B6.2 - selective breeding/ generic engineering Flashcards
what is selective breeding
the breeding of species for favourable characteristics
process of selective breeding
- decide which characteristic is desirable
- select parents with high levels of this characteristic
- breed from these individuals
- select the best offspring and breed again
- repeat for many generations
risks of selective breeding
- inbreeding may reduce gene pool - lead to accumulation of harmful recessive characteristics- reduction in variation
- may be animal welfare issues eg breathing problems
- ## any useful alleles not found in desired organisms may be lost - smaller gene pool won’t contain variation to deal with environmental changes
advantages of selective breeding
- sustainable food production is possible
- safe method of working as relies on natural processes and natural mutations
- selling produce that produces more meat/crops is profitable
- new varieties might be resistant to disease
- farmers and consumers can have desirable qualities
plant selective breeding
- the male parts are removed to prevent self pollination
- once pollen has been transferred to flower an exclusion bag is placed over to avoid pollen reaching flower
breeding plants to become disease resistant
- expose a population to a disease
- select those with resistance
- breed the resistant with each other and re expose to disease
- select those with resistance and repeat
genetic modification
the movement of genes from one organism to another
genetic engineering
when people selectively breed plants it’s slow
- altering an organisms genome to produce desired characteristics (faster and precise)
genetic engineering involves
- taking genes from one species and introducing them into another
- these are foreign genes
- can be transferred as all organisms contain same basic genetic material
genetic engineering process
- identifying gene that codes for a desired characteristic
- remove gene from donor organism
- insert the gene into the host organism (often bacterium)
how to modify bacteria to produce insulin
- restriction enzyme cuts insulin gene from the human DNA
- a plasmid is removed from bacteria
- plasmid is cut open using same restriction enzyme
- human insulin gene and plasmid are mixed
- insulin is joined into the plasmid using DNA ligase enzymes
- plasmid carrying human gene is inserted into the new bacteria
- plasmid is called a vector (carries human gene)
- the bacteria is grown in large no. to produce insulin
restriction enzymes
cut the donor dna at specific base sequences either side of the desired gene
sticky ends
a staggered cut leaves exposed unpaired bases
ligase enzyme
join donor DNA to host DNA at sticky ends
plasmid
small circular dna found in prokaryotes
vector
in genetic engineering a plasmid acts as a vector - used to transfer gene into an organism
why use bacteria to produce insulin
to treat illnesses
- can make lots of insulin quick
how scientists know foreign gene had been successfully transferred
- plasmid being used contains gene that codes for antibiotic resistance
- bacteria are transferred to an agar plate containing antibiotic and allowed to grow
- any bacterial colonies present must contain resistance marker gene - these also contain desired gene
- bacteria without plasmid die
- each bacterium with a plasmid makes a colony
type of antibiotic used
kanamycin resistance
- rarely used in medicine so resistance to it won’t be a problem
transgenic bacteria
have DNA from another organism
why bacteria that don’t take up insulin gene die
the insulin gene contains resistance genes do without insulin gene it would die from antibiotic as doesn’t have resistance
plant genetic modification
- plasmid removed and dna placed in it by restriction enzyme and ligase
- plasmid is a vector for the gene
- plant cells are infected with bacteria
- plant cells are screened with an antibiotic - any not taken up gene are killed
- cells grown into plantlets
- plants grown into a culture
gmos
name for genetic engineering in plants
golden rice modification
- produce beta carotene
- gene from daffodil
- body uses this to make vitamin A (deficiency leads to night blindness)
herbicide resistant crops modification
- resistant to herbicide
- gene from plants with natural herbicide resistance
- increases crop yield as crop doesn’t die - can get rid of weeds easily
Bt corn modification
- codes for protein that kills pest
- from soil bacterium
- don’t die as pests are killed
- crop yield increases
safety concerns of genetic engineering
- religious teachings think it’s wrong to change natural organisms
- think it can cause cancer
- think herbicide still present in crop cells cause harm
farmers cannot collect and sow seeds from gm crops why
will not breed true ( won’t have exact same characteristics) have to buy new seeds each season - seed companies exploit poor farmers
why people might want to know if plants are genetically modified
- so seeds will breed true
- concerns of safety / ethics
- not want to eat/ buy
embryo transplants - cloning
- cow is artificially inseminated with sorts from a bull with high dairy yield
- a developing embryo is removed from a pregnant female early so cells not yet specialised
- cells are separated and grown in culture and transplanted into host mothers (identical)
- in future it may be possible embryos may be genetically modified prior to implantation
- cows are clones
