Biomolecules & Amino Acids

Question 1

Name the major families of Biomolecules

hint- there are 8

Answer 1

Carbohydrates, nucleic acids, Lipids, Proteins, Cholesterol / Steroid Hormones/ Vitamins/ Co factors/ Xenobiotics

Question 2

What is the general formula for carbohydrates

Answer 2

(CH 2 ) n

Question 3

What is the function of carbohydrates, giving examples?

Answer 3

Energy source- glucose
Energy storage- glycogen
Structural- part of cell wall in bacteria - peptidoglycan
Cell Surface proteins can often be glycosylated- ABO blood groups

Question 4

What is the definition of isomers?

Answer 4

Same chemical group but different arrangement of atoms in the molecule

Question 5

What is the difference between aldoses and kotoses

Answer 5

Aldoses have the functional group aldehyde - glucose

Ketoses have the functional group ketone - fructose

Question 6

What is the anomeric carbon

Answer 6

Carbon attached to the original carbonyl group in cyclic form is the anomeric carbon

Question 7

What is the difference between alpha and beta glucose? And explain why the difference is important.

Answer 7

The OH group on the anomeric carbon in alpha glucose is down the plan whilst is up the plane in beta glucose.
This is important due to the formation of glycosidic bonds

Question 8

Sucrose =
Maltose =
Lactose=

Answer 8

glucose + fructose
2 x alpha glucose
glucose + galactose

Question 9

What is the difference between glycogen and amylase?

Answer 9

glycogen is branched and amylase is more linear

Question 10

Describe the structure of glycogen.

Answer 10

Linear alpha glucose molecule with alpha-1,4 and alpha-1,6 branches. This is beneficial because more branches means more terminal ends- this increases the number of sites for enzymes which act on terminal ends. Therefore more glucose can be converted form glycogen.

Question 11

Describe the digestion of glycogen

Answer 11

Salivary alpha amylase hydrolyses random alpha-1,4
Pancreatic alpha amylase hydrolyses to a mix of mono and di
Maltase hydrolyses maltose into glucose which is easily absorbed by intestinal mucusoal cells

Question 12

Comment on lactose Intolerance

Answer 12

Normally lactose is broken down by lactase into glucose and galactose in the small intestine. ( membrane bound)
However not possible in people lacking the enzyme-
undigested lactose is then digested by bacteria in the large intestine releasing CO2 and other metabolites.

Question 13

What are nucleotides made up of ?

Answer 13

Pentose sugar
Phosphate
Nitrogenous Base

Question 14

What are the functions of polymers of nucleotides?

Answer 14

Store genetic information (DNA)

Convert genetic information into proteins (RNA)

Question 15

Describe DNA structure

Answer 15

Helical structure
Long polymer of nucleotides 
Sugar Phosphate backbone 
Two strands are antiparralel 
The strands are complementary due to H bonds forming  between comp base Pairs

Question 16

Contrast the structure of DNA and RNA

Answer 16

RNA is smaller and single stranded

Question 17

Explain the function of mRNA

Answer 17

it is a copy of a gene hence provides the template for protein synthesis

Question 18

Explain the function of rRNA

Answer 18

acts a structural component to ribosomes

Question 19

Explain the function of tRNA

Answer 19

Transports the AA to the the ribosome that is complementary to the codon on the mRNA sequence. This ensures that the correct sequence of amino acids is coded for

Question 20

Why is ATP a highly useful molecule?

Answer 20

high energy bond between Pi
the bond is readily hydrolysed
This means that the energy released can be used to drive metabolic reactions which are not usually thermodynamically feasible.

Question 21

Describe Triaglycerols

Answer 21

It is a hydrophobic molecule
3 fatty acids and 1 glycerol
Ester bond between the glycerol and fatty acid components
Used mainly for energy storage- stored in adipose tissue
The fatty acids can be saturated, unsaturated etc

Question 22

What are the types of fatty acids? ( Hint- 4 types)

Answer 22

Non esterfied fatty acid- eg long chain aliphatic carboxylic acids. These can also be metabolised via beta oxidation pathway to generate ATP

Saturated- eg stearic acid
Unsaturated- eg oleic acid
Polyunsaturated- eg linoleic acid

Question 23

What is meant by the term amphipathic?

Answer 23

eg. phospholipids- polar head, non polar tail.

Useful in forming a membrane

Question 24

What defines Steroids?

Answer 24

4 Rings of a biologically active organic compound

eg. Steroids- from diet or de novo ( plays an important role in membrane fluidity )

Question 25

Explain the structure of amino acids

Answer 25

Composed of an amino group, carboxyl group, a side chain and a CH group.
It is water soluble
Amino acids are electrically charged at physiological pH
The R group is what defines the properties of the amino acid

Question 26

What is meant by the term essential amino acid?

Answer 26

An amino acid that cannot be synthesised de novo by humans due to lack of enzymes

Question 27

R 
Y
F
W
E
K
Q
N

Answer 27

arginine 
tyrosine 
phenylalnine 
trytophan 
glutamate 
aspartate 
lysine 
glutamine
asparagine

Question 28

What are the roles of amino acids in biology ?

Answer 28

polypeptide monemer
Taste enhancements
NT’s-glutamate 
NeuroTransmitters synthesis 
eg. tyrosine - epinephrine and dopamine
Histidine- histamine 
Tryptophan-serotonin

Question 29

How can peptide bonds be hydrolysed?

Answer 29

digestion and lysosome

Question 30

What is meant by the pKa of the side groups

Answer 30

The ease at which the R groups give up protons

Has influence on structure and function of proteins

Question 31

What is a reducing sugar?

Answer 31

If the anomeric carbon is not bonded to another molecule

Question 32

Clinical Considerations ?

Answer 32

PKU- Defective phenylalanine hydroxyalse (Phe — tyr)
Reduced tyr — reduced dopamine and melanin production
And increased in other phenylanine by products eg phenylacetate

Albanian - Defective tyrosine (tyr — melanin )