Structural and Storage Molecules Flashcards
Difference between Alpha and Beta Glucose
- Alpha glucose has the Hydroxyl group on the 1st carbon facing inside the ring, whereas Beta faces outwards
- Alpha glucose has H atom on 1st carbon facing outside the ring, whereas on beta it faces inwards
Describe the formation of glycosidic bonds in amylase
- Alpha glucose molecules
- Undergo condensation polymerisation
- Between hydroxyl groups on carbon 1 and 4, forming a 1,4 - Glycosidic bond
- Where a water molecule is released
What is starch made from?
Alpha glucose molecules
- Amylose (just 1,4 - glycosidic bonds)
- Amylopectin (forms 1,4 - glycosidic bonds and some 1,6 - glycosidic bonds forming the branches)
What is Cellulose made from?
Beta glucose molecules
What is Glycogen made from?
Alpha glucose molecules
- Forms 1,4 glycosidic bonds but also 1,6 glycosidic bonds
- These 1,6 glycosidic bonds cause the branching, and therefore its structure is similar to amylopectin but it has MORE branches
Properties of STARCH
- Insoluble (so wont affect water potential in cells)
- Spiral shape (compact, lots of glucose molecules stored in small space)
- Metabolically inactive, so doesn’t affect any effect on the chemical reactions in a cell
Properties of Glycogen
Similar in structure to Amylopectin, but forms 1-6 glycosidic bonds, making it a BRANCHED structure
- Insoluble (so will not affect water potential in cells)
- Compact Branched Structure (1) (many glucose molecule stored in a small place
- Compact Branched Structure (2) (More ends to be hydrolysed by enzymes)
Properties of Cellulose
Straight Chain polymer due to positioning of OH group involved in glycosidic bond
Parallel chains lying side by side held together by hydrogen bonds. Form microfibrils which join together in larger bundles to form cellulose fibres. These microfibrils can be surrounded by different polysaccharides.
- Extra Strength (comes from hydrogen bonds between chains)
- Cellulose is difficult to digest because animals dont have enzymes to break 1,4 -Glycosidic bonds
Uses of Carbohydrates
- Immediate source of energy (glucose)
- Transport carbohydrates (Sucrose in plants)
- Structural carbohydrates (cellulose)
- Storage carbohydrates (glycogen in animals, starch in plants)
Uses of Carbohydrates
- Immediate source of energy (glucose)
- Transport carbohydrates (Sucrose in plants)
- Structural carbohydrates (cellulose)
- Storage carbohydrates (glycogen in animals, starch in plants)
- Conjuncted Carbohydrates
- Glycolipids
- External structures of cell membranes
- Glycoproteins
- External structures of cell membranes (antigens)
- Mucus of respiratory and digestive tracts
- Glycolipids
Amylose Properties
- Helix shape (coiled)
- 1,4 glycosidic bonds
- Not Branched
- Monomer is alpha glucose
- Source is plants
What are hydrogen bonds?
- Form between water molecules
- Form due to water’s polarity (positively and negative charged regions of water molecule)
- Weak bonds, but in large numbers they can form a strong structure
What is a Triglyceride?
- One Glycerol Molecule
- Bonded to 3 fatty acid chains
How do Triglycerides form?
- Condensation reaction between -COOH group of fatty acid
- With each of the -OH groups on the glycerol molecule
- Ester bonds form between each 3 of the bonds between the -OH and -COOH groups
-H2O is released as a product too - Reaction is reversible if triglyceride is hydrolysed
What does saturated mean?
No double bonds
Triglyceride with 1 double bond
Monounsaturated
Triglyceride with more than 1 double bond
Polyunsaturated
What are Lipids
- Macromolecule containing lots of Carbon, Hydrogen and Oxygen
- Lipids are insoluble in water (because they are not soluble)
- They are soluble in alcohol
3 most important lipids in organisms
- Triglycerides
- Phospholipids
- Steroids
Fatty Acids structure and function
- Carboxyl group at one end of the molecule
- Attached to a hydrocarbon tail between 2-20 carbons long
- Useful energy source in animals
- Because it is an energy dense molecule
- More efficient since animals have to carry around their energy stores with them
- C2H4 acetyl groups along fatty acid tails can be used as respiratory substrates, passing through into Kreb’s cycle
- So acetyl groups can be mobilised, pinched off by enzymes then fed into Kreb’s cycle in respiration
Why do plants store bulky starch instead of fatty acids?
- Plants are generally immobile
- So can afford to store bulky starch
Structure and properties of a Phospholipid
- Glycerol molecule
- 2 fatty acids
- 1 phosphate group on 3rd OH group
- Phosphate group gives a phospholipid a bipolar nature
- Phosphate group is hydrophilic
- When added to water phospholipids self assemble into a bilayer, shielding hydrophobic fatty acids from water
Examples of Phospholipids
- Globules called Micelles
- Semi-stable and form emulsions in presence of emulsifying agent
- Liposomes are a further extension of Micelles and contain an inner pocket of water based medium
Uses of Phospholipids in organisms
- Form cell membranes which separate cell contents from external aqueous environment
- Compartmentalising internal structures of eukaryotic cells
Where is Cholesterol produced and what is its structure
- Steroid lipid
- Has 4 fused carbon rings
- Synthesised in liver and obtained from diet
- Small fatty micelles contain less fat, less cholesterol and more protein so is more dense (HDL)
Uses of Cholesterol in organisms
- Component of cell membranes and can be used to synthesise sex hormones
- Moves fat around
Examples of Cholesterols
- Testosterone
- Estradiol
- Sex hormones that are different by functional group only
Structure of Amino Acids
- Amine group one end (NH2) and Carboxyl group the other end (COOH)
- Amine group can form amine bonds (peptide bonds) with carboxyl group to form chains (condensation reaction also)
- The Acetyl R group of amino acids can form hydrogen bonds with each other which can affect the 3D formation of proteins
