OCR Gateway GCSE Biology B5.1 Inheritance

Alleles

Different versions of the same gene

Asexual reproduction

Reproduction which requires only one parent; results in clones

Cancer

A disease which occurs as the result of cell changes that lead to uncontrolled growth and division

Clone

An organism which is genetically identical to its parent

Continuous variation

Variation which can take any value between a minimum and a maximum

Diploid cells

Cells which contain two sets of chromosomes

Discontinuous variation

Characteristic which falls into distinct groups

Dominant allele

Version of a gene whose characteristics is always expressed if present in the genotype

Environmental variation

Variation caused by the environment

Fertilisation

Joining together of two gametes

Gametes

Sex cells

Genetic cross

Technique used to show the possible characteristics of an offspring

Genetic variation

Variation caused by an organism's genetic material

genome

All the genetic material present in an organism

Genotype

The combination of alleles present in an organism.

Haploid Cells

Cells which contains one set of chromosomes

Heterozygous

Organism who has different alleles of a gene

Homozygous

Organism who has two copies of the same alleles

Meiosis

Cell division which produces gametes

Phenotype

Characteristics which are observed in an organism

Punnett square

Diagram used to show the possible genetic makeup of offspring, bases on mother's and father's genes.

Recessive allele

Version of a gene whose characteristics is only expressed if two copies are present in the genotype

Sexual reproduction

Reproduction requiring two parent, which results in variation

Variation

Differences within a species

Zygote

fertilised egg

Mutation

Change in the sequence of DNA bases