molecular genetics

Question 1

what is DNA

Answer 1

• deoxyribonucleic acid
• double stranded, helical polymer found in nucleus of a cell

Question 2

what does DNA comprise of and what does it make up

Answer 2

DNA comprises of 2 strands of nucleotides which are the basic unit of DNA
it makes up genetic information which controls all cellular activities

Question 3

what are nucleotides made of

Answer 3

each nucleotide is made up of a deoxyribose sugar, phosphate group and one of 4 nitrogenous base (adenine, guanine, thymine, or cytosine)

Question 4

how is genetic info formed?

Answer 4

during cell division, molecule of DNA is wrapped around proteins to forms single chromatin threads that will coil more tightly to form genetic info during cd

Question 5

what are genes

Answer 5

genes are a sequence of nucleotides controlling the formation of a single polypeptide, the unit of inheritance in a living organism, the segment of DNA in a chromosome where genetic info is stored

Question 6

what does the polypeptide assist in?

Answer 6

it folds to make proteins that contribute to the development of many characteristics in our bodies

Question 7

what will a change in nucleotide sequence do

Answer 7

gene mutation – may or may not lead to change in protein product and hence may lead to observable change in phenotype (trait)

Question 8

what are chromosomes

Answer 8

condensed form of chromatin that consists of DNA wound around proteins to be more compact and contains a number of genes along its length

Question 9

what is complementary base pairing

Answer 9

where each dna molecule consists of 2 antiparallel polynucleotide chains that are coiled and form double helixes and are held by bonds between comp pairs of bases

Question 10

what are the nitrogenous bases and their ratios

Answer 10

adenine and thymine (uracil in mRNA)
guanine and cytosine
1:1

Question 11

what is the genetic code

Answer 11

where 3 bases genetic info accounts for 1 codon which is one amino acid that will be read by the ribosomes in cytoplasm to form a single polypeptide

Question 12

what is the process called where DNA turns into RNA and into protein?

Answer 12

transcription -> translation

Question 13

what is RNA

Answer 13

ribonucleic acid
ribose sugar instead of deoxyribose

Question 14

what is genetic engineering

Answer 14

the alteration of an organism’s genetic material

Question 15

what is a transgenic organism

Answer 15

a transgenic organism is whereby its genome has been altered by acquiring a foreign gene either from diff or same species

Question 16

what is a vector

Answer 16

a circular piece of DNA extracted from a bacterium ie plasmid and is used to transfer genes from one organism to the other

Question 17

what are the steps in genetically engineering a bacterial cell e.g inserting human insulin one to an E.coli cell

Answer 17

1. gene for insulin is extracted from the nucleus of human cell by cutting it out using restriction enzyme, which then cuts DNA that leaves single stranded segments nucleotides with their bases exposed
2. the plasmid from the bacterium is then cut using that same restriction enzyme to generate complementary bases
3. the plasmid will then be mixed with the human insulin gene where complementary ends will bind to each other and dna ligase will seal the gaps between the insulin gene and plasmid, and then catalyses the formation of sugar phosphate bonds between adjacent nucleotides
4. the recombinant plasmid (plasmid with target gene inserted) is then inserted into the bacterial cell by creating temporary pores in the bacterial cell membrane by electric or heat shocks
5. the recombinant plasmid is then transferred to a bacterial host (e.g e.coli) where electric or heat shocks are used to create temporary pores in the cell membrane for plasmid to enter, the transgenic bacteria will then express the new gene and then manufacture insulin
6. the bacteria will then be cultured in a fermenter so that a large quantity of human insulin can be manufactured and subsequently purified for medicinal use

Question 18

what happens if gaps between insulin gene and plasmid are not sealed?

Answer 18

the resulting e.coli will not contain the human insulin gene bc of weak complementary base pairing where the insulin gene will most likely dissociate from the plasmid and only the plasmid will enter the bacterium

Question 19

what are the advantages of genetically engineered organisms compared to obtaining them from animal sources

Answer 19

• lower costs compared to rearing animals
• more sterile conditions (animals may have viruses )
• DNA of animals are structurally different (WBCs can recognize as foreign hence allergic reaction
• lesser risk of contamination by disease causing microorganisms like bacteria as compared to ____ obtained from animal

Question 20

steps in genetically engineering a plant cell

Answer 20

1. gene of interest is extracted from the donor by cutting it out using a restriction enzyme where enzyme cuts DNA in way single stranded segments of nucleotides with bases exposed are left
2. the plasmid from ___ is cut using that same restriction enzyme to generate complementary sticky ends
3. Plasmid is then mixed with gene od interest where complementary sticky ends bind to e/o by complementary base pairing and gaps between __ gene and __ plasmid are sealed with DNA ligase
4. the recombinant plasmid is the inserted into bacterial cell by creating temporary pores in bacterial cell membrane by electric or heat shocks
5. the plant cells infected with the transgenic bacteria are then grown in culture in a lab will then be developed into a whole plant to produce ____

Question 21

what are the social implications of genetic engineering

Answer 21

• genetically engineered organisms are used for chemical / biologicL warfare might reproduce faster leading to an increased level of deforestation
• rich gain access to enhancement of health and physical capabilities, drives the rich poor gap wider

Question 22

what are the ethical implications of genetic engineering

Answer 22

• it is morally wrong to exploit animals for medical research / manipulate the genetic make up of animals
  -cpnsumption of medical products/ goo food can cause ethical issues in vegans
• what % of human genes does an organism have to contain until it is considered human

Question 23

what are some health hazards of genetic engineering

Answer 23

new proteins in GM food may cause allergies in humans that consume them
- modifying a single gene in plants could result in an alternative of metabolic processes in plants and hence results in production of toxins which pose health problems when consumed
- genes that code for antibiotic resistance may be accidentally incorporated into disease causing organisms

Question 24

what are the environmental hazards of genetic engineering

Answer 24

• GM crop plants producing insect toxins may result in death of useful insects that feed on the and result in loss of biodiversity

Question 25

what are some economic hazards of genetic engineering?

Answer 25

- poorer farmers not able to afford to seeds of modified crop plants -- richer farmers get richer through technology

Question 26

outline the relationship among DNA, genes and chromosomes

Answer 26

DNA — 2 strands of nucleotides twisted to form double helical structure Chromosomes — molecules of DNA wrapped around proteins Gene — a sequence of nucleotides that code for a polypeptide