Characteristics are controlled by...
What is a gene?
A section of DNA that codes for a particular characteristic (feature).
Different forms of the same gene are called...
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.
An allele that always expresses its characteristic in an organism is said to be a...
An allele that can only express its characteristic when there are two copies is said to be a...
How many copies of a dominant allele does a person need to express its characteristic?
How many copies of a recessive allele does a person need to express its characteristic?
The brown eye allele is a _______allele.
The blue eye allele is a _______allele.
How many copies of the blue eye allele does a person need to have blue eyes and why?
The blue eye allele is recessive
How many copies of the brown eye allele does a person need to have brown eyes and why?
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)
What is meant by a characteristic of an organism?
A feature of an organism e.g. eye colour, hair colour, flower colour etc.
The letter for a dominant allele is normally written as a __________ letter.
The letter for a recessive allele is normally written as a ________ letter
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.