8

Question 1

griffith

Answer 1

first experiments to demonstrate that molecules can transfer genetic information from one organism to another
Griffith concluded that some type of molecule in the debris of dead virulent cell carried the genetic information for virulence, but did not identify the molecule

Question 2

Watson and Crick

Answer 2

Doubel helix structure

Question 3

TATA box

Answer 3

many eukaryotic and archaea promoters contain a sequence similar to 5’-TATAAA-3’

Question 4

Pol II

Answer 4

In eukaryotes, the RNA polymerase complex responsible for transcription of protein-coding genes is called PoI II
Once the mediator complex and PoI II complex are in place, transcription begins (transcriptional initiation)

Question 5

Meselson and Stahl

Answer 5

found that DNA replicated semiconservatively

Question 6

Okazaki fragments

Answer 6

short pieces in the lagging strand

Question 7

Leading strand

Answer 7

daughter strand has its 3’ end pointed toward the replication fork so that as the parental double helix unwinds, nucleotides can be added onto the 3’ end and this daughter strand can be synthesised as one long, continuous polymer

Question 8

Lagging strand

Answer 8

5’ end is pointed toward the replication fork. As the replication fork unwinds, it grows away from the fork and forms a stretch of a few hundred or thousand nucleotides. Then as the parental DNA du[lex unwinds further, a new daughter strand is initiated with its 5’ end near the replication fork and this strand is elongated at the 3’ end as usual.

Question 9

Topoisomerase II

Answer 9

works upstream from the replication fork to relieve the stress on the double helix that results from its unwinding at the replication fork

Question 10

helicase

Answer 10

separates the strands of the parental double helix at the replication fork

Question 11

4 essential components for PCR

Answer 11

Template DNA
DNA polymerase
All four deoxynucleoside triphosphates (bases)
Two primers- two short sequences of single-stranded DNA required for the DNA polymerase to start synthesis. Enough primer is added so that the number of primer DNA molecules is much greater than the number of template DNA molecules

Question 12

Palindromic (restriction enzymes)

Answer 12

symmetrical cleaving that reads the same in both directions; typical of restriction sites
The cleaved molecules therefore each terminate in a short single-stranded overhang

Question 13

CRISPR

Answer 13

Transform a cell with a plasmid containing sequences that code for a CRISPR RNA as well as the CRISPR-associated protein Cas9
The RNA contains a region that can form a hairpin shaped structure as well as a region engineered to have bases complementary to any DNA molecule in the cell to be altered, known as the target DNA
When the RNA undergoes base pairing with the target DNA, Cas9 cleaves the target DNA
Exonucleases in the cell then expand the gap
The gap can be repaired using another DNA molecule that serves as a template for editing the target DNA
This editing template DNA is introduced to the cell by a plasmid and contains a sequence of interest to replace the degraded sequence of the target DNA, flanked by sequences complementary to the target
The strands of the gapped target DNA undergo base pairing with the complementary ends of the editing template and DNA synthesis elongates the target DNA strands and closes the gap
The results is that the target DNA is restored, but its sequence has been altered according to the sequence present in the editing template

Question 14

transposable elements/transposons

Answer 14

movable DNA sequences

Question 15

integrase

Answer 15

cuts genomic DNA and inserts the retrotransposon at the cut site