Unit 7 Nucleotides

Question 1

Bacteriophages

Answer 1

viruses that create a channel across the bacterial cell membrane and wall to transfer the viral genome DNA to the host cell cytoplasm, initiation infection in the bacterium

Question 2

DNA gyrase

Answer 2

relieves the strain on the coil, ready for helicase to start working

Question 3

Helicase

Answer 3

breaks hydrogen bonds between strands, allowing the helix to uncoil

Question 4

Single strand binding proteins

Answer 4

avoid re-binding of complementary base pairs

Question 5

DNA primase

Answer 5

starts adding RNA primer at the 5’ end

Question 6

DNA polymerase III

Answer 6

adds complementary nucleotides at the primer in the 5’ -5’ direction

Question 7

DNA polymerase I

Answer 7

Removes the primer

Question 8

DNA ligase

Answer 8

seals the nicks

Question 9

DNA polymerase I and DNA polymerase III

Answer 9

proofread the new DNA

Question 10

Regulators of gene expression

Answer 10

are non-coding regions of DNA that increase or decrease gene expression

Question 11

Introns

Answer 11

sections of mRNA that are edited out before translation

Question 12

Telomeres

Answer 12

the non-coding DNA extremes of Chromosomes

Question 13

Genes for tRNAs

Answer 13

DNA sections that are transcribed to RNA molecules that act as tRNAs

Question 14

Primary structure of proteins

Answer 14

the sequence and number of amino acids

Question 15

secondary structure of proteins

Answer 15

formation of alpha helices and beta pleated sheets stabilized by hydrogen bonds

Question 16

tertiary structure

Answer 16

the further folding of the polypeptides into globular or fibrous forms, stabilized by interactions between R groups. The bonds maintaining tertiary structure are disulfide bridges, hydrophobic interactions, electrostatic attractions and hydrogen bonds

Question 17

quaternary structure

Answer 17

exists in proteins with more than one polypeptide chain. It can have other molecules such as a prosthetic group