Biological molecules Flashcards
core concepts
what is the importance of magnesium?
it is an important constituent of chlorophyll and essential to photosynthesis, plants lacking magnesium can not make chlorophyll so the leaves turn yellow (chlorosis) growth is stunted from lack of glucose. mammals need magnesium for their bones
what is the importance of iron?
iron is part of haemoglobin and a lack of it can lead to anaemia in humans
what are phosphate ions used for?
making nucleotides and are a constituent of phospholipids found in biological membranes
what is calcium used for?
important structural component of plant cell walls & bones
what are inorganic ions?
an ion that has no more than one carbon atom
how much micro/macronutrients do humans need?
micronutrients= needed in minute traces
macronutrients= needed in small concentrations
describe polypeptide primary structure
primary structure is determined by the base sequence on one strand of the DNA, it is a sequence of amino acids joined together by peptide bonds to create a polypeptide chain
describe and draw a dipeptide
- NH^2,CHR^1,CO-NH,CHR^1,COOH
- the resulting compound of a condensation reaction
between two amino acids bonded together by a peptide
bond
what is hydrophobic interaction?
non-polar amino acids cluster together on the inside of a protein because they are repelled by water
explain polypeptide quaternary structure
consists of more than one polypeptide chain (tertiary structure) joined together mostly by disulphide and hydrophobic bonds, sometimes containing a prosthetic group e.g: haemoglobin
what is this?:
H
|
H - C - OH
|
H -C - OH
|
H - C - OH
|
H
A GLYCEROL
what is this?:
CH^2OH
|
C = O
|
HC - OH
|
HC - OH
|
CH^2OH
pentose sugar
a monosaccharide containing 5 carbon atoms
what is collagen
made from three identical left handed helix polypeptide chains wound around each other to form a triple helix.
held together by h-bonds. its insoluble in water. collagen molecules cross link through covalent bonds to form fibres which give strength
it is the most basic amino acid it fibrous and is found in the skin.
in each polypeptide chain every third amino acid is glycine.
describe haemoglobin
globular protein which has a metabolic function
it is a quaternary structure consisting of 4 globin molecules held together by h-bonds
has a prosthetic group made up of Fe atoms called the haem group which carry oxygen
what is this?:
H H O
| | ||
H - N - C - C - OH
|
R
amino acid
Amino group, R-group, variable group
what bond links phospholipids and triglycerides?
Ester bond
an oxygen atom joining two atoms one of which is a carbon atom attached by a double bond to another oxygen atom
O2 atom joins 2 atoms 1 of which is a C-atom attached by a = bond to O2
what is this?:
CHO
|
OH - CH
|
OH - CH
|
HC - OH
|
HC - OH
|
CH^2OH
hexose
what is a peptide bond
the chemical bond formed by a condensation reaction between the amino group of one amino acid & the carboxyl group of another
what is represented here?:
CH^2
|
S
|
S
|
CH^2
<
disulphide bond
a covalent bond between the sulphur atoms of two cysteine residues in a
what is this?:
O H
|| |
HO = O = C - …
|
H
head of a fatty acid
What is the difference between a saturated fatty acid and a non-saturated fatty acid?
a saturated fatty acids has only carbon- carbon single bonds where as an unsaturated fatty acid has one or more c=c double bond, which puts a kink in the chain
what is ?:
H O
| ||
H - C - O - C - R (1)
| O
| ||
H - C - O - C - R (2)
| O
| ||
H - C - O - C - R (3)
|
H
Triglyceride
1 glycerol & 3 fatty acid tails by a condensation reaction
draw a condensation reaction between a glycerol and three fatty acids
look up answer :)
what is an ionic bond?
a type of bond that occurs between oppositly charged ions
contribute to the folding of protiens into their tertiary structure
describe the structure of glycogen
highly branched alpha glucose 1,4 & 1,6 glycosididic bonds
main storage product in animal
branching happens every 8-10 molecules
what is the diffrence between alpha and beta glucose?
ABBA
Alpha above
Beta below
(OH group)
draw alpha glucose
C6H12O6
Describe the structure of cellulose
cellulose is made up of beta glucose 1,4 glycosidic bonds each roatated 180 degrees from the one adjacent to it forming inear colums connect by hydrogen bonds between the OH groups
describe the structure of chitin
beta glucose monomers and amino acids linked by 1,4 glycosidic bonds each rotated 180 degrees to the one adjacent and each paralel chain is is linked by h-bonds forming microfibrils
the linear chains are called heteroplysacharides
name three properties of chitin
- very strong
- light weight
- waterproof
what is a structual difference and similarity between cellulose and chitin
> a diiference is that chitin has an amino group on its carbon 2 whereas cellulose has a OH group
a similarity is that they both have their OH group on the top of carbon 1 which is lost during the condenation reaction joining them together because they are both beta glucoses
what is a glycosidic bond
the bond that joins to glucose monomers together
glucose + glucose =
maltose
why are hydrogen bonds formed
because of the diffrence in charges between the OH- and H+ atoms
decribe the structure of galactose
the OH group is above on both sides of the monomer
galactose + glucose =
lactose
describe the structure of fructose
it has CH2OH below H on carbon one as well as oncarbon 6
frutose + glucose =
sucrose
what does LDL do
LDL contains and transport saturated fatty acids which are harmful, a build up of these in the arteries may lead to heart disease
what do HDL do
HDL contain and transport unsaturated fatty acids which transport harmful fats to the liver for disposal, high concentrations of HDL reduce the risk of a heart attack
describe polypeptide tertiary structure
further folding of the polypetide chain to forma= a 3d globular shape
what is the structure of a phospholipid
glycerol, a phosphate group & two fatty acids
an important component of cell membranes
which part of the phopholipid is hydrophobic
the tail is hydrophobic because it is non polar (doesn’t have a charge) so will not interact with the water
describe polypeptide seconday structure
the polypetide chain folds due to hydrogen bonds forming between the amino acids along the chain into alpha helixes or beta pleted sheets
describe the structure of amylopectine
a-glucose monomer are joined together by 1,4 and 1,6 glycosidic bonds this means that the chain is branched
less so than glycogen it only brances every 24-36 monomer
describe the structure of amylose
tightly coiled linear chain of polysaccharides composed of 1,4 glycosidic bonds
what are the three main functions of carbohydrates
- storage of enery
- release of energy
- cellular structures
what is an isomer
molecules with the same chemical formulea but diffrent arrangments of atoms
what are two other hexose sugars
fructose and galactose
what is a property of monosaccharides
soluble in water
easily dissolved in cell and transported into the blood stream
properties of polysaccharides
- compact (easily stored)
- easily hydrolised (release glucose for respiration)
- storage/structure
give 4 examples of polysaccharides
- starch (storage in plants)
- glycogen (storage in animals)
- cellulose (structure in plants)
- chitin (structure in fungi & exosceletons)
which polysaccharides are used for storage
alpha
which polysaccharides are used for structure
beta
which two molecules make up starch
amylose and amylopectine
where is glycogen stored
liver and muscle cells
what are four properties of lipids
- insoluble in water
- soluble in organic solvents
- fats are solid at room tempreture
- oils are liquid at room tempreture
state the 6 functions of lipids
- storage of energy
- protection of vital organs
- thermal insulation
- boyance
- metabolic water
- waterproofing
there are twenty amino acids found in natur. how do they differ from eachother
they have diffrent variable groups
what bonds hold together tertiary structure of protiens
- hydrogen
- ionic (between oppositly charged R groups)
- disulphide bridges (between S atoms)
- hydrophobic/phylic interactions
- peptide bonds
what are the two classifications of protiens
globular and fiberose
why are fiberous protiens effective at carrying out STRUCTUAL functions
- tough
- non-specific
- insoluable
what are the properties of globular protiens
- they have a specific shape
- compact
- solubale in water
how do you test for protiens
- add a few drops of biuret reagent to a protiens solution
- shake gently
- turn from blue to lilac
how do you test for reducing sugars
- add a few drops of benedicts reagent to test sample
- heat in a water bath
- turn from blue to brick red
may be graduated between green yellow orange and brick red
semi-quantative
how do you test for non reducing sugars
if a negative result is initally found with the benedicts test:
1. add HCl to test sample
2. heat in a waterbath ( to hydrolyse any glycosidic bonds)
3. add bicarbonate of soda to nutralise
4. add benedicts reagent and heat in a waterbath
5. if present the solution will turn from blue to brick red
how do you test for lipids
- mix a sample with equal volumes of ethanol and water
- iflipids are present it will turn cloudy white
what is cohesion
water molecules sticktogether as a result of the formation of hydrogen bonds
what are the 7 properties of water
- surface tensionn
- universal solvent (excellent transport medium)
- metabolite
- high specific heat capacity
- high latent heat capacity
- density
- transparenct
how do you test for starch
add a few drops of iodine to samp,e and if its present it will turn from orange to blue black
