topic 1A: biological molecules Flashcards
monomers and polymers definition
MONOMERS
-smaller molecular units which can create larger molecules (e.g. monosaccharides, amino acids and nucleotides)
POLYMERS
-large, complex molecules composed of long chains of monomers joined together (e.g. polysaccharide, polypeptide and polynucleotide)
condensation and hydrolysis reaction
CONDENSATION
-joins two monomers together, with the formation of a chemical bond and involves the elimination of a molecule of water.
HYDROLYSIS
-separates two monomers by breaking a chemical bond and involves the addition of a water molecule.
monsachharides + examples
the monomers which form larger carbohydrates e.g. glucose, fructose and galactose
carbohydrates contain the elements…
-C (carbon)
-H (hydrogen)
-O (oxygen)
hexose sugar
a monosaccharide with six carbon atoms in each molecule e.g glucose
isomers
same molecular formula but different structure with atoms arranged in a different ways
draw alpha glucose molecule
H
OH
draw beta glucose molecule
OH
H
disaccharides + formulas
-a disaccharide is formed when two monosaccharides join together by a condensation reaction, forming a glycosidic bond (e.g. maltose, lactose and sucrose)
FORMULAS
-(2 alpha) glucose + glucose ->maltose + water (glycosidic bond)
-glucose + galactose -> lactose + water
-glucose + fructose -> sucrose + water
glycosidic bond
forms between two monosaccharides by a condensation reaction and releases a molecule of water
polysaccharides + examples
polysaccharides are formed when more than 2 monosaccharides join together by a condensation reaction, releasing a water molecule for each glycosidic bond
e.g. starch, glycogen and cellulose
starch function
-a main energy storage molecule in plants for excess glucose as starch (when a plant needs more glucose for energy, it breaks down starch to release the glucose)
starch structure + formation
-made up of a polysaccharides of alpha glucose by a condensation reaction
-coiled structure and branched
-amylose: -a long, unbranched chain of alpha glucose, the angles of the glycosidic bonds creates a coiled and compact structure
-amylopectin: a long, branched chain of alpha glucose, its side branches allows starch to hydrolyse and release glucose rapidly
starch structure related to function
-coiled structure - due to the angle of the glycosidic bond, therefore this makes it compact to store more glucose in a small space
-branched chains: can be hydrolysed (broke down) quickly so that glucose can be released quickly
-insoluble in water: no osmotic effect so this doesnt affect the water potential (good for storage as water cant enter the cell by osmosis)
glycogen function
-main energy storage molecule in animals for excess glucose as glycogen
-mainly stored in muscle and liver cells
glycogen structure
-made up of two polysaccharides of alpha glucose by a condensation reaction
-loads more side branches coming of it
-very compact molecule
glycogen structure related to function
-branched: rapid hydrolysis (break down) so that stored glucose can be released quickly which is important for energy release in animals
-compact: good for storage, so it can store more glycogen in a smaller space
-insoluble: no osmotic effect so it doesnt affect water potential
cellulose function
-provides structural strength in cell walls of plants due to the microfibrils (strong fibres) formed by the hydrogen bonds
cellulose structure
-polysaccharide of beta glucose monosaccharides bonded by a condensation reaction, they form straight cellulose chains
-the long, unbranched cellulose chains are linked together by many hydrogen bonds to form microfibrils (strong fibres) which provide structural support and strength for plant cells
cellulose structure related to function
-hydrogen bonds form between chains: forms microfibrils (strong fibres) which create collective strength to the cell wall making it rigid
-straight and unbranched
what elements are contain in lipids?
carbon, hydrogen and oxygen
structure of triglycecides
-contains one molecule of glycerol with three fatty acids attached to it
explain how glycerol is bonded with the three fatty acids
- molecule of glycerol and a fatty acid bond by a condensation reaction which releases a water molecule and removed (this reaction repeats 3 times)
- therefore three ester bonds and three molecules of water are released and removed
draw the basic structure of a fatty acid (RCOOH)
-variable R-group - hydrocarbon chain (this may be saturated or unsaturated
-COOH = carboxyl group.
what can fatty acids be?
two type of fatty acids: the R group may be saturated and unsaturated - difference is in their hydrocarbon tails (R group)
SATURATED: no double bonds in hydrobarbon chains - all carbons are fully saturated with hydrogen
UNSATURATED: one or more c=c double bond in hydrobarbon chains, this causes the chain to kink/ bend
structure of phospholipids
-similair to a triglyceride structure
-except one of the fatty acid molecules are replaced by a phosphate group, the two fatty acids are joined to the glycerol molecule by a condensation reaction
properties of triglycerides related to function
function: energy storage
-ENERGY SOURCE: a high ratio of C-H bonds to carbon atoms, so this contains lots of chemical energy - a load of energy is release when they are broken down
INSOLUBLE: the fatty acids are hydrophobic and non polar, so they are insoluble in water (clump together as droplets, tails inwards - shielding themselves from water), so there is no effect on water potential of cell
properties of phospholipids related to function
FUNCTION: forma bilayer in cell membrane, allowing diffusion of lipid-soluble (non polar) or very small substances and restricting movement of water soluble (polar) or larger substances
-phosphate heads are hydrophillic, so they are attracted to the water so point to water (aqueous environment) either side of membrane
-fatty acid tails are hydrophobic repelled by water so point away from water / to interior of membrane
protein
a protein is a polymer made up of the monomer, amino acids
4 groups from the structure of an amino acid
-carboxyl group (COOH)
-amine group (NH2)
-R (variable group- 20 different amino acids)
-hydrogen atom
describe how amino acids join together
the amino acids join together between the OH of carboxyl group of one and the H of amine group of another by a condensation reaction removing a water molecule, this forms a peptide bond.
definition of:
dipeptide
polypeptide
protein
-formed by the condensation of two amino acids
-formed by the condensation of many amino acids
-1 or more polypeptide chains is a protein
primary structure
a specific sequence of amino acids in a polypeptide chain, joined by peptide bonds
secondary structure
-hydrogen bonds form between the amino acids this causes the polypeptide chain to be coiled (alpha helix) or folded (beta sheet)
tertiary structure and additional bonds
-the tertiary structure is where it is coiled and folded further, which leads to additional bonds forming between different parts of the polypeptide chain
-hydrogen bonds, ionic bonds and disulphide bridges
-hydrogen bonds: between R groups
-disulphide bridges: only occur between cysteine amino acids (if there is a sulfur in R group)
-ionic bonds: between charged R groups
-tertiary structure creates the final 3D structure for proteins of only one polypeptide chain
Quaternary structure
-a Quaternary structure is a protein made up of more than one polypeptide chain (which are bounded together)
-the Quaternary structure is the proteins final 3D structure
-examples: haemoglobin, insulin collagen
relationship between protein structures and function
-the sequence of amino acids is determined by the genetic code, this effects the primary structure
-the primary structure determines how the polypeptide is coiled or folded in the secondary structure
-the secondary structure determines where bonds form, this affects the whole shape of the protein
-the shape of a protein determines its function
-altering the primary structure affects the tertiary structure shape, which affects its function
protein types
-globular- soluble, R group folded creates 3D shape (e.g. enzymes)
-fibrous- insoluble, structural, 3D shape (e.g. collagen + keratin - structural protein)
enzymes
enzymes are biological catalysts which speeds up the rate of a chemical reaction by lowering the activation energy without getting used up (a tertiary structure with a specific 3D shape)
lock and key theory
-old and outdated model
-the substrate is complementary to the enzymes active site, so the substrate binds to it - this forms an enzyme-substrate complex
- the enzyme catalyses a reaction to release products - enzyme is unchanged and can be reused
induced fit model
-the substrate binds to a not complementary active site of an enzyme, this causes the active site to change shape slightly and to mould itself around the substrate in order to complete the fit
-the enzyme is flexible causing bonds in the substrate distort the hydrogen bonds holding the enzyme
-this forms an enzyme-substrate complex, the enzyme catalyses a reaction and releases products
- the enzyme’s active site returns to its original shape
enzymes properties relate to their tertiary structure - enzyme specificity
-enzymes are very specific - they only catalyse on reaction as only one substrate is complementary to the active site
-the shape of the active site is determined by the tertiary structure which is determined by the primary structure (sequence of amino acids in a polypeptide chain)
-if there is a mutation which affects the gene, the primary structure is affected, this changes the way the polypeptide is bonded and folded, and therefore affects the shape of the protein in its tertiary structure which alters the shape of the active site, this means that the substrate will not fit and the reaction wont be catalysed
factors affecting enzyme activity
-pH
-temperature
-enzyme concentration
-substrate concentration
-competitive inhibitor
-non competitive inhibitor
temperature affecting enzyme activity
-As temperature increases to optimum, rate of reaction increases
-More kinetic energy
-So more enzyme-substrate complexes form
-As temperature exceeds optimum, rate of reaction decreases
-Enzymes denature-tertiary structure and active site change shape
○ As hydrogen/ionic bonds break
○ So active site no longer complementary
○ So fewer enzyme-substrate complexes form
pH affecting enzyme activity
-as pH increases/decreases above/below an optimum, rate of reaction decreases
-Enzymes denature-tertiary structure and active site change shape
-As hydrogen/ionic bonds break
-So active site no longer complementary
-So fewer enzyme-substrate complexes form
substrate concentration affecting enzyme activity
-As substrate concentration increases, rate of reaction increases
-Substrate concentration = limiting factor (too few substrate molecules to occupy all active sites)
-More enzyme-substrate complexes form
-At a certain point, rate of reaction stops increasing/ levels off
-Enzyme concentration=limiting factor
-as all active sites saturated/occupied (at a given time)
enzyme concentration affecting the rate of reaction
-As enzyme concentration increases, rate of reaction increases
-Enzyme concentration=limiting factor(excess substrate)
-More enzymes so more available active sites
-So more enzyme-substrate complexes form
-At a certain point, rate of reaction stops increasing/ levels off
-Substrate concentration =limiting factor (all substrates in use)
competitive inhibitors affecting enzyme activity
-As concentration of competitive inhibitor increases, rate of reaction decreases
-competitive inhibitors molecules have a similar shape to the substrate molecule, which means it competes to bind to the active site, they block the active site so no substrate molecules can bind
-so fewer enzyme-substrate complexes forms
-increasing competitive inhibitors, reduces the effect of inhibitor
non competitive inhibitors affecting rate of reaction
- As concentration of non-competitive inhibitor increases, rate of reaction decreases
-non competitive inhibitor molecules binds away from the enzyme’s active site and binds to the allosteric site, this changes the tertiary structure of the enzyme so the substrate is no longer complementary to the active site of the enzyme and substrates can no longer bind to it
-so fewer enzyme-substrate complexes form
-increasing the substrate concentration, has no effect to the rate of reaction, as the change to active site is permanent
