Biological molecules Flashcards
carbohydrates lipids proteins nucleic acids
macromolecule definition and examples
giant molecule, eg. Proteins, Carbohydrates, Nucleic acids
organic molecule definition
molecules containing carbon and hydrogen
natural polymers and the monomers they are made out of
polysaccharides (monosaccharides and disaccharides)
proteins (amino acids)
nucleic acids (nucleotides)
NOT LIPIDS
manmade polymers
PVC, nylon, polyester, polythene
General formula of carbohydrates
Cx(H2O)y
elements in carbohydrates
Carbon
hydrogen
oxygen
monosaccharides examples
glucose
fructose
galactose
uses of monosaccharides
energy and respiration (broken bonds transfer energy for ATP)
building blocks for larger molecules
characteristics of monosaccharides
sweet, water soluble, single molecules CH20n
glucose formula
C6H12O6
isomers
Molecules of the same molecular formula with diferent structural formulae.
alpha glucose positioning of hydroxyl groups
down, down, up, down (right to left)
beta positioning of hydroxyl groups
up, down, up down (right to left)
Disaccharides
2 monosaccharides joined together
sucrose monomers
a glucose + b fructose
maltose monosaccharides
a glucose + a glucose
lactose monosaccharides
b galactose + b glucose
Where do you start numbering carbon atoms?
From the end with a double bond to oxygen
Structure of pentoses and hexoses
ring structure with carbon 1 bonded to carbon 5 so that carbon 6 is isolated from the ring.
How are disaccharides formed?
via a condensation reaction forming a glycosidic bond between the 2 monosaccharides and releasing a water molecule.
disadvantages of qualitative biological molecules tests
cant be quantified to give exact concentrations or types of molecules.
protein test
biuret solution heated w sample and turns from blue to purple.
starch test
iodine turns starch black
lipids test
mix ethanol with solution and add water to turn cloudy
reducing sugars
sugars with an aldehyde/ketone/hydroxyl group so therefore acts as an oxidising agent.
test for reducing sugars
add benedicts solution to sample in water bath and will turn brick red
test for non reducing sugars
sample is boiled and HCl is added to it (hydrolysis via acidification) before cooling and adding benedicts reagent.
colorimeter
measures a solutions absorbance of specific wave lengths to create a calibration curve at 735nm.
proteins function
structure and functioning of cell for transport and movement, eg centrioles
inorganic ion function
participate in metabolic reactions. eg chlorophyll has aluminium
water function
metabolic processes, fluid pressure, temp control and solvent.
nucleotides and nucleic acids function
coding of cell, construction and functioning. ATP is derivative of nucleotide
carbohydrates
structure, energy storage and cellular recognition
lipids function
energy storage and cellular membrane
organic macromolecule groups
carbs, lipids, proteins, nucleic ACIDS
CARB elements and monomer
sugars
CHO
protein monomer and elements
amino acids
C H O N S
lipids monomer and elements
ISNT A POLYMER
C H O
nucleic acids monomer and elements
nucleotides
C H O N P
reactions that split disaccharides and polysaccharides
hydrolysis using hydrogen and a hydroxyl group, catalysed by specific enzymes
functional properties of polysaccharides depend on?
composition and isomers involved
polysaccharides
macromolecules consisting of straight/branched chains of monosaccharides, eg starch, cellulose, glycogen
cellulose,
where’s it found?
structure?
what’s it made of? bonding?
cell walls of plants
unbranched
beta glucose molecules joined by stable 1,4 glycosidic links
produces parallel chains which are cross linked w hydrogen bonds to form microfibrils
microfibrils
properties
cross linked hydrogen bonded chains of cellulose.
strong, provide cell wall w strength and rigidity
40-70 cellulose chains
starch
what’s it made of?
structure?
function?
long chains of alpha glucose linked together w 25-30% amylose and 70-75% amylopectin
energy storage
amyloplasts in plants to be hydrolysed by enzymes as an energy source when required
amylose structure
linear, helical, unbranched a glucose chains linked via 1,4 glycosidic bonds
every turn requiring six a glucose molecules
25-30% structure of starch
amylopectin structure and composition
branched chains of 1,6 glycosidic bonds every 24-30 glucose units
1,6 provide branching points
allows millions of molecules to be joined in a compact form.
glycogen
structure?
composition?
properties?
branched polysaccharide composed of a glucose molecules
glycosidically linked via 1,6 and 1,4
more highly branched and water soluble than starch
storage compound in animal tissues
amyloplasts
non-pigmented storage organelles within plant cells
Why is amylopectin less soluble than glycogen?
because it has less 1,6 glycosidic links w 1,4 links so is less soluble
lipids
non-polar, hydrophobic organic molecules made up of fatty acids, classified as saturated/unsaturated fatty acids.
eg fats, waxes, sterols and phospholipids
why do lipids not dissolve in water?
hydrophobic so repel water molecules
fatty acid composition
even number of carbon atoms with hydrogen bound along the chain length, carboxyl group at end forms an acid.
neutral fats
form fats and oils in plants and animals, consisting of a glycerol attached to one (mono), two (di) or three (tri) fatty acids via ester bonds
why are lipids good at storing energy?
metabolism of the molecule releases chemical energy from hydrogen present in fatty acid chains. Are v reduced and anhydrous, meaning provide much energy for small stores.
saturated fatty acids
contain maximum number of hydrogen atoms
unsaturated fatty acids
contain double bonds between carbons
monounsaturated
containing only one double bond
polyunsaturated
containing two or more double bonds
how does proportions of saturated fatty acids affect the state of a molecule?
why?
higher proportion leads to a more solid state
however higher proportion of unsaturated leads to a liquid state at rtp.
unsaturation causes kinks so chains don’t pack as closely together
formation of triglycerides
condensation reaction between glycerol and 3 fatty acids.
ester bond is formed between the glycerol hydroxyl group and a hydrogen off of a fatty acid, releasing a water molecule.
glycerol
an alcohol with 3 carbons bonded to a hydroxyl group.
esterification
condensation reaction of an alcohol with an acid with an acid, forming an ester and water.
lipolysis
breakdown of lipids involving hydrolysis of triglycerides into glycerol molecules and fatty acids.
biological functions of lipids
concentrated sources of energy, fuel for respiration structure of cell membranes waterproofing in plants and animals shock absorbers for protection source of metabolic water insulation
phospholipids
modified triglycerides in which a phosphate group replaces the fatty acid
phosphate ion
PO43-
hydrophilic end of the phospholipid
phosphate end of the molecule
hydrophobic end of a phospholipid
fatty acid end repels water molecules
phospholipid bilayer
when the hydrophilic phosphate end of a phospholipid turns inwards towards the water and hydrophobic turns away, forming a bilayer.
amphipathic
having hydrophobic and hydrophilic ends
structure of saturated vs unsaturated fatty acid tails
unsaturated forms kinks and saturated forms straight chains.
greater number of double bonds increases the fluidity of the membrane.
amino acid formation
join together in condensation reactions in a linear chain to form polypeptides, sequence defined by a gene and encoded in the genetic code.
they also are joined via peptide bonds to form long polypeptide chains
how are genes broken down?
in the presence of water, they break down via hydrolysis into their constituent amino acids.
what’s a nucleotide made up of?
one carbon joined to a hydrogen, amine group (NH2), carboxyl group and chemically variable ‘r’ group
whats different in each type of amino acid?
the R group determines interactions with other amino acids and therefore how it folds up into a functional protein.
cysteine
forms disulphide bridges with other cysteine amino acids to form cross links in a polypeptide chain.
lysine
r group donating an alkaline property
aspartic acid
donates acidic property
where do peptide bonds form between amino acids?
between the carboxyl group of one and the amine group of another, forming water
primary structure
the sequence of amino acids in a polypeptide
what determines the primary structure?
the order of nucleotides in DNA and mRNA
what determines the secondary structure of proteins?
the composition and position of amino acids along with hydrogen bonding between amino acids.
What determines tertiary structure
Interaction between R groups
Tertiary structure
A three dimensional shape held by ionic bonds and disulphide bridges
Channel proteins
Proteins that fold to form channels in the plasma membrane.
Non-Polar R groups face the membrane and polar face the inside of the channel so hydrophilic molecules pass and ions pass through into the cell.
Enzymes
Globular proteins that catalyse reactions.
Polar active sites specific to polar substances
Non polar specific to non polar substances
Sub-unit proteins
Consist of two or more subunits in a complex quarternary structure.
Denaturation
When chemical bonds holding a protein break and can’t hold its 3 dimensional shape so can’t carry out biological function.
Causes of denaturation
pH
Heat
Proteins
Complex macromolecules built up from linear sequence of units of amino acids
Primary structure
Amino acid sequence linked via peptide bonds to form giant polypeptide chains organised by attractive and repulsive charges on amino acids.
Secondary structures
Alpha helix or beta pleated sheet
Maintained by hydrogen bonds between neighbouring CO and NH groups (collectively strong).
Alpha helix
Hydrogen bonds collectively strong, joining amino acids.
Beta pleated sheet
Formed via 2 peptide chains joined via hydrogen bonds.
Tertiary structure
3 dimensional shape formed in folding of secondary structures via disulphides bonds between cysteine amino acids, ionic bonds and hydrogen bonds as well as hydrophobic interactions.
How are tertiary structures broken?
Heavy metals
Solvents
pH and temp extremes
Quarternary structure
Arrangement of the polypeptide chains into a functional protein.
Globular protein properties
Water soluble
Necessary tertiary structure
Polypeptide chains folded
Globular proteins function
Catalytic eg enzymes
Regulatory eg insulin
Transport eg haemoglobin
Protection eg antibodies
Haemoglobin
Oxygen transporting protein in red blood cells, consisting of 4 polypeptide chains (2 alpha and 2 beta).
Each subunit contains a non-protein prosthetic group and ahem group (w Fe) which binds to oxygen.
Insulin
Peptide hormone composed of 2 peptide chains (A and B) linked via 2 diulfide bonds.
RuBisCo
Multi-unit enzyme found in green plants catalysing carbon fixation in the Calvin cycle, consisting of 8 large and 8 small subunits arranged as 4 dimers.
Properties of fibrous proteins
Water insoluble
Tough (stretchy)
Long fibres/sheets
Function of fibrous proteins
Structural
Contractile
Collagen structure
3 polypeptides wound via hydrogen bonds to form a helical rope with every third amino acid as a glycine.
Self assemble into fibrils by covalent cross linkages, bundling to form fibres.
Collagen function
Component of connective tissue, mostly found in fibrous tissues.
Keratin
Polypeptide chains arranged in parallel sheets held together by hydrogen bonds.
Polarity of water
How does this affect it?
Oxygen has slight negative chart while hydrogen have slight positive.
Means weak hydrogen bonds are formed between each molecule. Also affects intermolecular forces between other polar molecules, allowing ions to stay dissolved in water.
Water functions
Provides medium in which metabolic reactions occur (also able to act as base/acid).
Provides an aquatic environment due to high heat capacity, keeping large bodies of water thermally stable.
Water properties
Cohesive
Adhesive
Solvent
Thermal
Cohesive property of water
Stick together due to hydrogen bonds formed between each molecule, allowing development of surface tension.
Adhesive property of water
Attracted to other molecules as forms hydrogen bonds between other polar molecules.
Solvent property of water
Dipolar nature allows it to surround other charged molecules and prevent them clumping.
Thermal properties of water
Highest heat capacity so forms thermally stable bodies of water.
High bp as much energy is needed to break the H bonds, supporting life and metabolic processes.
High latent heat of vaporisation, meaning sweat has cooling effect.
Water solvent properties in the wild
Dissolved minerals are available to aquatic organisms.
Blood plasma transports many substances.
Thermal properties of water in wild
Allows temp sensitive metabolic processes to take place in organisms
water role in cells
main component and provides an aqueous environment for metabolic reactions to occur
