B5- Genes, Inheritance and Selection Flashcards
(20 cards)
Allele
Different versions of the same gene
Dominant
The allele that is expressed if present.
Recessive
The allele that is only expressed if both the alleles are the same.
Genotype
The alleles present on the two chromosomes for a particular
characteristic
Phenotype
The appearance of a particular characteristic, how it is expressed.
Homozygous
When the two alleles present are the same
Heterozygous
When the two alleles present are different
Gene
Section of DNA that code for a protein
Genome
the entire genetic material of an organism
Asexual reproduction
reproduction involving only one parent
Sexual reproduction
form of reproduction involving two parents, which introduces variation
Genetic variation
the product of meiosis, mutations and sexual reproduction, which all lead to changes in our genome
Gamete
the male and female sex cells (sperm and eggs)
Diploid
describes cells with two copies (or a pair) of each chromosome
Haploid
describes cells with a single chromosome from each pair (e.g. egg or sperm cells)
Meiosis
cell division that results in gametes being produced, with half the number of chromosomes as the parent cell
Sex determination
whether a fertilised egg develops into a male (XY) or female (XX) depends
on the 23rd pair of chromosomes
X- chromosome
sex chromosome present in males (XY) and females (XX)
Y- chromosome
sex chromosome found only in males
Genetic cross
a way of working out the probability of the genotype of the offspring
produced from the parents’ genotype for a particular characteristic, e.g.
using a Punnett square
