Inheritance and selection Flashcards
What is genotype?
Genotype is the genetic make up of an organism.
What is phenotype?
Phenotype is the observable characteristics of an organism. It is the result of the interaction between genotype and the environment.
What is a gene?
A gene is a section of DNA, a sequence of nucleotide bases, that usually determines a single characteristic of an organism.
What is an allele?
A different version of the same gene. They are dominant, recessive or co-dominant
What is the phenotype of alleles that are co-dominant?
Usually a blend of the two dominant alleles. e.g: If the colour gene for a flower is red which is dominant and it reproduced with a dominant white allele then the offspring might be pink.
What are the chances of the offspring of two carriers of cystic fibrosis being sufferers?
Draw the diagram.
25%
Draw a diagram to show the chances of the offspring of a female carrier of haemophilia (X^H X^h) and a non suffering male (X^H Y) being a suffering female. (the Y chromosome cannot carry haemophilia and the allele for it is recessive)
0%
What is co dominance?
When both alleles are equally dominant.
Name one example of multiple alleles to code for a gene.
Blood type A and B are co-dominant and O is recessive.
Draw a diagram to show the chances of the offspring of a homozygous O and a an A(AO) blood group to have the blood type O.
50%
Write down the Hardy-Weinberg equations.
Frequency of allele A = p
Frequency of allele a = q
p + q = 1.0
p^2 + 2pq + q^2 = 1.0
What conditions does the Hardy-Weinberg principle need to work?
No mutations to arise
Isolated populations, no immigration or emigration
No selection, no alleles make it more likely an organism will survive and reproduce.
Large population
Random mating within the population
