Chapter 16: Molecular Basis of Inheritance

Question 0

Why did researchers originally think that protein was the genetic material?

Answer 0

Identified as a class of macromolecules with great heterogeneity and specificity of function

Question 1

What are the two chemical components of chromosomes?

Answer 1

DNA and protein

Question 2

Distinguish between the virulent and nonvirulent strains of pneumonia

Answer 2

Virulent: living s cells
Nonvirulent: living r cells and heat killed s cells

Question 3

What was the purpose of griffiths studies

Answer 3

Find a vaccine for pneumonia

Question 4

Define transformation

Answer 4

Defined as a change in genotype and phenotype due to the assimilation of external DNA by a cell

Question 5

What did Avery determine to be the transforming factor?

Answer 5

DNA

Question 6

Explain Avery’s experimental approach

Answer 6

Took out the contents of a heat killed pathogenic bacteria. Treated three samples with an agent that inactivated one type of molecule. Tested the sample for ability to transform live nonpathogenic bacteria. Only when DNA stayed did transformation happen

Question 7

How does a bacteriophage destroy a bacterial cell

Answer 7

Attachment 
Entry 
Synthesis 
Assembly
Release

Question 8

How did Hershey and Chase label viral DNA and viral proteins so that they could be distinguished

Answer 8

They wanted to see which of these molecules entered the cells and could reprogram them to make more Phages

Question 9

Describe the means by which Hershey and Chase established that only the DNA of the phages entered an E. coli cell. What conclusions did the scientist draw based on these observations

Answer 9

Phage DNA entered bacterial cells but phage proteins did not. Hershey and Chase concluded that DNA, not proteins, function as the genetic material of phage T2

Question 10

What are chargaffs rules? How did he arrive at them?

Answer 10

The bass composition varies between species
Within a species the number of A and T bases are equal and the number G and C bases
He studied the ratios between the bases

Question 11

This the three components of a nucleotide

Answer 11

Phosphate, deoxyribose, nucleic acid

Question 12

Who built the first model of DNA and should the 1962 Nobel Prize for discovery of its structure

Answer 12

Watson and Crick

Question 13

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

Answer 13

X-ray crystallography

Question 14

Do you distinguish between the structure of pyrimidines and purines. Explain why adenine bonds only to thymine

Answer 14

Pyrimidines have one organic green while purines have two organic rings
They fit together like a puzzle

Question 15

How did Watson and crick’s model explain the basis of chargaffs rules

Answer 15

The model show that for DNA double helix structure to work. A -T and C-G

Question 16

Adenine and guanine are both…

Answer 16

Purines

Question 17

Cytosine thymine and Uracil are all

Answer 17

Pyrimidine

Question 18

Explain the base pairing rule

Answer 18

A forms two hydrogen bonds with T
G forms three hydrogen bonds with C
Pyrimidines always bind to purines

Question 19

Distance across molecule
Distance between nucleotides
Distance between turns

Answer 19

1nm
.34nm
3.4nm

Question 20

Components of the backbone

Components of the rungs

Answer 20

Sugar (deoxyribose) and phosphate

Nitrogenous base

Question 21

Explain what is meant by five’ and three’ ends of the nucleotide

Answer 21

Third carbon and deoxyribose close the phosphate group

Fifth carbon in the deoxyribose close to the OH group

Question 22

What is a semi conservative model of replication

Answer 22

Double strand separate a new DNA forms old strand as template

Question 23

Who performed experiments that elucidated the correct mechanism of DNA replication

Answer 23

Meselson and Stahl

Question 24

How did Meselson and stahl create heavy DNA for their experiments

Answer 24

Marking with N15

Question 25

Defined the origins of replication

Answer 25

Short stretches of DNA having a specific sequence of nucleotides

Question 26

Distinguish between leading in the lagging strands during DNA replication

Answer 26

Leading: DNA pol 3 adds nucleotides to the new complementary 5'-3' Lagging: DNA pol3 world along the other template in the othe direction 3'-5'

Question 27

What is the direction of synthesis of the new strand

Answer 27

From 5' to 3'

Question 28

What are Okazaki fragments? How are they welded together?

Answer 28

The lighting is synthesized discontinuously as a series of segments welded together by DNA ligase

Question 29

Which enzyme untwists and separate strands

Answer 29

Helo case

Question 30

Which enzyme holds DNA strands apart

Answer 30

Single-stranded binding protein

Question 31

Which enzyme synthesizes RNA primer

Answer 31

Primase

Question 32

Which enzyme ads DNA nucleotides to new strands

Answer 32

DNA polymerize three

Question 33

Enzyme to relieve strain cause by unwinding

Answer 33

Topoisomerase

Question 34

Which enzyme joins DNA fragments together

Answer 34

DNA ligase

Question 35

Which enzyme removes are in a primary replaces with DNA

Answer 35

DNA polymerase one

Question 36

Steps that occur in the synthesis of a new strand

Answer 36

Helicase unwinds the double helix SSBP stabilizes Leading strand synthesizes in 5'-3' direction by DNA pol lll Primase synthesizes RNA primer for Okaxaki fragments DNA nucleotides added to RNA primer Okazaki fragments DNA pol l removes RNA primer and adds DNA DNA ligase bonds Okazaki fragments

Question 37

What is the role of DNA pol

Answer 37

Adds new nucleotides

Question 38

What is the role of the nuclease

Answer 38

Exices damage area of DNA

Question 39

What is the role of ligase

Answer 39

Seals free ends of DNA

Question 40

What is the role of repair enzymes

Answer 40

To repair a genetic damage

Question 41

What is a thymine dimer? How might it occur? How is it repaired?

Answer 41

Covalent the linking of thymine is Thymine dimer It is repaired by nucleotide exicion repair It can occur by exposure of ultraviolet rays from the sun

Question 42

Explain telomere erosion and the role of telomerase

Answer 42

Catalyzes the lengthening of telomeres and eukaryotic germ cells thus restoring their original length compensating for the shortening that occurs during DNA replication

Question 43

Why are cancer cells immortal but most body cells have a limited life span

Answer 43

Cancer cells have the ability to stabilize the telomerase causing it to be able to live longer

Question 44

Distinguish between heterochromatin and euchromatin

Answer 44

In heterochromatin it is more compact and in irregular clumps. In euchromatin it is more dispersed and can be expressed