Biological Molecules- Topic 1A Flashcards
What is a polymer?
A large molecule made up of monomers (smaller units)
What are polysaccharides a type of?
Polymer
What is a disaccharide?
A disaccharide is made up of two monosaccharides joined together by a chemical reaction.
What type of chemical reaction results in a disaccharide?
A condensation reaction as a molecule of water is also produced.
Name two polysaccharides
Starch and cellulose.
Which disaccharide is composed of 2 molecules of glucose?
Maltose
Name two monosaccharides.
Fructose and glucose.
Where is cellulose found?
Only in plant cells.
How many different amino acids are used in proteins?
20
What do all proteins contain?
Hydrogen, oxygen, carbon and nitrogen.
What are proteins held together by?
Peptide bonds which are strong.
What does the order of amino acids determine?
The structure of the protein.
What does the structure of the protein determine?
How it works
What is the primary structure of protein?
The order in which the amino acids are arranged in a protein chain.
What type of bonds hold together the secondary structure of a protein?
Hydrogen (weak forces of chemical attraction)
What is a tertiary structure?
Coiled chain of amino acids folded into a ball, which are held together by strong and weak chemical bonds.
If the protein has a roughly spherical shape it’s called a….
Globular protein.
What is a secondary structure?
Chains folded and coiled up into pleats.
What are carbohydrates made up of?
ONLY Hydrogen, carbon and oxygen.
Which disaccharide is formed with glucose and fructose?
Sucrose.
What do lipids contain?
Oxygen, hydrogen and carbon.
Lipids are…
Oils and fats.
What does a triglyceride consist of?
A molecule of glycerol with three fatty acids attached to it.
Plant oils and animal fats are mostly made up of a group of lipids called?
Triglycerides.
What are phospholipids?
Similar to triglycerides however they have 2 fatty acid chains and a phosphate group.
What are cell membranes made from?
A double layer of phospholipds
What is metabolism?
The sum of the biochemical reactions in a living cell.
How do enzymes work?
They reduce the activation energy.
Enzymes can … or … molecules
Enzymes can build or break down molecules.
Give an example of an enzyme which breaks down molecules.
Digestive enzymes break down food into smaller molecules e.g carbohydrases into carbohydrates.
Give an example of an enzyme which builds molecules.
DNA replication help to build molecules such as DNA polymerase.
What will be affected if the shape of the active site is changed?
How well the enzyme works.
Give the formula for monosaccharides
(Cn(H2O)n)
Give examples of monosaccharides
Triose (glyceraldehyde)
Pentose (ribose and deoxyribose)
Hexose (glucose, fructose and galactose)
Give examples of disaccharides
Sucrose
Maltose
Lactose
Chemical formula for glucose?
C6H12O6
What is a monomer?
A small basic molecular unit.
What is an amino acid?
A repeating protein
What is a polypeptide?
A single protein.
What is the removal of water in a reaction called?
Condensation
What is the addition of water to a reaction called?
Hydrolysis.
What are the 4 different components that make up an amino acid?
An amino group (NH2), Carboxyl group (COOH), a hydrogen atom (-H) and an R group.
Name the type of bond that joins an amino acid together?
A peptide bond.
State the type of reaction involved in joining amino acids together.
Condensation reaction.
Which polysaccharide is made up of B glucose?
Cellulose
Which polysaccharides are made up of a glucose?
Starch and Glycogen
Why do large molecules often consist of carbon?
As carbon atoms readily bond with each other so can form chains of various lengths
What is the general name for a molecule made up of many similar repeating units?
Polymer!
Why does Benedicts reagent turn red when heated with a reducing sugar?
Sugar donates electrons that reduces blue Copper II sulphate to orange Copper I oxide.
What is lactose an example of and what’s it made up of?
A disaccharide made up of glucose and galactose.
What is the bond formed in a disaccharide (condensation) reaction called?
A glycosidic bond.
What acid is added in the test for Non-Reducing sugars and why?
Dilute hydrochloric acid to hydrolise the disaccharide into it’s original monosaccharides.
What chemical is added after the acid to then neutralise the solution? (Non-reducing sugars test)
Sodium hydrogencarbonate.
Describe the test for starch?
Add iodine to solution to test solution, shake solution and if starch is present it will turn a blue-black colour.
What is the main role of starch?
Energy storage
How is starch suited for its role?
It’s insoluble so doesn’t affect water potential.
It is large so does not diffuse out of cells
It is compact due to helical structure so can be stored in a small place.
Why do the OH groups occur on both sides of a cellulose molecule?
So it can form other hydrogen bonds with other chains on both sides.
How is the structure of cellulose suited to its function?
composed of B glucose so forms long, straight unbranched chains.
The chains run parallel to each other and are cross linked by hydrogen bonds giving them collective strength.
Molecules grouped to form microfibrils which are, in turn, grouped to form fibres, which provides yet more strength
Where can you find cellulose?
In a pant cell wall to make the plant rigid and to prevent it from bursting.
Which 2 substances are formed when two amino acids join together?
A Water molrcule
(Di)peptide
Name the type of bond formed between the joined pair of amino acids?
Peptide bond.
Why do organisms that move (animals) or plant seeds use lipids instead of carbohydrates as an energy store?
Lipids provide more than twice as much energy as carbohydrates when oxidised and if fat is stored it can contain the same energy is more than half the mass, so is a lighter storage product.
What is an isomer?
An isomer is when molecules have the same molecular formula but with atoms connected in a different way.
What are enzymes?
Biological catalysts that speed up chemical reactions
What is a catalyst?
A substance that speeds up a chemical reaction without being used up in the reaction itself.
How do enzymes complete their function?
They speed up reactions by lowering the activation energy
What is an enzyme-substrate complex?
Forms when a substrate fits into the enzyme’s active site- this is what lowers the activation energy.
What was the first Enzyme model?
The lock and key model
What is the improved second Enzyme model called?
The induced fit model
What do the properties of enzymes relate to?
Enzyme properties relate to their Tertiary Structure
What is the active site’s shape determined by?
The enzyme’s tertiary structure (which is determined by the enzyme’s primary structure)
What is a reason for the active site shape changing?
A change in the tertiary structure, due to pH or temperature.
What is the primary structure of a protein determined by?
A gene
Why does enzyme concentration affect the rate of reaction?
The more enzyme molecules in a solution, the more likely a substrate molecule is to COLLIDE with one and form an enzyme-substrate complex.
Why may an increase in enzyme concentration eventually have no further affect?
If the substrate amount is limited.
What does a peptide bond look like?
C—N
Name 4 specialised proteins.
Enzymes
Structural proteins
Antibodies
Transport proteins
Name 2 things affecting the rate of reaction for enzymes
Enzyme concentration Substrate concentration (up to a point)
Name 2 things that influence the Enzyme Activity
Temperature and pH
Name two ways Enzyme activity can be Inhibited
Competitive Inhibition
Non-Competitive Inhibition
What happens during competitive inhibition?
Competitive inhibitor molecules have a similar shape to substrate so can bind to active site (without reaction)
This means no substrate can get in.
What happens during non-competitive inhibition?
Non-competitive inhibitor molecules bind to the enzyme away from its active site which changes the shape of the active site so substrate molecules can’t bind to it.
Why are enzymes usually spherical?
Due to the tight folding of polypeptide chains
Where do enzymes commonly have roles in the body? Name a property useful for this.
Roles in metabolism
Soluble
What causes structural proteins to fold up and form a channel?
The hydrophobic and hydrophilic amino acids cause it to fold.
Describe Antibodies?
Consist of two light (short) polypeptide chains and two heavy (long)
What are Triglycerides mainly used as ?
Energy Storage Molecules
How are Triglycerides suited to their function?
Hydrocarbon tails contain lots of chemical energy so lots is released when they’re broken down.
Insoluble so don’t affect water potential (cell can’t swell so more room)
Triglycerides clump together as ……… …….. in cells
Insoluble droplets.
Why do fatty acid tails face inwards?
As they are shielding themselves from the water using their glycerol heads.
What does an ester bond look like?
C-O-C
What is an unsaturated hydrocarbon? What does this mean for a fatty acid tail?
One with double bonds( C=C )
Causes kink in chain.
How is a Triglyceride formed?
By a condensation reaction (fatty acid to glycerol) this must happen 3 times therefore + 3 (H2O) molecules
What does the ester bond forming lead to?
A molecule of water being released.
Describe briefly the Emulsion Test?
Add sample + ethanol
Shake
Add water
positive if milky white emulsion.
Why can’t water soluble substances easily pass through a phospholipid bilayer?
Because the centre of the Bilayer is Hydrophobic due to arrangement of phospholipids (tails get away from water) Membrane acts as a BARRIER.
What do cell membranes do?
Control what enters and leaves the cell
What part of a Triglyceride molecule is an R (variable) group?
The hydrocarbon tails vary.
Name 2 other functions for Triglycerides other than their named main function (in mammals)?
Thermal insulation
Waterproofing of skin/fur.
Name 2 functions of lipids in plants
Energy storage
Leaf waterproofing
What is an inhibitor
chemicals that slow down the rate or stop the reaction
Name two useful properties of ATP
Soluble
Single simple reaction
Why is ATP useful?
Can rapidly re-synthesise
Immediate energy source
Very easily broken down.
Why is it necessary for humans to synthesise such a large amount of ATP.
Relatively small amounts of energy released at a time
ATP cannot be stored (immediate energy source)
What happens to the substrate just before binding to an active site?
The bonds distort
Describe the beginning of the induced fit
Before reaction active site isn’t complementary
How are Haemoglobin and Collagen similar?
Both formed from amino acid monomers
Peptide bonds formed in condensation reaction.
How are Haemoglobin and Collagen different?
Haemoglobin= 4 polypeptide chains Collagen = 3
Haemoglobin has a HAEM prosthetic group collagen has no prosthetic group
Haemoglobin is soluble Collagen is insoluble
Haemoglobin is globular whereas collagen is helical.
Name 2 molecules that make up a ribosome
RNA and protein
