Topic 6: Inheritance, Variation and Evolution Flashcards
What is meiosis?
Where number of chromosomes in gamete is halved, only to be restored in fertilisation
Why must gametes be unique?
Must be genetically unique to create genetic variation between species
What is fertilisation?
Where the nuclei of gametes fuse
What is a zygote?
Fertilised egg cell containing set of chromosomes
Where does mitosis and meiosis take place?
Mitosis - Muscle Cells
Meiosis - Testes / Ovaries
How are genes different in people?
Everyone has same genes, but different people have different versions of them
What is an allele?
Different form / version of the same gene, have two per gene
What is a dominant allele?
Always expressed if present e.g. brown - dominant for eye colour
Written in uppercase
What is a recessive allele?
Only expressed if no dominant allele is present e.g. blue - recessive for eye colour
Written in lowercase
What are genes?
Basic unit of inheritance, codes for a characteristic / protein, found in chromosomes
What do you call someone who has the same genotype?
Homozygous
BB (dominant) or bb (recessive)
What do you call someone who has different genotypes?
Heterozygous
What is the phenotype?
Expressed characteristic ( Brown eyes is a phenotype )
What is the rule for writing out genotypes?
Don’t use different letters to express the same genes, even if they have different characteristics
Example:
Grey - G
Black - b (Cannot be b, must be g)
