Biology E4 Chapter 1

Question 1

Process of recombinant DNA technology

Answer 1

obtain DNA fragments containing gene of interest
obtain vectors suitable plasmids obtained from bacteria
cut DNa fragments and plasmids using a restriction enzyme
join DNA fragments and plasmids together using a DNA ligase

Question 2

What are plasmids

Answer 2

small rings of double-stranded extrachromosomal DNA

Question 3

Why only some plasmids possess DNA after transformation

Answer 3

some plasmids joined by themsleves and restored to original form without picking up DNA
some bacteria did not pick up any plasmids

Question 4

Method of selecting bacteria that picked up plasmids

Answer 4

bacteria first culutred on agar plate containing ampicillin to select transformed bacteria
transofmred bacteria carry ampicillin resistance gene
bacteria did not pick up any plasmid do not carry ampicillin resistance gene -> cannot survive

Question 5

Method of identifying plasmid with recombinant DNA gene

Answer 5

insertion of DNA fragment into plasmid interrups resistance gene -> non-function bacteria with recombinant plasmid cannot survive
bacteria with non-recombinant plasmid carrying function reistance gene can survive

Question 6

Advantage of recombinant DNA technology

Answer 6

product yield higher
extraction cost lower
structurally same as that in human body, not rejected by immue system
pure, risk of contamination, causing infection is low

Question 7

AGROBACTERIUM

Answer 7

obtain DNA fragment containing toxin gene from toxin-producing bacterium, cut it using restriction enzyme
obtain plasmid from agrobacterium, cut it using restriction enzyme
join DNA fragment and plasmid together using a DNA ligase
introduce recombinant plasmid into agrobacterium
infect cells with transfroemd agrobacterium

Question 8

Gene gun

Answer 8

DNA containing gene coated on tiny particles. metal particles fired into plant tissues. DNA diffuses out from the surface of metal particles. some incorporate randomly into plant chromosomes

Question 9

GM animals

Answer 9

DNA containing new gene obtained
DNA containing new gene injected into fertilized ova using very fine needle
Ova allowed to grow and develop into embryos
Embryos transferred to mothers for further growth and development

Question 10

Disadvantage of GM animals

Answer 10

success rate low
many damage fertilized ova
time consuming

Question 11

Benefits of introducing gene into animals using virus

Answer 11

biological factories
increase food supply
higher nutritional value
reduce pollution

Question 12

Potential hazards of introducing gene into animals using virus

Answer 12

unknow long term health effect
may cause allergic reactions
may cause superbug
transfer their genes to wild types to cause genetic polllution
out compete wild types, upset ecological balance, decrease in biodiversity
adds genes to gene pool of species

Question 13

Process of tissue culture

Answer 13

remove piece of tissue from plant and sterilize it
put piece of tissue into sterile culture mediuk containing all nutrients necessary for growth.
transfer cells of callus to culture medium containing hormones
hormones promote growth of roots and shoots. cells differentiate into different types of cells, plantlets formed
grow plantlets in soil for further development

Question 14

benefits of tissue culutre

Answer 14

produce large numbers of plants that are economically impertant
produce disease -free plants for agricultural purpose
rescue disease - infected plant populations
produce plants that are endangered hard to grow
maintain a special breed
produce genetically identical plants

Question 15

Process of cloning animals

Answer 15

mammary gland cell collected from an adult sheep. nucleus obtained
ovum was collected from another sheep and its nucleus was removed
nucleus of mammary gland cell was transferred to ovum. cells started to develop into embryo in vitro
the embryo was implanted into uterus of surrogate sheep to allow further develop
surrogate sheep gave birth to dolly

Question 16

Applicatin of cloning animal

Answer 16

propagate farm animals and endangered animals
mass-produce GM animals for production of valuable pharmaceutical products
produce genetically identical animals for use in drug test/ research
obtain stem cells for use in research or medicine

Question 17

Limitation of cloning animal

Answer 17

low success rate
animal clones get old sooner, shorter life spans

Question 18

Advantage of cloning animal

Answer 18

desirable characteristics can be preserved because offspring produced have an identical genetic make=up to their parents
used as method to overcome repdocutive ifficulties of plants and animals

Question 19

Issues of cloning animals

Answer 19

ethical
economic
environment

Question 20

What is needed for PCR

Answer 20

DNA sample
Free nucleotides dNTPs
DNA polymerase
primers

Question 21

What are primers

Answer 21

short synthesized single-stranded DNA

Question 22

3 steps of PCR

Answer 22

DNA denaturation, primers annealing, extension

Question 23

DNA denaturation

Answer 23

reaction mixture heated to 95C. high temperature breaks hydrogen bonds between two strands of DNA sample. two strands separate, so that each strand can be used as template for synthesis of new DNA strand

Question 24

Primers annealing

Answer 24

reaction mixture cooled to temperature between 50C-65C. primers anneal to the single-stranded DNA template by complimentary base pairing

Question 25

Extension

Answer 25

temperature raised to 70C. free nucleotides attached to DNA template by complementary base pairing. DNA polymerase catalyses joining of adjacent nucleotides so that free nucleotides are added to the primers to extend the new DNA strands. the higher temperature provides optimum temperature for the heat-stable DNA polymerase to act.

Question 26

Application of PCR

Answer 26

amplify DNA of prenatal diagnosis of genetic diseases amplify DNA to produce DNA fingerprints in forensic science amplify DNA from remains of historical figures or extinct species for study to diagnose infections diseases to identify GM foods

Question 27

Why can we determine a person's identity through VNTRs.

Answer 27

VNTRs present at many loci in non-coding regions on human chromosomes. Each VNTR consists of repetitive base sequences positioned one after another

Question 28

How to find VNTRs RFLP

Answer 28

restriction fragment length polymorphobism RFLP analysis restriction enzyme used to cut DNA sample from individuals, produces DNA fragments in different lengths. DNA fragments separated according to their lengths by gel electrophoresis

Question 29

How to find VNTRs with raioactive DNA probes

Answer 29

position of DNA fragments containing specific VNTRs visualized by photographic film. patterns of bands formed -> DNA fingerprints

Question 30

Application of DNA fingerprints

Answer 30

forensic science percentage tests victim identification authentification of foods and Chinese medicine conservation of endargered species tracing source of infection screening for genetic disease

Question 31

DNA WHATEVER

Answer 31

DNA extracted from blood sample and cut with specific restriction enzymes DNA fragments separated according to their lengths by gel electrophoresis DNA fragments containing specific VNTRs detected using radioactive DNA probes.Positions of DNA probes visualized by photographic film

Question 32

What is DNA probe

Answer 32

short single-stranded DNA fragment complementary to a target sequences. positions of DNA probes visualized by photographic film