Biological Molecules Flashcards
Momomer of carbohydrates
Monosaccharides
2 polysaccharides in starch
Amylose and amylopectin
Describe structure of amylose
Unbranched
Alpha glucose
Coiled = angles of glycosidic bonds (1,4)
Describe structure of amylopectin
Branched
Alpha glucose
Why is starch going for plant storage
Amylose = coiled = compact Amylopectin = highly branched = enzymes break glycosidic bonds quickly Insoluble = doesn’t affect water potential
What is the test fir starch
Iodine dissolved in potassium idiode
Orange -> blue/black
Describe structure of glycogen
Alpha glucose
Highly branched
How is glycogen adapted for its function
Highly branched = enzymes can break glycosidic bonds quickly and release e
Compact
Describe the structure if cellulose
Unbranched
B glucose
Straight chains linked my H bonds
Every other glucose flips
How does cellulose provide structure and support
H bonds link chains
Form microfibrils
What is the structure of triglycerides
Glycerol + 3 fatty acids
What is a fatty acid
Hydrophobic hydrocarbon chain
How does a triglyceride form
Condensation reaction
Forms ester bond with glycerol and fatty acid
What are saturated fatty acids
No double bonds
Max no of H
Why do unsaturated fatty acids kink
Double bond
What is the structure of a phospholipid
1 glycerol + 1 phosphate group + 2 fatty acids
Is the phosphate group hydrophobic
No - it’s hydrophilic
What is the function of triglycerides
Energy storage
Why are triglycerides good for their function
Long hydrocarbon tails release lots of energy when broken down = 2x amount In same mass of carbs
Insoluble = dont affect water potential
= clump together in insoluble droplets because fatty acids are hydrophobic
What is the function of phospholipids
Bilayer of plasma membrane
Describe the emulsion test fir lipids
Add ethanol
Shake for 1 min
Pour into water
Lipid = milky
How to know if there’s more lipid in a food
More milky emulsion
What is the monomer of proteins
Amino acids
What is the structure of amino acids
Amine group
Carboxyl group
Variable group
What is the bond that joins amino acids
Peptide bonds
What type of reaction is the formation of polypeptides
Condensation
Describe the primary structure of a protein
Séquence of amino acids
Describe the secondary structure of a protein
H bonds form between amino acids
Coil = a helix
Fold = b pleated sheets
Describe the tertiary structure of a protein
More bonds forms between amino acids
H bonds
Ionic bonds
Disulfide bridges
Describe the quarternary structure of a protein
Multiple polypeptide chains bonded together
What amino acids form disulphide bridges
Cysteine
Why are keratin and collagen structural proteins
Polypeptide chains are parallel to each other
Form cross links
Give 4 uses of proteins
Enzymes
Structural proteins
Antibodies
Transport proteins
Describe the buiret test
Add NaOH Add Cu(II)SO4 \+ve = purple -ve = blue
What is the Biuret test for
Proteins
Where is enzyme action
Intracellular (inside cell) and extra cellular (outside cell)
Why are enzymes highly specific
Tertiary structure
What forms when a substrate and enzyme bind
Enzyme-substrate complex
What do enzymes do when 2 molecules need to be joined
Both attached to the same enzyme
Held close together
Reducing repulsion
Bond more easy
What does the enzyme do when 2 molecules need to break up
Fitting into the AS causes stress on bonds in the substrate
Breaks more easily
What is the lock and key model
Specific Substrate fits into the specific AS
What is the induced fit model
Enzyme binds to substrate
Enzyme-substrate complex changes shape slightly to complete fit
Locks substrate more tightly
Why does the tertiary structure affect the AS
Tertiary structure determine AS
every enzyme has different tertiary structure = different AS
What happens if the tertiary structure of the enzyme changes
AS changes shape
Substrate won’t fit
Can’t form enzyme-substrate complex
How can a gene mutation affect enzyme function
Change amino acid gene codes for
Different primary structure
Different tertiary structure
What is a competitive inhibitor
Similar shape to substrate
Compete to bind to AS
blocks substrate from binding
Slows rate of reaction
Does increasing conc of sub affect the rate of reaction with a competent be inhibitor
Yes
The substrate has more chance of binding to the AS
What is a non competitive inhibitor
Bind away from AS
AS changes chape
Substrate can’t bind = AS no Longer complimentary
Will increasing conc of sub affect rate of reaction with a non comp inhibitor
No
Once the enzyme has been denatured it can’t bind to the sub
What is the monomor of dna
Nucleotides
What is in a DNA nucleotide
Pentose sugar (deoxyribose)
Base containing N
Phosphate group
Give 2 difference between rna and dna nucleotides
Oxyribose not deoxyribose
Uracil not tymine
What bond forms between nucleotides
Phosphodiester bonds
What is the chain of sugars and phosphate in dna
Sugar phosphate backbone
How many H bonds between c and g
3
How many H bonds between T and A
2
Why does dna form a double helix
H bonds between complementary base pairs
On strands going antiparallel
Describe dna semi conservative replication
- Dna helicase break h bonds between complementary base pairs
- Helix unwinds
- Each original strand is a template for a new
- Free floating nucleotides join to complementary base pairs attracted to Éxposed bases
- DNA polymerase catalysés condensation reaction to form H bonds between bases
What is semi conservative replication
Each new dna molecule contains 1 strand from original and 1 new
Why is replication semi conservative
Maintain Genetic continuity
Why does anti parallel strands affect DNA polymerase
DNA polymerase can only complementary to 3’
Nucleotides only added to 3’ end
So it binds to the original strands 3’ end
New = works from 5’ to 3’
So the DNA polymerase works in opposite directions
Describe the experiment that proved semi conservative replication
- 2 samples of bacteria grown
- 1 grown in N14 and 1 in N15
- Bacteria reproduced taking up the N in dna
- Sample of dna taken and spun in centrifuge
- N15 settled lower
- Bacteria grown in N15 put into N14
- Allowed 1 round of replication
- Dna taken and spun in centrifuge
- DNA settled inbetween N15 and N14 because it had 1 strand of each
Why is water a good metabolite
Used in condensation and hydrolysis reactions
Why is water a good at temp control
High latent heat of vaporisation = takes lots of energy to break h bonds between water molecules = lots of energy used when it evaporates
Eg. Sweat
Why can water buffer temp changes
High specific heat capacity = H bonds between molecules can absorb lots of energy
No rapid temp changes
Good habitat for marine life
Good inside body = maintain constant body temp
Why is water a good solvent
It’s polar
So surrounds ions
Why is water good at moving up a plant
It’s cohesive because they’re polar
Strong attraction between molecules
Helps pull whole water column in xylem
Why does sweat form droplets
Strong cohesion = string surface tension when water is in contact with air
Droplets can evaporate to cool skin
What is the structure of ATP
Adenine
Ribose
3 phosphate groups
Why is atp a nucleotide derivitive
Modified nucleotide
Why is glucose turned into atp
Cells can’t get energy directly from glucose
What is the reaction for energy release from atp
Atp → adp + pi
Hydrolysis
Where is energy released from atp
The bond breaking between 2 phosphate groups
What is the break down of atp catalysed by
Atp hydrolase
What is the formation of atp catalysed by
Atp synthase
What does it mean by atp hydrolysis can be “coupled”
Energy released from atp can be directly used to an energy needed reaction so it’s not lost by heat
What can the Pi be used as
Can be added to other compounds (phosphorylation)
Make them more reactive
