ch.16/17 ap bio

Question 1

Who were watson and crick?

Answer 1

in 1953, they built models of a double helix and determined the base pairings (A w/ T, C w/ G)

Question 2

Who was T.H Morgan?

Answer 2

in 1910, he identified genes were on chromosomes through breeding fruit flies.

Question 3

Who was Griffith?

Answer 3

in 1928, he stained bacterium with S and R groups and discovered the transforming principle.

Question 4

Who was Avery, McCarty, and MacLeod?

Answer 4

in 1944, they discovered that the transforming substance was DNA

Question 5

Who were Hershey and Chase?

Answer 5

in 1952, they proved DNA was the genetic material because it entered an E. coli

Question 6

Who was Chargaff?

Answer 6

in 1950, he found that DNA composition varies from one species to another in quantities of A,T,G and C.

Question 7

Who were Franklin and Wilkins?

Answer 7

in 1950, studied the molecular structure of DNA using x-ray crystallography to take a picture of the structure.

Question 8

What is the role of DNA polymerase?

Answer 8

to catalyze the elongation of new DNA in a 5’ to 3’ direction (pol III- leading strand) (poly I- replaces primer with DNA on lagging strand)

Question 9

What is the role of DNA ligase?

Answer 9

joins the Okazaki fragments together.

Question 10

What is the role of primase?

Answer 10

starts an RNA chain from scratch

Question 11

What are telomeres?

Answer 11

postpone the erosion of genes near the ends of DNA strands.

Question 12

describe the direction/complementary sequence from DNA all the way to amino acids.

Answer 12

DNA is read from 3’ to 5’ direction and the mRNA is made in a 5’ to 3’ direction (attaches at 3’ end) using complementary base pairing. Then the mRNA is coded into amino acids read from 5’ to 3’ direction.

Question 13

What does RNA polymerase do?

Answer 13

used in RNA synthesis by prying the DNA strands apart and hooking the RNA nucleotides together

Question 14

Whats a promoter

Answer 14

in transcription, the DNA sequence in which RNA polymerase attaches.

Question 15

What are transcription factors?

Answer 15

they mediate the binding of RMA polymerase and the initiation of transcription.

Question 16

what is a crucial promoter found in eukaryotes called?

Answer 16

the TATA box

Question 17

what happens during the elongation of transcription?

Answer 17

RNA polymerase will move along the DNA, untwisting the double helix

Question 18

how does termination work during transcription in prokaryotes?

Answer 18

the polymerase stops transcription at the end of the terminator (the stopping sequence of DNA)

Question 19

how does termination work during transcription in eukaryotes?

Answer 19

the polymerase eventually falls off of the DNA

Question 20

how is mRNA modified in eukaryotes?

Answer 20

introns are taken off and a modified nucleotide cap is added to the 5’ end and a poly-A tail is added to the 3’ end.

Question 21

What are ribozymes and spliceosomes?

Answer 21

catalytic RNA molecules that can splice RNA

Question 22

describe the structure of tRNA molecules

Answer 22

the top end carries a specific amino acid and on the bottom end is an anticodon whose base pairs with a complementary codon on mRNA.

Question 23

what does aminoacyl-tRNA synthetase do?

Answer 23

helps to match a tRNA molecule to an amino acid

Question 24

what are the three binding sites on ribosomes and what happens at each?

Answer 24

A site- holds the tRNA that carries the next amino acid
P site- holds the tRNA that carries the growing polypeptide chain
E site- exit site where tRNA’s leave

Question 25

what happens during the initiation stage of translation?

Answer 25

an mRNA molecule and tRNA come together in the small ribosomal subunit and initiation factors bring in the large subunit so that the tRNA occupies the p site.

Question 26

what happens during the elongation stage of translation?

Answer 26

amino acids are added one by one to an amino acid chain and each addition involves three steps: codon recognition, peptide bonding, and translocation.

Question 27

what happens during termination in translation?

Answer 27

a stop codon is reached at the A site and it accepts a release factor, adding a water molecule

Question 28

what are missense and nonsense mutations?

Answer 28

missense mutations use substitution and still code for an amino acid, but not the right one. nonsense mutations use substitution but code for a stop codon

Question 29

what are mutagens?

Answer 29

physical or chemical agents that can cause mutations