Genetics word list

Alleles

Different versions of the same gene

Asexual reproduction

A single parent copies itself to form a genetically identical offspring

Chromosomes

Molecules made of DNA that are found in the nucleus of the cell

Carrier

A person who does not show symptoms of a disease but carries the recessive allele for that disease. This means that they could pass it onto their offspring

Continuous variation

A feature that can vary, i.e height or weight

Crossing over

During meiosis, homologous chromosomes pair up and line up along the equator of the cell. Sections of DNA are exchanged between the homologous chromosomes. They swap alleles for the same genes, creating new combinations of alleles and increasing genetic variation in the gametes.

Diploid

A cell consists of two sets of chromosomes, usually one set from the father and another set from the mother.

DNA

Deoxyribonuleic acid, found inside the nucleus of the cell and carries the genetic information

DNA sequencing

Determining the exact order of bases in the DNA

Dominant allele

An allele that shows up as a characteristic in an organism even if only one copy of the allele is present

Double helix

The twisted ladder shape that DNA takes

Fertilisation

Fusing of the egg and sperm to create zygote that will become a new individual

Genes

A section of DNA that codes for a organisms characteristics/trait

Genetic marker

A DNA sequence with a known physical location on a chromosome

Gene tracking

The process of following a specific gene through generations of organisms or tracing it through different individuals or populations. Methods include punnett squares and pedigree charts

Genetic variation

Differences in genes between individuals in a population or between different populations

Genotype

The combinations of alleles that a person or an organism has for a particular trait

Haploid

A cell with only a single set of chromosomes. For example, egg or sperm

Heterozygous

Different forms of an allele are present in the genotype

Homologous chromosomes

Matching chromosomes (1 maternal and 1 paternal) that carry the same sequence of genes, but not necessarily the same alleles

Homozygous

The same form of allele is present in the genotype

Independent assortment

Homologous chromosomes are randomly paired up. Maternal and paternal chromosomes can be on either side of the equator. This gives different combinations of alleles in the gametes

Meiosis

A form of cell division that creates gametes which have half the amount of chromosomes (haploid)

Migration

Movement of organisms into and out of a population

Mutation

A permanent change in the base sequence of DNA

Natural selection

A process where the organisms with the characteristics most suited to their environment are more likely to survive and pass on their genes

Non-random mating

When individuals choose mates based on specific traits or preferences, rather than by chance. This means that certain alleles are more likely to be passed on to the next generation, which can affect the genetic variation of the population

Nucleotide

The building block of DNA. It is made of sugar, phosphate and base

Nucleus

The central part of the cell, which contains the chromosomes

Pedigree chart

A diagram that shows the relatedness between an organism and its ancestors

Phenotype

How a gene is expressed as a characteristic/trait. Describes the appearance of an individual

Popualation

All the members of a single species that live in a habitat

Protein

A molecule made of amino acids that determine the structure and function of an organism. Genes code for protein molecules

Punnett square

The punnett square is a diagram used to predict the outcome of a particular genetic cross

Recessive allele

An allele that only shows up as a characteristic in an organism if contains the two copies of it

Somatic cells

Another name for body cells that are not involved in reproduction. They have two sets of chromosomes (diploid)

Sexual reproduction

The combining of genetic information from two parents results in genetically unique offspring