Carbohydrates Flashcards
What is a carbohydrate ?
A simple unit (CH2O)n
What do carbohydrates occur as ?
- Simple sugars (monosaccharide and disaccharides)
- Complex glucose polymers (polysaccharides)
What are the main fuctions of carbohydrate ?
- Primary: short-term energy generation
- Secondary: intermidiate-term energy storage
- Tertiary: structural components in cells
What are monosaccharides?
- Aldehydes or ketones which contain a carbonyl group : a carbon oxygen double bound
- Depending on the number of C atoms they contain
e.g. trioses (3)
tetroses (4)
pentoses (5)
hexoses (6)
heptoses (7)
What is monosaccharide cyclisation ?
- Ring form is more energetically stable
- Aldehyde or ketone can react with -OH
- Monosaccharides that contain five or more carbons atoms form cyclic structures
What are the name of the bonds in carbohydrates?
Glycosidic bonds
Linking carbohydrates will form:
- Disaccharides (sucrose)
- Oligosaccharides (ABO glycolipids)
- Polysaccharides (cellulose)
How do disaccharides form?
2 sugar residues joined together via condensation
Examples of polysaccharides
- Glycogen
- Starch
- Cellulose
What is the storage form of glucose ?
Glycogen
What is the link of the main chian of glucose ?
a1→4 linked
What is the link of the branches of glucose?
a1→6 linked
What is starch used as ?
A nutritional reservoir in plants
What are the 2 forms of starch?
- Amylose
- Amylopopectin
What is the structure of amylose?
- Unbranched
- a-1,4-linked glucose residues
- Coils into a helical structure
What is the structure of amylopetin?
- Branched (identical to glycogen)
- a-1,6-linked residue every 30 a-1,4-linkage
What is the role of cellulose?
It has a structural role rather than a nutritional role
How many glucose monomers does celulose have ?
8,000 to 10,000
What is the structure of cellulose ?
- Unbranched glucose polymer
- b-1,4-linked residues
- multiple OH groups from hydrogen bonds
- forms long and streight chains
- Rigid, supporter structure
What is the structure and role of Oligosaccharides?
- Contains 3-9 monosaccharides
- Linked by O or N glycosidic bonds
Where can the oligosaccharides be found?
- Cell memebrane
- ABO blood grouping
- Cell recorgnition
- Cell walls
Meaning ABO blood groups ?
- ABO regers to oligosaccharide chains (antigens) on red blood cells
- Group O - universal donor
- Group AB - universal acceptor
What process are complex oligosaccharides involved in?
Cellular recorgnition (non repetitive sequence)
What are oligosaccharides involved in ?
- Bacterial and viral infections
- Cancer metastatsis
- Intercellular recorgnition processes
Break down the word
- amino acids (peptido)
- sugar (glycan)
where are peptidoglycans found ?
- Bacterial cell walls
- Responsible for their structure rigigity
where are peptidoglycans found ?
- Bacterial cell walls
- Responsible for their structure rigigity
What is the structure of gram positive peptidoglycans ?
- Many layers of peptidoglycans in cell wall
- Retain crystal violet dye when stained
- Purple when under miroscope
What is the structure of gram negative peptidoglycans ?
- Cell wall in thin-inside is made of peptidoglycan
- Outer memebrane composed of phospholipids and lipopolysaccharides
- Thin wall cannot stop violent stain leeching out (pink)
