Section 6: DNA Replication and Gene Expression

Question 1

4 nucleotides

Answer 1

Adenine
Thymine
Guanine
Cytosine
(A-T) (G-C)

Question 2

Codon

Answer 2

set of 3 nucleotides on a single strand = specific amino acid

Question 3

DNA replication

Answer 3

• begins at Origin
• synthesized by both strands = semi-conservative
• 5’-3’ direction, continuous = leading strand; discontinuous = lagging strand (okazaki fragments)

Question 4

Replication process

Answer 4

1. open DNA double helix
2. build primers
3. assembly of complementary strands
4. remove primers and join okazaki fragments

Question 5

Gene expression

Answer 5

info passes from DNA to an RNA copy of the gene, RNA directs sequential assembly of a chain of amino acids

Question 6

Central Dogma

Answer 6

DNA -(transcription)->RNA-(tranlsation)->protein

Question 7

Transcription

Answer 7

mRNA from DNA template by RNA polymerase
RNA - A-U, G-C
Newly formed mRNA is moved to ribosomes for translation

Question 8

Translation

Answer 8

process of synthesizing proteins that occurs same time as transcription
occurs on ribosome
aa’s assembled into growing polypeptide chain (protein when folded)

Question 9

Operons

Answer 9

• Definition: set of adjacent genes controlled by a regulatory protein and transcribed as a single RNA
• bacteria have multiple genes encoded on ONE RNA, and uses only ONE promotor. Regulatory protein binds NEAR the promotor = on/off switch
• inducible / repressible operons

Question 10

Inducible Operons

Answer 10

genes that are not always being transcribed and must be TURNED ON (or induced) to function
- requires an inducer to bind to operator so that a repressor operon doesn’t bind instead.

Question 11

Repressor Operons

Answer 11

genes that are always turned on and must be repressed to stop proteins from being made.
- requires a repressor operon to bind to operator.

Question 12

Feedback Inhibition

Answer 12

end products inhibit earlier pathway enzymes, thus preventing production of the end product

Question 13

Replication of Plasmids

Answer 13

occurs separately from chromosomal replication;
each plasmid has own ori (origin);
often carry antibiotic resistance genes and virulence genes