Biological Molecules Flashcards
What is a monomer
Small repeating unit from which polymers are made
What is a polymer
Long chain of monomers joined together
Examples of monomers
Monosaccharides, amino acids, nucleotides
Describe the chemical reactions involved in the conversion of polymers to
monomers and monomers to polymers.
Give two named examples of polymers and their associated monomers to
illustrate your answer.
A condensation reaction joins monomers together and forms a
(chemical) bond and releases water;
2. A hydrolysis reaction breaks a (chemical) bond between
monomers and uses water;
dna is a polymer made of nucleotide monomers with phosphodiester bonds
proteins are polymers of amino acids with peptide bonds
What elements do all carbohydrates have and what are carbohydrates
C
H
O
Polymer
What are carbohydrates monomers and 3 examples
Monosaccharides
Glucose, fructose and galactose
What kind of sugar is glucose
Hexose sugar
Monosaccharides with 6 carbons
What are 2 isomers of glucose
Beta and Alpha
Isomers definition
Molecules with the same molecular formula as eachother but with atoms connected in a different
Where is OH and H on beta and alpha
OH ABBA - alpha below beta above
On alpha glucose : OH below on Carbon 1
On beta glucose: OH above on carbon 1
What does the OH group look like on left of alpha and beta glucose on carbon 4
HO
What reaction joins monomers/ monosaccharides together
Condensation reaction
Describe condensation reaction
2 mol join together forming chemical bond with an exclusion of water molecule
Condensation bet 2 monosaccharides
OH and H bond to form water molecule
This forms glycosidic bond
What is a disaccharide
Formed when 2 monosaccharides join
Name 3 disacharides and their monomers
Glucose + glucose —-> maltose
Glucose + fructose —-> sucrose
Glucose + galactose —-> lactose
What is a hydrolysis reaction
Splitting of polymer into monomers using water that breaks chemical bond
What can sugars be classified as
Reducing or non reducing
What are reducing sugars and name 5
Include all monosaccharides and maltose
Donate electrons
Glucose
Galactose
Maltose
Fructose
Ribose
Test for reducing sugars
Place 2cm^3 food sample in test tube
Add equal volume of Benedict’s reagent
Heat with boiling water in water bath
Positive test result
Forms coloured precipitate
Higher the conc of red sugar the deeper the colour
Blue —> green —> yellow —> orange —> brick red
More accurate way of doing red sug test
Filter solution and way precipitate
Use colourimeter
When would you do non red sugar test
If red sugars test is negative
Non red sugar may be present
Non red sug test
Get a new sample of test sol
Add dilute HCL
Heat in water bath until brought to boil
Neutralise with sodium hydrogen carbonate
Carry out Benedict’s test as you would for reducing sugar
Non red sugar postive test
+ negative test
Postive: Will form coloured precipitate
Negative : sol wil stay blue —> doesn’t contain any sug red or non red
What is a polysaccharide
Formed when 2 or more monosaccharides are joined by condensation reaction forming glycosidic bond
What is starch and where is it found
Main energy store in plants
Cells get energy from Glucose - excess glucose stored as starch in starch grains
What polysaccharides are in starch
Amylose and amylopectin
Amylose struc and function
Long unbranched chain of alpha glucose
Angles of glycosidic bond give coiled Struc - HELICAL
Makes it compact so it’s
Good for storage cus a lot can fit in small space
What bond is in amylose
1-4 glycosidic bond
Amylopectin Struc and function
Long branched chain of alpha glucose
Has side branches - enzymes can break mol easily to break glycosidic bond - glucose can be released quickly
Larger surface area for enzymes to attach too
Amylopectin bond
1-6 glycosidic bond + 1-4 glycosidic bond
Struc of starch rel to function
Insoluble - doesn’t affect cells water potential - water won’t enter via osmosis causing cell to swell
Large mol - can’t leave cell via diffusion
Helical - compact - can store lots of energy
Test for starch
Add iodine solution/ potassium iodide to test sample
If starch is present colour change from orange to blue black
Glycogen struc and function
Animals get energy from glycogen (stir of excess glucose)
Alpha glucose
Highly branched + lots of free ends
Hydrolysed quickly to prod lots of glucose (energy) in animals for movement
Compact mol - good for storage
1-4 +1-6 glycosidic bonds
Glycogen was more 1-6 glycosidic bonds than starch (more branched structure) insoluble-want affect cells water potential
Cellulose struc and function
Long unbranched chains of beta glucose that run parallel
Chains liked by hydrogen bonds that go on to form fibres - microfibrils
Structural support
Strength of h bonf
1 h Bond is weak but many hydrogen bonds are strong
2 types of lipid
Triglyceride
Phospholipid
Triglyceride struc
1 glycerol attached to 3 fatty acids
Fatty acid struc and components
Made of hydro carbons
Hydrophobic tails that repel water
Making lipids insol in water
Have
O = C — R
|
HO
HO at angle to C
How are triglycerides formed
Condensation of 1 glycerol to a fatty acid produced ester bond
Happend 2x more for 2 more fatty acids and 2 more ester bonds
Total 3 molecules of water produced
H2O prod from H in glycerol and HO in fatty acid
Fatty acids can either be …..
Saturated or unsaturated
Difference between fatty acids
Difference in hydrocarbon tails (R GROUP)
Saturated fatty acid
No double carbon bond
Unsaturated … + causes whag in chain
Have at least one double carbon to carbide bond , causing chain to kink
Phospholipid struc
1 phosphate group 1 glycerol 2 fatty acids
Phosphate group is hydrophilic
Fatty acid tail is hydrophobic
Uses of lipids
Waterproofing
Insulation
Protection
Energy
Phospholipid only - component of cell mem
Struc of triglyceride rel to function
1) Mainly energy storage molecules
Long hydrocarbon tails of fatty acids - lots of chem energy
Lipids contain ab 2x as much energy per gram as carbs
2) insol in water so doesn’t affect cells water pot . Water won’t enter via osmosis causing cell to swell
Triglycerides clump as insoluble droplets bc fatty acids hydrophobic tails face inward shielding themselves from water w glycerol heads
Phospholipid struc rel to function
Bilayer of cell mem
Heads hydrophilic ans tails hydrophobic so form double layer with heads facing outwards toward water on other side
Centre of bilayer is hydrophobic, water sol sub can’t easily pass so mem Acts as barrier to those sub
Test for lipids
Add sample to test tube
Add ethanol and shake
Add water
Milky white emulsion
Protien def
Long chain of amino acids
What’s formed whne 2 amino acids Join
Dipeptide
Whag is a poly pep
Formed whne 2 or more amino acids join together
What are protiens made up of
One or more poly pep
Struc of amino acids
R
|
H2N —C — COOH
|
H
R group
Variable group
Diff bet amino acids is their R group
How many amino acids do living things share
20
Condemnation of 2 amino acids
OH from COOH reacts w H on amine group of next amino acid forming water mol and leaving a peptide bond bet C and N
Primary structure
Specific seq of amino acids in polypeptide chain
Secondary struc
Folding due to H bonds making protien coil into alpha helix or beta pleated sheet
Tertiary struc (final pro struc)
Further folding due to either ionic, hydrogen, disulfide bonds on diff parts of poly pep chains
Quarternary struc
Several poly pep chains held together
4 functions of pro
1) enzymes
2) antibodies - 2 light and 2 heavy polypeptide chains
3) transport protiens
4) structural pro - strong and contain crosslinks - keratin and collagen
globular pro
enzymes (such as amylase), hormones (such as insulin) or proteins like haemoglobin. Globular proteins unravel and denature when the temperature or pH deviates from optimum levels. Globular proteins with prosthetic groups attached (such as haemoglobin) are referred to as conjugated proteins.
fibrous pro
long and thin
Examples of fibrous proteins include collagen, keratin
Test for pro
Add sample to test tube
Add biuret sol
Colour change from blue to purple/lilac
What are enzymes
Biological catalysts that speed up chemical reactions by lowering the activation energy without getting used up
Enzymes are protiens
Enzymes have a highly specific active site which binds to only one type of substance
Why are enzymes highly specific
Due to tertiary struc giving unique 3D struc
What happens if enzyme is catalysing a breakdown reaction
Fitting into the active site puts a strain on the bonds in sub so sub breaks up easily
lock and key
Sub fits into enzyme like key fits into lock
What’s wrong w lock and key
Enzyme and sub do fit together but it doesn’t talk about how e-s complex changes shape so locks fits even more tightly
Induced fit model
BEFORE reaction active site not complementary to sub
Active site slightly alters its shape as substrate approaches
As enzyme changes shape it puts pressure on sub molecule distortingthe bonds in substrate
This causes the activation energy needed to break bonds to be lowered
Substrate fits more tightly
E-s complex formed
Sub broken down into products
How can enzymes be affected by mutations
Random 🔼 in amino acid seq
Primary struc altered , position of bonding now diff …. 🔼 shape of active site so sub no longer binds
No reaction
4 factors affecting enzyme activity
Temp
Ph
Enzyme conc
Sun conc
Temp
Increase in temp causes particles to vibrate more due to gain in eK
Mol move faster = ⬆️ e-s complexes
If temperature increases too much = h bonds start to break shape of active 🔼
At first sub fits less easily
Then doesn’t fit at all
Enzymes denatured
Ph + what is arrangement of active site det by
Ph = measure of H+ ion conc
🔼 in ph (H+ conc) Alter charges on amino acids at active site
Arrangement of active site partly det by hydrogen bond between amine and COOH groups
Bonds break leading to distortion in shape of active site so sub can no longer attach no longer complementary
Denaturtion due to ph
If bonds in tertiary struc break enzyme will denature
Enzyme conc
⬆️enzyme conc = ⬆️rate
More e-s complexes formed
But if sub conc limited
Not enough sub to bind to all the enzymes
Do ⬆️ enzyme conc has no effect
Sub conc
⬆️sub conc = ⬆️ rate mostly
More collisions = more e-s complexes
True up until saturation point
Whereby all active sites used up
So ⬆️ sub conc has no effect
No active sites to bind to
Competitive inhibition
A competitive inhibitor has a sim shape and struc to the sub mol
So are this complementary to enzymes active site and thus bind instead of of Sub
So n e-s complexes formed
⬆️ sub conc can ⬆️ rate as there’s a higher chance of sub binfing not inhibitor
Non competitive inhibition
Binds to allosteric site of enzyme
This causes active site to change shape so sub mol are no longer complementary and cannot bind
⬆️ sub conc won’t have an effect on rate bc sub won’t be able to bind
2 ways for Enzyme req prac
Measure how fast product of reaction is made
You can measure how fast the substrate is broken down
How fast product is made
Catalyse catalyses the breakdown of hydrogen peroxide in to water and oxygen
So we work out vol of o2
How do we measure vol of o2
Boiling tube w hydrogen peroxide sol and catalyse enzyme w bung w delivery tube attached into upside down measuring cylinder in trough of water
How to set out expirment step 1
To measure how fast product is made
Set up boiling tube containing same vol and conc of hydrogen peroxide
Keep ph constant - add buffer sol
Set up apparatus
Eg boiling tube w bung attached to delivery tube in upside down measuring cylinder in trough of water
Step 3
But boiling tube in water bath set to diff temp
10, 20 , 30, up to 40 along with another tube containing catalyse
Why do you wait 5 mins after step 3
So enzymes gets to right temp
Step 4)
Use pipette to add Same vol and conc of catalyse to boiling tube then quickly attach bind and delivery tube
Step 5
Record how much o2 prod in 1 min
Use stopwatch to measure time
Step 6
Rep experiment ar each temp 3x
And use results to find an average vol of o2 prod
Calc av rate of reaction at each temp by diving vol of o2 prod by time taken
Units for rate
Cm^3 s^-1
What does enzyme amylayse catalyse break down of
Starch to maltose
Apparatus of measuring how fast product broken down
A test tube - starch solution and amylayse enzyme
Dropping pippete
Spotting tile w drop of iodine in potassium iodide in it
Step 1
Use pippete to drop mix of sol in one well at regular intervals until colour observed
What colour does iodine sol turn
In presence of starch - blue black
No starch - orange brown
How do we see how fast amylayse is working
Use stop watch to rec how long it takes for iodine sol to not turn blue black when mix added
Step 2
Repeat experiment with different conc of amylayse
Repeat 3x for each conc
What are dna and rna
Nucleic acids found in all living cells
DNA
Stores genetic info
RNA
Transfer genetic info from dna to ribosomes
Ribosomes make poly peptides (protiens) during translation
Monomer for dna and rna
Nucleotide monomers that make up dna and rna polymers
Nucleotide struc
A Pentose sugar w 5 carbons
Phosphate group
Nitrogenous base
What is struc of nucleotide in dna
Deoxyribose sug
Phosphate group
Nitrogenous base (adenine thymine guanine and cytosine)
Struc of rna nucleotide
Ribose sugar
Phosphate group
Nitrogenous base - Adenine uracil guanine and cytosine
Nucleotides join to form what via what reaction
Via condensation reaction between phosphate group of one nucleotide and sugar of the next
Forming polynucleotide
What bond forms and what does it consist of
Phosphodiester bond
Consisting of the phosphate group and 2 ester bonds
Chain of sugars and phosphates known as ..
Sugar phosphate backbone
DNA structure
2 antiparralel polynucleotide strands twist and join together to form double helix due to hydrogen bonding between complementary base pairs
Adenine has 2 h bonds wiht thymine
Cytosine has 3 h bonds wiht guanine
describe dna structure (5)
Polymer of nucleotides
Each nucleotide formed from deoxyribose, a phosphate (group) and
an organic/nitrogenous base;
3. Phosphodiester bonds (between nucleotides);
4. Double helix/2 strands held by hydrogen bonds;
5. (Hydrogen bonds/pairing) between adenine, thymine and guanine and cytosine
Describe how a phosphodiester bond is formed between two nucleotides
within a DNA molecule. (2)
Condensation (reaction)/loss of water;
2. (Between) phosphate and deoxyribose;
3. (Catalysed by) DNA polymerase;
differences in structure of rna and dna
RNA is usually single-stranded, while DNA is double-stranded.
RNA is composed of ribonucleotides, which contain a ribose sugar, while DNA is composed of deoxyribonucleotides, which contain a deoxyribose sugar.
RNA contains the nitrogenous base uracil instead of thymine, which is found in DNA.
rna is shorter mol than dna
who theorised semi conservative dna replication and chemical structure of dna
watson and crick
what is semi conservative replication
half of the strands in each new molecule is from the original dna mol so there is genetic continuity bet generations of cells
describe how dna is replicated
via semi conservative replication dna helicase enzyme is breaks hydrogen bonds and strands sep
helix unwinds and strands act as templates
free activated nucleotides attach to complementary base pairs
dna polymerase joins nuc on new strands via condesnation reaction
hydrogen bonds reform
2 new dna mol each with one og dna strand
why new nucleotides can only be added in a 5’ to 3’
direction.
DNA polymerase;
2. (Which is) specific;
3. Only complementary with / binds to 3’ end (of strand);
Reject hydrogen bonds / base pairing
4. Shapes of 5’ end and 3’ end are different /
so anti parallel strands
role of dna helicase
Breaks hydrogen bonds between base pairs/ AT and
GC/complementary bases
Describe the role of DNA polymerase
) 1. Joins (adjacent DNA) nucleotides;
2. (Catalyses) condensation (reactions);
3. (Catalyses formation of) phosphodiester bonds (between adjacent
nucleotides);
features of DNA and explain how each one is important in the
semi-conservative replication of DNA.
Weak / easily broken hydrogen bonds between bases allow two
strands to separate / unzip;
Two strands, so both can act as templates;
Complementary base pairing allows accurate replication;
Contrast the structures of ATP and a nucleotide found in DNA
ATP has ribose and DNA nucleotide has
deoxyribose;
2. ATP has 3 phosphate (groups) and DNA
nucleotide has 1 phosphate (group);
3. ATP – base always adenine and in DNA
nucleotide base can be different
what did evidence for semi conservative replication use
2 isotopes of nitrogen
light N-14
heavy N-15
step 1
2 samples grown in nutrient broth containing isotopes
step 2
sample of each dna taken and spun in centrifuge
where does each isotope settle
14 - top
15 - bottom
step 3
heavy nitrogen taken out and grown in light nitrogen left for one round of replication and then spun
where did dna settle
in middle
how did this prove semi conservative replication
new dna mol has one strand of old dna w heavy and one strand w light
what would it look like if rep was conservative
heavy dna at bottom
light dna on top
water mol struc
one atom of oxygen w delta negative 2 atoms of hydrogen w delta positive
so water polar
o atoms attract h atoms attraction called hydrogen bonding
Explain five properties that make water important for organisms.
A metabolite in condensation/hydrolysis/ photosynthesis/respiration;
2. A solvent so (metabolic) reactions can occur
OR
A solvent so allowing transport of substances;
3. High (specific) heat capacity so buffers changes in temperature;
4. Large latent heat of vaporisation so provides a cooling effect (through
evaporation);
5. Cohesion (between water molecules) so supports columns of water in plants (transpiration streams)
6. Cohesion (between water molecules) so produces surface tension supporting small organisms
State and explain the property of water that can help to buffer changes in
temperature
(water has a relatively) high (specific) heat capacit
Can gain / lose a lot of heat / energy without changing temperature;
Give two properties of water that are important in the cytoplasm of cells.
For each property of water, explain its importance in the cytoplasm.
Polar molecule; Acts as a (universal) solvent;
Reactive;
Takes place in hydrolysis / condensation / named reaction;
what is atp
immediate source of energy
when its made where does it go
diffuses to parts of cell that needs energy
where is energy in atp stored
bonds bet phosphate groups rel via hydrolysis
Describe how an ATP molecule is formed from its component molecules.
condensation between 3 phosphate groups, adenine base and ribose sugar
catalysed by atp synthase
how and when is atp broken down
when energy is needed by cell atp hydrolayse enzyme breaks phosphate bond
products of atp hydrolysis
ADP + Pi
ways in
which ATP is a suitable energy source for cells to use.
little energy lost as heat as hydrolysis coupled with other energy req reactions so energy used to make that reaction happen
Phosphorylates other compounds, making them more reactive;
rapidly re synthesised
how is atp resynthesised
From ADP and phosphate;
By ATP synthase;
3. During respiration/photosynthesis;
what is an inorganic ion
doesnt contain carbon
are a few exeptions
name 4 inorganic ions
iron ions
hydrogen ions
sodium ions
phosphate ions PO4^3-
FE2+
haemoglobin made of 4 polypep chains w fe2+ ion in centre
Haemoglobin binds/associates with oxygen in rbc
H+
ph calc based on conc of ion
more ions = lower ph + more acidic
na+
Co-transport of glucose/amino acids (into cells);
3. (Because) sodium moved out by active transport/Na – K pump;
4. Creates a sodium concentration/diffusion gradient;
5. Affects osmosis/water potential;
po43-
Joins nucleotides/in phosphodiester bond/in backbone of
DNA/RNA/in nucleotides;
8. Used in/to produce ATP;
Reject ‘energy produced’
9. Phosphorylates other compounds (usually) making them more
reactive;
how does struc of protein dep on amino acids it contains
- Structure is deternmined by (relative) position of
amino acid/R group/interactions; - Primary structure is sequence/order of amino
acids; - Secondary structure formed by hydrogen
bonding (between amino acids); - Tertiary structure formed by interactions
(between R groups); - Creates active site in enzymes
OR
Creates complementary/specific shapes in
antibodies/carrier proteins/receptor (molecules); - Quaternary structure contains >1 polypeptide
chain
OR
Quaternary structure formed by
interactions/bonds between polypeptides;
describe the roles of iron ions, sodium ions and phosphate ions in cells
Iron ions
1. Haemoglobin binds/associates with
oxygen
OR
Haemoglobin transports/loads
oxygen;
Sodium ions
2. Co-transport of glucose/amino
acids (into cells);
3. (Because) sodium moved out by
active transport/Na – K pump;
4. Creates a sodium
concentration/diffusion gradient;
5. Affects osmosis/water potential;
Phosphate ions
6. Affects osmosis/water potential;
7. Joins nucleotides/in
phosphodiester bond/in backbone
of DNA/RNA/in nucleotides;
8. Used in/to produce ATP;
9. Phosphorylates other compounds
(usually) making them more
reactive;
10. Hydrophilic/water soluble part of
phospholipid bilayer/membrane;
