Lesson test: What the gene is made of

Sign in

Libre University uses your GitHub account. Signing in is only needed to sit a final test, so the score is kept on your profile.

What the gene is made of

1.[2p]
Why did most biologists before 1944 expect the genetic material to be protein?

Proteins are built from twenty units and DNA was believed to be a monotonous repeating tetranucleotide

Correct

DNA had not yet been found in chromosomes

The answer is: Proteins are built from twenty units and DNA was believed to be a monotonous repeating tetranucleotide

Proteins were the only molecules known to be inherited

The answer is: Proteins are built from twenty units and DNA was believed to be a monotonous repeating tetranucleotide

DNA was thought to be present only in bacteria

The answer is: Proteins are built from twenty units and DNA was believed to be a monotonous repeating tetranucleotide

2.[2p]
Put these experiments in the order they were published.

Griffith's transformation in mice
The Watson and Crick model
Chargaff's base ratios
Avery, MacLeod and McCarty's enzymatic subtraction
Hershey and Chase's blender experiment

Show the answer

a, b, c, d, e

3.[3p]
What was the logical structure of the Avery, MacLeod and McCarty experiment?

Everything else could be destroyed without abolishing transformation, and only deoxyribonuclease abolished it

Correct

Purified DNA was synthesised and shown to transform

The answer is: Everything else could be destroyed without abolishing transformation, and only deoxyribonuclease abolished it

Protein was shown to be absent from the extract

The answer is: Everything else could be destroyed without abolishing transformation, and only deoxyribonuclease abolished it

Transformation was shown to require living donor cells

The answer is: Everything else could be destroyed without abolishing transformation, and only deoxyribonuclease abolished it

4.[1p]
The Hershey and Chase experiment gave a clean separation, with all protein outside the cell and all DNA inside.

True

The answer is: False

False

Correct

5.[3p]
Which of Chargaff's two findings did most damage to the tetranucleotide hypothesis at the time?

That the ratio of AT to GC varies widely between species

Correct

That adenine equals thymine within a species

The answer is: That the ratio of AT to GC varies widely between species

That guanine equals cytosine within a species

The answer is: That the ratio of AT to GC varies widely between species

That all four bases are present in every organism

The answer is: That the ratio of AT to GC varies widely between species

6.[2p]
Photo 51 gave a base spacing of 0.34 nm and an axial repeat of 3.4 nm. How many base pairs are there per turn of the helix?

CorrectNot quite: 10

7.[2p]
Why must a purine always pair with a pyrimidine in the double helix?

Only that combination gives every rung the same width, so the backbones stay a constant distance apart

Correct

Purines cannot form hydrogen bonds with each other

The answer is: Only that combination gives every rung the same width, so the backbones stay a constant distance apart

Two pyrimidines would be too heavy

The answer is: Only that combination gives every rung the same width, so the backbones stay a constant distance apart

It is a consequence of the sugar phosphate backbone charge

The answer is: Only that combination gives every rung the same width, so the backbones stay a constant distance apart

8.[3p]
What does the two-stranded, complementary structure buy a cell?

Select all that apply

A template for copying, since each strand specifies the other

Correct

A repair mechanism, since damage to one strand can be read off the other

Correct

Chemical protection, since the reactive base edges are turned inward

Correct

A higher mutation rate, which speeds adaptation

The answer is: A template for copying, since each strand specifies the other, A repair mechanism, since damage to one strand can be read off the other, Chemical protection, since the reactive base edges are turned inward

9.[2p]
At two bits per base pair, how many megabytes does a haploid human genome of 3.2 billion base pairs hold?

CorrectNot quite: 800

1.[2p] Why did most biologists before 1944 expect the genetic material to be protein?

2.[2p] Put these experiments in the order they were published.

3.[3p] What was the logical structure of the Avery, MacLeod and McCarty experiment?

4.[1p] The Hershey and Chase experiment gave a clean separation, with all protein outside the cell and all DNA inside.

5.[3p] Which of Chargaff's two findings did most damage to the tetranucleotide hypothesis at the time?

6.[2p] Photo 51 gave a base spacing of 0.34 nm and an axial repeat of 3.4 nm. How many base pairs are there per turn of the helix?

7.[2p] Why must a purine always pair with a pyrimidine in the double helix?

8.[3p] What does the two-stranded, complementary structure buy a cell?

9.[2p] At two bits per base pair, how many megabytes does a haploid human genome of 3.2 billion base pairs hold?

1.[2p]
Why did most biologists before 1944 expect the genetic material to be protein?

2.[2p]
Put these experiments in the order they were published.

3.[3p]
What was the logical structure of the Avery, MacLeod and McCarty experiment?

4.[1p]
The Hershey and Chase experiment gave a clean separation, with all protein outside the cell and all DNA inside.

5.[3p]
Which of Chargaff's two findings did most damage to the tetranucleotide hypothesis at the time?

6.[2p]
Photo 51 gave a base spacing of 0.34 nm and an axial repeat of 3.4 nm. How many base pairs are there per turn of the helix?

7.[2p]
Why must a purine always pair with a pyrimidine in the double helix?

8.[3p]
What does the two-stranded, complementary structure buy a cell?

9.[2p]
At two bits per base pair, how many megabytes does a haploid human genome of 3.2 billion base pairs hold?