Genetics Definitions Review

A complete question and answer flashcard set covering foundational genetics definitions from DNA structure and inheritance to population genetics and evolutionary mechanisms.

DNA

A long strand of genetic information that contains the code for all aspects of your body.

shape of DNA

Double Helix.

nucleotides

The monomers that make up DNA, which contain phosphate, sugar, and a base.

weak bonds between bases

Hydrogen Bonds.

complementary base pairing

A bonds with T, G bonds with C.

chromosome

Packaged DNA containing many genes.

genetic code

The order of the bases.

gene

A section of DNA that codes for a particular trait.

$46$ Chromosomes.

the number of chromosomes in human body cells

Organelle that contains DNA in a cell

Nucleus.

asexual reproduction

Offspring from one parent which is genetically identical.

meiosis

Cell division to make gametes with half the chromosome number.

site of meiosis in animals

Ovary, testes.

number of chromosomes in human gametes

$23$ Chromosomes.

independent assortment

Homologous pairs of chromosomes line up in random order on the equator during first division of meiosis giving new allele combinations.

crossing over

Sections of homologous chromosomes swap before the 1st division of meiosis giving new allele combinations.

variation

Differences between individuals.

genetic variation

Differences in the DNA/alleles between individuals.

sexual reproduction

Offspring formed from the fusing of gametes mixing the genetics of $2$ parents.

homologous chromosomes

Pair of chromosomes with the same genes on them in the same place.

zygote

Fertilized egg with whole set of chromosomes.

homozygous

Both alleles are the same (eg BB, bb).

heterozygous

Two alleles are different (eg Bb).

dominant allele

Only one allele is required for this phenotype to be expressed.

recessive alleled

Both alleles are required for this phenotype to be expressed.

phenotype

Physical expression of the gene.

genotype

Combination of alleles present for a gene.

pure breeding

Homozygous, the offspring will always show the dominant trait.

mutation

Permanent change in base sequence of DNA (makes new alleles).

pedigree chart

Family tree showing phenotypes of individuals in a family over generation.

carrier

Heterozygous/has one dominant and one recessive allele for a disease.

gene pool

Total number of all the alleles in a population.

allele frequency

The number/proportion of one type of allele in a gene pool.

genetic drift

Random change in allele frequency by chance, lowering genetic variation.

bottleneck effect

A catastrophic event results in only a small population surviving.

founder effect?

A small number of an original population relocate to a new area forming a new, small population.

gametic mutation

Mutation that occurs in a gamete and can be passed on to offspring.

somatic mutation

Mutation that occurs in a 'body' (somatic) cell so cannot be passed on.

migration

Gene flow/Individuals move into or out of the population.

immigration

Individuals move INTO a population, increasing genetic variation.

emigration

Individuals EXIT from a population, decreasing genetic variation.

natural selection

Individuals with alleles that give them a phenotype that gives them a survival and reproductive advantage will pass on these 'fit' alleles more often, so increase in frequency in the gene pool.

gene tracking

Following the inheritance of a specific gene.

DNA sequencing

Determining the base order of DNA.

genetic marker

A section of DNA that is unique to an individual or family.

relatedness

How closely related living things are (eg same family/ancestry).

diagnosis

DNA sequencing and tracking to see if an individual has an allele/mutation.

genetic variation important

Some members of the population might have alleles that give them resistance to a disease/environmental change so they survive and reproduce.

inbreeding

When two closely related individuals breed.

captive breeding

Selecting individuals from an endangered population and placing them in a safe environment (no predators, lots of food/resources) to reproduce.