Inheritance, Variation and Evolution - P2T6

Adult cell cloning

A type of cloning that forms an embryo from an adult body cell.

Allele

A version of a gene.

Amino acids

Small molecules from which proteins are assembled.

Archaea

Primitive bacteria existing in extreme environments.

Asexual reproduction

A form of reproduction involving a single parent. Creates genetically identical offspring.

Binomial system

The universal system of naming organisms using their genus and species.

Charles Darwin

The scientist who developed the theory of evolution by natural selection.

Chromosome

A long, coiled molecule of DNA that carries genetic information in the form of genes.

Classification

The organisation of organisms into groups based on their characteristics and structure.

Coding DNA

A sequence of DNA that codes for the production of a protein.

Complementary

Describes how the chemical bases in DNA pair up with each other. A pairs with T and C pairs with G.

Cuttings

The simplest method of cloning plants. A branch is cut from a parent plant and replanted in compost after removing the lower leaves.

Cystic fibrosis

A cellular membrane disorder resulting from the presence of a recessive allele.

DNA

A double-stranded polymer wound to form a double helix. Carries the genetic code.

Dominant

Describes an allele that is always expressed. Represented by a capital letter.

Embryo screening

A procedure used to determine the presence of faulty genes in an embryo produced by IVF.

Embryo transplants

The simplest method of animal cloning. Cells are removed from a developing embryo, split apart and grown in culture, before being transplanted into host mothers.

Evolution

The gradual change in the inherited traits within a population over time. Occurs due to natural selection.

Evolutionary tree

A diagram which illustrates the evolutionary relationships between organisms.

Extinction

The death of all members of a species.

Family tree

A chart used to show the inheritance of a condition in a family.

Fertilisation

The fusion of the nucleus of male and female gametes. Restores the full chromosome number.

Fossil

The remains of dead organisms found in rocks which are millions of years old.

Gametes

Sex cells (sperm and egg cells) with half the usual number of chromosomes.

Gene

A section of DNA that codes for a specific sequence of amino acids which undergo polymerisation to form a protein.

Genetic engineering

The modification of the genome of an organism by the insertion of a desired gene from another organism.

Genome

The complete genetic material of an organism.

Genotype

An organism’s genetic composition. Describes all alleles.

GM crops

Crops that have had their genomes modified by the insertion of a desired gene from another organism.

Heterozygous

When someone has two different alleles of a gene e.g. Ff.

Homozygous

When someone has two identical alleles of a gene e.g. ff.

Inbreeding

The formation of offspring from the breeding of closely related individuals.

Linnaean system

The classification of organisms into kingdom, phylum, class, order, family, genus and species.

Meiosis

A form of cell division that produces gametes, non-identical cells with half the usual number of chromosomes.

Mitosis

A form of cell division that produces two genetically identical daughter cells from one parent cell.

MRSA

A type of bacteria that is resistant to the antibiotic, methicillin.

Mutation

A random change in DNA which may result in genetic variants.

Natural selection

The process by which the frequency of advantageous traits passed on in genes gradually increases in a population over time.

Non-coding DNA

DNA which does not code for a protein but instead controls gene expression.

Nucleotide

The monomers of DNA consisting of a sugar, phosphate group, and one of four chemical bases (A, T, C, G).

Phenotype

An organism’s observable characteristics due to interactions of the genotype and the environment.

Polydactyly

A condition where an individual is born with extra fingers or toes due to a dominant allele.

Protein synthesis

The formation of a protein from a gene.

Punnett square

A grid used to predict the potential outcomes of a genetic cross.

Recessive

Describes an allele that is only expressed in the absence of a dominant allele. Represented by a lowercase letter.

Ribosomes

Sub-cellular structures where protein synthesis takes place.

Selective breeding

The process by which humans select organisms with desirable characteristics to breed offspring with those traits.

Sex chromosomes

A pair of chromosomes responsible for the determination of gender. XY in males, XX in females.

Sexual reproduction

A form of reproduction involving the fusion of male and female gametes. Creates genetic variation.

Speciation

The formation of new species in the course of evolution, often due to the evolution of two isolated populations.

Species

A group of similar organisms that are able to breed with one another to produce fertile offspring.

Three-domain system

A method of classification where organisms are grouped into Archaea, Bacteria and Eukaryota.

Tissue culture

A method of growing living tissue or cells in a suitable medium to produce clone plants.

Variation

The differences between individuals due to genes, the environment, or both.

Vector

A carrier used to transfer a gene from one organism to another.