Bio Paper 2

The base pairing in DNA was discovered by

Crick and Watson

A gene codes for the production of

a protein

Name one characteristic of stem cells

They can be stimulated to form any type of cell needed

Name one reason why colour blindness is more common in males than females

T

Name one part of the reason for why colour-blindness is more common in males than in females

The allele for colour-blindess is recessive and located on the X-chromosome

The scientist who discovered Little Foot is…

Ron Clarke

Prophase I

- Pairing of homologous chromosomes is visible

- Development of spindle fibres

- Crossing over is taking place

- Centriole/ centrosome moved to opposite poles

- Disintegration of the nuclear membrane

Crossing over steps

- Parts of the homologous chromosomes overlap and

- DNA/genetic material is exchanged

Metaphase I

- In Metaphase I/Meiosis I chromosomes are arranged in

pairs at the equator

- In mitosis the chromosomes are arranged singly at the

equator

DNA replication

- The (DNA) double helix unwindsand

- unzips/hydrogen bonds break

- to form two separate strands

- Both (DNA) strands serve as templates

- to build a complementary (DNA) strand/ A pairs with T and C

pairs with G

- using free (DNA) nucleotides from the nucleoplasm

- This results in two identical (DNA) molecules

what is meant by autosomal dominant allele

- A form of a gene

- that is carried on chromosome 1 to 22 and

- is always expressed in the phenotype of an individual

- in the heterozygous condition

Describe one way in which the process of artificial selection is different from genetic engineerings

- Artificial selection: organisms with a desired characteristic are

interbred

- Genetic engineering: genes coding for the desired characteristic

are inserted into an organism

Describe Darwin’s theory of evolution by natural selection

- There is variation amongst the offspring in a population

- Some have favourable characteristics and some do not

- When there is a change in the environmental conditions/there is

competition

- organisms with a favourable characteristic survive

- whilst organisms with an unfavourable characteristic die

- The organisms that survive, reproduce

- and pass on the allele for the favourable characteristic to their offspring

- The next generation will therefore have a higher proportion of

individuals with the favourable characteristic

term for position of a gene on a chromosomes

Locus

Term for the type of evolution characterised by long periods of little or no change followed by short periods of rapid change

Punctuated equilibrium

Term for the type of vision shared in primates that allows for depth perceptions

Stereoscopic/binocular vision

The name for the X and Y chromosomes in humans

Gonosomes

The type of dominance which results in an intermediate phenotype in the heterozygous condition

Incomplete dominance

Term for body cells

Somatic cells