Carbohydrates

Question 1

Formula of Carbohydrates:

Answer 1

(CH2O)n where n is no greater than 3.

may also have N, S, P

Question 2

Carbohydrates - Function

Answer 2

• most common biomolecules
• 50-60% of human diet
• energy
• energy storage
• structural; components in molecules/cells
• cell surface recognition

Question 3

Carbohydrates - Four Major Groups:

Answer 3

1. Monosaccharudes
2. Disaccharides
3. Oligosaccharides
4. Polysaccharides

Question 4

Carbohydrates - Classifications:

Answer 4

Simple: fast digesting, usualy mono/di
Complex: longer to digest, usually oligo/poly

Question 5

Monosaccharides:

Answer 5

e. g. glucose, fructorse, galactose
- minimum 3 carbons: 1 C conatins carbonyl group (C=O) the rest contain hydroxyl group (-OH)
- divided into aldoses/ketoses
- are reducing sugars

Question 6

Hemiacetal:

Answer 6

Occurs when alcohol reacts with a aldehyde

Question 7

Hemiketal:

Answer 7

Results when a alcohol reacts with a ketone

Question 8

Dissaccharides:

Answer 8

• 2 monosaccharides linked via glosidic bonds (covalent)
  e. g. surose
• bonds form between hemiacteal group of 1st monosaccharide and alcoholgroup of 2nd monosaccharide
• condensation reaction = h20 formation & acetyl group?
• hemiacetal group can convert to an aldehyde and act asa reducing end

Question 9

Polysaccharides:

Answer 9

• long polymers of monosaccharides
  e. g. starch, glycogen
• functions: energy storage, structure, linear or branched

Question 10

Polysaccharides - Glycogen:

Answer 10

• multibranched
• provides energy storage in animals
• more compact than starch
• each branch has non-reducing end

Question 11

Polysaccharides - Cellulose:

Answer 11

• water incoluble
• found in plant cell walls
• homopolysacc of beta-D-glucose
• straight, stable fibres of high strength
• can be degraded into D-glucose

Question 12

Glycoconjugates - Structure:

Answer 12

• a carbohydrate joined to a lipid (e.g. glycosphingolipid) or protein (e.g. glycoproteins)

Question 13

Glycoconjugates - Functions:

Answer 13

• cell communication
• labelling proteins for transport or destruction
• recognition sites for extracellular signal molecules

Question 14

Glycoconjugtes - Types:

Answer 14

1. Proteoglycans: glycosaminoglycan chain joined to a membrane protein
2. Glycoprotein: one or more olihosaccharide joined to a membrane protein
3. glycosphingolipid: oligosaccharide forms hydrophillic head group on a sphingolipid

Question 15

Energy Storage - Starch:

Answer 15

• plant storage polysaccharide
• amylose 10-30%
• Amylopectin 70-90%
• amylose linear non branched molecules alpha links, on reducing end

Question 16

Energy Storage - Amylose:

Answer 16

• poorly soluble in water, forms micellar suspensions -> fors helical conformation which allows iodine to fit nicely, iodine to identify strach such as potatoes. iodine trappend within helic of amylase

Question 17

Energy Storage - Amylopectin:

Answer 17

• portion of starch, branched 12-13 residues. 24-30 residues total
• branched occur in alpha 1-6 bond.
• linear linkages alpha 1-4

Question 18

Glycoproteins - function:

Answer 18

• provides info
• cell surface receptors and care capable of recognising binding of other molecules
• cell surface anigen
• target protein to specific location insde or outside the cell