SCIENCE LEVEL 1 NCEA

DNA

Is a long strand of genetic information. It contains the code for all aspects of your body.

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 particular trait/characteristic/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

It means the best suited to survive. Individuals more suited to the environment reproduce more often and passes on their favourable alleles. the frequency of these alleles increase every time.

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

Protein

A long strand of amino acids

Random fertilisation

Increases variation because the gametes that are fertilised occur randomly

Albinism

When your body doesn’t produce any melanin due to mutation, as there is a change in the base sequence of DNA

Adaptation

An adaptation is an inherited special feature an organism has that allows them to survive in their own environment.

Genetic screening

Can be used to prevent diseases or to assure their early detection and treatment

DNA profiling

A technique used which individuals can be identified and compared to others. VIA their genetic markers.

Sickle cell

Red blood cells stiffen, changing shape into sickles.

Huntington disease

Dominant. fatal genetic disorder that causes nerve cells in the brain to slowly break down and die.

Cystic fibrosis

Recessive. Inherited genetic disorder that causes severe damage to the lungs, digestive system and other organs in the body.

Inbreeding depression

Reduces fertility, higher mortality, weakened immunity.