DNA STRUCTURE

Question 1

What is a polar molecule?

Answer 1

Molecule that contains atoms at either end with differing attractive forces to the electrons they share. This results in one end having a slightly negative charge whilst the other positive.

Question 2

What are two examples of substances that are hydrophillic?

Answer 2

Ionic and polar molecules. (e.g. NaCl and urea)

Question 3

What is a property of hydroxyl group?

Answer 3

Polar

Question 4

What is a property of a methyl group?

Answer 4

Nonpolar

Question 5

What is a property of a carbonyl group?

Answer 5

Charged, ionises to release H+ (acidic)

Question 6

What is a property of an amino group?

Answer 6

Charged, accepts H+ to form NH3+ and is basic (because amino groups can remove H+ from solution)

Question 7

What is a property of a phosphate group?

Answer 7

Acidic (charged and releases H+ into solution)

Question 8

What is a property of a phosphodiester group?

Answer 8

Charged and present in DNA

Question 9

What is a property of a sulfhydryl group?

Answer 9

Polar

Question 10

Where is ‘extragenic ‘ information read from in DNA?

Answer 10

The surfaces exposed in the double helix

Question 11

What is the extragenic information in DNA used for?

Answer 11

Used by proteins to read the code without unwinding the DNA helix and targeted by toxins and drugs that attack DNA

Question 12

What conditions is A-DNA formed under and what conformation does it have?

Answer 12

Formed under dehydrating conditions and contains tipped bases with a deep major groove.

Question 13

Why is RNA in the A form?

Answer 13

Extra hydroxyl group on the sugar is in the way and as result, the B form is unstable.

Question 14

What is B-DNA and what conditions is it in?

Answer 14

This is the DNA double helix that is found under NORMAL conditions inside cells.

Question 15

What is Z DNA and what conditions is it formed in?

Answer 15

Formed under high salt conditions and has lots of alternating C-G G-C pairs

Question 16

If messenger RNA carries the code for only one polypeptide, what is it termed?

Answer 16

Monocistronic

Question 17

If messenger RNA carries the code for more than one polypeptide, what is it termed?

Answer 17

Polycistronic

Question 18

Between which types of bases in base stacking are interactions strongest?

Answer 18

Between purines

Question 19

What is strange about base pairing in RNA?

Answer 19

Sometimes G pairs with U when two single strands of RNA pair or if RNA folds back on itself

Question 20

Which properties of DNA are often used to help scientist manipulate and study DNA?

Answer 20

Solubility, Charge, Viscosity, UV absorption, Denaturation, Stability

Question 21

In UV light absorption, where does Dye bind to in DNA to emit a blue light under UV?

Answer 21

The dye binds to the minor groove in AT rich regions

Question 22

If there are more G-C bonds, what effect does this have on DNA?

Answer 22

Increases melting temperature and increases stability (linear relationship)

Question 23

The phosphodiester bonds that link nucleotides in both RNA and DNA are broken by…… and join……

Answer 23

broken by mechancal shearing and join the 3’ hydroxyl of one nucleotide to the 5’ hydroxyl of the next

Question 24

Do DNA binding proteins interact with the bases on the major or minor groove?

Answer 24

They interact on the major groove side because the backbones are not in the way.