inheritance evolution and variation processes

meiosis

1. all chromosomes are copied

2. cell divides in two

3. both cells divide one more time forming the gametes

4. produces four gametes from one original cell - genetically different

5. after fertilisation - normal number of chromosomes restored

6. new cell divides by mitosis - embryo

protein synthesis

1. transcription - base sequence of gene copied into a complementary template molecule

2. mRNA passes out of nucleus into cytoplasm

3. translation - mRNA attaches to a ribosome

4. amino acids brough to the ribosome on carrier molecules (tRNA)

5. ribosome reads triplets of base on mRNA - joins correct amino acids in correct order

6. protein chain folds in its unique shape

evolution by natural selection

• predator moves into area with prey

• prey with alleles that help them have an advantages (eg better hearing) there is variation and a mutation

• more likely to detect/escape predator

• more likely to survive and reproduce

• beneficial alleles passed onto offspring

• these alleles will overtime be widespread

selective breeding

• mixed population of animals and select male and female who have the most of the characteristic

• breed together

• offspring will be a mixture

• find female and male within offspring who have characteristic

• breed

• continue dong this until all offspring have desirable characteristic

genetic engineering

• identify gene we want to transfer

• use enzymes to isolate gene

• transfer gene into small DNA - plasmid

• plasmid can transfer DNA

• desired gene is transferred into cells of target organism

• always transfer gene at an early stage of development

cloning plants - cuttings

1. small piece of plant is removed and end is dipped in rooting powder

2. powder contains plant hormones and encourages roots of develop

3. only works if we want a few

cloning plants - tissue culture

1. plant we want to clone

2. divide plant into hundreds of tiny pieces

3. cells incubated with plant hormones - agar jelly/petri dish

4. grow and develop into full clones

5. must be sterile

cloning animals - embryo transplants

• sperm and egg cell from animal with characteristic we want

• fertilisation - egg

• allow to develop into an early stage embryo

• use glass rod to spilt embryo into two

• transplant two embryo’s into surrogate

• embryo grows and develop

• two identical offspring

cloning animals - adult cell cloning

• remove cell from animal we want to clone

• remove nucleus - enucleate

• unfertilised egg cell - same species

• remove nucleus from unfertilised egg and throw it away

• insert nucleus into empty egg cell

• give egg cell electric shock - egg divides

• inserted into womb of surrogate

specication

• area contains one species

• isolation occurs - geographical barriers

• population split into two

• new environment presents new factors

• genetic mutation occurs in population

• natural selection occurs mutations suit new environment

• reproduce - genes inherited by offspring

• new species - no longer reproduce successfully with the original

fossilisation

• creature is alive

• creature dies sinks to bottom of sea/ground

• creatures hard remains are covered by sediment

• layers of sediment compressed - sedimentary rock

• hard shell replaced by minerals

• rock is worn away - fossil can be discovered

resistant bacteria

• population of bacteria

• mutation causes resistance

• antibiotic strain survives and reproduces