Carbohydrates (Biological Molecules) Flashcards
What are carbohydrates?
Large mol made from monosacc
What is the gen formula of carbs?
(CH2O)n
What is the function of glucose?
- Energy source
- Broken down to smaller mol in series of reactions releasing energy cell can use to do work
What is the function of glycogen?
- Energy storage
- long term storage of glucose
What’s special about cell surface proteins and why is this important?
- Glycosylated = sugars added
- Important aspect of structure as diff glycos species attached to diff mol
Give 2 e.g.s of glycosylated species
ABO blood groups
Immunoglobulins
What is the sol of carbs?
Water-sol - hydrophilic, polar
What is a triose sugar?
Has 3 Cs
Give 2 e.g.s of triose sugars
Glyceraldehyde
Dihydroxyacetone
What is a pentose sugar?
Has 5 Cs
Give 2 e.g.s of ribose sugars
DNA
RNA
What is a hexose sugar?
Has 6 Cs
Give 2 e.g.s of hexose sugar
Glucose
Fructose
What are isomers?
Have same chem formula but diff structures
What are aldoses?
Contain aldehyde group
Give an e.g. of aldose
Glucose
What are ketoses?
Contain ketone group
Give an e.g. of a ketose
Fructose
Which 2 forms/OI do sugars exist in and which form do humans use?
D-form + L-form
D
Which C is C1?
C of C=O
How many hexoses in % in linear form?
<1%
What is the anomeric C?
C of original C=O in cyclic form
What is an alpha form of carb?
OH group on anomeric C in down pos
What is beta form of carb?
OH group on anomeric C in up pos
Why are alpha/beta forms important?
For glycosidic bond formation between sugars
What happens to alpha and beta forms in sol?
In equilibrium and interconvert
What is a monosaccharide?
simplest sugars
Give 3 e.g.s of monosacc
Glucose
Fructose
Galactose
What is a disaccharide?
2 monosacc linked together by glycosidic bond
Give 3 e.g.s of disacc and constituents
Sucrose (glucose + fructose)
Maltose (glucose + glucose)
Lactose (galactose + glucose)
What is a polysaccharide?
Many monosacc linked together
Give e.g. of polysacc and constituent
Glycogen (glucose)
What is a glycosidic bond?
Covalent bond between -OH group of 1 sugar + -OH group of next by cond reaction
What happens in cond reaction?
H2O expelled
What is enz involved in glycosidic bond formation?
Glycosyltransferase
- involved in formation + breakdown of glycosidic bond
Why can’t you have beta 1,4 links in humans?
Don’t have enz for their formation/breakdown of cellulose
How is the glycosidic bond broken?
By hydrolysis
What happens during hydrolysis?
H2O mol consumed
What is a reducing sugar?
One where anomeric C is not attached to another mol
What is glycogen?
Linear glucose polymer with alpha 1,4 links and alpha 1,6 branches
What is adv of branched chains compared to linear chains and what does this allow in the case of glycogen?
- Many ends - free OH groups that can form links to other monosacc/mol for enz to act
- Linear mol has just one end
- Rapid breakdown of glycogen
How is glycogen digested in diet?
1 glucose removed from 1 end and enz act on ends
What is salivary alpha amylase?
Catalyses random hydrolysis of internal alpha 1,4 links in glycogen during 1st stage of glycogen digestion
What is pancreatic alpha amylase?
Catalyses further hydrolysis of glycogen into mix of monosacc + disacc in 2nd stage of glycogen digestion
What is maltase?
- produces glucose
- absorbed by intestinal mucosal cells in final stage of glycogen digestion
What occurs in mobilisation of glycogen in liver?
Glycogen phosphorylase hydrolyses terminal alpha 1,4 link to produce glucose 1-phosphate
What is lactose intolerance?
Can’t met lactose correctly
What normally occurs in small intestine?
Lactose converted to galactose + glucose by lactase/Beta galactosidase
What causes lactose intolerance?
- red activity of Beta galactosidase
- undigested lactose
- gets digested by bacteria in large intestine - excess CO2 + other metabolites
- cause bloating, diarrhoea etc
