Module 6.1.2 - Patterns of inheritance and variation Flashcards
What is an allele?
Different versions of same gene
What does genotype mean?
Alleles an organism
What does phenotype mean?
Characteristics displayed by an organisms
What does epistasis?
More than one gene affecting characteristic
e.g. eye colour
What are the 2 genetic factors?
- polygenic
- monogenic
What is polygenic?
- continuous variation
- controlled by many genes
What is monogenic?
- discontinuous variation
- controlled by 1 gene
What is etiolation?
Plants grown abnormally long and spindly due to not enough light
What is chlorosis?
Plants dont produce enough chlorophyll due to lack of magnesium (prosthetic group)
What us interspecific variation?
Variation between species
What us intraspecific variation?
Differences between individuals of same species
What is continuous variation?
- many genes/alleles
- quantitative
- controlled by both genes and environment
- normal distribution curve
What is discontinuous variation?
- limited amount of genes/alleles
- qualitative
- controlled by genes
- not environment
- bar chart
What is monogenetic inheritance?
Characteristics controlled by 1 gene
What is codominance?
Both alleles are expressed and neither one is recessive
Give an example of codominant alleles
Sickle cell anaemia
What is dihybrid inheritance?
Inheritance of 2 characteristics controlled by different genes
What are the 4 blood groups?
A, B, AB, O
What are the allele combinations of each blood group?
A - I^A I^A, I^A I^O
B - I^B I^B, I^B I^O
AB - I^A I^B
O - I^O I^O
What are some example of sex linkage?
- hemophilia
- colour blindness
- duchenne muscular dystrophy
What is an autosome?
Chromosome that’s not a sex chromosome
What does linkage of autosomal chromosomes crossing over during meiosis do?
The closer the genes, the less likely they are to get separated from crossing over
What is epistasis?
When 1 gene masks or suppresses the expression of another
What does linkage of autosomal chromosomes independent assortment during meiosis do?
Genes on same autosome are said to be ‘linked’ as they stay together during independent assortment
What is an example of epistasis?
In humans, if you have the gene for baldness then it doesn’t matter if you have the gene for widow’s peak as you have no hair
What does epistasis dominant mean?
Having a dominant epistasis allele, 1 copy will mask the expression of other gene
What is the chi-squared test?
- measures size of difference between observed and expected results
helps determine whether differences are significant or not - null hypothesis=no significance
What is a species?
Group of organisms that can reproduce to form a fertile offspring
What is speciation?
The development of new species when population becomes reproductively isolated and can no longer interbreed, changes in allele frequency lead to change in phenotype
What is allopatric speciatio?
- physical barrier occurs and causes geographical isolation, 2 populations now
- mutations occur but the new alleles aren’t shared between populations as no interbreeding
- separates gene pool
- natural selection creates variation from the mutations
- change in allele frequency
- differential reproductive success
- barrier is removed
- new species are created that can’t be bred together, speciation
What is sympatric speciation?
- don’t have to be geographically isolated to become reproductively isolated
- random mutations could lead to reproductive isolation
- is rare as difficult for sections or as population reproductively isolated
What are the 2 types of speciation?
- allopatric
- sympatric
What is reproductive isolation?
Changes in alleles and phenotype of 2 populations that prevents them from successfully breeding together
What are some examples of reproductive isolation?
Seasonal changes - different flowering/mating seasons
Mechanical changes - changes in gentitalia prevent successful mating
Behavioural changes - different courtship rituals developed
What is artificial selection?
Type of selective breeding
What are some problems with artificial selection?
- cause health problems
- reduced genetic diversity and gene pool
- more susceptible to genetic diseases
- alleles are lost
- certain traits may be exaggerated
