Exam 1 CHP 1-2

Question 1

What are the two chemical components of chromosomes

Answer 1

DNA and Protein

Question 2

Why did researchers originally think that protein was the genetic material

Answer 2

They had a lot of functions, complex, more of them

Question 3

Distinguish between S and R strains; summarize the experiment in which Griffith discovered there had to be hereditary information

Answer 3

The r strain was safe, but the S strain was not. Living R bacteria had been transformed into S strain by an unknown heritable substance (S factor)

Question 4

How did Avery, Mcarthy, and Macleod determine the transforming S-factor was likely DNA and not protein? What enzymes were used and why?

Answer 4

The N/P ratio of the S-strain was closer to DNA and not protein. They used RNase, Protease, and DNase to destroy those molecules

Question 5

Three different bonds S-W, describe them

Answer 5

Covalent (shared) Ionic (donate receive electrons) Hydrogen (partial charges)

Question 6

How did Hershey and Chase “label” viral DNA and viral protein so that they could be distinguished?

Answer 6

Used radioactive isotopes of sulfur and Phosphorous to tag protein and DNA

Question 7

Explain why Hershey and Chase chose each radioactive tag considering the chemical composition of DNA and protein

Answer 7

Only protein contains sulfur and only DNA contains phosphorus

Question 8

How many different DNA sequences of eight bases can you make?
How many different Amino Acid sequences of eight amino acids can you
make?

Answer 8

4^8, 20^8

Question 9

How did Hershey and Chase establish that only DNA entered the cell? What conclusions did they draw

Answer 9

Radioactive DNA cells entered the host cells but the protein did not. DNA must hold the genetic information

Question 10

List the three components of a nucleotide

Answer 10

Phosphate group, 5 pentose carbon sugar, nitrogenous group

Question 11

What was Rosalind Franklin’s role in the discovery of the double helix

Answer 11

she had conducted critical experiments that allowed Watson and Crick to get the double helix

Question 12

What are the structures of Pyrimidines and Purines? What are they? Why do they bond

Answer 12

Pyrimidines (Cytosine and Thymine) are 6-membered rings and Purines (Adenine and Guanine) are 6-membered rings fused to 5-membered. Because they are opposites

Question 13

what is meant by 5’ and 3’

Answer 13

one end is attached to a 5’ carbon other is 3’

Question 14

What is the semiconservative model of replication

Answer 14

Two Strands of the parental DNA molecule separate and each serves as a template

Question 15

Draw and Explain the three banding patterns after 1 and 2 rounds of bacterial replication

Answer 15

See drawing

Question 16

What is a hypothesis

Answer 16

Testable explanation for a set of observations

Question 17

In the mouse coloration experiment what factors were held constant

Answer 17

Camoflouged mouse in normally resident area

Question 18

Which enzyme adds DNA nucleotides, and why? What is the direction of the new strand

Answer 18

DNA Polymerase, because of its structure. 5’-3’

Question 19

If the population is 6x larger than the initial population how many generations passed

Answer 19

2.585

Question 20

How many times larger is a population 10^8 than 10^3

Answer 20

100,000

Question 21

A DNA molecule has 180 base pairs and 20% are adenine. What percentage is cytosine, and how many nucleotides

Answer 21

.30 108 Cytosine

Question 22

Draw and label the 3 types of RNAs and describe them in the central dogma

Answer 22

mRNA-dispersed throughout the whole thing, because it varies in size since they are long strands. least abundant. (DNA is copied into mRNA)

tRNA- the bottom, the smallest (brings correct amino acid to ribosomes)

rRNA-most abundant. 2 rings, has two sizes. Structure of a ribosome (synthesize protein)

Question 23

What is RNA splicing? what are kept and whats removed

Answer 23

mRNA can be spliced in different ways to produce multiple versions. allows a single gene to code for many proteins. Introns are removed, exons are kept.

Question 24

What is gene expression

Answer 24

information encoded in DNA directs the synthesis of proteins

Question 25

How many nucleotide bases are there, amino acids. How many are required code for each of these 20 amino acids

Answer 25

4, 20, 3

Question 26

Promoter

Answer 26

Binds to RNA Polymerase. Tells RNA where to start

Question 27

Operator

Answer 27

Binds with the repressor. The on-and-off switch

Question 28

Operon

Answer 28

The whole thing

Question 29

Repressor

Answer 29

binds to the operator to prevent RNA Polymerase from transcribing the code

Question 30

Regulatory genes

Answer 30

Codes for protein (LAC B, LAC Y, LAC T)

Question 31

Corepressor

Answer 31

binds to the repressor and changes its shapes, allowing the repressor to be on or off

Question 32

Draw the Lac operon when it’s on and off

Answer 32

see Drawing

Question 33

What is a codon, and how many variations exist

Answer 33

triplet mRNA sequences, 64

Question 34

Transcription

Answer 34

synthesis of RNA using DNA as the template

Question 35

Translation

Answer 35

the synthesis of a polypeptide using mRNA

Question 36

Which enzyme uses the DNA template to transcribe new mRNA? which direction

Answer 36

RNA Polymerase 5’-3’

Question 37

What is a ribosome

Answer 37

translate genetic code into corresponding amino acid (cytoplasm)

Question 38

what is an anticodon

Answer 38

triplet that bases pair with a complementary codon

Question 39

What do I,O, B,P mean

Answer 39

I-repressor
O-operator and promoter
B-beta enzyme
P-permease