Biological molecules

Question 1

What is a monomer?

Answer 1

small repeating units from which larger molecules called polymers are made

Question 2

What is a polymer?

Answer 2

Molecules made from a large number of monomers (3 or more) joined together

Question 3

What is a condensation reaction?

Answer 3

A condensation reaction joins 2 molecules together with the formation of a chemical bond by removing water

Question 4

What is a hydrolysis reaction?

Answer 4

A reaction which breaks a chemical bond between 2 molecules and involves the use of a water molecule

Question 5

What is a monosaccharide? plus examples and extra info

Answer 5

they are the monomers from which all larger carbohydrates are made, for example Glucose, Galactose and Fructose (C6H12O6)
they are soluble
general formular of (CH²0)n
2 join to form disaccarides
many join to form polysaccharides

Question 6

Important monosaccarides

Answer 6

Alpha glucose (penguin)
Beta glucose (Egyptian)
Galactose (raver)
Fructose (witches hat)

Question 7

Disaccarides

Answer 7

2 monosaccarides joined in a condensation reaction with glycosidic bonds
equation- c6H12O6 + C6H12O6 —-> C12H22O11 + H20
reaction happens between OH groups on carbon 4 and 1
examples; Glucose+glucose= Maltose
Glucose+fructose=sucrose Glucose+Galactose=Lactose

Question 8

Hydrolysis of disaccarides

Answer 8

During digestion glycosidic bonds in dissacarides are hydrolyzed into monosaccarides as only monomers are small enough to cross the cell surface membrane
equation; C12H22O11 + H2O —–> C6H12O6 + C6H12O6

Question 9

What is a polysaccharide?

Answer 9

A type of polymer formed by many monosaccarides together via condensation reactions, large and insoluble so great for energy storage and structural molecules

Question 10

Structure and function of starch

Answer 10

Starch is a storage polysaccharide in plants, it is how they store glucose made in photosynthesis ( it is later hydrolysed for respiration)
it is a polymer of alpha glucose with alpha 1-4 glycosidic bonds
It has a helical structure so is compact
also contains 1-6 glycosidic bonds so it can branch which provides more ends for faster enzyme action

Question 11

structure and function of Glycogen

Answer 11

Glycogen is a polymer of alpha glucose
found mostly in liver and muscle cells
alpha 1-4 glycosidic bonds
is coiled which makes it compact
it is insoluble so doesn’t effect water potential
large so can’t move out of cell
highly branched 1-6 glycosidic bonds to give it a larger surface area for faster hydorolysis for respiration

Question 12

Structure and function of cellulose

Answer 12

Cellulose is a polymer of beta glucose ( every other beta glucose has to flip 180⁰)
adds structure to cell walls
beta glucose form 1-4 glycosidic bonds and long straight chains
several chains are joined by many hydrogen bonds (Strong in large numbers)
This forms microfibrils which are further wound into cellulose fibers which provide strength and rigidity and support cell walls

Question 13

Test for reducing sugars

Answer 13

1. Add equal volumes of benedicts solution and sample to a test tube
   2.heat to 95⁰c for 5 mins
   3.formation of a brick red precipitate shows positive if it stays blue it is negative.

Question 14

Test for non reducing sugars (sucrose)

Answer 14

1.boil a fresh sample with hydrochloric acid for 5 mins
(thus hydrolysises the glycosidic bonds to produce reducing sugars)
2. neutralise the solution by adding sodium hydrogen carbonate
3.Do reducing sugars test same result show positive/negative

Question 15

Test for unknown concentrations of reducing sugars

Answer 15

Calibration curve to turn it into a quantities test
1. make up several known concentrations of reducing sugar
2.carry out Benedicts test
3.use a colourmeter to measure the absorbance
4.plot calibration curve
conc on x axis and Absorbance on Y axis
5.Carry out benedicts test on sample+measure its absorbance
6. use Y value on curve to find conc of unknown sample on X axis

Question 16

Role of lipids

Answer 16

Source of energy- 2x as much energy per g the carbs when oxidised( so are good for respiration)

insulation- Don’t conduct heat well so help animals retain heat.Also electrical insulators and so make up myelin sheath around axons
protection-Important organs have a layer of fat to protect them
Waterproofing- plants and insects have waxy lipid cuticles to conserve water.Animals produce sebum

Question 17

Triglycerides structure

Answer 17

Made of 1 molecule of glycerol joined to 3 fatty acids via 3 condensation reactions to form 3 Esther bonds between the carboxyl group of fatty acid and hydroxyl group of the glycerol

Question 18

Saturated fatty acids vs unsaturated fatty acids

Answer 18

Saturated fatty acids have no double bonds(all bonds are saturated)
Unsaturated fatty acids have double bonds between the carbon atoms in the hydrocarbon chain thus makes them bend+ liquid at room temp as cannot pack Close together
Polyunsaturated- more than 1 double bond between carbons

Question 19

structure of triglycerides related to their properties

Answer 19

Triglycerides are hydrophobic/non polar
They conatin lots of energy as high ration of C-H bonds compared to C-C
Low energy:Mass ratio excellent for energy storage as more energy smaller space
High ratio of H-O bonds, they release water when oxidised so xan be important water source for animals(dessert)

Question 20

Emulsion teat for lipids

Answer 20

Add ethanol to sample and mix
then add water and mix
White emulsion will be visible if fat present
Seed must be crushed first

Question 21

Phosopholipids structure

Answer 21

1 glycerol bonded with 2 fatty acid tails with Ester bonds formed between the Carboxyl and hydroxyl groups the other fatty acid is replaced with phosphate group
they are made of 2 parts
Hydrophilic head- attracted to water this is caused by polar nature of the phosphate group (-)
Hydrophobic fatty acid tails-these are repelled by water and face away from water as they are non polar

Question 22

What do phosolipids form in water?

Answer 22

Form a bilayer with the fatty acid tails pointing inwards as they repel water and attract fats and the hydrophilic heads pointing outwards as they attract water and repel fats.
Can also form a micellar and ect

Question 23

Water properties

Answer 23

A metabolite- This meas water can be involved in metabolic reactions such as condensation and hydrolysis
Solvent- allows metabolic reactions to occur and aslo allows transport of substances
High specific heat capacity- This buffers change in temp helps mammals maintain core temp despite enviro changes as it takes lots of energy to break bonds
Large latent heat of vapourisation- provides cooling effect as lots of energy is required to evapourate it and so when this occurs it takes heat energy away from body to cool it
Cohesion- supports the formation of continuous coloums of water (xylem)
Also produces surface tension which supports small organisms on water surface
Density- water us more dense than ice, provides a habitat

Question 24

Structures of amino acids

Answer 24

They contain N C H O and some contain sulphur
there are 20 different amino acids
general structure is
H H O
H N C C OH
R
Amino group, R group and Carboxylic acid group
The oxygen has a double bond
Ejat differentiates them is there R group all of whichbl have diff sizes and are grouped by properties

Question 25

Formation of a peptide bond

Answer 25

2 amino acids join to form a dipeptide by a condensation reaction The hydroxyl group(OH) from the Carboxyl group react with hydrogen of another amino acids forming peptide bonds through condensation reaction/removal of water

Question 26

Polypeptide chains

Answer 26

These are formed by many amino acids joining together through condenstation reactions to form a polypeptide chain They always have an amine group at one end and a Carboxyl group at the other end number of peptide bonds will be one less than the no of amino acids orginaly joined together

Question 27

Primary structure

Answer 27

This is the number and sequence of animosity acids in a polypeptide chain The primary structure determines the position of the bonds- between R groups so affects final shape Shape dictates function so a single amino acid in P structure can change whole shape and possibly make it inactive Primary structure- sequence of amino acids joined together by peptide bonds formed from condensation reactions

Question 28

secondary structure

Answer 28

Hydrogen bonds form between the slightly positive charge of the hydrogen in the -N-H group and the slightly negative charge of the oxygen in the -C=O group. That the polypeptide chain has form weak H bonds throughout the polypeptide, no of them makes them strong due to these bonds the polypeptide coil into alpha helices or folds into beta pleated sheets

Question 29

Tertiary structure

Answer 29

This is the further folding of the secondary structure into specific, complex 3D shape which determines function The tertiary structure shape is decided by where bonds form between R groups H bonds- weak and easily broken as temp rises Ionic- also weak form between oppositly charge R groups+ PH breaks them Disulphide bridges- covalent bonds between sulphur atoms, extremely strong primary structure decides where these bonds form and therefore tertiary structure

Question 30

Quaternary structure

Answer 30

Contains 2 or more polypeptide chain that are also linked by H, ionic and disulphide binds They can also contain prosthetic groups e.g. Haemoglobin is 4 polypeptide chains and a prosthetic group

Question 31

denatured proteins

Answer 31

the shape of a protein is essential to function proteins denatured at high Temps increase temp increases k energy of molecules making them vibrate this can break weak H bonds holding structure together as bond break tertiary shape is lost this is denaturation also be caused by PH which can disrupt ionic bonds in T structure

Question 32

How Enzymes work

Answer 32

Enzymes are biological catalysts.They increase the rate of reaction of a chemical reaction without being effected or used up. They speed up the r of r by lowering the activation energy needed foe a reaction to occur by placing pressure on the bonds and bending the bonds in the substrate during the formation of the enzyme substrate complex, meaning bonds can break easier and less energy is nessecary substrates--------> products

Question 33

What conditions must be met for reactions to occur (enzymes)

Answer 33

They must successfully collide to form enzyme substrate complexes free energy of products must be higher than free energy or substrates Must reach activation energy (minimum amout of energy required to start a specific reaction)

Question 34

Enzyme structure

Answer 34

enzymes are proteins with specific tertiary structure giving them a unique 3D shape The part of the enzyme involved in reactions is the active site the rest hold thus in the correct shape using H, I and Disulphide bonds a sites have a shape which is complimentary to one substrate allowing them to fit/bind together This fitting or binding is called a enzyme substrate complex where the substrate is held to the A site with temporary bonds formed with the amino acids this is what stresses bonds + lowers A energy

Question 35

Induced fit model of Enzyme action

Answer 35

In this model the active site isn't sully fixed in its shape and the substrate induces a change in shape of the active site making it more complimentary to the substrate. 1. A site is not complimentary to substrate 2.substrate enters A site and induces change in shape of A site as enzyme substrate complex forms 3.this stresses the bonds in substrate and lowers A energy 4.When the product leaves A site it then returns to previous shape

Question 36

Factors effecting enzymes

Answer 36

temp ph substrate conc enzyme conc inhibitors

Question 37

Effect of tempreature

Answer 37

Every enzyme has a optimum temp as temp increase so doesn't kinetic enrgy so they move around more and collide more to form enzyme substrate complexes so r of r increases if it gets too high this causes the H bonds and ionic bonds between R groups to break, changing tertiary structure and shape of A site so no longer complimentary to substrate so fewer ES complexes form enzyme is now denatured- permenant

Question 38

Effect of PH

Answer 38

Ph is a measure of hydrogen ions concentration each enzyme has an optimum Ph a decrease in Ph of 1 means 10x more H+ ions If the Ph rises too low or too high it can break the hygmdrogeb bonds and the ionic bonds between the -NH and -C=O groups of the amino acids in T structure this causes the active site to change shape and the substrate is no longer complementary.No ES complexes will form and r of r decreases either side of optimum as it is denatured

Question 39

effect of substrate conc

Answer 39

as the substrate conc increase the r of r increase and them levels off the initial r of r is slow when little cubstrate conc as not all A sites of the enzymes are saturated substrate is the limiting factor as substrate conc increases A site's are filled and r of r increase due to more ES complexes forming, Substrate no longer limiting factor when R of R levels off this is due too enzymes not being able to form and more ES complexes as all A sites are filled/saturated and all the substrates are used up enzyme conc is now limiting factor

Question 40

effect of enzyme conc

Answer 40

As enzyme conc increases the r of r does too and then levels off This is beacause the r of r is low when there is a low enzyme conc as all the A sites of the enzymes are saturated and so the enzyme conc is limiting factor. As the enzyme conc increases, there are more A sites available for substrates to bind to.So r of r increases due to more ES complexes forming. When r of r levels off as the enzymes cannot form any more ES complexes as there are more A sites than substrates Substrate conc is now the limiting factor

Question 41

Effect of inhibitors

Answer 41

Competitive- similar shape to substrate so can bind to A site and block it prevent ES complexes forming not permenantly bound to A site so when it leaves substrate can bind reduces r of r as fewer ES complexes can form so fewer products form some products will still be formed because not all A sites are occupied by the inhibitors Non competitive- bind to site on enzyme away from A site Bind to allosteric site change shape of A site so no longer complimentary to substrate fewer ES complexes form and r of r is decreased fewer products form

Question 42

what are the larger molecules broken down into in digestion

Answer 42

carbohydrates hydrolysed into simple sugars fats are hydrolysed into glycerol,fatty acids and monoglycerides polypeptides and proteins are hydrolysed into amino acids

Question 43

Enzymes what they break down and where they are produced

Answer 43

salivary glands- salivary amalyse- carbohydrates stomach- endopeptidase and exopeptidase- protein pancreas- pancreatic amalyse - carbohydrates, Lipase- fats, exopeptidase- proteins Ileum-membrane bound dipeptidase- Protein dissacharidases- Carbohydrates

Question 44

Key organs in digestive system

Answer 44

Salivary glands- salivary amalyse, hydrolysed starch to maltose oesophagus- peristalsis stomach- mix with gastric juices, kills microorganisms and contains exopeptidase and endopeptidase hydrolysed polypeptide to dipeptides pancreas- secrete pancreatic juices containing amalyse, exopeptidase , endopeptidases and lipase small intestine (ileum)- adapted to provide a large surface area for the absorbtion of the products of digestion Maltase embedded in epithelium cell membrane, hydrolysed Maltose to glucose for rapid absorption.Also sucrose,lactase and dipeptase large intestine rectum

Question 45

Starch digestion

Answer 45

1.food enters the mouth and is broken up by teeth, then mixed with saliva 2.salivary amalyse starts to hydrolyse glycosidic bonds in starch producing maltose 3. in the stomach this salivary amalyse is denatured due to Ph 4.in small intestine pancreatic amalyse continue to hydrolyse 5.maltose then hydrolysed to glucose by membrane bound maltose, embedded in cell membrane of epithelial cells In ileum. 6.Glucosr is then absorbed in the Ileum

Question 46

protein digestion

Answer 46

endopeptidase- proteins and polypeptide are hydrolysed by protease.Beginning in the stomach.Endopeptidase hydrolyse internal bonds within the polypeptide chain producing shorter chains+ increasing surface area for next enzyme Exopeptidase- hydrolyse peptide bonds at the terminal ends of polypeptide chain producing dipeptides and animo acids. They are specific , one complimentary to N terminal and one to C terminal end dipeptidase- enzymes embedded in the cell surface membrane of the epithelial cells Hydrolyse the single peptide bond in the dipeptide to single amino acids.These can now be absorbed by cotransport

Question 47

Glucose absorption

Answer 47

They are absorbed into the epithelial cells by co transport and enter blood via facilitated diffusion 1. sodium ions are actively transported out of cells into blood by sodium pottasium pump, requiring ATP 2.This creates concentration gradient of Na+ 3.Na+ and glucose enter via facilitated diffusion using co-transporter proteins. 2 binding sites one specific to Na+ and one to glucose Na diffuses down its concentration gradient Glucose diffuses against conc gradient 4. glucose moves into blood by facilitated diffusion

Question 48

Amino acid absorption

Answer 48

1. Sodium ions actively transported out of E cell into the blood by sodium pottasium pump 2.Creates a conc gradient of Na+ 3.Na+ and amino acids enter by facilitated diffusion using co transporter proteins. 2 bindings one specific for Na+ and one specific for amino acids Na moves into cell down its conc gradient amino acids against its conc gradient 4. amino acids move into the blood by facilitated diffusion

Question 49

Lipid digestion and absorption

Answer 49

1.Lipid droplets are mixed with bile salts to form smaller droplets 2. Increase SA for faster hydrolysis by lipase 3.triglycerides are hydrolysed into glycerol, fatty acids and monoglycerides 4.bule salts, glycerol and fatty form Micelles 5.Micelles make fatty acids soluble in water and bring them to surface of E cell membrane + maintains higher conc relative to E cell 6.fatty acids enter E cell by simple diffusion 7.Smooth endoplasmic reticulum- fatty acids+glycerol recombine to make triglycerides 8.Golgi- triglycerides are modified+ proteins added to form chylomicrons and packaged into vesicals 9.chylomicrons transported into a lymph vessel by exocytosis, then enter blood