Topic 6- Variation Keywords Flashcards
Variation
Differences in the characteristics of individuals in a population
Evolution
A change in the inherited characteristics of a population over time through the process of natural selection
Natural selection
A process which gives rise to phenotypes best suited to their environment
Selective breeding
The process by which humans breed plants and animals for particular genetic characteristics
Genetic engineering
A process which involves modifying the genome of an organism by introducing a gene from another organism to give a desired characteristic
Fossils
The ‘remains’ of organisms from millions of years ago, which are found in rocks
Extinction
There are no remaining individuals of a species still alive
Binomial system
Naming organisms by their genus and species
Sexual reproduction
The fusion of male and female gametes
Asexual reproduction
Involves only one parent with no fusion of gametes
Meiosis
Cell division which halves the number of chromosomes, forming gametes
DNA
A polymer made up of 2 strands, forming a double-helix, contained in chromosomes
Gene
A small section of DNA on a chromosome which codes for a protein
Genome
The entire set of genetic material of an organism
Mutation
A change in the DNA
Gametes
Sex cells, such as egg and sperm cells
Allele
Different versions of a gene
Dominant
A gene that is expressed in the phenotype when at least one allele is present
Recessive
A gene that is expressed in the phenotype if both alleles are present
Heterozygous
Alleles present are different
Homozygous
Alleles present are the same
Genotype
Alleles that are present
Phenotype
Physical characteristics/features
Cystic fibrosis
A disorder of cell membranes where mucus is thick and sticky
Polydactyly
Inherited disorder where the individual has extra digits (fingers or toes)
Nucleotide
Sugar + phosphate + base
Tissue culture
Method of cloning using small groups of cells from part of a plant to grow identical new plants
Cuttings
A simple method used by gardeners to produce many identical new plants from a parent plant
Embryo transplants
Method of cloning. Splitting apart cells from a developing animal embryo before they become specialised, then transplanting the identical embryos into host mothers
Adult cell cloning
Nucleus is placed into empty egg cell and is inserted into the womb of an adult female
Speciation
Formation of a new species through natural selection from an isolated population
