CB3 Genetics Flashcards
(29 cards)
What are alleles?
Different forms of the same gene.
What causes a new allele for a gene to appear?
A mutation in the genetic code (DNA) for the gene.
How many alleles of a gene are in a haploid cell?
1
How many alleles of a gene are in a diploid cell?
2
What is a genotype?
The combination of alleles for a gene.
What is a phenotype?
The feature produced by the combination of alleles.
What is meant by being homozygous for a gene?
The 2 alleles are the same.
What is meant by being heterozygous for a gene?
The 2 alleles are different.
How many dominant alleles are needed for the dominant feature to be expressed?
1
How many recessive alleles are needed for the recessive feature to be expressed?
2
What are the 2 human sex chromosomes?
X, Y
What combination of sex chromosomes produces a human female?
XX
What combination of sex chromosomes produces a human male?
XY
What is a Punnett square?
A genetic diagram used to work out the possible genotypes for offspring produced from parents.
What is the probability of an offspring being male?
50% or 0.5 or 1/2
What is the probability of an offspring being female?
50% or 0.5 or 1/2
What is the ratio of male to female offspring produced through sexual reproduction?
1:1
What is monohybrid inheritance?
Inheritance where one gene controls the characteristic
What is meant by a genetic carrier?
A person with a heterozygous genotype for a recessive genetic disorder.
What is genetic variation?
Differences between individuals caused by the combination of alleles inherited.
What is environmental variation?
Differences between individuals caused by their surroundings.
What is discontinuous variation?
Variation in a characteristic where the data can only take a limited set of values.
What are 3 examples of discontinuous variation?
Number / frequency of characteristic, colour, shape
What is continuous variation?
Variation in a characteristic where the data can be any value in a range.
