1A-biological molecules

Question 1

What are polymers? List some examples.

Answer 1

A polymer is a long complex molecule made up of many short repeating chains of monomers including carbohydrates, nucleic acid and protein.

Question 2

What is a monomer? Give a few examples.

Answer 2

A monomer is a small molecular unit which joins up in many repeating units to make a polymer these include monosaccharides, nucleotides and amino acids.

Question 3

Carbohydrates are made up of monomers. What are these monomers called.

Answer 3

They are called monosaccharides and these include Glucose, Fructose and Galactose

Question 4

There are two types of glucose molecules explain the difference between the two and what are they called?

Answer 4

There is alpha-glucose and there is also beta-glucose. The alpha glucose has the H on top and the OH on the bottom only on the right side vice versa for the beta-glucose. These are both isomers as they both have the same molecular formula of C6H1206 BUT THEY HAVE DIFFERENT ARRANGEMENT OF ATOMS.

Question 5

Define and explain the process of two monomers joining together.

Answer 5

This is called a condensation reaction and it involves the process of two monomers joining together to form a bond however in the process they form and release a water molecule

Question 6

When two monosaccharides join together what do they form?

Answer 6

They form a glycosidic bond and in the process release a water molecule in order to create a disaccharide.

Question 7

List the three reactions for the formation of a disaccharide

Answer 7

1.) A-glucose + A-glucose = maltose + water

2.) A-glucose + fructose = sucrose + water

3.) A-glucose + galactose = lactose + water

Question 8

Define and explain the reaction to how polymers are broken down.

Answer 8

This is called a HYDROLYSIS reaction where polymer chains have the bonds between them broken down by the addition of a water molecule.

Question 9

Explain how a student would define between three solutions of water, sucrose and glucose.

Answer 9

Firstly you would take all three solutions and add them to a test tube then I would add benedicts solution to each test tube then I would add them to a water bath and bring them to a boil of 70 degrees for 10 mins then I would see that the solution which has formed a coloured precipitate (usually brick-red but it can be a spectrum depending on sugar concentration) would be glucose as it is a reducing sugar. then the other two test tubes I would take a fresh sample of each add it to a new test tube add HCl and then bring it to a SLOW boil in the water bath then I would add sodium hydrogencarbonate to neutralize the solutions then I would carry out the benedicts test again and I would see that the solution which produced a coloured solution would be sucrose as it is a non-reducing sugar and the test tube which still had no colour change would be water as there is no sugar present.

Question 10

Define what a polysaccharide is and list all the examples you need to know.

Answer 10

A polysaccharide is where multiple monosaccharides join together via condensation reactions to form a long chain of sugars examples include amylose, amylopectin, glycogen and cellulose.

Question 11

Give the structure and function of starch.

Answer 11

Starch is energy storage used by plants as they make glucose from photosynthesis they store excess glucose as starch. Starch contains two polysaccharides amylose and amylopectin.

Amylose- is a long unbranched chain of alpha glucose monosaccharides the angle of its (1,4) glycosidic bond causes it to form a cylinder shape which makes it compact and good for storage.

Amylopectin- is a long-branched chain of alpha glucose monosaccharides with (1,4) and (1,6) glycosidic bonds giving it branches that allow enzymes to easily access glycosidic bonds and release glucose for the plant.

Starch is also insoluble which makes it great for storage as it doesn’t affect the water potential and doesn’t allow water to enter cells causing them to swell up and burst.

Question 12

Give a process for how a student would test if a sample contained starch.

Answer 12

Take a sample and put it in a test tube then add iodine dissolved in potassium iodide solution and add to the test tube. If starch is present then the solution should go from orangy to black else it will stay orangy.

Question 13

Give the structure and function of glycogen.

Answer 13

Glycogen is energy storage for animals and is also a polysaccharide it has a similar structure to amylopectin but has more branches which allow quick release of energy for the animal to use it is also compact making it good for storage.

Question 14

Give the structure and function of cellulose.

Answer 14

Cellulose is what plant and algal cell walls are made up of it is a polysaccharide as it is a long chain of beta glucose monosaccharides called a cellulose chain these cellulose chains link together and form hydrogen bonds to form strong fibres called microfibrils this is good as it gives the cell structural support.

Question 15

How is a triglyceride formed and what is its main feature.

Answer 15

Triglycerides are made from three fatty acids and one glycerol molecule they form together via a condensation reaction when a fatty acid joins to a glycerol molecule an ester bond is made and in the process, they form a water molecule which is released this process takes place three times as there are three fatty acids. the key feature is that the fatty acid is hydrophobic (it repels water).

Question 16

What is the difference between a saturated fatty acid and an unsaturated fatty acid.

Answer 16

Saturated contains no C=C bond and it is completely saturated with hydrogen atoms.

Unsaturated contains a C=C bond causing the hydrocarbon chain to kink.

Question 17

What is a phospholipid and what is its key feature that enables its function.

Answer 17

A phospholipid is a lipid containing one phosphate group one glycerol molecule and 2 fatty acids the fatty acid tail is hydrophobic (repels water) and the phosphate group is hydrophilic (attracts water).

Question 18

What is a triglyceride used for and how is it good for its use.

Answer 18

Triglycerides are used as an energy storage molecule as the fatty acids hydrocarbon tails store a lot of chemical energy and lots of energy is released when the tail is broken down they can store twice as much energy per gram as a carbohydrate. Its hydrophobic tail forces the triglyceride molecules to clump together as insoluble droplets forming a structure where its tail is inwards and the glycerol molecule faces outwards which prevents any water from entering affecting water potential and prevents cells from swelling up and bursting via osmosis.

Question 19

What is a phospholipid used for and how does its structure help its function.

Answer 19

Phospholipids are used as a lining for cell surface membranes they line up and form a structure where the hydrophobic fatty acid tail faces inwards on both sides and the hydrophilic phosphate group faces outwards on both sides this acts as a barrier as it prevents water-soluble substances from passing the cell membrane.

Question 20

Explain how a student could test if a solution contained lipids.

Answer 20

Take a solution and add it to a test tube then add ethanol and shake the test tube then add to water if the solution turns milky then there is a lipid present in the solution else there are no lipids present.

Question 21

Define what is a protein and give examples.

Answer 21

A protein (polymer) is a long chain of amino acids a chain of two amino acids is a dipeptide and a chain of two or more amino acids is called a polypeptide examples of proteins include all enzymes, all hormones, antibodies, keratin, collagen.

Question 22

Explain all the functional groups of an amino acid

Answer 22

The variable R group- this is where the variation of every protein occurs out of the bank of 20 amino acids that all the proteins share this is where the difference between them arrives.

The carboxylic group-this is the same for all proteins COOH.

The amine/amino group- this is also the same for all proteins NH2.

Question 23

Explain how protein chains are formed.

Answer 23

Proteins are formed via a condensation reaction when two amino acids link together they form a peptide bond and in the process form a molecule of water which is released when two amino acids link together they form a dipeptide chain and when two or more amino acids link they form a polypeptide chain the reverse reaction occurs during digestion where proteins get broken down into amino acids.

Question 24

Explain the primary structure of a protein.

Answer 24

a sequence of amino acids in a polypeptide chain

Question 25

Explain the secondary structure of a protein.

Answer 25

The sequence of amino acids in a polypeptide chain begins to either fold or coil as hydrogen bonds between the amino acids begin to occur forming either an alpha helix or a beta-plated sheet.

Question 26

Explain the tertiary structure of a protein.

Answer 26

Protein begins to spiral or fold even more as more hydrogen bonding, ionic bonding (attraction from oppositely charged charges on the protein chain) and disulfide bridges form (where sulfur atoms found in the cysteine amino acid bond to another sulfur atom in another cysteine amino acid elsewhere on the protein chain). for protein containing only one polypeptide chain, this is its final 3D structure.

Question 27

Explain the Quan tertiary structure of a protein.

Answer 27

Some proteins are made up of several protein chains in this case multiple polypeptide chains will then begin the bond together and assemble for proteins like haemoglobin, insulin and collagen this is the end of its 3D structure.

Question 28

Different proteins have a variety of different functions give 4 proteins and their characteristics.

Answer 28

Enzymes- it has a roughly round shape as it consists of tightly folded polypepetide chains it is insoluble it has roles in metabolism and digestion. Antibodies-this consists of two large polypeptide chains and also two short polypeptide chains bonded together. Has roles in immune responses. It is in the antibodies variable R group in amino acids where most of the variety occurs. Transport proteins- channel proteins are located on the cell surface membrane. channel proteins contain amino acids which are hydrophilic and also some that are hydrophobic so it forms channels in the cell surface membrane in order to transport molecules and ions across the cell membrane. Structural proteins-this includes for example collagen (structural tissue) and keratin (hair and nails) where polypeptide chains arrange themselves parallel and form crosslinks making them really strong.

Question 29

explain how a student could test if a solution contained proteins

Answer 29

the student could take the solution add it to a test tube and add sodium hydroxide solution and then add copper(II) sulfate solution if proteins are present the solution should turn blue to purple else no proteins present

Question 30

what are enzymes

Answer 30

enzymes are biological catalysts made by proteins used to speed up a chemical reaction without being used up in the reaction. it does this by lowering the activation energy of the reaction (the energy required to allow a reaction to occur) which is usually provided by heat and this allows for a reaction to occur with less heat. enzyme action can be both intracellular or extracellular and they are also responsible for metabolic reactions and also digestion of food molecules. enzymes can affect structure e.g it is responsible for the production of connective tissue all over the body and also function e.g respiration

Question 31

we know enzymes speed up reaction how do they do this

Answer 31

if it involves building up molecules enzymes will grab both substrates and allow them the bond easily without the repulsion of the two however if it involves the breaking down of molecules then enzymes will latch onto molecules and put a strain on the bonds allowing them to break with more ease

Question 32

how does an enzyme work

Answer 32

an enzyme is a protein with an active site which is specific to the substrate it needs to catalyse and the enzyme will latch onto the substrate and catalyse the reaction leaving with two products. enzymes are indeed highly specific as their active site is only meant for one catalyst and it is the protein's final structure which determines the active site of the enzyme.

Question 33

what is the difference between the lock key model and the induced model of enzyme action

Answer 33

the lock and key model shows that both the enzyme and substrate are complimentary to each other however there was an improved model which showed that it was not only the active site that had to be specific but the substrate had to be correct in order for the active site of the enzyme to change shape slightly in a correct way and gain an induced fit to the substrate.

Question 34

As we know enzymes contain an active site that is extremely specific to its substrate. what is responsible for the shape of the enzyme's active site

Answer 34

the shape of the enzyme's active site is determined by its tertiary structure (which is determined by its primary structure) if the enzyme's tertiary structure was to be altered then the enzymes active site would be different preventing it from linking with any substrate the enzyme is useless

Question 35

how can the enzymes active site be altered

Answer 35

the enzyme's active site can be altered by heat and ph. and if there were to be an altercation to the gene which codes for the primary structure of an enzyme it could completely change its shape

Question 36

list the factors that affect enzyme activity

Answer 36

temperature, PH, enzyme concentration, substrate concentration, competitive inhibitors and non-competitive inhibitors

Question 37

How does temperature affect enzyme activity

Answer 37

when the temperature of a reaction containing enzymes increases so does the rate of reaction as molecules will then begin to gain kinetic energy allowing the enzyme and substrate to collide to form the enzyme-substrate complex and catalyse reaction more often also the molecules have enough energy to collide up to its optimum temperature however if the temperature of the reaction gets too high the enzymes will denature as the enzymes bonds which holds the enzymes tertiary structure in place will begin to break causing the enzymes active site to change leaving it useless

Question 38

how dos ph affect enzyme activity

Answer 38

when the enzyme is at its optimum ph the rate of reaction is at its peak e.g pepsin enzyme has an optimum ph of 3 which is very acidic which is good as it is found in the stomach containing HCl if the ph of the enzyme is too high or too low then the enzyme will denature as the H+ and OH- ions will cause the hydrogen and ionic bonds in the enzyme which hold together the tertiary structure to mess up causing the enzymes active site to change

Question 39

how does enzyme concentration affect enzyme activity

Answer 39

if there is a high concentration of enzymes then there will be a high rate of reaction as there are plenty of enzymes to collide with and latch onto the substrate forming an enzyme substrate and catalyzing the reaction however if the amount of substrate is limited then this occurs up to a point when there are plenty of enzymes present to catalyse with substrates and adding more enzymes has no effect on the rate of reaction

Question 40

what affect does substrate concentration have on enzyme activity

Answer 40

when you increase the concentration of substrates then the rate of reaction will increase as there are more frequent collisions with enzymes forming an enzyme-substrate complex causing the reaction to be catalyzed however this only occurs up to a certain point called a saturation point where adding more substrate molecules has no effect on the rate of reaction as there are not enough enzymes to occupied the high concentration of substrates as all the active sites are full eventually substrate concentration will decrease in some time (if no more is added) causing the rate of reaction to then to decrease so the rate of reaction is highest at its initial point.

Question 41

what is a competitive and what effect do they have on enzyme action

Answer 41

A competitive inhibitor is a molecule which has the exact same shape as a substrate once the inhibitor is onto the enzyme nothing will happen it will simply occupy the enzyme these inhibitors will compete with substrates in order to collide with an enzyme. the number of enzymes that are limited depends on the relative concentration of substrates and inhibitors if there are more inhibitor molecules than substrates then there will be more inhibitors that occupy the enzymes however if there are more substrates then more substrates will reach enzymes and increase the rate of reaction up to a certain point a saturation point

Question 42

what is a non-competitive inhibitor and what effect does it have on enzyme activity

Answer 42

a non-competitive inhibitor is a molecule which will latch onto the enzyme not on its active site and will cause the enzymes to change its active site so that no substrate is able to latch and form a enzyme-substrate complex these inhibitors don't compete and increasing substrate concentration has no effect on enzyme activity what so ever

Question 42

what is a non-competitive inhibitor and what effect does it have on enzyme activity

Answer 42

a non-competitive inhibitor is a molecule which will latch onto the enzyme not on its active site and will cause the enzymes to change its active site so that no substrate is able to latch and form a enzyme-substrate complex these inhibitors don't compete and increasing substrate concentration has no effect on enzyme activity what so ever