module 6 - 19.6 inheritance Flashcards
what is intraspecific variation?
organisms of the same species have different characteristics
what are the 2 types of intraspecific variation?
- genetic variation
- phenotypic variation
what is genetic variation?
- difference in DNA between organisms of the same species
- results from organisms having a different genetic makeup
- caused by genetic factors (different alleles mutations)
when does genetic variation occur?
- during meiosis (different combinations of alleles are produced)
during sexual reproduction (random fusion at fertilisation)
what is phenotypic variation?
- difference in phenotypes between organisms of the same species
- genetic factors and environmental cause phenotypic variation
what are 2 examples of phenotypic variation?
- chlorosis (genes coding for chlorophyll/photosynthesis)
- diet (colour change in flies)
what is monogenic inheritance?
inheritance of one gene
what is a monogenic cross?
used to look at how a single gene is passed from one generation to the next, and record findings in a punnet square
what is dihybrid inhertiance
inheritance of 2 genes
what is a dihybrid cross?
- to look at how the alleles of 2 genes are passed from one generation to the next
- record findings in a punnet square
what is the phenotypic ratio of a dihybrid cross?
9:3:3:1
what is Mendel’s law of independence?
when 2 or more pairs of genes segregate from one another at gamete formation, the distribution of any one of them is independent from any other
what is independent assortment?
2 or more pairs of alleles located in different non-homologous pairs of chromosomes orientate randomly on spindle of metaphase 1 in meiosis
what is a test cross?
- involves crossing individuals with the corresponding recessive homozygote
- used to verify the genotype of individuals displaying dominant phenotype
what are genetic ratios?
- e.g. 9:3:3:1
- analysed using statistical tests
- determine whether the deviation of observed and expected values are acceptable in basis of chance
