Multicellular Organisms - 2.4 Variation and inheritance Flashcards
What is the comparison of discrete variation and continuous variation ?
Discrete variation is a single-gene inheritance.
Continuous Variation is polygenic inheritance
What is a gene ?
A gene is a location on a chromosome where a section of DNA contains the codes for a particular protein
What is Allele ?
Alleles are different forms of a gene
Example:
Different version of the eye colour gene
What is a Phenotype ?
The organism’s Physical appearance is called its phenotype
What is a genotype ?
The genotype of an organism is a statement of the alleles i has for a characteristic
example:
BB or Bb or bb
What does dominant mean ?
An allele can be recessive or dominant.
A dominant allele always shows in the Phenotype, even if the individual only has one copy of the allele
BB (Bb) bb
brown ( brown ) Blue
What does recessive mean ?
A recessive allele only shows if the individual has 2 copies of the recessive allele
BB Bb (bb)
brown brown ( Blue)
What is Homozygous ?
Individuals who are homozygous for a gene carry 2 copies of the same allele
(BB) Bb (bb)
( brown) brown ( Blue)
What is heterozygous ?
individuals who are heterozygous for a certain gene carry two different alleles
BB (Bb) bb
brown ( brown ) Blue
What is P ?
The letter (P) is used to indicate the original parents in the cross
They may become grandparents later but we still call them (P)
What is F1 ?
An (F1) generation is the first generation of offsprings of the parental types
What is F2 ?
An (F2) generation is the second filial generation, which is comprised of offspring(s) resulting from a cross of the members of (F1) generation
What is a Monohybrid cross ?
A monohybrid cross is the study of the inheritance of one characteristic
What are the reasons that the predicted ratio of the offspring phenotype is not always achieved ?
- Fertilisation is a random process
- The sample was not big enough
