bio moles (1) Flashcards
what is the formula of glucose
C6H1206
what do alpha and beta glucose have in common
they are both 6-carbon hexose sugars
how is the structure of glucose adapted to its function
they are small + water soluble -> meaning they are easily transported in the blood
what are the 3 monosaccharides
glucose fructose galactose
what are the 3 disaccharides
maltose sucrose lactose
what is maltose made of
2 glucose
what is sucrose made of
glucose + fructose
what is lactose made of
glucose + galactose
what are the bonds between monosaccharides
glycosidic
how are glycosidic bonds formed
condensation reactions
what are the 3 polysaccharides
starch glycogen cellulose
describe the structure of starch
make up of amylose + amylopectin
amylose
- 1,4 bonds
- helix with intermolecular H bonds -> making it compact
amylopectin
- 1,4 and 1,6 bonds
- highly branched -> meaning many terminal ends for hydrolysis into glucose
give 2 structural benefits of starch
large -> meaning it doesn’t diffuse out of cells
insoluble -> meaning no osmotic effect on cells
what is the function of starch
for storage of a-glucose in plants
describe the structure of glycogen
- made up of a-glucose
- 1,4 and 1,6 bonds
- highly branched -> meaning many terminal ends for hydrolysis into glucose
give 2 structural benefits of glycogen
large -> meaning it doesn’t diffuse out of cells
insoluble -> meaning no osmotic effect on cells
what is the function of glycogen
for storage of a-glucose in animals and fungi
describe the structure of cellulose
- made up of b-glucose
- 1,4 bonds
- unbranched + straight chained
give a structural benefit of cellulose
H-bonds between parallel strands form microfibrils -> which gives it a high tensile strength
what is the function of cellulose
it gives rigidity to plant cell walls
what is the structure of a triglyceride
1 glycerol + 3 fatty acids
what are the bonds in triglycerides
ester bonds
how are ester bonds formed
condensation reactions
contrast the structure of saturated and unsaturated fatty acids
and state where they are found
- saturated only have single bonds between carbons whereas unsaturated also has double
- saturated are straight chained molecules with many contact points
whereas unsaturated are kinked molecules with fewer contact points - saturated have a higher melting point and are solid at room temp
whereas unsaturated have a lower melting point and are liquid at room temp - saturated are found in animal fats whereas unsaturated are found in plant oils
state how the structure of triglycerides relates to their role
high energy:mass radio -> meaning high energy storage (double calories/gram than carbs)
insoluble hydrocarbon chain -> means there is no effect on the osmotic potential of cells + can be used for waterproofing
its a slow conductor of heat -> useful for thermal insulation
its less dense than water -> giving buoyancy to aquatic animals
what is the structure phospholipids
a glycerol backbone attached to 1 hydrophilic polar phosphate head + 2 hydrophobic fatty acid tails
state how the structure of phospholipids relates to their role
its amphipathic (has both hydrophobic and hydrophilic parts) -> so it forms the phospholipid bilayer of cell membranes
its tails can splay outwards -> waterproofing
how many R groups are there
20
what are the bonds between amino acids
peptide bonds
how are peptide bonds formed
condensation reactions
describe the primary structure of a protein
the sequence of amino acids in a polypeptide chain
describe the secondary structure of a protein
folding of the polypeptide chain into an alpha helix or beta pleated sheet
hydrogen bonds added
describe the tertiary structure of a protein
the further folding of the polypeptide into a 3D structure
ionic and disulphide bridges are added
describe the quaternary structure of a protein
this is the final arrangement of several polypeptides
it can either be globular or fibrous
what are the ionic bonds doing
forming between oppositely charged R groups
what are the disulphide bridges doing
they are covalent bonds between sulphur
describe the structure and function of globular proteins
- soluble
- (sometimes) have a complex quaternary structure
- used in metabolic processes
- e.g. haemoglobin, enzymes, antibodies
describe the structure and function of fibrous proteins
- insoluble
- mainly secondary structure
- used for structure + support
- e.g. collagen
describe the structure of haemoglobin
4 polypeptides
each has 1 haem group
contains Fe2+ ions
oxygen binds to Fe2+
oxygen carried in blood
and released when required
e.g. in tissues for respiration
describe the structure of collagen
triple helix made of 3 polypeptides
many H and disulphide bonds
gives it a high tensile strength
used as a component in bones, cartilage and connective tissue
what is the structure of a nucleotide
pentose sugar, nitrogenous base + a phosphate group
what are the bonds between nucleotides
phosphodiester bonds
how are phosphodiester ester bonds formed
condensation reactions
describe the structure of DNA
double helix
2 sugar phosphate backbones joined together by hydrogen bonds between complementary bases
sugar phosphate backbones are polynucleotides
name the purines
A + G
2-ring molecules
name the pyrimidines
C+ T (and U)
1-ring molecules
what is semi-conservative replication
a strand from the original DNA molecule acts as a template
the new DNA molecule contains 1 old + 1 new strand
name the enzymes involved in semi-conservative replication
helicase, polymerase + ligase
explain the role of DNA helicase
helicase breaks the H-bonds between base pairs via
forming 2 single strands with exposed bases
which act as a template
explain the role of DNA polymerase
polymerase joins adjacent nucleotides onto the new strand
in a 5’ -> 3’ direction
via condensation reactions
forming phosphodiester bonds
H-bonds then reform between complementary bases
explain the role of DNA ligase
ligase joins gaps in fragments
to form a continuous strand
what is a gene
a sequence of bases on a DNA molecule
coding for a specific sequence of amino acids in a polypeptide chain
what is the genome
all of the DNA in an organism
describe the structure of mRNA
1 sense strand
composed of a sugar phosphate backbones + codons
describe the structure of tRNA
an anticodon (3 bases)
name the stages of protein synthesis
- translation
- splicing
- translation
what is transcription
making mRNA from a strand of DNA in the nucleus
explain the process of transcription
DNA polymerase binds onto DNA at certain sites
a small part of the DNA uncoils into 2 strands with exposed bases
free nucleotides attach to antisense strand
RNA polymerase joins adjacent nucleotides by phosphodiester bonds
what happens between transcription and translation
- splicing (only in eukaryotes)
introns are removed
turning pre mRNA to mRNA - the mRNA then moves out of the nucleus via a nuclear pore and to the ribosomes
what is translation
making proteins from mRNA in ribosomes (found in the cytoplasm or on the rough ER)
explain the process of translation
mRNA attaches to a ribosome
tRNA anticodon attaches to codon on mRNA
ribosome catalyse condensation reactions between animo acids on tRNA
forming peptide bonds
process continues
until stop codon is reached on mRNA
then the polypeptide + mRNA is released
what is the role of ATP in translation
the hydrolysis of ATP provides energy to form peptide bonds between amino acids
state 2 characteristics of the genetic code
it is non-overlapping -> meaning each triplet is only read once
it is degenerative -> meaning many triplets code for the same amino acid (64 possible triplets for only 20 amino acids)
what is a DNA triplet
a sequence of 3 bases that codes for a particular amino acid
what is a start codon
a triplet on mRNA that initiates the translation of the polypeptide
what is a stop codon
a triplet on mRNA that terminates translation of the polypeptide
what are exons
coding regions of DNA
what are introns
non-coding regions of DNA
what is a gene mutation
any change in the base sequence of DNA
often arises spontaneously during replication
what can increase the risk of mutations
mutagens e.g. chemicals, radiation
name the types of mutations
substitution, deletion, insertion + point
explain a substitution mutation
a base from each strand is replaced with another
(if the new codon codes for the same amino acid)
it is likely to be silent
causing no change to the amino acid sequence
explain a deletion mutation
a base is lost from each strand
causing a frame shift
entire sequence past the point of the mutation will be different
meaning the mutation is likely to be significant
explain a insertion mutation
one or more bases is added to each strand
causing frame shift
entire sequence past the point of the mutation will be different
meaning the mutation is likely to be significant
explain the causes and effects of sickle cell anaemia
caused by a substitution in the gene that codes for haemoglobin
change in the primary structure
meaning a different tertiary
resulting in abnormal haemoglobin molecules
makes RBCs sickle shaped
impairing their ability to transport oxygen
causing a rapid heartbeat, fatigue + dizziness
RBCs can also get stuck in vessels
this is called sickle crisis
causing tissue damage + severe pain
describe the structure of enzymes
globular proteins
tertiary structure determines shape of active site
complementary to a specific substrate
explain the function of enzymes
act as biological catalysts
the formation of enzyme-substrate complexes
lowers the activation energy
of metabolic reactions
explain the induced fit model
a theory that suggests the shape of enzymes active site is NOT directly complementary to the substrate
instead
conformation change (a change in tertiary structure as a response to external factors e.g. temp, pH)
enables enzyme-substrate complexes to form
this puts strain on substrate bonds
lowering activation energy
name the factors affecting enzyme controlled reactions
temperature, pH, enzyme conc, substrate conc
how does temperature effect enzyme reactions
as temperature increases
kinetic energy increases
rate of reaction increases
above optimum
H + ionic bonds in tertiary structure break
denaturing the active site
how does pH effect enzyme reactions
narrow optimum pH range
outside ranges
(H+ if too acidic or hydroxide if too alkaline) interact with H + ionic bonds in tertiary structure
denaturing the active site
how does enzyme concentration effect enzyme reactions
ADJUST
when substrate is in excess
the rate increases proportionally to the enzyme conc
max number of complexes forming at a given time= rate levels off
how does substrate concentration effect enzyme reactions
ADJUST
when enzyme is in excess
the rate increases proportion to the substrate conc
what are the types of inhibitors
competitive, non-competitive + end-product
what are competitive inhibitors
they have a similar shape as the substrate
therefore bind to active sites
temporarily preventing enzyme-substrate complexes from forming
until released
increasing substrate conc = decreases their effect
what are non-competitive inhibitors
they bind at the allosteric binding sites
triggering conformational change of actives sites
increasing substrate conc = no impact on their effect
what is end-product inhibition
when the product of a reaction acts as a competitive or non-competitive inhibitor for an enzyme involved in the pathway
preventing further formation of the products
how do you calculate the rate of enzyme activity from a graph
use the initial rate
so the gradient at 0s
why do we calculate the initial rate of a reaction
its the only point where the concentration of both enzymes and substrates is known
allowing for comparisons
neither are limiting factors affecting the rate yet
name the ions found in plants
nitrate, calcium, magnesium + phosphate
describe the role of nitrate ions
to make amino acids and DNA
describe the role of calcium ions
to make calcium pectate for the middle lamellae
describe the role of magnesium ions
to make chlorophyll
describe the role of phosphate ions
to make ATP and ADP
explain what is meant by the dipole nature of water
O is more electronegative
so it attracts more electrons in the covalent bond
H bonds form between other dipolar water molecules
state the 5 important properties of water
high specific heat capacity
polar solvant
high surface tension
incompressibility
maximum density at 4C
what is the importance of water having a high specific heat capacity
it acts as a temperature buffer
enabling endotherms to resist fluctuations in their body temperature
maintaining optimum enzyme activity
what is the importance of water being a polar solvent
means it is able to dissolve and transport ions in bodily reactions
what is the importance of water having a high surface tension
slows water loss via transpiration in plants
water rises unusually high in narrow tubes
lowering demand on root pressure
provides a habitat for insects who can skim across the surface of water
what is the importance of water being incompressible
it provides turgidity to plant cells
it provides a hydrostatic skeleton for some small organisms e.g. earthworm
what is the importance of water having a maximum density at 4C
ice is less dense than water
causing it to float
insulating water underneath in cold climates
allowing aquatic organisms to survive
