Selective breeding (paper 2)

Question 1

definition of selective breeding

Answer 1

the process by which humans artificially select plants and animals to breed for particular genetic characteristics

Question 2

what is the basic process of selective breeding

Answer 2

1. take 2 individuals with the (named) desirable characteristics
2. Breed them together
3. Select individuals with the desirable from the offspring
4. Breed them together
5. Repeat over many generations

Question 3

give 4 instances where selective breeding is used

Answer 3

• Cattle (animals) that produce more meat or milk
• Domestic dogs with a gentle temperament
• Disease/ Insect resistant crops
• large or unusual flowers in decorative plants

Question 4

name the 3 problems with selective breeding

Answer 4

• leads to a reduction in the gene pool
  number of different alleles in the population decreases, as those chosen to breed are closely related (inbreeding)
• inbreeding can result in health problems
  - increased risk that offspring inherit harmful genetic defects as gene pool is limited
  - dalmatians prone to deafness
• New diseases and defects can easily occur
  - not much variation, if one killed, others likely to sucuumb

Question 5

advantage of selective breeding

Answer 5

increase frequency of desired characteristics

Question 6

genetic engineering definition

Answer 6

process which modifies the genome of an organism by introducing a gene from another organism to give it a desired characteristic

Question 7

give 4 examples of genetic engineering

Answer 7

1. Treating diabetes: produces more human insulin
2. Modified crops –> increase size, improve quality, insect/ chemical resistant
3. Genetically modified sheep: produces specific substances in their milk Pharming e.g. production of clotting factor IX to treat blood clotting disorders
   4.Gene Therapy: genetically modified treatments for people with inherited diseases –> inserting working alleles into people w/ disease

Question 8

what are organisms which have been given gees from other organisms called

Answer 8

transgenic

Question 9

what are GM crops

Answer 9

Genetically Modified crops

Question 10

examples of GM crops

Answer 10

• insect / herbicide resistant
• larger fruit size

Question 11

describe the process of the genetic engineering of human insulin

Answer 11

1. Human cell DNA containing insulin gene is extracted
2. Insulin gene extracted from DNA using restriction enzymes
3. Plasmid extracted from bacteria cell
4. Section of plasmid is cut out of plasmid
5. Insulin gene inserted into empty section of plasmid DNA using ligase
6. Engineered bacteria multiply, producing insulin
7. Insulin separated and purified to produce human insulin

Question 12

what are the advantages of genetically engineered bacteria producing human insulin

Answer 12

• greater availability of insulin for diabetes
• reduces cost of treatment
• very few side effects

Question 13

what are the pro’s of GMOs

Answer 13

• Nutritional values of foods improved (introducing protein, vitamins, vaccines)
• crops can be produced without know allergens
• can grow in poor quality soils and harsh environments
• resistant the herbicides and insecticides
• improve food supply / improved crop yields –> help achieve global food security
• longer shelf life

Question 14

Cons of GMOs

Answer 14

• not yet know the long-term side effects
• limit biodiversity of local environment, outcompete the native species
• Cross pollination of non-GM plants could lead to ‘super weeds’
• disrupt food chains and food webs
• different government may have conflicting regulatory standards concerning safe usage

Question 15

Cons of genetically modified medicine

Answer 15

• Ethical issues: not right to transfer genes from one organism to another
• concerns that genetically engineered viruses may reproduce inside cells of organisms
• not yet know the long-term side effects
• may be possible for rise in certain types of allergies

Question 16

describe the main steps of genetic engineering

Answer 16

1. restriction enzymes used to isolate the required gene
2. gene inserted into a vector, usually a bacterial plasmid or virus
3. thevector is used to insert the gene into the required cells
4. genes are transferred to the cells of animals, plants or microorganisms at an early stage int heir development so they develop with those desired characteristics

Question 17

what are taking cutting also known as

Answer 17

vegetative propagation

Question 18

what are the advantages of taking cuttings

Answer 18

• cheap
• easy
• tools are easily accessible

Question 19

describe the steps of taking a cutting

Answer 19

1. a shoot is cut from part of the parent stock plant which has the desirable characteristics
2. end of shoot is treated with plant hormones, Auxin to encourage roots to develop + grow
3. cutting panted in moist compost
4. kept well-watered to avoid wilting

Question 20

describe the steps of tissue culture

Answer 20

1. Small amounts of the parent tissue or a small number of cells are taken (explants)
2. tissue samples transferred to grow in vitro using plates containing sterile nutrient agar jelly
3. Plant hormones (auxin) are in agar to stimulate cell division
4. cells grow rapidly into small masses of tissue
5. tissue grows, forms plantlets and transferred into potting trays where they develop into plants

Question 21

name 2 advantages for using tissue culture

Answer 21

1. preserving a rare plant species
2. grow commercially in larger nurseries as it allows very large numbers of clones to be produced in a relatively small space

Question 22

what is cloning plants by tissue culture also called

Answer 22

micropropagation

Question 23

disadvantages of tissue culture

Answer 23

• more expensive
• more difficult

Question 24

describe the steps of embryo transplants

Answer 24

1. sperm is taken from male with desirable characteristic
2. egg cell is artificially inseminated / fertilised with sperm
3. Zygote develops into embryo in female and the removed from uterus
4. embryo is split at an early stage before the cells have become specialised
5. cells are separated and grown in culture in ‘vitro to develop into new embryos
6. identical embryos are transplanted into uterus of surrogates

Question 25

will the embryos have the surrogates genetic information in embryo transplants and why?

Answer 25

No, but the embryos will be **genetically identical to each other**

Question 26

describe the process of adult cell cloning

Answer 26

1. Adult body cell (skin / udder) taken from animal with the desired characteristic. 2. nucleus is removed and cell is now **enucleated** 3. nucleus removed **unfertilised egg cell** 4. **nucleus** from the adult body cell is **inserted** into enucleated egg cell 5. **electric shock stimulates** egg cell to **divide by mitosis** to form an embryo 6. embryo **inserted into uterus** of **surrogate** female 7. embryo cells contain identical genetic information as adult body cell

Question 27

Pros for animal cloning

Answer 27

- technique allows **mass production** of genetically identical offspring in a **short period of time** - study of animal clonees can lead of a greater **understanding of embryo development** --> help **IVF** - study of animal clones lead to better understanding the process of ageing --> may be able to **reduce negative side effects of ageing**

Question 28

Cons + points against cloning

Answer 28

- **Ethical issues**: view as ethically + morally wrong to manipulate cells + organisms which are not able to give consent - mass production of clones leave to a **reduced gene pool** - reduction in gene pool can cause **one new disease or change in environment to result in death** of entire cloned population - concerns in cloning humans in future --> meaning **many disabled children born** in testing process until technique is perfected