3.1.1 Genetics Flashcards
Characteristics are controlled by…
Genes
What is a gene?
A section of DNA that codes for a particular characteristic (feature).
Different forms of the same gene are called…
Alleles
An allele is…
A form of a gene e.g. Black hair gene, blonde hair gene etc.
A person receives ______ copies of every gene from their parents.
2
An allele that always expresses its characteristic in an organism is said to be a…
Dominant allele
An allele that can only express its characteristic when there are two copies is said to be a…
Recessive allele
How many copies of a dominant allele does a person need to express its characteristic?
1
How many copies of a recessive allele does a person need to express its characteristic?
2
The brown eye allele is a _______allele.
Dominant allele
The blue eye allele is a _______allele.
Recessive allele
How many copies of the blue eye allele does a person need to have blue eyes and why?
2 copies
The blue eye allele is recessive
How many copies of the brown eye allele does a person need to have brown eyes and why?
1
The brown eye allele is a dominant allele
How do a mother and fathers genes become mixed?
When a sperm cell enters an egg cell (fertilisation)
How can we calculate the chance of a child inheriting a certain characteristic from its parents?
Perform a genetic cross (punnet square)
The Punnett Square below shows a brown eyed father (BB) and a blue eyed mother (bb). Fill in the Punnett squares to show the alleles that their children would inherit. What eye colour would they have?
They would all have brown eyes because they all have the brown eye dominant allele.
