Biology flashcards

DNA

unit of heredity that contains genetic instructions

Double helix

Shape of DNA

Nucleotide

Building block of DNA made up of a phosphate, sugar, and base

Hydrogen bonds

Weak bonds between bases in DNA

complimentary base pairing

A bonds with T and G bonds with C

Chromosome

Packaged DNA containing many instructions

genetic code

Order of the bases

Gene

Piece of DNA that codes for a protein

46 chromosomes

number of chromosomes in human body cells

Nucleus

Organelle that contains DNA in a cell

Asexual reproduction

Offspring from one parent which is genetically identical (clone)

Meiosis

Cell division to make gametes with half the chromosome number

Ovary, testes

Site of meiosis in animals

23 chromosomes

number of chromosomes in human gametes

Independent assortment

Homologous chromosomes line up randomly during meiosis, creating new combinations of alleles.

Crossing over

Sections of homologous chromosomes swap during meiosis, creating new allele combinations.

Variation

Differences between individuals

Genetic variation

Differences in 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 in the same place

Zygote

Fertilized egg with a whole set of chromosomes

Homozygous

Both alleles are the same (BB, bb)

Heterozygous

The two alleles are different (Bb)

Dominant

Only one allele is needed for this phenotype to be expressed

Recessive

Both alleles are needed 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 if 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 change in allele frequency following a dramatic reduction in the size of a population

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 that can be passed on to offspring

Somatic mutation

a mutation that occurs in a 'body' (somatic ) cell that 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 à population, decreasing genetic variation

Natural selection

Individuals with helpful alleles are more likely to survive and reproduce, so these alleles become more common in the population.

Gene tracking

Following the inheritance of a specific gene

DNA sequencing

Determining 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 family/ancestry)

Diagnosis

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

Genetic variation importance

Some individuals have alleles that help them survive changes or diseases, allowing them to survive and reproduce.

Inbreeding

When two closely related individuals breed

Captive breeding

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

Autosome

A chromosome that is not a sex chromosome

Genome

A whole set of DNA in a cell

Gene flow

Alleles being passed on via sexual reproduction

Non-random mating

Every individual does not get equal opportunity to reproduce.

Cystic fibrosis

Human recessive genetic disease that in heritable

Huntingtons disease

Human dominant genetic disease that is heritable.

Adaptation

Features/traits that enable better survival and reproduction

Punnett square

Chart to predict probability / chance of offspring phenotypes

Mitosis

Cell division or growth and repair

Protein

Long chain of amino acids, coded for by a gene, is expressed as a phenotype