Unit 2: Genetics

Question 1

Structural units that make up DNA:

Answer 1

• two long strands wrapped around each other to form a double helix
• the double helix looks like a twisted ladder, and each strand is composed of many nucleotides
• each strand of DNA composing the double helix has a “backbone” consisting of alternating deoxyribose sugar and phosphate groups

Question 2

The nitrogen-containing bases are cyclic compounds made up of:

Answer 2

• carbon, hydrogen, oxygen, and nitrogen atoms

Question 3

The nitrogen-containing bases are named:

Answer 3

• adenine (A)
• thymine (T)
• cytosine (C)
• guanine (G)
• uracil (U)

Question 4

“A” and “G” are double-ring structures called:

Answer 4

purines

Question 5

“T”, “C”, and “U” are single-ring structures referred to as:

Answer 5

pyrimidines

Question 6

Purine A is always paired with:

Answer 6

Pyrimidine T

Question 7

Purine G is always paired with:

Answer 7

Pyrimidine C

Question 8

If one strand has the sequence … ATGC …, then the other strand has the sequence:

Answer 8

… TACG …

Question 9

Structural units that make up RNA:

Answer 9

• second principal kind of nucleic acid
• usually single stranded
• five-carbon sugar in the RNA nucleotide = ribose; which has one more oxygen atom than deoxyribose

Question 10

One of RNA’s bases is uracil (U) instead of:

Answer 10

thymine

(the other three bases (A, G, C) are the same as DNA

Question 11

Three major kinds of RNA have been identified in cells; each have a specific role in protein synthesis:

Answer 11

• messenger RNA (mRNA)
• ribosomal RNA (rRNA)
• transfer RNA (tRNA)

Question 12

type of RNA molecule that directs the incorporation of amino acids into proteins:

Answer 12

mRNA

Question 13

type of RNA molecule that forms ribosomes:

Answer 13

rRNA

Question 14

type of RNA molecule that brings amino acids to the ribosomal site where they are incorporated into proteins:

Answer 14

tRNA

Question 15

• first major step in cell reproduction

- in bacteria, this is followed by the rest of the binary fission process

Answer 15

DNA replication

Question 16

DNA replication process (simplified):

Answer 16

• DNA double helix is untwisted by special enzymes
• DNA strands are separated from each other and held apart by special enzymes
• new DNA strands are built by DNA polymerase enzymes according to complementary base pairing
• new strands twist with matching old strands to form two complete double helices

Question 17

allows cells the build cell parts made of protein and enzymes, providing them with unique characteristics / abilities:

Answer 17

Protein Synthesis (Transcription + Translation)

Question 18

Transcription process (simplified):

Answer 18

• DNA double helix is untwisted at a gene by special enzymes
• DNA strands are separated at a gene and held apart by special enzymes
• RNA Polymerase enzyme uses the DNA template strand as the pattern or guide for building mRNA by complementary base pairing

Question 19

The newly built mRNA floats away from the gene in the DNA toward a:

Answer 19

ribosome

meanwhile, the two DNA strands are rejoined and twisted back together

Question 20

permanent change in the base sequence of DNA

• sometimes cause a change in the product encoded by that gene
• ex. when the gene for an enzyme mutates, the enzyme encoded by the gene may become inactive or less active because its amino acid sequence has changed

Answer 20

mutation

Question 21

the transfer of genetic material form one cell to another involving cell-to-cell contact:

Answer 21

conjugation

Question 22

Conjugation process (simplified):

Answer 22

• donor is typically F+ (contains a Fertility Plasmid / Conjugation Plasmid)
• recipient is F-
• cell-to-cell contact occurs (by way of a Conjugation Pilus or a Conjugation Bridge)
• a copy of the F factor (the fertility plasmid) is usually transferred into the recipient