Carbohydrates Flashcards
What 3 categories of carbohydrates are there?
Monosaccharides
Disaccharides
Polysaccharides
What elements do carbohydrates contain?
Carbo = carbon
Hydr = hydrogen
Ate = oxygen
Monosaccharides
Organic molecules that act as a monomer for complex carbs
Examples of monosaccharides
Glucose
Galactose
Fructose
Glucose formula
C6H12O6
Glucose forms
Alpha
Beta
Isomers
Molecules with same chemical formula but different arrangements of atoms
2 isomers of powdered glucose
Alpha
Beta
Alpha glucose placement of hydroxide
Below the first carbon
Beta glucose placement of hydroxide
Above the first carbon
Properties of monosaccharides
Soluble in water (HYDROPHILIC)
Monomer to form disaccharides and polysaccharides
Why are monosaccharides soluble in water?
They have many hydroxide (hydroxyl) groups which form hydrogen bonds with water molecules due to charges being attracted to each other
As hydroxyl groups are polar
Reducing sugars
Act as a reducing agent
By losing electrons from atoms which other substances gain
Such as indicators
Therefore = reduced
Disaccharide
Formed by the condensation of 2 monosaccharides
Forming a glycosidic bond between both monomers
and water
Glycosidic bond
Formed in a condensation reaction between 2 monosaccharides in OH groups where H2O is released from the compound leaving oxygen which connects the molecules
Disaccharide list
Maltose
Lactose
Sucrose
Maltose
Glucose and glucose
Lactose
Glucose + galactose
Sucrose
Glucose + fructose
Polysaccharide
A polymer of monosaccharides, formed from the condensation of many joined together by glycosidic bonds
Large macromolecules
What do polysaccharides hydrolyse into?
Monosaccharides or disaccharides
Function of polysaccharides
Store energy for use later eg in contraction
Structural role
Three polysaccharides to learn
Starch
Glycogen
Cellulose
How are starch and glycogen formed
If the monomer is alpha glucose
Function of starch and glycogen
Store energy in cells
How is cellulose formed
If the monomer is beta glucose
Function of cellulose
Structural by reinforcing plant cell walls
Starch forms
Made up of 2 polysaccharides:
Amylose
Amylopectin
Starch use
Energy storage in plants as it’s insoluble
Found in storage organs and seeds in plants
Major energy source in our diet
Amylose
Polymer formed from condensation or alpha glucose monomers with a 1,4 glycosidic bond between each
Is in a coiled shape (helix)
Hydrogen bonds between the molecules in the chain
Amylopectin
Polymer formed of condensation of alpha glucose monomers with 1,4 glycosidic bonds between
Can form branches off by forming 1,6 glycosidic bonds every 25-30 molecules
1,4 glycosidic bonds meaning
The bond between carbon 1 in one glucose and carbon 4 in another glucose
1,6 glycosidic bonds meaning
The bond between carbon 6 on one glucose and carbon 1 in another glucose causing it to branch out from the chain and carry on the chain of molecules
What happens if there’s more branches in the amylopectin?
It is easier to be hydrolysed into glucose or maltose
Why does it matter to store glucose for energy in different ways?
It is very soluble
So if a cell has a lot of glucose it will have a lower water potential (concentrated with glucose) so water will move into it via osmosis down a water potential gradient = must store as starch or the cell will swell up by drawing in water
Potentially causing lysis
What uses starch to store energy?
Plant stores only, converts glucose to it
What happens if the plant needs to use glucose as energy but has starch?
Uses water to hydrolyse the starch to form the glucose molecules
Helped by enzymes by breaking glycosidic bonds
Starch and glycogen important structural features
Helical
Insoluble in water
Large
Polymer of glucose
How does starch and glycogen being helical help serve its function?
So it is compact
Can store a large amount of glucose for its size so can remain more compact and be used for energy
How does starch and glycogen being insoluble help serve its function?
Water won’t enter the plant cell by osmosis because it’s insoluble so won’t effect the water potential of a cell
So won’t decrease water potential = no osmosis (OSMOTICALLY INACTIVE)
How does starch and glycogen being large help serve its function?
Won’t diffuse through cell membrane and pass out the plant cell
What glucose storage molecule do animal cells have?
Glycogen
Where are the major stores of glycogen?
Liver + muscle cells
Glycogen polymer description
A polymer Formed from the condensation of alpha glucose monomers
Contains 1,4 glycosidic bonds
Branches joined by 1,6 glycosidic bonds but more than amylopectin = free ends
How does glycogen having many Branches help serve its purpose?
Enzymes hydrolyse it with water into its alpha glucose monomers
By joining to ends, so more ends can hydrolyse it at a rapid rate
Important, animals have high rate of respiration so require the energy
How does glycogen being large help serve its function?
Won’t diffuse out of the cell through the membrane so can be stored as an energy store in the cell
Cellulose role
Strengthens plant cells walls to prevent it from bursting with too much water = becomes ‘turgid’
Cellulose molecule description
Polymer formed from condensation or beta glucose molecules bonded by glycosidic bonds
But every other molecule is flipped so the OH group is adjacent
Is cellulose branched?
No!
Where is cellulose found?
Plant cell walls
How is cellulose arranged in a cell wall?
Each molecule chain gets close together as its not branched
Hydrogen bonds form between the chains
These grouped together = microfibril
Microfibrils
When cellulose polymer chains grouped together by hydrogen bonding
These group together to form macrofibrils
Macrofibrils
Large structure forming a cellulose fibre
Cellulose fibre chain of what forms it
Beta glucose
Cellulose
Microfibril
Macrofibril
Cellulose fibre
Plant cell wall
Why does cellulose have hydrogen bonding between chains?
So can be a strong compartment of the cell wall structure
Why does cellulose have high tensile strength?
So it can be stretched without breaking to withstand increase in water potential
How does glycogen and starch being a polymer of glucose help?
Can provide glucose to be respired for energy release
Why do plants need to have high hydrostatic pressure?
To stay upright maximising photosynthesis
Why is cellulose not helical or branched?
So they can sit parallel to each other to form q string network of hydrogen bonds to make up macrofibrils which strengthen cell walls in plant cells
