Carbohydrates 1 Flashcards
What is a carbohydrate?
Sugar and starch molecules
Why are carbohydrates and major energy source?
They are high oxidisable, containing large amounts of high energy H atoms and associated electrons
What are some functions of carbohydrates?
Store potential energy
Structural and protection functions (EM)
Cell to cell communication
How are carbohydrates used to store potential energy?
As glycogen
What are monosaccharides?
Any class of sugar that cannot be hydrolysed to give simpler sugars
What are the 3 important hexoses (6C sugars)?
Glucose
Fructose
Galactose
What are disaccharides?
Formed from monomers that are linked by glycosidic bonds
How do monosaccarides combine to form disaccharides?
Covalent bonds are formed when hydroxyl groups of one monosaccharid reactions with another anomeric carbon of another
What is the anomeric carbon of glucose?
C1 on glucose
What are properties of the anomeric carbon of glucose?
Stabalises the structure and is the only one that can be oxidised
What are different anomers to each other?
Mirror images
What are 3 important disaccarides?
Maltose
Lactose
Succrose
Do we get much maltose in our diet?
No, it is found in starch and beer
Why is maltose termed a reducing sugar?
Anomeric C1 is available for oxidation
What forms maltose?
Two molecules of glucose
What is a reducing sugar?
A sugar that can be oxidised
What is lactose the main sugar of?
Milk
How is lactose formed?
Glycosidic bond between galactose and glucose
Galactose + Glucose ⇔ Lactose
Why is lactose a reducing sugar?
Anomeric carbon in the glucose available for oxidation
Where is succrose commonly found?
Table sugar
What is succrose only made by?
Plants
Is sucrose a reducing sugar?
No, because no free anomeric carbon atom
How is succrose formed?
By glucose and fructose
Glucose + Fructose ⇔ Succrose
What are polyassacharides?
Carbohydrate whole molecule consists of a number of sugar molecules bonded together
How can polyassacharides differ from one another?
Types of monomers
Length of chain
Types of bonds linking monomers
Amount of bonding
What are the 2 types of polyassacharides?
Homopolyassacharides (single monomer spieces)
Heteropolyassacharides (two or more monomer spieces)
What 2 types of glucose monomers does starch contain?
Amylose (D glucose in a1-4 linkage)
Amylopectin (glycosidic a1-4 bonds join glucose in chain but branches are a1-6)
What does aX-Y refer to in terms of bonding?
The number of carbon in the sequence connected to each other
How many reducing and non reducing ends does starch have?
Many non reducing and very few reducing ends
Do enzymes act of non reducing or reducing ends?
Reducing ends
What allows for glycogen to have lots of non reducing ends?
Branch points (a1-6) every 8 to 12 residues
What do lots of branches in glycogen allow for?
To be quickly broken down or built up
Where is 90% of glycogen found?
Liver
Skeletal muscle
What is the purpose of the glycogen in the liver?
Replenish blood glucose whilst fasting
What is the purpose of glycogen in skeletal muscles?
Catabolism to produce ATP for contraction
Why is glycogen osmotically inactive?
It is not in solution
Why is glycogen being osmotically inactive important?
If it was free glucose (osmotically active) it would constantly leave the cell down its concentration gradient
What are glycoproteins?
Proteins that have carbohydrates covalently attatched
What may carbohydrates attached to proteins do?
Increase protein solubility
Influence protein folding
Protect it from degradadtion
Act as communication between cells
What are glycoaminoglycans (GAGs)?
Unbranched polymers made from repeating units of hexuronic acid and an amino-sugar
What are properties of glycosaminoglycans (GAGs) and where are they found?
Slimy, sticky molecules found in mucous and synovial fluid
What are proteoglycans?
Formed from glycosaminoglycans (GAGs) covalently attatched to proteins, more carbohydrates than protein
Where are proteoglycans found?
In connective tissue
What do proteoglycans do?
Allow the cell to connect to the extracellular matrix (EM)
Do glycoproteins have more protein or carbohydrate?
Protein
Where are glycoproteins often found?
On the outside of the cell membrane and in the extracellular matrix (EM)
What do you generally find anywhere you need to stick things together?
Proteins attatched to carbohydrates
What are mucopolyassacharides?
Group of genetic disorders caused by absence or modification of enzymes that are required for breakdown of glycosaminoglucans (GAGs)
What do mucopolyassacharide disorders cause?
A build up of glycosaminoglycans in cells which is damaging
What is an example of a mucopolyassacharide disorder?
Hurler syndrome
