Topic 3.5: Genetic Modification and Biotechnology

Question 1

PCR

Answer 1

Artificial method of replicating DNA

Question 2

Stages of PCR

Answer 2

a) Denaturation
b) Annealing
c) Enlogation

Question 3

Denaturation

Answer 3

DNA sample is heated to separate it into two single strands.

Question 4

Annealing

Answer 4

DNA primers attach to the 3’ ends of the target sequence

Question 5

Elongation

Answer 5

A heat-tolerant DNA polymerase (Taq) binds to the primer and copies the strand

Question 6

PCR Materials

Answer 6

a) DNA sample
b) Primers
c) Taq polymerase
d) Nucleotides

Question 7

Gel electrophoresis

Answer 7

Technique that separates proteins or fragments of DNA according to size

Question 8

Gel electrophoresis process

Answer 8

a) Samples placed in a block of gel and current is applied

b) Smaller samples move faster through the gel (Less resistance)

Question 9

DNA Separation in Gel Electrophoresis

Answer 9

a) DNA is negatively charged (due to phosphate group)

b) Samples will move towards the positive terminus.

Question 10

Protein Separation in Gel Electrophoresis

Answer 10

Proteins are treated with an anionic detergent in order to impart a uniform negative charge on all molecules

Question 11

DNA Profiling

Answer 11

Technique by which individuals can be identified and compared by their genetic sequences

Question 12

DNA Profiling Process

Answer 12

a) Individuals have different lengths of particular DNA segments called short tandem repeats (STR)
b) These segments are amplified by PCR and then separated by gel electrophoresis for comparison
c) Unique profiles appear when multiple loci are compared

Question 13

Gene transfer process

Answer 13

a) Isolation of gene and vector (by PCR)
b) Digestion of gene and vector (by restriction enzymes)
c) Ligation of gene and vector (by DNA ligase)
d) Selection and expression of transgenic construct

Question 14

Benefits of GM Crops

Answer 14

a) Could be used to improve nutritional standards
b) Can grow in a wide range of environments
c) Could reduce farming costs and associated deforestation
d) Can be used to reduce spoilage (longer shelf life)

Question 15

Risks of GM Crops

Answer 15

a) Could trigger unexpected health issues (e.g. allergies)
b) Patent protections could restrict access (equity issues)
c) Possible cross-pollination with weeds (hard to contain)
d) Could compete with native plants (reduce biodiversity)

Question 16

Example of GM Crops

Answer 16

a) Bt corn is a transgenic crop that produces an insecticide
b) Bt corn may be impacting survival of monarch butterflies
c) In lab conditions, butterfly mortality is higher when fed plants dusted with Bt pollen
d) There is insufficient field evidence to support this

Question 17

Clones

Answer 17

Groups of genetically identical organisms, derived from a single original parent cell

Question 18

Animal cloning

Answer 18

a) Binary fission
b) Budding
c) Fragmentation
d) Parthenogenesis

Question 19

Binary fission

Answer 19

a) The parental organism divides equally into two clones

b) Occurs in flatworms (also used by bacteria and protists)

Question 20

Budding

Answer 20

a) Cells split off from parent, generating smaller clones

b) Occurs in Hydra, but is also common to yeast

Question 21

Fragmentation

Answer 21

a) New organisms grow from separated fragment of parent

b) Common to starfish and some species of annelid worm

Question 22

Parthenogenesis

Answer 22

a) Embryos formed from an unfertilised (diploid) ova

b) Occurs in some species of fish, insect, reptile, amphibian

Question 23

Human cloning

Answer 23

Identical twins (monozygotic) are created when a fertilised egg (zygote) splits into two identical cells, each forming an embryo

Question 24

Plant cloning

Answer 24

a) Plants have the capacity for vegetative propagation, whereby small pieces of plant can be induced to grow independently
b) Adult plants possess totipotent meristematic tissue capable of cellular differentiation

Question 25

Stem cutting

Answer 25

A separated portion of a plant stem that is used to regrow a new clone via vegetative propagation

Question 26

Artificial cloning

Answer 26

a) Embryo cloning

b) Adult cloning

Question 27

Embryo cloning

Answer 27

a) Animals can be cloned from an embryo by separating the embryonic cells into groups
b) As embryonic stem cells are pluripotent, each cell can potentially form a cloned offspring
b) As this method occurs after random fertilization, it is not possible to control the genetic features of potential clones

Question 28

Adult cloning

Answer 28

a) Adults can be cloned via the process of somatic cell nuclear transfer (SCNT)
b) The nucleus is removed from an adult body cell (diploid) and fused with an enucleated egg cell
c) An electric shock stimulates division of the egg cell and the growing embryo is implanted into a surrogate