Cell division - chromosomes Flashcards
What does nucleus of a cell contain?
Chromosomes made of DNA.
How do chromosomes come?
In pairs, one chromosome from each parent.
How many pairs of chromosomes does a human cell have?
23 pairs
What do chromosomes carry and what do these do?
They carry genes, different genes control the development of different types of characteristics (e.g. hair and eye colour.)
What are different versions of the same gene called?
Alleles
What does genotype mean?
Set of genes responsible for a trait.
What does phenotype mean?
Physical characteristics as a result of the genotype and environment.
What does heterozygous mean?
Having two different alleles for a trait.
What does homozygous mean?
Having two identical alleles for a trait.
What does dominant mean?
Characteristic is always expressed even if a different allele is present - only one copy of the allele is required.
What does recessive mean?
Two copies of allele are required for characteristic to be expressed.
