1a (bio mols) Flashcards
what is a monomer?
examples
A small, basic unit from which larger molecules are made
monosaccharides, amino acids, nucleotides
What is a polymer?
A large, complex molecule composed of long chains of monomers joined together
What is a condensation reaction?
Joins two molecules together with the formation of a chemical bond and involves the elimination of a molecule of water
What is hydrolysis?
Breaking a chemical bond between two molecules with the use of a water molecule
What is a monosaccharide? Examples?
Monomers that all carbohydrates are made of. Glucose, fructose, galactose
What is an isomer? What are the isomers of glucose?
A molecule with the same molecular formula but with atoms in a different way.
Alpha and beta glucose
What is a disaccharide? Examples?
Two monosaccharides joined by a reaction which forms a glycosidic bond.
Sucrose,lactose, maltose
Fructose+ glucose->
Sucrose
Glucose+ galactose->
Lactose
Glucose+ glucose->
Maltose
(2 alpha glucose)
All monosaccharides and some disaccharides are reducing sugars. True /False
True
What is a reducing sugar?
Sugars that can donate electrons to other chemicals
What is the test for reducing sugars?
HEAT reducing sugar with Benedict’s reagent ( copper 2 sulphate). it reduces benedict’s reagent forming INSOLUBLE RED PRETICIPATE of copper 1 oxide.
What is the test for non-reducing sugars?
Add 2cm3 ground sample to benedict’s and filter. place in boiling water for 5 mins- should remain blue (proves its not reducing). Add another 2cm3 sample to 2cm3 dilute HCL and gently boil for 5 mins (hydrolyses disaccharide into monosaccharide). Add sodium hydrogen carbonate to neutralise hcl so benedicts works. After this, test is same as for reducing sugars.
What are polysaccharides?
3 examples?
they are carbohydrates- multiple monosaccharides joined by condensation reactions.
starch, glycogen, cellulose.
Which polysaccharides are made of a-glucose?
starch and glycogen
Which carbohydrates are made of b-glucose?
cellulose
What is the structure of starch?
Mixture of 2 polysaccharides of a-glucose:
amylose- long, unbranched chain. angles of bonds cause it to coil so compact.
amylopectin- long branched chain
What is the function of starch?
How does its dtructure help its function?
plants store excess glucose as starch which can be broken down when needed.
amylose- coiled so compact and can store lots in small space
amylopectin- side branches allow enzymes to break down molecule and get to bonds easily so glucose quickly released.
starch is insoluble in water and doesnt affect water potential so water doesnt enter by osmosis which would make it swell.
What is the structure of glycogen?
polymer of a-glucose monosaccharides joined by glycosidic bonds. Highly branched and very compact.
What is the function of glycogen?
Highly branched so can be acted on by enzymes and be more quickly broken down into glucose for respiration. very compact so good for storage.
What is the structure of cellulose?
long, unbranched chains of b-glucose. alternate molecules are flipped so bonds can form. straight chain held by hydrogen bonds forming strong fibres (microfibrils)
What is the function of cellulose?
hydrogen bonds forming strong microfibrils mean it is good for structural support.
What is the test for starch?
Place 2cm3 sample into test tube add 2 drops potassium iodide and shake. starch changes colour of the iodine in the compound so turns BLUE/BLACK if not present, remains yellow.
What are lipids?
2 examples?
Fats and oils. Variety off diff components but all are hydrocarbons. components determine function.
triglycerides and phospholipids
What is the structure of a triglyceride?
One molecule of glycerol with 3 fatty acids attached. Fatty acids have hydrophobic tails.
all fatty acids have same basic structure but tail varies. 2 types: saturated, unsaturated (causes kinks)
How do triglycerides form?
Condensation reaction which forms an (RCOOH) ester bond between fatty acid and glycerol.
What are the properties of triglycerides?
-good for energy storage- long tail of fatty acids contain lots of chemical energy released when broken down
- insoluble in water (immiscible) due to hydrophobic tails so doesnt affect water potential of cell/ cause water to enter by osmosis. they form insoluble droplets (tails facing in shielding with glycerol heads)
What is the structure of a phospholipid?
Similar to triglyceride but one fatty acid is replaced by a phosphate group. phosphate is hydrophilic and fatty acid hydrophobic
What do phospholipids form?
make up bilayer of cell membranes.
form double layer with heads facing out and tails facing in to act as a barrier.
What is the test for lipids?
emulsion test- shake substance with ethanol then add water lipid shows as milky emulsion.
What is the monomer for proteins? what does this form?
monomer is amino acid
this forms a dipeptide or a polypeptide
a protein is more than one polypeptide
What is the structure of an amino acid?
central C atom
amine group (NH2)
carboxyl group (COOH)
R group- what makes them diff to each other
Hydrogen atom (H)
What is the tertiary structure of a protein?
secondary structure twists/ folds, more bonds form
How do dipeptides/ polypeptides form?
Amino acids link by condensation reactions forming peptide bonds (C-N)
the water molecule is from OH from carboxyl and H from amine group
What is the secondary structure of a protein?
Hydrogen bonds form between amino acids (hydrogen is+ oxygen is -)
This forms alpha helix or beta pleated sheet
What is the primary structure of a protein?
Sequence of amino acids in the polypeptide chain. specific order determined by DNA base sequence
What is the quaternary structure of a protein?
some large proteins made of several polypeptide chains held by bonds
What are the 2 types of protein?
Structure?
1) fibrous- structural functions (parallel chains with crosslinks)
.collagen- 3 polypeptide chains coiled
. keratin-parallel chains with crosslinks
2) globular- metabolic functions
.enzymes- spherical(tightly folded polypeptide chains) and soluble
. haemoglobin-compact and channel proteins- hydrophobic and phillic amino acids so form channel
.antibodies-2 light and 2 heavy polypeptide chains
Which 3 bonds form in tertiary structure?
1) disulphide bridge- 2 molecules of amino acid cysteine come close forms between sulfur of one r group and that of neighbouring amino acid
2) ionic bonds- between carboxyl and amino groups
3) hydrogen bonds- weakest, easily broken, numerous
What is the test for proteins?
Add few drops sodium hydroxide to make sample alkaline then add copper (2) sulphate (sodium hydroxide +copper sulphate=biuret) . protein- turns purple, if not it remains blue
What is an enzyme?
Acts as a biological catalyst and speeds up chemical reactions without being used up so can be repeatedly used
made of proteins- globular
What are the 2 types of enzyme?
intracellular- within cells
extracellular- outside cells
what is activation energy?
Minimum amount of energy needed to activate reaction. enzymes lower activation energy
What conditions are needed for reaction to start?
- substrates must collide w enough activation energy to alter arrangement of atoms to form products
- free energy of products must be less than that of substrates
- many reactions require initial amount of energy to start
how do enzymes decrease activation energy?
enzyme-substrate complex forms so if trying to join 2 molecules, enzyme holds them together reducing repulsion and if breaking down, fitting in active site puts strain on bonds so breaks easier
Describe the structure of an enzyme
-specific 3d shape due to base sequence
-active site made of amino acids
-enzyme substrate complex held by temporary bonds between amino aids in active site and groups of substrate molecule
-specific active site (diff tertiary struct) mutation in gene change tertiary structure
limitations of lock and key
-enzyme considered rigid
-other molecules can bind at diff places to active site to alter enzyme activity
Describe induced fit
enzyme flexible and moulds around substrate
substrate gets closer changing shape of active site. enzyme puts strain on substrate distorting bonds and decreasing activation energy
2 ways to measure enzyme activity
- how fast product made (measure amount of product at diff times)
- how fast substrate broken down (measure amount of substrate at diff times)
Effect of temp on enzyme activity
increase temp increases Ek so molecules collide with more energy so more likely to result in reaction. increase until optimum where bonds break due to Ek and enzyme denatures
effect of pH on enzyme activity
pH is measure of hydrogen ion conc
pH= - log10 [H+]
increase/ decrease from optimum, ionic and hydrogen bonds disrupted in tertiary structure so denatures
effect of substrate conc on enzyme activity
increase conc increases rate proportionately as more collisions so more active sites occupied. After Vmax (all full) no effect so graph platos
effect of enzyme conc on enzyme activity
increase conc increases rate proportionately as more likely to collide and form e-s complex. if amount of substrate is limited, not enough to fill active sites so graph platos
What does an enzyme inhibitor do?
directly/indirectly interferes w functions of active site
what is a competitive inhibitor?
binds to active site (similar shape to substrate) but no reaction happens- just less spaces for substrates. effect on enzyme depends on conc of substrate and inhibitor. dont usually permanently bond so leaves and another mollecule takes its place
What is a non-competitive inhibitor?
Bind to enzymes at allosteric site altering shape so substrate cant fit. increase substrate does nothing as not competing. as long as inhibitor attached (tend not to release) , substrate not complimentary
What are the 5 roles of lipids?
Cell membranes, source of energy, waterproofing, insulation, protection
Why arent triglycerides considered polymers?
they arent made of repeating units
where are glycosidic bonds present in glycogen?
1,4 and 1,6 (branched)
where are glycosidic bonds present in cellulose?
1,4
where are glycosidic bonds present in starch?
1,4 and 1,6 (branched)
Enzyme structure
Spherical (tightly folded chains)
Antibodies structure
2 light and 2 heavy polypeptide chains bonded together
Transport proteins structure
Eg channel proteins
Hydrophobic and hydrophilic amino acids so fold up and form channel
Structural proteins structure
Collagen
Long polypeptide chains parallel to each other with cross links between them
Eg keratin and collagen (3 polypeptide chains coiled tightly
What does polyunsaturated mean?
More than one double bond
