biological molecules

monomers

individual small units that make up a polymer

polymers

large molecules of regular repeating units

all carbohydrates contain

C H O

Examples of monosaccharides

alpha glucose

beta glucose

galatacose

fructose

examples of disaccharides

alpha glucose + alpha glucose - maltose

Alpha glucose + galatose - lactose [milk]

Alpha glucose + fructose - sucrose {only non reducing sugar}

Polysaccharides

Starch {excess glucose stored as starch in plants} [ lots of alpha glucose joined togther]

Glycogen {excess glucose in animlas} [ lots of alpha glucose joined togther]

Cellulose {for cell wall strengthening} [lots of beta glucose]

Alpha glucose and beta glucose molecule drawing

What is the test for reducing sugars

Benedicts test

How to do benedicts test for a reducing sugar

1. Add benedicts

2. Heat it

3. Blue to red color chnage

Whats the test for non reducing sugars

1. If benedicts test is negative we do this - solution stays blue

2. Heat it with HCL to hydrolyse the disaccharide [ sucrose broken into alpha glucose and fructose]

3. Neutralise it with sodium hydroxide NaOH - base

4. Add benedicts again

5. Blue to red

What is the color spectrum for benedicts test

Blue-green-yellow-orange-red

Properties of starch - polyschhardie made of lots of alpha glucose

1. Large - cnnot diffuse out of cell

2. Insoluble - osmotically inactive

3. Alpha helix shape- compact enegry store

4. Branched - rapid release of glucose

Test for starch

1. Add iodine dissolved in potassium iodide to the test sample

2. Browny orange- blue black

Glycogen properties

1. Large- cannot diffuse ou of cell

2. Insolube- osmotically inactive

3. Alpha helix shape- compact negery store

4. Branched- rapid release of glucose

Properties of cellulose

1. Forms a straight chain molecule

2. Forms glycosidic b0nds

3. Monomers are flipped

4. Made from beta glucose- allows striaght unbranched chains to join

5. parallel chains form weak hydrogen bonds[ crosslinks]

6. cellulose forms microfibrils - adds strength

What is a condensation reaction

A reaction that joins two molecules together with the formation of a chemical bond and involves the elimination of a molecule of water.

What is hydrolysis?

reaction that breaks a chemical bond between two molecules and involves the use of a water molecule.

whats the bond for a carbohydrate

glycosidic bond

Why is cellulose suitable for plant cell walls?

Hydrogen bonds between cellulose chains form strong microfibrils, giving the cell wall high tensile strength.

Why is glycogen suitable for energy storage in animals?

Highly branched structure provides many ends from which glucose can be rapidly released by hydrolysis.

are lipids polymers

lipids are NOT polymers

structure of a triglyceride

basic strcture of a fatty acid

COOH

WHAT ARE LIPIDS USED FOR

1. cell membrne - phospholipid bilayer

2. enegey store

3. waterproofing - waxy cuticle of leaves is insolublein water

4. used in insulation- thermal + electrical insulation

5. protection - covers the heart and kidneys

what are rhe two types of lipids

phospholipids an trigycerides

diagram of triglyceride formation

saturated fatty acids

1. no double bonds

2. striaght hydrocarbon chain

Why do phospholipids form bilayers?

Hydrophilic heads interact with water while hydrophobic tails avoid water, causing phospholipids to arrange themselves into a bilayer.

proteins

made from long chains of amino acids as monomers

amino acid contain,

1. a carboxyl group COOH

2. AMINE GROUP

3. R GROUP newcastle city council

functions of proteins

dipeptide formation

describe how a quaternary protein is formed from its monomers

primary structure

1. sequence of animo acids

2. joined by peptide bonds

3. the sequence s determined by genes

secondary structure of a protein

1. initial folding due to hydrogen bonding

2. either coil into an alpha helix or beta pleated sheet

tertiary struture of a protein

1. 3D shape

2. held togther by hydrogen, ionic, disulfide bonds [strongest bonds]

3. formed by interactions between R GROUPS

quaternary stricture of a protein

multiple polypeptides folded togther

test for proteins

1. add biuret

2. blue- lilac purple

What is a peptide bond?

A bond formed between two amino acids in a condensation reaction.

Dipeptide

Two amino acids joined by a peptide bond.

Polypeptide

Many amino acids joined by peptide bonds.

VERY IMPORTANT

Primary structure determines the final three-dimensional structure of a protein, which determines its function.

Definition of enzyme

A biological catalyst that lowers the activation energy of a reaction.

Activation energy

The minimum energy required for a reaction to occur.

breakdown and synthesis reaction

induced fit model

1. before the reaction the enezymes active site is NOT complemtry to the substarte

2. shaope of the active site chnages as te enzyme substrate complex forms

3. this either strains the bonds or brings the substrates closer

4. lowerinf the acivtation emnergy

factors affcetin enzuymes

what is the active site of an enzymes shape determined by

the tertiary structure

what can alter the tertiary structure of an enzyme

PH and Tempreature changs

causes the shape of the active site to chnage an the substrate woukld no longer fit in

what is the primary structure of a protein determined by

genes

if theres a mutation in genes the primary structure chnangs so does the tertiary strcure which determines the shape of he active site, leaving the enzyme substrte complex unable to form

what are factors that affcet enzyme activity

tempreture and PH - higher than optimum level ould. cuase the enzyme to denature

what are factors that affect rate of reaction of enzyme subtrate complexes

substrate concentration and enzyme concentration

what are th two types of enzyme inhibitors

1. competitive inhibitor

2. non competetive inhibitor

what does competetive inhibitors do and hw to prevent it

they are molecules with a similar shape to the substartes so they compete with the substrate to bibd to the active site, reducing the amount of e-z complxes able o be fomed

if we increase the substrate concentration theres a higher chnace itll bind to the actiive site faster than the inhibitors

What does non compettive inhibitors do and how to prevent it

Binds to the enzyme away from the active site and chnages the tertiary structure of the active site so the substrate wont fit to the active site anymore, reducing he amount of e-z complexes formed.

Factors affecting enzyme activity

Temperature

Increasing temperature:
→ more kinetic energy
→ more successful collisions
→ rate increases

Above optimum:
→ bonds holding tertiary structure are disrupted
→ active site changes shape
→ substrate no longer binds effectively
→ enzyme denatures
→ rate decreases rapidly.

Important:

Don’t say “enzyme dies.”

Say “enzyme becomes denatured.”

pH

Changing pH changes the concentration of H⁺ ions.

This can disrupt:

• ionic bonds

• hydrogen bonds

→ changes tertiary structure
→ changes active-site shape
→ reduces enzyme-substrate complex formation.

Substrate concentration

Initially:
→ increasing substrate concentration increases rate.

Eventually:
→ all/most active sites occupied
→ enzyme concentration becomes limiting
→ rate reaches a maximum.

Enzyme concentration

If substrate is in excess:

Increasing enzyme concentration → more active sites → increased rate.

DNA

Deoxyribose nucleic acid

RNA

Ribonucleic acid

Function of dna and rna

Dna- store genetic materil

Rna- transfer genetic material to the ribosomes[in the ribosomes they need genetic material to code for a polypeptide [protein]

What are polymers of dna and rna

Nucleotides

Dna has a

Double stranded helix structure

A strand of dna is a

Polynuclotide made up of mononucleotides

A nucleotide is made of

Pentose sugar- ribose or deoxyribose sugar

Phosphate group

Base- nitrogenous organic base

the bases of nucleotides could be,

Adenine- - thymine they are COMPLEMENTARY BASE PAIRING

cytosine - - - guanine

HYDROGEN BONDS BEETWEN EM

How os a phosphodiester bond formed

Structure of dna

How does the structure of dna help ts function

1. Phosphodiester bond- prevnets organiic base from reacting with the environment

2. Large molecule- can store a lot of information

3. Double helix shape- makes dna compact

4. Weak hydrpgen bonds - can eaisly be broken down for dna replicaction;+ when a lot of hydrogen bonds are present its very strong so it provides stability

5. Double stranded- allows replication from template strands

6. Base sequence- allows info to be stored

7. Base stackng- makes dna stable

DNA REPLICATION - SEMI CONSERVATIVE REPLICATION

1. Dna helicase

2. Causes the strands to sepreate / breaking the hydrogen bonds

3. Both strands act as template strands

4. Free floating nucleotides are attached

5. Hydrogen bonds reform

6. Complementary base pairing occurs -AT and CG

7. Dna polymerase joins nucleotides via phosphodiester bonds

8. Dna has been replicated

Whats the name of dna replicaction

Semi conservative replicaction

What does phosphodiester and hydrofen bonds dop

Hydrogen bonds - joines nitrogous organic bases togther

Phosphodiester bonds - joins nucleotides togther to form a polynuclotide

What does dna helicase and polymerase do

Dna helicase - breakes hydrogen bonds

Dna polymerase- joins nucleotides via phosphodiester bonds

Who did the experiment on semi conservative replication

Melson and stahl

Differene bwteen dna nd rna

DNA	RNA
Deoxyribose	Ribose
Thymine	Uracil
Double helix	Usually single polynucleotide chain
Long	Relatively short

Atp

Adenosine triphosphate - 3 phosphates

What is atp

Immediate sruce of energy in a cell

Whats the structure of atp

Adenine base, ribose sugar, 3 phosphte groups

Uses of ATP

Active transport- ions uptake at roots/ glucose absorption

Muscle contraction- movemrnt

Protein synthesis- for growth and repair

Phosphorylation- making molecules more reactive by lowering their activation eergy

In rna the base thymine is swapped with

uracil

unsaturated fatty acids

1. at least one double bond betwen carbon atoms

2. caues the chain to kinkk

phospholipids

1. found on cell surafce membrasnes

2. phosphate group replaces a fatty acid

3. phosphate group is hydrophillic [attrats water] fatty acid tails are hydrophobic

phospholipid syracture

describe phospholipids

1. hydrophillic head and hydrophobic tail- allows he formation of phsopholipid bilayer

2. glycolipids can form - allows cell recognition

triglycerides structure

describe an explain tiglycerides

1. insoluble- osmotically inactive

2. high ratio of H;O atoms- release water when needed

3. high ratio of C;H - excellent storage of enegry

4. kow mass; enegry ratio- dont need to carry a large mass

test for lipids - emulsition

1.grind the sample

2. add ethanol

3. shake

4. add distilled water

5. white emulsion formed

phospholipids

What is a triglyceride?

A lipid formed by condensation of one glycerol molecule with three fatty acid molecules.

Three ester bonds are formed.

What is an ester bond?

The bond formed between glycerol and a fatty acid during a condensation reaction.