genetic variation/ decreased gene pool
- weaker selection against less healthy animals
- disease may be homozygous recessive
- breeders select for looks not health
define genotype
combination of alleles possessed by organism
define allele
alternative version of a gene
List two factors that might cause allele frequencies to change from generation to generation
in a population that meets the Hardy-Weinberg criteria.
- natural selection
- genetic drift
- mutation
- migration
what is linkage
if genes for multiple traits are on the same chromosome, they are inherited together
what is epistasis
one gene affects expression of another via enzyme pathway
what are the different types of isolating mechanism for natural selection
- geographical
- behavioural
- mechanical
- gamete incompatibility
biological species concept vs phylogenetic species concept
bio- members of same species can interbreed to produce fertile offspring
phylo- common ancestry
-one species may have a lot of phenotypic variation
Suggest a suitable technique by which the student might have collected his samples of ladybirds along this transect.
- sweep netting
- beating
- pooter
define recessive
only expressed when homozygous
Over time, the frequency of a new allele increased in the gene pool of the human populations whose diet included milk.
Name the process by which this increase occurred.
natural selection
Distinguish between the terms ‘regulatory gene’ and ‘structural gene’.
regulatory- makes transcription factor to turn structural gene on/off
structural- makes polypeptide
Describe how genes Z and Y (in lac operon) are switched on in bacteria that are moved to a nutrient medium
that contains lactose.
- lactose binds to repressor protein
- changes shape of protein
- stops it binding to operator
- RNA polymerase binds to promoter
- Z and Y are transcribed
in eye colour epistasis, explain how the products coded for by the genes interact to give the different pigments
- gene products are enzymes
- multi enzyme pathway
- product of one reaction is substrate for next
- dominant allele gives functional enzyme
- recessive allele gives non-functional enzyme
outline the main ways that human presence and activity has put some species at risk of extinction
- habitat destruction
- land for buildings or farming
- deforestation
- more pollution
- hunting
Name the type of gene which, if mutated, gives rise to dramatic changes in body plan
homeotic/homeobox
Describe how the information coded on genes is used to synthesise polypeptides and how these polypeptides control the physical development of an organism
- gene copied into mRNA
- transcription
- one strand copied
- complementary base pairing
- ribosome
- translation
- tRNA contains anticodon on one end and amino acid on opposite side
- enzymes
- hormones
- structural proteins
- cAMP
- receptor proteins
- apoptosis
State two developments, other than selective breeding, that could account for the total increase in wheat yield per hectare
- new technology
- fertiliser
- pesticide
State the term used to describe the random changes in allele frequency in a small population
genetic drift
hypothesis: genes assort independently
the observed ratio is different to the expected. Suggest a genetic explanation for this difference.
- alleles are linked
- on same chromosome
- linked alleles inherited together
- crossing over produced rare recombinants
- tight linkage
Give two reasons why it is not appropriate to use the Hardy-Weinberg principle to estimate the frequencies of alleles for a group of rabbits in the pet shop
- small population
- not all members of population are breeding
- mating is not random
- migration occuring
