Module 1: Biological Molecules Flashcards
What are biological molecules?
Molevules made and used by living organisms e.g. carbohydrates, proteins, lipids, DNA, ATP, water, inorganic ions
Function of carbohydrates?
Energy source (glucose in respiration) Energy store (starch in plants, glycogen in animals) Structure (cellulose in plant cell walls)
Monomers of carbohydrates
Monosaccharides
Examples of monosaccharides
Glucose (alpha and beta)
Galactose
Fructose
Formula for monosaccharides
C6H12O6 (isomers= same formula different arrangement)
Difference between alpha and beta glucose
On carbon 1 alpha has OH on bottom but beta has OH on top
How do you join monosaccharides?
Condensation reaction between 2 OH groups, removes water
Bond in carbohydrates?
1-4 glycosidic
Examples of disaccharides
Maltose (GG)
Lactose (GGL)
Sucrose (GF)
Formula for disaccharides
C12H22O11
How are polymers separated?
Hydrolysis reactions (removes water but requires a catalyst)
What is a polysaccharide?
Many monosaccharides joined by condensation reactions/glycosidic bonds
Examples of polysaccharides
Starch (alpha, energy store in plants)
Glycogen (alpha, energy store in animals)
Cellulose (beta, structure in plants)
Structure of starch
Amylose (long straight coiled chain of alpha glucose)
Amylopectin (strsight chain with side branches with 1-6 glycosidic bonds)
Structure of glycogen
Straight chain of alpha glucose (1-4 glycosidic) with side branches (1-6 glycosidic)
Properties of starch and glycogen as energy stores
Insoluble: doesn’t affect water potential, doesn’t diffuse out of cells
Coiled/branched: compact
Branched/chained: easily hydrolysed
Structure of cellulose
Beta glucose in straight chains (alternative rotated 180 degrees)
Cellulose chains cross linked by hydrogen bonds to form microfibrils
Microfibrils join to form macrofibrils
Strong material
Test for starch
Iodine
Turns blue black
Test for reducing sugar
Heat in a water bath with benedicts
Turns brick red
Test for non-reducing sugars
Heat in bath with benedicts-no change
Add dilute HCL (hydrolyses glycosidic bond)
Add Sodium hydrogencarbonate (neutralise)
Heat in bath with benedicts
Turns brick red
Two types of proteins
Globular
Fibrous
Globular proteins
Soluble proteins with a specific 3D (tertiary shape)
Enzymes, antibodies, haemoglobin, hormones
Fibrous proteins
Strong
Insoluble
Inflexible
Collagen/keratin
Monomers for proteins
Amino acids
Structure of an amino acid
Central carbon Carboxyl to the right Amine to the left Hydrogen above R below
How do different amino acids differ
Have different R groups
How are amino acids joined together
Condensation reactions
Between carboxyl group and amine group
Peptide bond between carbon and nitrogen
Primary structure
Sequence of amino acids, polypeptide chain held by peptide bonds
Secondary structure
Polypeptide chain coils to form alpha helix or beta pleated sheets held by hydrogen bonds
Tertiary structure
Secondary structure further folds to form 3d tertiary structure held by hydrogen/ionic bonds and disulfide bridges
Quaternary structure
More than one polypeptide chain
May contain prosthetic group
Example of quaternary structures
Collagen
Antibodies
Haemoglobin
Structure of collagen
Strong material to make tendons/ligaments/connective tissues
Primary structure made up of glycine
Secondary forms tight coil with little branching due to glycine
Tertiary coils again
Quaternary has 3 tertiary wrapped around like rope
Test for protein
Biuret
Turns purple/lilac
What is an enzyme?
Biological catalyst that speeds up the rate of reaction without being used up, lowers activation energy
Specific tertiary structure
What makes an enzyme specific?
Specific active site shape
Only complementary substrates can bind to active site
Forms enzyme-substrate complexes
Lock and Key VS induced fit
LK: active site is rigid, only exactly complementary substrates can bind to form ES complexes
IF: active site changes shape, substrate binds, forms ES complex
Affect of substrate concentration on enzyme activity
Increase SC increases chances of successful collisions, increases chances of ES complexes forming, increases rate of reaction
Continues until all enzymes active sites are saturated
Affect of enzyme concentration on enzyme activity
Increase EC increases chance of successful collisions, increases chance of forming ES complexes, increases rate of reaction
Continues until substrates are used up
Affect of temperature on enzyme activity
Temp increases Kinetic energy increases Molecules move faster Increased chance of successful collisions Increased chance of forming ES complex Increased rate Until optimum Hydrogen and ionic bonds in tertiary structure break Lose active site shape Substrate no longer complementary No ES complexes Enzyme denatured
Affect of ph on enzyme activity
Change ph away from optimum Bonds in tertiary structure break Lose active site shape No longer form ES complex Enzyme denatured
Competitive inhibitors
Substance with similar shape to substrate and complementary shale to active site of enzyme, binds to active site and blocks it, prevents ES complexes from forming
Non-competitive inhibitors
Substance that binds to allosteric site on enzyme
Causes active site to change shape
Less ES complexes can form
3 types of lipids
Triglycerides (fat for energy store, insulation, organ protection)
Phospholipids (membranes)
Cholesterol (membrane stability, hormones)
Structure of a triglyceride
1 glycerol and 3 fatty acids
Condensation reactions, ester bonds
Bond is COOC
2 types: saturated fat and unsaturated fat
Saturated fat
No carbon-carbon double bonds in R group
Unsaturated fat
Has carbon-carbon double bonds in R group
Structure of phospholipid
1 glycerol, 2 fatty acids, 1 phosphate
Hydrophillic heads
Hydrophobic tails
Phospholipid bilayers
What are nucleic acids?
Polymers made from nucleotides
DNA and RNA
What is DNA
DeoxyriboNucleic Acid
Found in all organisms
Carries genes (sections of DNA that code for protein)
DNA monomer
Nucleotides (made of phosphate, deoxyribose sugar, nitrogenous base)
Adenine, Thymine, Guanine, Cytosine
DNA structure
Double helix
2 polynucleotides hydrogen bonds between bases
Antiparallel strands
Coiled
Bonding in base pairs
AT
GC
GC most common, triple bond
AT have double bond
Properties of DNA structure
Double stranded: more stable, act as templates in semi-conservative replication
Coil into helix: more compact
Sugar-phosphate backbone: protects bases
hydrogen bonds between bases: weak so strands can separate
Complementary base pairing: so identical copies can be made in replication
DNA replication
In interphase before mitosis and meiosis
Semi-conservative replicatiom
Semi-conservative replication process
DNA helicase breaks hydrogen bonds between complementary bases
Double strand separates leaving two template strands
Free complementary nucleotides bind to exposed bases on template strands
DNA polymerase catalyses reformation of sugar-phosphate backbone
Evidence for SCR?
Replicating bacterial DNA in nitrogen isotopes 15N and 14N
Nitrogen found in bases of DNA
15N will have heavy density but 14N will be light
15N replicated in environment of 14N, produces DNA with half 15N and half 14N, DNA has medium density
What is RNA
RiboNucleic Acid mRNA: messenger tRNA: transfer Single stranded Phosphate, ribose sugar, nitrogenous bases AUGC
What is ATP
Adenosine Tri Phosphate
Energy carrier molecule
Structure of ATP
1 adenosine, 3 phosphates ADP + Pi (+energy used)= ATP condensation reaction using ATP synthase Carries energy in its bonds Hydrolysis uses ATP hydrolase
Why is ATP a good source of energy
Immediate source: only need to break one weak bond
Managable source: releases small amount of energy
Uses of ATP
Protein synthesis Organelle synthesis DNA replication Cell division Active transport Metabolic reactions Movement Maintaining body temperature
Role of water in biology
Found in living organisms: cytoplasm, xylem/phloem, tissue fluid and blood
Acts as habitats for living organisms
Properties of water
Water is dipolar
Hydrogen has slight positive charge
Oxygen has slight negative charge
Forms hydrogen bonds
Role of water in habitats (sea)
High specific heat capacity due to hydrogen bonds
Freezes=ice which is less dense than water so can float to insulate water
Role of water as a solvent
Water molecules are dipolar so can separate solutes based on their charge
Hydrogen mixes with negative and oxygen mixes with positive so solute dissolves
Useful in cytoplasm and diffusion
Role of water hydrostatic pressure
Water pressurised can provide strong physical pushing force
Mass flow theory and turgidity in plants
Role of water homeostasis
Control body temperature by sweating
Sweat made of hydrogen bonds so has a stable structure and requires large amount of heat to evaporate
Called latent heat of vaporisation
What are inorganic ions
Salts/minerals
Inorganic=no carbon
Ion=charged
