Biological Molecules

Macromolecule

Many same micromolecules joined together to make one giant molecule

Monomer

Small basic molecular unit

Polymer

Many same type monomers joined together in a chain (repeated monomers)

Anabolism

The process of building up smaller molecules into bigger molecules

Catabolism

Process of breaking down larger molecules into smaller ones

Metabolism

The sum of all chemical reactions in the body

Condensation reaction

This joins 2 molecules together with the formation of a chemical bond and involves the elimination of a molecule of water.

Hydrolysis reaction

Breaking a chemical bond between 2 molecules and involves the use of a water molecule

Examples of monomers

Monosaccharides, amino acids, nucleotides

Polymers and their monomers

carbohydrates-monosaccharides
nucleic acid-nucleotide
protein-amino acids
lipids-fatty acids and glycerol
water - no monomer

How does hydrogen bonding work?

A molecule with an uneven distribution of charge is polarised. The negative region of the polar molecule and the positive region attract each other to make an electrostatic bond. These bonds collectively can form a force that alters the physical properties of molecules

3 Monomers for carbohydrates you need to be able to draw

Alpha glucose, beta glucose, galactose. (You dont have to be able to draw fructose but you need to know it)

Alpha Glucose (Image)

Beta Glucose (Image)

Galactose (image)

What 2 monomers is the disaccharide maltose made from

Condensation of 2 glucose molecules

What 2 monomers is the disaccharide sucrose made from?

Condesnation of a glucose molecule and fructose

What 2 monomers is the disaccharide lactose made from?

Condensation of a glucose molecule and a galactose molecule

How is glycogen and starch formed?

The condensation of alpha glucose

How is Cellulose formed?

The condensation of beta glucose.

What is a reducing sugar

A sugar that can donate electrons to another chemical

Molar solution

A solution that contains one mole of solute in each litre of solution

Isomers

Molecules with the same molecular formula but different structural formula.

Polysaccharide

Carbohydrates that are made up of more than two monosaccharides

Bonds that form between monomers

Glycosidic bond

What is a condensation reaction

When two molecules bond through the loss of a water molecule.

What is a hydrolysis reaction

A covalent bond is broken by adding a molecule of water.

Where is glycogen found?

In animal s liver and muscle cells

What are the monomers of glycogen

Alpha glucose

Structure of glycogen

Chains of glucose in 1-4 glycosidic bonds and highly branched with alpha glucose in alpha-glucose in 1-6 glycosidic bonds

Function of glycogen

Stores sugar and an energy source its more soluble so can be broken down rapidly

Where is starch found

plants starch grains in plastids ( green chloroplasts and amyloplasts)

Monomers of starch

alpha glucose

Structure of starch

Glucose molecules are arranged in 2 different ways amalyse and amylopectin. These are built up in the chloroplasts or inn storage oragns

Amylase structure in starch

Unbranched chain of alpha glucose in a 1-4 glycosidic bond a compact vertical structure

Amylopectin structure in starch

Chain of alpha glucose in a 1-4 glycosidic bond with many more chains of alpha glucose 1-6 glycosidic bonds - compact

Function of starch

Used as storage ibn plants as starch granules are insoluble in water

Where is Celluose found

Cell wall of plants , monomers: beta glucose

Structure of Cellulose

Every other glucose molecules is rotated 180 degrees so that the hydrogen group on each molecule are adjacent to each other. Made up of about 10,000 beta glucose molecules in an unbroken chain

Function of Cellulose

Hydrogen bonds between chains gives cellulose great tensile strength cellulose is strong and prevents cell from bursting

Testing for carbohydrates (Starcg)

Potassium iodide is utilised as a solution starch-iodide complex forms a strong blue-black colour

Test for reducing sugar

Add benedicts solution to the sample in a water bath that has been boiled to 100 degrees for 5 minutes, positive test blue to orange/brick red

Test for non reducing sugars

Hydrolyse, dilute HCL is added to sample - breaks glycosidic bond . neutralise it by adding sodium hydrogen carbonate. Then add benedicts reagent in a water bath thats been brought to a boil of 100 degrees Celsius. Positive test blue to orange/brick red.

What type of bond is formed together when monosaccharides join together

glycosidic bond

What type of raection joins together proteins

condensation reactions

What are the advantages of storing glucose as starch

Starch is insoluble and therefore does not affetc water potential so water is not drawn into the cell via osmosis. Starch is also compact so alot of it can be stored in a small space.

What happens when starch is hydrolysed

It forms an alpha glucose which is both easily transported and readily used in respiration

What are the adaptations of glycogen

it is insoluble and is more branched than starch so has more ends that can be acted on simultaneously by enzmes. It is therefore more rapidly broken down to form glucose monomers.

What are the adaptions of celluose

celluose has straight unbranced chains. These run parallel to one another allowing hydrogen bonds to form cross-linkages between and adjacent chains. While each individual hydrogen bond adds very little strength. Then combine contributes heavily to strenght

what does a amino acid look like?

Diagram of a phospholipid

Why are phospholipids polar molecules.

They have a hydrophilic phosphate head and a hydrophobic taail of 2 fatty acis. This means that phosphoplipids form a bilayer within cell surface memvrabes.

What are some examplesthat lipids are used for

Insulation secondary food storage.

Triglyceride diagram

Simple way to denotew a general fatty acid moleucle

R-COOH (R represents the hydrocarbon chain)

Ester bond (image)

glycerol (image)

Saturated fats

Fats dont have any bonds between their carbon atoms. No kinks, less fluid

Unsaturated fats

Fats that have at ;easy one double bond between carbon atoms causing the chain to kink, more fluid

How many glycosidic bonds are between 3 monosaccharides

2

Give 2 features that may be found in a prokaryotic cell which would not be found in a plant cell

Peptidoglycan cell wall (celluose in plant cells). 70s ribosomes compared to 80 s in plant cells. Circular DNA compared to linear DNA in plants.

How many carbon atoms does a molecule of fructose contain?

2

How are triglycerides formed?

Through the reactions of 3 fatty acids and 1 glycerol. It is formed through a type of condensation reaction called esterification due to formation of ester bonds

What does the “R” represent on a fatty acid

The hydrocarbon chain

What 2 parts make up a phospholipid

A hydrophilic head (Attracted to water) and a hydrophobic tail (afraid of water)

diagram of phospholipid

Why do phospholipids form a bilayer within cell-surface membranes

They are polar molecules, having a hydrophilic phosphate head and a hydrophobic tail of 2 fatty acids. This means that in an aqueous environment, phospholipid molecules form a bilayer within cell -surface membranes. As a result a hydrophobic bbarrier is formed between the inside and outside of a cell.

How do hydrophilic heads of phosphate molecules help the phopsholipid molecule

It helps to hold at the surface of the cell surface membrane

How are glycolipids formed at a cell surface membrane

The phospholipid structure allows them to form glycolipids by combinding with carbohydrates within the cell surface membrane

What bond forms between fatty acid and glycerol

ester bond

E coli has no cholesterol in its cell surface membrane. Despite this the cell maintains a constant shape

it has a peptidoglycan cell wall.

What are the roles of proteins

Defence, - Structural, -carriers, hormones, enzymes

amino acid

NH2 = Amine group COOH = carboxylic acid group

The structure of haemaglobin explained

Globular, soluble in water, many different amino acids 4 polypeptide chains, 4 haem groups containing iron.

The structure of collagen explained

Fiborous, insoluble in water, lots of smallest amino acids (glycine). 3 Polypetide chains Helix Rope like and strong.

How is a peptide bond formed

the C-N is the chemical bond formed but the peptide bond is the C=O , H-N and C-N

What type of protein is Insulin

Globular protein

What 2 substances are formed when 2 amino acids join together

watrer and polypeptide

Primary structure of protein explained

The sequencee of amino acids provides the primary structure

Secondary structure of protein explained

This is how the polypeptide chain is folded. It may form an alpha helix or beta fold or pleated sheet. It is held together by hydrogen bonding.

Tertiary structure of protein explained

Further folding of the polypeptide chain, it is held by hydrogen bonds, hydrophobic interactions, disulphide bridges and ionic bonds

Quaternary structure of protein explained

Furyjer folding of the polypeptide chain, it is held by hydrogen bonds, hydrophobic interactions, disulphide bridges ionic bonds

What is meant by a receptor molecule

A molecule that is on the surface of a protein and receives signals.

Explain how a proteins tertiary structure might allow a protein molecule to act as a receptor molecule

Folds into specific shape which can be complimentary to specific substances.

What is the relationship between enzymes and substrates in terms of reactions

Ezymes enable substrate to react but it is not used during the reaction

What are enzyme’s structures

They are proteins, large macromolecules, proteins with tertiary structures

Why can enzymes not catalyse multiple reactions

The active site of the enzyme is complimentary to a specific substrate

Enzyme induced fit diagram

What type of reactions do enzymes catalyse?

They catalyse both anabolic and catabolic reactions

Investigating the effect of enzymes practical

First add 10ml of 30% powder milk solution in tube C and T and draw an x on tube T

1) In one tube add 4ml of pH7 buffer (test tube C) in another add 2ml of pH7 and 2ml of 0.5trypsin solution (Test tube T)

2)Place tets tubes in water bath until tubes reach 40^oc

3) In tube labelled T add trypsin enzyme tube and in the tube labelled C add tube without enzyme trypsin

4) Then start timer and record the time it takes for x to appear on the T tube

Rate of teaction = 1/time(s)

What is the induced fit model

The active site shape is not initially complimentary to the substrate. The active site moulds itself around the substrate. The change of shape alters the substrate, putting stress on the bonds and therefore lowers the activation energy required for the reaction

Graph for rate of reaction with pH

Graph for rate of reaction with temperature

Rate of reaction and enzyme graph

This is the same as the substrate concentration and rate graph. Sometimes the graph is shown with the rate decreasing at high enzyme concentration this is due to the fact that if there is too many enzymes, then enzymes will collide with one another instead of binding with the substrate to create an enzyme substrate complex

What is an advantage of using a pH meter rather than a pH indicator in an experiment

It is more objective than subjective

Why does the pH decrease when lipase is added ti milk

Lipase breaks down fat in milk to fatty acids and glycerol. The fatty acids decrease the pH

What type of biological molecule are enzymes

proteins

How do inhibitors prevent reactions?

through blocking the active site or changing the active site shape so enzymes can not bind to substrates

How do competitive inhibitors work?

They have a similar shape to the normal substrate so compete with the substrate for the active site of the enzyme and block the active site preventing a reaction from occuring.

How does a non competitive inhibitor work?

The inhibitor binds to the allosteric site causing a confirmational change so that the active site no long has an induced fit with the substrate and no reaction occurs.