Biological Molecules

Question 1

List the ways mRNA is different to DNA.

Answer 1

1) mRNA is single stranded 2) Has uracil instead of thymine 3) It is not helical 4) It is a smaller/shorter molecule 5) Contains ribose instead of deoxyribose

Question 2

Why is mRNA shorter than DNA?

Answer 2

It only copies one section of DNA (a gene) whereas DNA has lots of genes.

Question 3

How does heat affect a proteins structure?

Answer 3

Increased kinetic energy makes the protein vibrate causing the weak hydrogen bonds to break, changing its 3D shape and denaturing the protein.

Question 4

What does an inorganic ion cofactor do in a reaction?

Answer 4

Bonds with the substrate or enzyme to increase the rate of reaction.

Question 5

What bond joins amino acids together in a polypeptide chain?

Answer 5

Peptide bond. C=ON-H

Question 5

Name the 4 bonds that can occur in the tertiary structure of a protein.

Answer 5

1) Disulfide bonds 2) ionic bonds 3) hydrogen bonds 4) hydrophobic/hydrophilic interactions

Question 6

True/False: Fibrous proteins are soluble.

Answer 6

False. They are insoluble and globular proteins are soluble.

Question 7

What is the sugar in a nucleotide of DNA?

Answer 7

Deoxyribose (a pentose monosaccharide)

Question 8

What bond joins nucleotides to each other?

Answer 8

Phosphodiester bonds on C3 and C5.

Question 9

Which of the bases are purines?

Answer 9

Adenine and guanine.

Question 10

Which pair of bases has 3 hydrogen bonds?

Answer 10

Cytosine and guanine.

Question 11

What does polymerase do in semi-conservative replication?

Answer 11

Joins the nucleotides together using phosphodiester bonds.

Question 12

What is a codon?

Answer 12

Sequence of 3 bases. Each codon codes for an amino acid.

Question 13

Name the section of DNA testing that codes for a entire protein.

Answer 13

Gene

Question 14

What is the role of tRNA in translation?

Answer 14

It carries the amino acids to its corresponding codon.

Question 15

What is ATP made of?

Answer 15

3 phosphate groups, nitrogenous base (adenine) and ribose sugar.

Question 16

Why is ice being less dense than water good for organisms?

Answer 16

Because it insulates the water below and helps regulate their environment.

Question 17

When two monosaccharides react what is the bond that joins them?

Answer 17

Glycosidic bond.

Question 18

True/False: Amylopectin has many branches.

Answer 18

True. It has 1,4 and 1,6 glycosidic bonds which causes branching.

Question 19

Why is cellulose in a rigid straight chain?

Answer 19

Because it is made of beta glucose where every other one is flipped.

Question 20

If Benedict’s reagent is added to a substance and it produces a brick red precipitate, what is in the substance?

Answer 20

A monosaccharide (reducing sugar) eg. Glucose

Question 21

When iodine is added to a substance and it changes from yellow to black, what is in the substance?

Answer 21

Starch

Question 22

What is a triglyceride made of and what is the bond that joins them?

Answer 22

1 glycerol molecule and 3 fatty acids joined by an ester bond.

Question 23

Name three roles of lipids.

Answer 23

1) phospholipid bilayer in membranes 2) waterproofing the surface of leaves 3) thermal insulation