Chapter 14 - Molecular Genetics

Question 1

What does DNA stand for?

Answer 1

Deoxyribonucleic acid.

Question 2

How much DNA is in each human cell’s nucleus?

Answer 2

Approximately 2 metres.

Question 3

Why is DNA important for cellular functions?

Answer 3

It carries genetic information required for cell division and cell differentiation.

Question 4

What is the basic unit of a DNA molecule?

Answer 4

A nucleotide.

Question 5

What three components make up a nucleotide?

Answer 5

A 5‑carbon deoxyribose sugar, a phosphate group, and a nitrogenous base.

Question 6

Name the four nitrogenous bases in DNA.

Answer 6

Adenine, Thymine, Cytosine, Guanine.

Question 7

What is the sugar‑phosphate backbone?

Answer 7

The alternating sugar (deoxyribose) and phosphate groups that form the DNA strand’s exterior.

Question 8

What is complementary base pairing?

Answer 8

Adenine pairs with Thymine (2 hydrogen bonds) and Cytosine pairs with Guanine (3 hydrogen bonds).

Question 9

Why is the A:T and C:G ratio always 1:1?

Answer 9

Because complementary base pairing dictates equal numbers of each.

Question 10

What does “antiparallel strands” mean?

Answer 10

The two DNA strands run in opposite directions (5′→3′ and 3′→5′).

Question 11

What 3D shape does DNA form?

Answer 11

A double helix.

Question 12

How does DNA form a chromosome?

Answer 12

DNA wraps around proteins (histones) and coils up into a chromosome.

Question 13

What is a gene?

Answer 13

A sequence of DNA nucleotides that codes for a particular protein.

Question 14

Where is information stored in a gene?

Answer 14

In the sequence of bases (the genetic code).

Question 15

What could happen if the genetic code is altered?

Answer 15

It may affect protein structure or function, altering body structure or function.

Question 16

What is transcription?

Answer 16

Copying the gene’s information from DNA into mRNA in the nucleus

Question 17

What happens to mRNA after transcription?

Answer 17

It travels from the nucleus to the cytoplasm.

Question 18

Where does translation occur?

Answer 18

At the ribosome in the cytoplasm.

Question 19

What is a codon?

Answer 19

A sequence of three mRNA bases that codes for one amino acid.

Question 20

Q: What is the final product of translation?

Answer 20

A polypeptide (chain of amino acids).

Question 21

What is genetic engineering?

Answer 21

The technique of transferring genes from one organism to another.

Question 22

What is a vector?

Answer 22

A carrier that transfers genetic material; e.g., a plasmid, bacterium, or virus.

Question 23

What is a plasmid?

Answer 23

A small circular DNA molecule from bacteria used as a vector.

Question 24

Define a transgenic organism.

Answer 24

An organism with a foreign gene inserted into its genome.

Question 25

Step 1 of producing transgenic bacteria for insulin?

Answer 25

Isolate the human insulin gene by cutting at its restriction site using a restriction enzyme to create sticky ends.

Question 26

Step 2 of producing transgenic bacteria?

Answer 26

Cut the bacterial plasmid with the same restriction enzyme to produce complementary sticky ends.

Question 27

Step 3 of producing transgenic bacteria?

Answer 27

Mix gene fragment and plasmid; sticky ends base‑pair; use DNA ligase to seal → recombinant plasmid.

Question 28

Step 4 of producing transgenic bacteria?

Answer 28

Introduce the recombinant plasmid into E. coli via heat shock or electric shock (opens cell membrane pores).

Question 29

Step 5 of producing transgenic bacteria?

Answer 29

Grow transgenic bacteria in fermenters; they express the human insulin gene; harvest and purify insulin.

Question 30

Why is genetically engineered insulin preferred over animal insulin?

Answer 30

It is identical to human insulin → no allergic response, cheaper, large‑scale production, fewer contamination risks, acceptable to vegetarians/religious groups.

Question 31

How does GE reduce medicine costs?

Answer 31

Low‑cost production of important drugs increases accessibility.

Question 32

How can GE help crops grow in extreme conditions?

Answer 32

Engineering drought‑resistant, salt‑tolerant, or nutrient‑efficient crops increases yields.

Question 33

What is Bt crop technology?

Answer 33

Inserting the Bt gene from bacteria into plants → plants produce toxin to kill insect pests.

Question 34

What is Golden Rice?

Answer 34

Rice engineered with daffodil and Erwinia uredovora genes to produce high vitamin A.

Question 35

What allergy concern exists with GM foods?

Answer 35

New proteins may cause allergic reactions; requires extensive safety testing.

Question 36

What are “terminator seeds”?

Answer 36

Engineered seeds that do not germinate, forcing farmers to buy new seeds each season.

Question 37

What animal welfare concern arises in GE research?

Answer 37

Use of transgenic animals (e.g., oncomouse) must consider humane treatment.

Question 38

How could GE be misused for warfare?

Answer 38

Creation of harmful biological or chemical agents via novel gene combinations.

Question 39

Why are antibiotic‑resistance genes a safety issue?

Answer 39

They could accidentally transfer to pathogenic bacteria, making antibiotics ineffective.

Question 40

Now might GE exacerbate inequality?

Answer 40

High costs may limit access to wealthy individuals or nations.