Biological Chemistry - Week 22-23

Question 1

What type of molecule are sugars?

Answer 1

Organic molecules with a lot of hydroxyl (OH) groups.
Also called (mono/poly) saccharides or carbohydrates.

Question 2

What is the relationship between the linear and cyclic form of glucose?

Answer 2

Groups on left are up in cyclic form

Groups on right are down in cyclic form

Question 3

What is an enantiomer?

Answer 3

When everything has flipped sides.

Question 4

What would C-3 epimer mean?

Answer 4

The 3rd carbon (carbon 3) has flipped sides.

Question 5

What is a glycoside linkage?

Answer 5

bond formed between two monosaccharides.

Forms a stable acetal between two sugar molecules

Question 6

What type of reaction forms a glycoside linkage?

Answer 6

a condensation reaction because it produces a molecule of water

Question 7

Where are glycoside linkages found?

Answer 7

Found in cellulose, chitin and lactose.
Used for branches in glycogen and other polysaccharides.
Found in main backbone of a polysaccharide

Question 8

What is the difference in a reducing vs a non-reducing sugar?

Answer 8

Reducing sugars can revert back to linear form and be oxidised.

Question 9

What conditions are needed to reduce a carbonyl to an alcohol?

Answer 9

D-Glucose —-> D-glucitol

formation of sugar alcohols (alditols)

=NaBH4

Question 10

What are the 2 types of nucleic acids?

Answer 10

Deoxyribonucleic acid (DNA)
Ribonucleic acid (RNA)

Question 11

What are the 2 categories of nucleic bases?

Answer 11

Purines and Pyrimidines

Question 12

What are the purine bases?

Answer 12

Adenine and Guanine

Question 13

What are the pyrimidine bases?

Answer 13

Thymine, Cytosine, Uracil

Question 14

What bases pair and how many bonds from between them?

Answer 14

A and T/U —-> 2 bonds

G and C —> 3 bonds

Question 15

What is the complementary DNA and RNA strand for: 5’-AGC CGA AGC AGA CTT-3’

Answer 15

Complementary DNA:
5’-TCG GCT TCG TCT GAA-3’

Complementary RNA:
5’-UCG GCU UCG UCU GUU-3’

Question 16

What position are nucleic bases attached to nucleosides?

Answer 16

On the 2 position of the sugar

Question 17

Where are phosphates attached on nucleotides?

Answer 17

One or more phosphates are attached at the 5’ position of the sugar.

Question 18

What are the 3 types of RNA?

Answer 18

messenger RNA (mRNA)
ribosomal RNA (rRNA)
transfer RNA (tRNA)

Question 19

What is the difference between mRNA and tRNA?

Answer 19

for generic RNA give the mRNA sequence, tRNA will be different

tRNA is the complementary sequence of mRNA.

Question 20

What are amino acids the building blocks of?

Answer 20

building blocks of peptides and proteins

Question 21

What determines the type of amino acid present?

Answer 21

Amino acids contain a minimum of two groups with acid-base character.
Their net charge determines pH.

Question 22

What are the three different forms of amino acids possible?

Answer 22

Acidic, basic or neutral amino acids.

Question 23

What is the isoelectric point (pl)

Answer 23

the pH at which an amino acid is in its zwitterionic form

5.5 - 6.0 for neutral amino acids

Question 24

What is the formula for isoelectric point?

Answer 24

pl = (pKa1 + pKa2) / 2

Question 25

Which direction is an amino acid sequence read?

Answer 25

from the N to the C terminus

Question 26

How are amide bonds formed?

Answer 26

When the amine group of one amino acid forms a bond with the carboxyl group of another amino acid
Resulting in the loss of a single water molecule