Biological molecules Flashcards
how does hydrogen bonding occur in water
the slightly negatively charged oxygen atom attracts the slightly positively charged hydrogen atoms
why is water a good solvent
water is polar so the slightly positive oxygen atom will be attracted to negative ions and the slightly negative hydrogen atoms will be attracted to positive ions, as most substances in biological reactions are ionic
why is water a good coolant
it has a high latent heat of vaporisation meaning it takes a lot of energy to break hydrogen bonds between molecules, cools surface of skin
why is water cohesive and what does this mean
cohesion is the attraction of molecules to the same type of molecule, this helps water to flow making it great for transporting substances like in the transpiration stream
why does water have a high heat capacity and why is this a benefit
it takes a lot of energy to raise the temperature by 1oc as hydrogen bonds can absorb a lot of energy, makes it a good habitat as temperature of water doesn’t fluctuate too much
why does water have a lower density when said and how is this a benefit
molecules are held further apart in a lattice structure as each water molecules forms four hydrogen bonds , this means in freezing conditions ice forms an insulation layer on top of water preventing it from freezing
what are macromolecules
complex molecules with a large molecular mass, proteins, lipids, carbohydrates
what is a monomer
small, basic molecular units, amino acids, monosaccharides
what is a polymer
large complex molecules made up of small repeating units (monomers) joined together
What reaction can breakdown polymers and how dos this happen
hydrolysis- breaks a bond using a water molecules
what reaction can form a polymer and how does this happen
condensation- forms a chemical bond and releases a molecule of water
what chemicals make up carbohydrates
C,H and O
What chemicals make up lipids
C,H and O
What chemicals make up proteins
C,H,O, N and S
What chemicals make up nucleic acids
C,H,O,N and P
what are the two types of monosaccharides that make up carbohydrates
glucose and ribose
describe or draw the structure of alpha glucose
Ch2OH at top, 5 carbon atoms and an oxygen in top right, H above OH attached to right carbon
describe or draw the structure of beta glucose
CH2OH at top, % carbon atoms and O in top right, Oh above H on right carbon
What is the structure of ribose
O at top, CH2OH attached to top left carbon, pentagon shape, pentose sugar
what is the difference between a hexose sugar and a pentose sugar
hexose has an extra carbon atom
what are monosaccharides joined together by
glycosidic bonds
how are glycosidic bonds made and broken
condensation and hydrolysis
What is sucrose and what is it made up of
disaccharide- alpha mucose and fructose
what is lactose and what is it made up of
disaccharide- galactose and either alpha or beta glucose
what is maltose and what is it made up of
disaccharide- two alpha glucose molecules
What is starch and describe its structure
main energy storage molecule in plants, insoluble in water, mixture if two polysaccharides of alpha glucose (amylopectin and amylose)
Give the structure of amylose
long, unbranched chain of a glucose, coiled, compact so can fit more in a small space
Give the structure of amylopectin
long, branched chain of a glucose, allow glycosidic bonds to be broke down easily, glucose can be released quickly
What is glycogen and describe its structure
main energy storage in animals, made of a glucose, very branched, can be released quickly, very compact
What is cellulose and describe its structure
major component of cell wall in plants, long unbranched chains of b glucose, linked by hydrogen bonds, form microfibrils, means strong, structural support
What is the structure of a triglyceride
one molecule of glycerol with three fatty acid tails attached to it by ester bonds
how are triglycerides synthesised and broken down
esterification and hydrolysis
what is the structure of a phospholipid
a phosphate group, molecule of glycerol and two fatty acid tails
what is the structure and properties of fatty acid tails
made out of hydrocarbons, hydrophobic, insoluble in water
what is a saturated fatty acid
no double bonds ‘saturated with hydrogen
what is an unsaturated fatty acid
double bonds between at least one carbon
Give the structure of cholesterol
hydroxyl group attached to hydrocarbon rings with a hydrocarbon tail
What is the function of triglycerides and how does their structure support this
mainly energy storage in animals and plants, long hydrocarbon tails containing lots of chemical energy, insoluble (form droplets) so they don’t cause water to enter cells via osmosis
What is the function of phospholipids and how does their structure support this
found in cell membranes of E and P cells, make up bilayer, hydrophilic heads and hydrophobic tails which face inwards so water soluble substances can’t pass through easily, helps control what enters and leaves the cell
What is the function of cholesterol and how does its structure support this
regulates fluidity of membrane, has a small flattened shape so can fit between phospholipids, bind to tails in high temps so they pack together making membrane less fluid, opposite in low temps
What is the general structure of an amino acid
amine group, carbon, carboxyl; group with a variable group attached above or below central carbon and a hydrogen opposite the variable group
what are amino acids joined together by
pptide bonds
how are peptide bonds made and broken
condensation and hydrolysis
describe the primary structure of a protein
sequence of amino acids in the polypeptide chain
describe the secondary structure of a protein
hydrogen bonds form causing the coil into an alpha helix or fold into a beta pleated sheet
Describe the tertiary structure of a protein
ionic bonds form between negatively charged and positively charged R variable groups, disulfide bonds between sulphur atoms in cysteine, hydrophobic and hydrophilic interactions cause hydrophilic R groups tone push to outside, hydrogen bonds form between slightly positive H atoms in R groups and slightly negatively charged atoms in other R groups
Describe the quaternary structure of a protein
for proteins made up of more than one polypeptide chain , creates a 3D structure, example is haemoglobin
Describe the structure, function and give some examples of globular proteins
round and compact, soluble, haemoglobin, insulin amylase, transport
Describe the structure, function and give examples of fibrous proteins
tough, rope-shaped, in soluble, structure, collagen (found in connective tissue’s), keratin (found in skin and nails), elastin (found in skin and large blood vessels)
what is a conjugated protein and give an example
it is a protein with a non-protein group attached called a prosthetic group, each of the four polypeptide chains in haemoglobin have a prosthetic group called ham which contains iron
What cation is involved in the transmission of nerve impulses and release of insulin from the pancreas, acts as a cofactor for many enzymes e.g blood plotters, important in bone formation
calcium (Ca2+)
What cation is important for generating nerve impulses for muscle contraction and regulating fluid balance in body
Sodium (Na+)
What cation is important for generating nerve impulses for muscle contraction and regulating fluid balance in body. Activates essential enzymes needed for photosynthesis in plant cells
Potassium (K+)
what cation affects pH of substances, important for photosynthesis reactions that occur in thylakoids and respiration reactions occurring in the inner membrane of the mitochondria
Hydrogen (H+)
What cation is absorbed from the soil by plants and is an important source of nitrogen
Ammonium (NH4+)
What anion is absorbed from the soil by plants and is an important source of nitrogen
nitrate (NO3-)
What anion is important in acting as a buffer for blood pH
hydrogencarbonate (HCO3-)
What important anion is used in the chloride shift to help maintain pH of blood and acts as a cofactor. of the enzyme amylase, also involved in some nerve impulses
chloride (Cl-)
What anion is important in photosynthesis and respiration, needed for synthesis of biological molecules such as ATP and phospholipids
Phosphate (PO43-)
What anion is important in affecting the pH of substances
hydroxide (OH-)
what is the test for proteins, how is it carried out and what would a positive test result in
biuret test, add NaOH and copper sulphate, turns from blue-purple
what is the test for starch, how is out carried out and what would a positive test result in
iodine test, add iodine, solution turns fro. orange to blue /black
what is the test for lipids, how is it carried out and what would a positive test result in
emulsion test, shake in ethanol and pour into water, if present the solution will turn milky
what is the test for reducing sugars, how is it carried out and what would a positive test result look like
add Benedict’s solution, heat in a water bath, will form a coloured precipitate green-yellow-orange-brick red (( the further the colour change the higher the conc if no reducing sugar is present then solution remains blue
what types of sugars are reducing
monosaccharides and maltose/lactose
what is the test for non-reducing g sugars, how is it carried out and what would a positive result look like
carry out Benedict’s test first the using a new sample add HCl and heat in a water bath, then neutralise with NaOH and carry out Benedict’s test, same results as reducing sugar
how do you use a calorimeter
do a Benedict’s test on each solution and remove any precipitate that forms,
switch calorimeter on and allow 5 mins to stabilise
use red filter
add distilled water to cuvette and place inside with the light passing through the clear sides, calibrate machine to zero
use pipette to transfer sample of solution into a clean cuvette
put cuvette in calorimeter and record absorption, relate for remaining solutions
what is the mobile phase in chromatography
where the molecules can move, a liquid solvent like water or ethanol
what is the stationary phase In chromatography
where the molecules can’t move, e.g thin layer of solid
how do you calculate the Rf value
distance moved by solute/distance moved by solvent
