Biological Molecules and Enzymes Flashcards
What ratio is hydrogent to oxygen in carbohydrates
2:1
What is molecular formula of 3 main hexose sugar?
C6H12O6
Name 3 types of hexose sugar?
Glucose
Galactose
Fructose
What is difference between alpha and beta glucose?
Alpha has glucose above
Beta has glucose below
What is main 3 disaccharides and what they consis of?
Maltose, 2 glucose
Sucrose, 1 glucose and 1 fructose
Lactose, 1 glucose and 1 galactose
Name and describe reaction joining 2 monomers?
Condensation reaction
It form chemical bond between 2 molecules releasing 1 water molecule as byproduct
Name and describe reaction breaking a dimer or polymer?
Hydrolysis
Chemical bond between 2 molecules is broke by instertion of 1 water molecule
Describe test for reducing sugar?
Add benedicts solution to sample
Boil for 5 minutes
A brick red/orange colour if present
If not solution remain blue
Describe test for non-reducing sugar?
First test sample with benedicts solution to confirm negative results
Then boil sample with dilute acid
Then cool then add sodium hydroxide solution to neutralise it
Then add benedicts solution and boil
If non-reducing sugar, now red brick colour shoud appear
What is example of non-reducing sugar?
Sucrose
What is 4 main similar and different properties of cellulose, starch and glycogen?
They differ in num and arrangement of glucose
They function as storage or structural molecules
They are non-reducing
They are unsweet
What is cellulose?
Consist of beta glucose
Fromed by 1-4 glycosidic bond so every beta glucose invert
Long, straight chain
Hydroxyl group form hydrogen bond with other chain hydroxyl group called microfibril
What is macrofibrils?
Bundle of microfibril
One macrofibril goes in same direction
Succesuve layers are in different direction
They are interwoven and embedded in matrix to provide rigidity
Gaps between layer allow fully permeable cell wall
What is purpose of cellulose?
Rigid, structural support preventing cell from bursting
What is starch?
Storage used for respiration made by alpha glucose
Found in starch grain of plant
Amylose and amylopectin
What is properties of starch?
Long chain of alpha glucose
Compact, helical shape due to hydroxyl group forming hydrogen bond
Amylopecting is branched but amylose is straight
Amylopectin has 1-4 and 1-6 glycosidic bond and amylose only 1-4 glycosidic bond
Insoluble so osmotically inactive
Too large to cross cell membrane but compact
Name and describe test for starch test?
Iodine test
Add few drops of iodine to sample
If starch is present blue/black colour appear
If no starch remains orange/yellow
What is glycogen?
Energy store in animal and fungi
Same properties as starch but more branched
Mostly liver and muscle tissue
What is 2 types of lipids?
Triglycerides and phospholipid
What is properties of triglycerides?
Made of 3 fatty acid and 1 glycerol
Insoluble so osmotically inactive
Soluble in various solvent e.g. alcohol but water
Formed by condensation reaction
Has ester bond
Acts as structure and enery storage
Release twice as much energy than carbohydrates
Higher portion of H
Can be saturated or unsaturated
Is saturated solid or liquid?
Usually fat
Unsaturated usually oil
As less surface contact of molecule due to bending
Describe and name test for lipids?
Emulsion test
Add ethanol to sample
Shake so lipid dissolve
Then add water and mix
White emulsion should appear as indication
What is properties of phospholipid?
Made of glycerol, 2 fatty acid and 1 phosphate
Joined by condensation reaction
Polar hydrophilic head is phosphate
Non-polar hydrophobic tail is fatty acid
Why is phospholipid important?
Cell membrane is formed mainly by phospholipid bylayer
Also form micelles used in lipid digestive absorbtion
What element does amino acid contains?
C,H, O and N
Sometimes S
Properties of amino acid
Monomer of polypeptide
All have amine group, a carboxylic group, H attached to C but differ in R group
Theres 20 different R group
Peptide bond joined by condensation reaction
Condensation reactionn is between carboxylic and amine group
2 types of enzymes hydrolysing peptide bond and how they differ?
Exopeptidases - hydrolyse ends of polypeptide chain
Endopeptidases - hydrolyse internal of polypeptide chain
Primary structure
Sequence of amino acids in the polypeptide chain, determines the specific shape of the protein
Secondary structure
H-bond caused by C=O and N-H groups
They can be alpha helix or beta pleated sheet
Tertiary structure
Ionic, H, disulfide bridge and hydrophobic bonds
Quaternary structure
More than 1 peptide chain
Held by same bonds as tertiary structure
Maybe assosiated with non-protein/prosthetic groups(e.g. Fe2+)
Where does H-bond occurs in amino acid?
May form by C=O and N-H groups
Occurs within same chain
May also form between R groups of polar amino acids
Check
Where does Ionic bond form in amino acid?
Form between + and - charged side chain of bacis and acidic amino acids respectively
Where does Hydrophobic region happens in amino acid?
Hydrophobic side chains exclude H2O and attracted to each other
Where does Disulfide bridge form in amino acid?
Oxidation reaction forms it between 2 cystine amino acid
2 types of protein?
Fiburous and globural
Explain what is fiburous proteins and e.g.?
Structural function
Insoluble and simple tertiary and quaternary structure made of long parallel chain
Provide strenght and flexibility
Collagen and keratin
Explain what is globural protein and e.g.?
Highly folded and coiled polypeptide chain forms specific tertiary structure
Soluble in water
Insulin, antibodies, enzymes, receptor
What breaks hydrogen bonds?
pH, temperature
What breaks ionic bonds?
pH
What breaks disulfide bridges?
Reducing agent
What is 2 methods to change shape of protein?
Heavy metal binding
Denature
Describe biochemical test for protein?
Add biuret agent to sample
If purple protein present
If remains blue no protein present
Define enzymes?
Globural protein that acts as biological catalyst with specific active site due to specific tertiary structure
How does enzymes work?
Lower activation energy
So rate of reaction increase
So more easier for reaction to take place at low temperature
Name and describe 2 hypothesis related to Enzymes substrate complex formation?
Lock and key hypotheis:
Only substrate with complementary shape to substrate form ESC
Enzymes remains unchanged at end
Induced fit hypotheis:
Enzymes have more flexibility as change shape slightly
Substrate change enzyme active site, and may stain on bonds of substrate so easier hydrolysis
Active site allow molecules to come closer so easier condensation
List limiting factor for ESC formation?
Enzyme concentration
Substare concentration
Temperature
pH
How does enzyme concentration effect ESC?
If more enzyme conc, then more active site available
More likely for substrate to collide
So rate increase
If substrate does not limit rate
How does substrate concentration effect ESC?
More likely for enzymes to collide
Then rate levels off as they saturare active site
So enzyme concentration is limiting factor
How does temperature affect ESC?
More kinetic energy
So more collision so more ESC
Optimum temperature leads to highest rate
Hydrogen and ionic bond break if too high. leading to denaturation
This alter active site shape
So no ESC
Temperature coefficient
Rate of reaction at (x+10)/rate of reaction at x
How does pH effect ESC?
pH different from optimum causes denaturation
As alters ionic charges of acidic and basic groups
So shape of active site change
No longer ESC formation
Name 3 types of enzyme inhibitor and how they work?
Competitive inhibitor
Inhibitor has similar shape to substrate
So competes with substrate to bind with active site
Reduced by inc substrate concentration
Non-competitive inhibitor
Not similar in shape to substrate
Bind to allosteric sire
Alters tertiary shape and so active site shape
Some would not be able to form ESC or would bind but product dosent form
End-product inhibition
When end product inhibits
It happens when accumulate
So it switch off reaction as builds up
Self-regulatory, so if product decrease switch on
Example of negative feedback
Example is glycolysis
What is Immobilised enzymes?
Allows to reduce cost and inc efficiency in commercial use
Traps enzymes to plastic support, so recovered easier after reaction
So enzymes can be re-used
Also make enzymes more stable by restricting abillity to change shape or denature
No contamination occurs
Example of enzymes that become stable by immobilising them?
Glucose isomerase
Stable for a year at 65 degrees celsius in immobilised state but denature whitin few hours at 45 degrees celsius without
Physical bonding process in immobilisation?
Adsorbed onto an isoluble matrix, e.g. collagen
Held inside a gel, such as silica gel
Held within a semi-permeable membrane e.g. polymer microsphere
Trapped in a micro-capsule e.g. alginate beads
Chemical bonding in immobilisation process?
Enzymes can be chemically bonded to the support medium
E.g. use glutaraldehyde
to binf it to cellulose fibers
Since enzymes are covalently bonded, enzymes activity is high
Difficult process
