10 - CARBOHYDRATES II

Question 1

How can monosaccharides be joined together?

Answer 1

A glycosidic bond forms between the anomeric carbon of one sugar and a
hydroxyl group of another
This reaction produces water and is called a CONDENSATION reaction

Question 2

REDUCING SUGARS

Answer 2

Sugars containing a free aldehyde or ketone group
In solution, the open-chain forms of aldoses and ketoses can reduce indicators such as Cu2+ (cupric ion) to Cu+ (cuprous ion)

Question 3

Carbohydrates have a direction

Answer 3

Reducing end: anomeric is not linked so sugar can mutarotate

Non-reducing end: anomeric is linked so sugar cannot mutarotate

Question 4

Structural Diversity

Answer 4

Sugars are joined together by GLYCOSYLTRANSFERASES
Carbohydrates can achieve great structural diversity because of the many types of monosaccharides and linkage possibilities

Question 5

Ogliosaccharides

Answer 5

2-5 sugars

Question 6

Monosaccharide Derivatives

Answer 6

The OH groups of monosaccharides can be replaced by other 
groups, e.g. 
-NH2 = Amino
-NHCOCH3 = N-acetyl
-OPO32- = Phosphate
-OSO3- = Sulphate
-COO- = Carboxylate
-H = Hydrogen (Deoxy)

Question 7

Glycolysis

Answer 7

• A series of reactions in the cytosol of the cell that:
– Convert Glucose (a six Carbon molecule) into 2x three carbon molecules known as PYRUVATE.
– In doing so some of the chemical energy stored in glucose is released.
• Involves multiple steps:
• For each molecule of glucose we create a net total of 2 molecules of ATP

Question 8

What happens if glycolysis takes place in the presence of molecular oxygen?

Answer 8

– Pyruvate is transported into the mitochondrion

– Enters citric acid cycle/Krebs cycle/tricarboxylic acid cycle

Question 9

Pyruvate is first converted to Acetyl-Coenzyme A

Answer 9

• This cycle take place in the matrix of the mitochondria
• Before entering the citric Acid cycle pyruvate is first combined with a sulphur containing compound known as coenzyme A
• The product of this reaction is Acetyl-CoA

Question 10

Citric Acid cycle

Answer 10

• Takes place within the mitochondrial matrix
• Acetyl-CoA joins the cycle by binding to Oxaloacetate forming a molecule of citrate
• The NADH and FADH2 are fed into the electron transport chains and this is where the majority of ATP is produced.
• This cycle oxidises organic “fuel” in the form of Acetyl-CoA (a derivative of Pyruvate)
• This cycle produces 1xATP (GTP), 3xNADH and 1xFADH2 per turn