Topic 1 - Biological molecules Flashcards
what type of molecules are carbohydrates ?
Carbohydrates
polymers
what are polymers ?
Monomers and Polymers
large complex molecules composed of long chains of monomers joined together
what are monomers ?
Monomers and Polymers
small, basics molecular units that join together to form polymers
name 3 monomers
Monomers and Polymers
monosaccharides, amino acids and nucleotides
what elements to all carbohydrates contain ?
Carbohydrates
C, H and O
what monomers are carbohydrates made from ?
Carbohdrates
monosaccharides
name 3 monosaccharides
Carbohdrates
glucose, galactose and fructose
what are monosaccharides
Carbohdrates
sugar molecules that create polymers
what type of molecule is glucose and what does this mean
Carbohdrates
hexose sugar - a monosaccharide with 6 carbon atoms in each molecule
what are the two types of glucose ?
Carbohdrates
alpha glucose and beta glucose
Draw the structure of alpha glucose
Carbohdrates
.
Draw the structure of beta glucose
Carbohdrates
.
what’s an isomer
Carbohdrates
molecules with the same formula as each other but the atoms are connected differently
what’s a condensation reaction ?
Monomers and Polymers
two molecules join together with the formation of a new chemical bond and the release of a water molecule
what is a disaccharide ?
Carbohdrates
two monosaccharides joined together
what bond is formed during a condensation reaction for carbohydrates
Carbohdrates
1,4 glycosidic bond
glucose + glucose =
Carbohdrates
maltose
glucose + galactose =
Carbohdrates
lactose
glucose + fructose =
Carbohdrates
sucrose
what happens during a hydrolysis reaction
Monomers and Polymers
polymers are broken down into monomers by breaking the chemical bond using a water molecule
what disaccharides are reducing sugars ?
Carbohdrates
maltose and lactose
list the method for testing for reducing sugars
Carbohdrates
- Add blue benedict’s reagent to the sample and heat it in a water bath that’s been brought to the boil.
- if the test is positive a coloured precipitate will form
what is the colour scale for positive reducing sugar test ?
Carbohdrates
blue, green, yellow, orange, brick red
Give an accurate way to compare the amount of reducing sugars in a solution
Carbohdrates
filter the solution and weigh the precipitate
what disaccharide is a non reducing sugar
Carbohdrates
sucrose
list the method for testing for non reducing sugars
Carbohdrates
- Add dilute hydrochloric acid to the food sample and heat it in a water bath that’s been brought to the boil.
- Add sodium hydrogencarbonate to neutralise it.
- Add blue benedict’s reagent and heat in a water bath that’s been brought to the boil.
4.If the test is positive a coloured precipitate will form depending on the concentration of the non reducing sugar.
What is a polysaccharide and how is it formed
Carbohdrates
A polymer formed when more than 2 monosaccharides are joined together by condensation reactions
What are the three polysaccharides
Carbohdrates
starch, glycogen and cellulose
in plants, what’s alpha glucose stored as
Carbohdrates
starch
What’s starch a mixture of
Carbohdrates
two polysaccharides of alpha glucose: Amylose and amylopectin
Describe the structure and function of amylose
Carbohdrates
- long, unbranched chains of alpha glucose.
- The angles of the 1,4 glycosidic bonds give it a coiled shape making it compact and good for storage as you can fit more into a smaller space.
describe the structure and function of amylopectin
Carbohdrates
- long, branched chains of alpha glucose.
- it’s side branches allowed the enzymes that break down the molecule to get to the glycosidic bonds easier so glucose can be released quickly.
- made from 1,4 and 1,6 glycosidic bonds.
Give a positive of starch
Carbohdrates
it’s insoluble in water so doesn’t affect water potential meaning it won’t draw water into cells by osmosis which prevents them from swelling, making it good for storage.
give the method for testing for starch
Carbohdrates
- Add iodine dissolved in potassium iodide solution to the food sample
- if the test is positive the colour will change from orangey brown to blue back
what’s glycogen’s role
Carbohdrates
to store glucose in animals so it is the main energy source for animals
what type of molecule is glycogen
Carbohdrates
polysaccharide of alpha glucose
describe the structure and function of glycogen
Carbohdrates
- it is made from long branched chains meaning that enzymes can reach the binds easily so stored glucose can be released quickly which is important for energy release in animals.
- It’s also a very compact molecule so is good for storage as more can fit into a smaller space.
- 1,4 and 1,6 glycosidic bonds.
what type of molecule is cellulose
Carbohdrates
polysaccharide of beta glucose
describe cellulose’s structure and function
Carbohdrates
- it’s long and unbranched.
- When beta glucose molecules bond (1,4 glycosidic bonds) they form cellulose chains these cellulose chains bond together by hydrogen bonds to form strong fibres called microfibrils.
- these fibres give cellulose strength allowed it to provide support and structure for plant cell walls
name a type of lipid
Lipids
triglyceride phospholipid
Draw the structure of a triglyceride
.
what’s a triglyceride made of
Lipids
one glycerol molecule and 3 fatty acids
draw the basic structure of a fatty acid
Lipids
O
||
HO—C—-R
Draw a saturated and unsaturated fatty acid
Lipids
.
Describe the fatty acids structure and function
Lipids
- fatty acid molecules have long tails made of hydrocarbons.
- the tails are hydrophobic so repel water molecules.
- these tails make lipids insoluble in water.
What bond holds lipids together
Lipids
ester bonds
how is a triglyceride formed
Lipids
a glycerol molecule joins 3 fatty acids, when the ester bonds are formed, 3 molecules of water are released
what are saturated fatty acids
Lipids
fatty acids that don’t have any carbon carbon double bonds, the fatty acid is saturated with hydrogen
what are unsaturated fatty acids
Lipids
unsaturated fatty acids have at-least one carbon carbon double bond causing the chain to have a kink.
what are phospholipids
Lipids
lipids found in cell membranes
describe the structure of phospholipids
Lipids
one glycerol molecule with 2 fatty acids and one phosphorus group bonded to it.
Draw the structure of a phospholipid
Lipids
.
explain the relation with water both the phosphorus group and the fatty acid tails have.
Lipids
the phosphorus ‘head’ is hydrophilic so attracts water, the fatty acid (hydrocarbon) tails are hydrophobic so repel water.
what’s the main use of triglycerides
Lipids
energy storage
describe the structure and function of triglycerides
Lipids
- The long hydrocarbon tails of the fatty acids contain lots of chemical energy so lots of energy is released when they’re broken down.
- Because of these fails the lipids contain about twice as much energy per gram than carbohydrates.
- They’re insoluble in water so don’t affect water potential so no water is drawn into cells by osmosis which would cause the cell to swell.
- The triglycerides clump together as insoluble droplets in cells because the fatty acid tails are hydrophobic so the tails face inwards protecting them from water by the glycerol heads
what are phospholipids structure and function
Lipids
- Phospholipids make up the cell membranes.
- Their heads are hydrophilic and their tails are hydrophobic so they from a double layer with their heads facing out towards the water either side.
- The centre of the bilayer is hydrophobic so water molecules can’t easily pass through them - the membranes act as a barrier to those substances.
describe the test for lipids
Lipids
- add ethanol to the food sample
- add decanted water
- mix
4 any lipid will show as a white/ milky emulation. the more lipid there is, the more noticeable the milky colour will be.
what’s the monomers of protein
Proteins and Enzymes
amino acids
what’s a dipeptide
Proteins and Enzymes
two amino acids joined together
what’s a polypeptide
Proteins and Enzymes
more than two amino acids joined together
what’s a protein
Proteins and Enzymes
a polymer made of one or more polypeptides ( long chains of amino acids)
give the general structure of an amino acid and draw it
Proteins and Enzymes
an amine group (H2N), a carbnonatom, a carboxyl group (COOH), a hydrien atom, and a variable group (R).
how are polypeptides formed
Proteins and Enzymes
- condensation reactions reactions between amino acids.
- a molecule of water is released once the peptide bond is formed between the amino acids.
what bonds are formed between amino acids
Proteins and Enzymes
peptide bonds
For proteins, what is the primary structure ?
Proteins and Enzymes
The sequence of amino acids in a polypeptide chain.
For proteins, what is the secondary structure ?
Proteins and Enzymes
Hydrogen bonds form between the amino acids in the chain causing the chain to coil into an alpha helix or fold into a beta pleated sheet.
For proteins, what is the tertiary structure ?
Proteins and Enzymes
- The coiled or folded chain of amino acids is coiled or folded further.
- More bonds from between amino acids R groups, hydrogen bonds, ionic bonds and disulphide bridges form when 2 of the amino acid cysteine come close together.
- For proteins made from a single polypeptide chain, this is there final 3D structure.
For proteins, what is a quaternary structure ?
Proteins and Enzymes
- Some proteins are made from several polypeptide chains held together by bonds.
- The quaternary structure is the way these chains are assembled together.
- This is their final 3D structure for proteins made of more than one polypeptide chain.
What are the 4 functions of proteins ?
Proteins and Enzymes
Enzymes, antibodies,transport proteins and structural proteins.
What’s the role of proteins in antibodies ?
Proteins and Enzymes
- They’re involved in the immune system.
- Made of two light polypeptide chains and two heavy polypeptide chains bonded together.
- Antibodies have variable regions, the amino acid sequence in these regions vary greatly.
What’s the role of proteins in structural proteins ?
Proteins and Enzymes
- They’re physically strong and consist of long polypeptide chains lying parallel to each other with cross links between them.
- It includes keratin (hair and nails) and collagen (connective tissue).
How would u test for proteins ?
Proteins and Enzymes
Biuret test
1. Add a few drops of sodium hydroxide solution in order to make the solution alkaline.
2. Add some copper (II) sulfate solution.
3.if proteins are present the solution will turn purple, if not it will remain blue.
What are enzymes ?
Proteins and Enzymes
Biological catalysts
What do enzymes do ?
Proteins and Enzymes
They speed up the rate of reactions by lowering the activation energy without being used up or changed.
What’s the active site of an enzyme ?
Proteins and Enzymes
The area on the enzyme that the substrate binds to which forms an enzyme substrate complex.
How do enzymes lower the activation energy in a breakdown reaction ?
Proteins and Enzymes
- When the substrate fits to the active site if the enzyme an enzyme substrate is formed
- its this that lowers the activation energy as the active site changes shape to get a tighter fit around the substrate (induced fit).
- this puts a strain on the bonds, making them weaker so that less energy (heat) is needed to break them.
How does an enzyme catalyse the joining molecules ?
Proteins and Enzymes
Being attached to the enzymes active site holds them closer together, reducing any repulsion between the molecules so they can bond easily.
What’s the lock and key model ? and what did new evidence suggest ?
Proteins and Enzymes
- The idea that the substrate fits into the enzyme’s active site the way a key fits into a lock.
- However, new evidence suggest that the enzyme substrate complex changes shape slightly to complete the fit this locks the substrate into the active site and is called the induced fit model.
What’s the induced fit model ?
Proteins and Enzymes
the enzyme substrate complex changes shape slightly to complete the fit this locks the substrate into the active site forming an enzyme substrate complex.
What are enzymes active site shape determined from ?
Proteins and Enzymes
- The enzymes active sit shape is determined by it’s tertiary structure (which is determined by its primary structure).
- Each enzyme has a different tertiary structure so has a different shaped active site.
- Making only one substrate complimentary to it.
What will happen if the tertiary structure of an enzyme is altered ?
Proteins and Enzymes
- The tertiary structure of the enzyme determines thee shape of the active site, therefore if the tertiary structure is altered the active site shape will change.
- This means that the substrate will not fit to the active site so an enzyme substrate complex will not form and the enzyme cannot carry out its function.
- The enzyme will become denatured
What things can change the enzymes tertiary structure ?
Proteins and Enzymes
- pH and temperature.
- Also, the primary structure is determined by a gene, if mutations occur in the genes it could change the tertiary structure produced.
Explain the relationship between rate of reactional and temperature in enzymes.
Proteins and Enzymes
- The rate of reaction increases as temperature increases as more heat means more kinetic energy, so molecules move faster meaning enzymes are more likely to collide with the substrate and from enzyme substrate complexes.
- However, if temperature gets too high the reaction stops.
- This is because as temperature increases particles vibrate more, if the temp is above the enzymes optimum temp the vibrations break the ionic and hydrogen bonds which hold the enzyme in shape.
- The active site then changed shape and the enzyme substrate complex can no longer form - the enzyme is denatures and can no longer function as a catalyst.
Explain the relationship between rate of reaction and pH in enzymes.
Proteins and Enzymes
- All enzymes have an optimum pH value. Above and below the optimum pH values the OH- and H+ ions can mess up the hydrogen bonds that hold the tertiary structure together
- changing the shape of the active site and the enzyme becomes denatured.
Explain the relationship between rate of reaction and enzyme concentration
Proteins and Enzymes
- The more enzyme molecules there are in a solution, the more likely a substrate molecules is to collide with one and form an enzyme substrate complex.
- So, increasing enzyme concentration increases the rate of reaction.
- But, if the amount of substrate is limited, there will be a point where there’s excess enzyme molecules to deal with the substrate, so adding more enzymes wouldn’t affect the rate of reaction.
Explain the relationship between the rate of reaction and substrate concentration
Proteins and Enzymes
- The higher the substrate concentration, the faster the rate of reaction - more substrate molecules means that more collisions will occur to form enzyme substrate complexes- more active sites are used.
- However, this is only true until the saturation point.
- After that there are extra substrate molecules as all active sites are occupied.
What’s a competitive inhibitor ?
Proteins and Enzymes
- Competitive inhibitor molecules have a similar shape of the substrate molecules.
- they compete with the substrate molecules to bind to the enzyme’s active site, but no reaction takes place.
- instead they block the active site so that no substrate can fit to it.
Explain the relationship between rate of reaction substrate concentration and competitive inhibitors
Proteins and Enzymes
- If there’s a high concentration of the substrate then the substrates chances if colliding with the enzyme before the inhibitor does increases.
- so increasing the substrate concentration increases the rate of reaction.
- however if there’s a high concentration of inhibitors they have more chance of colliding with the enzyme and binding the the active site - hardly any substrate will collide with the enzyme decreasing the rate of reaction.
What’s a non competitive inhibitor ?
Proteins and Enzymes
- A non competitive inhibitory binds to the alosteric site of the enzyme this causes the active sites shape to change so substrates can no longer bind to it.
- they don’t compete with the substrate to bind to the active site because they’re a different shape to the substrate.
Explain the relationship between the rate of reaction with non competitive inhibitors and substrate concentration
Proteins and Enzymes
increasing the concentration of the substrate won’t make any difference to the rate of reaction as the enzyme activity is inhibited as the inhibitor changing the shape of the active site so enzyme substrate complexes can no longer form so less reactions are catalysed.
what are cofactors ?
Proteins and Enzymes
an additional non protein molecule that is needed by some enzymes to help the reaction
