Biological Molecules Flashcards
what is a monomer?
a small, soluble molecule that can join to other similar monomers to make polymers
what is a polymer?
a large, insoluble molecule made of many similar, repeating monomers.
which monomers and polymers form carbohydrates?
monosaccharides and polysaccharides
which monomers and polymers form proteins?
amino acids and poly-peptides
which monomers and polymers form DNA/RNA?
nucleotides and polynucleotides
why are lipids not polymers?
not made of similar subunits, consist of both fatty acids and glycerol.
what is a condensation reaction?
one that joins 2 molecules together with he formation of a chemical bond involving the release of a water molecule.
what is a hydrolysis reaction?
one that breaks down a chemical bond between 2 molecules involving the use of a water molecule
side note lol DONT SAY BREAKS DOWN SAY HYDROLYSED
what are monosaccharides + name 3 + give their general formula
monosaccharides are monomers from which larger carbohydrates are made.
glucose, galactose, fructose
C6H1206 but little numbers
which bond does a condensation reaction between 2 monosaccharides form?
a glycosidic bond
draw an alpha glucose
which elements are found in carbohydrates?
carbon, hydrogen, oxygen
what are 2 other names for glucose?
a 6-carbon/ hexose sugar
draw a beta glucose
what is an isomer?
a molecule that has the same general formula but different structural formula.
what is a disaccharide + name 3 with combinations + general formula
formed by the condensation of 2 monomers.
glucose + glucose = maltose
glucose + galactose = lactose
glucose + fructose = sucrose
C12H22O11 + H20
how does a condensation reaction to form a disaccharide work?
the reaction occurs between the OH groups on carbon 4 of one monosaccharide and carbon 1 on the other, forming a 1,4 glycosydic bond
forms an H20 molecule
forms a glycosydic bond
results in a disaccharide
draw a diagram of a condensation reaction:
side note lol ADD THE H20 MOLECULE OR ELSE
when and why are disaccharides hydrolysed into monosaccharides?
in digestion
so they can be absorbed and assimilated (used) for processes e.g. respiration
draw a hydrolysis reaction
how does a hydrolysis reaction work?
the disaccaharide is hydrolysed to give 2 monosaccharides
a molecule of H20 is required
the glycosidic bond is broken
what is a polysaccharide?
polysaccharides are formed by the condensation of many monosaccharide units
name 3 polysaccharides, which type of glucose they are made from, and where they are used
starch- alpha glucose- storage in plants for carbohydrates
cellulose- beta glucose- plant cell wall
glycogen- alpha glucose- storage in animals as glucose, to be used in respiration
draw how 3 molecules of alpha glucose would form starch/ glycogen
draw how 3 beta glucose molecules would form cellulose
name starch properties and how the properties relate to its function
insoluble- doesn’t affect the cell’s water potential, therefore doesn’t affect osmosis
coiled into a helix- compact so many can fit in a small space for storage
1,4 and 1,6 glycosidic bonds- allows branching to occur
branched- provides many ends for rapid hydrolysis by enzymes to form an alpha glucose for respiration
large- wont diffuse out of the cell
name glycogen properties and how they relate to the function
insoluble- doesn’t affect osmosis
coiled into a helix- compact so many can fit into a small space for storage
1,4 and 1,6 glycosidic bonds- allows branching
very highly branched with shorter chains- more ends for rapid hydrolysis by enzymes to form alpha glucose for use in respiration
large- won’t diffuse out of the cell
name cellulose properties and how they relate to its function
only 1,4 glycosidic bonds- allows long, straight, unbranched chains of beta glucose
long,straight, unbranched chains of glucose- allows formation of many hydrogen bonds, so microfibrils are created
many microfibrils- allows formation of cellulose fibres
cellulose fibres and many hydrogen bonds- provides strength to cell wall
which 5 sugars are reducing?
glucose, galactose, lactose, fructose, maltose
which sugar is non-reducing?
sucrose
what is the benedict’s test for reducing sugars?
1) add benedict’s solution to sample and heat to 95 degrees
2) colour change from blue to red precipitate indicates reducing sugar
3) if there’s no change, a non-reducing sugar could be present
the other colours can be used as a qualitative test on the concentration of the sugar- green = low, red = high.
if you want a quantitative measure, you could remove the liquid and measure the mass of the precipitate
what is the benedicts test for non-reducing sugar?
1) add benedict’s solution to sample and heat to 95 degrees, if there’s no colour change in the test for reducing sugar, boil a fresh sample with dilute HCl for a few minutes to hydrolyse the glycosidic bonds.
2) neutralise by adding sodium hydrogen carbonate
3) add benedict’s reagant and heat to 95 degrees
4) as the sucrose has been hydrolysed to glucose and fructose, there will be a red precipitate and a colour change from blue to red.
what is the test for starch?
1) add iodine to potassium iodide solution to your sample
2) a colour change from orange to blue/black indicates starch
what are the 2 groups of lipids and where are they found?
triglycerides- found in food and used for energy storage
phospholipids- help to form cell membranes
how are triglycerides formed?
by the condensation of one molecule of glyerol and 3 fatty acid molecules (not a polymer)
which elements do triglycerides contain?
carbon, hydrogen and oxygen
which type of bond forms between a glycerol and a fatty acid (RCOOH)?
an ester bond (so there are 3 ester bonds in a triglyceride)
draw the structure of a glycerol molecule
fatty acids consist of a hydro______ c_____ and a carbo_______ ____ group
fatty acids consist of a hydrocarbon chain and a carboxylic acid group
R = hydrocarbon chain
COOH = carboxyl group
whole fatty acid = RCOOH
what is a saturated fatty acid?
all the bonds between the carbon atoms in the hydrocarbon chain are single bonds
what is an unsaturated fatty acid?
at least one of the bonds between the carbon atoms in the hydrocarbon chain are double bonds
draw 2 ways a fatty acid can be represented
RCOOH
or
O
II
HO—-C—-R
draw how 3 molecules of fatty acid join to a molecule of glycerol
for every triglyceride molecule, 3 water molecules are produced
fatty acid tails are hydrophobic, what does this mean?
they repel water, this is what makes lipids insoluble in water and means they form insoluble droplets.
the fatty acid tails face inwards, shielding themselves with the glycerol heads
how many fatty acids do phospholipids have, and if not 3, what are they replaced by?
2 fatty acids, one is replaced by a phosphate group
why is the phosphate head in phospholipids hydrophilic, and the fatty acid tails are hydrophobic?
the phosphate group is negatively charged (polar) and the fatty acid tails are non-polar, meaning that the phosphate head attracts water because they are oppositely charged, and the fatty acid tails repel it
how do phospholipids form a bilayer in water?
the fatty acid tails are arranged in the middle away from water and the hydrophilic heads are arranged on the outside in contact with water
the phospholipid bilayer forms the basis of cell membrane surface + organelle membranes
draw how phospholipids are arranged in a bilayer
name the properties of a triglyceride, and why it’s useful
long, hydrocarbon fatty acid chains- contains a lot of stored chemical energy- used as an energy storage molecule
hydrophobic fatty acid tails- doesn’t affect the water potential of a cell- won’t dissolve and release stored energy in water
name the properties of a phospholipid and why it’s useful
hydrophobic fatty acid tails and hydrophilic phosphate heads- forms a phospholipid bilayer with hydrophilic phosphate heads pointing towards the water and hydrophobic fatty acid tails pointing away- forms cell membranes, this means water soluble molecules can’t pass easily across the membrane
name 2 other uses for lipids apart from storage and membranes
certain hormones (eg testosterone)
respiratory substances
what elements do all proteins contain?
nitrogen, carbon, hydrogen, oxygen
what element do some proteins contain?
sulfur
name roles of proteins in the body
haemoglobin- transports oxygen
antibodies- defend against infection
enzymes- biological catalysts
actin and myosin- muscle contraction
keratin- nails and hooves
collagen- tendons
draw the general structure of an amino acid + label the amine group, carboxyl group and R group (a carbon-containing side chain)
draw a diagram of a dipeptide being formed
draw a sketch of the induced fit model
in this model the active site isn’t fully fixed, the substrate induces a change in shape of the active site making it complementary
explain the effect of substrate concentration on enzymes
the rate of reaction is low at low substrate concentrations as not all active sites are saturated (filled)- the substrate is a limiting factor
as substrate concentration increases, the active sites are filled and the rate of reaction increases, due to more successful collisions between enzyme active sites and substrates so more E-S complexes form per second- the substrate is no longer a limiting factor
at high substrate concentrations, there is no further rise in rate for reaction since the enzymes can’t form any more E-S complexes as all active sites are saturated- enzyme concentration is now the limiting factor
explain the effect of enzyme concentration on enzymes
the more enzyme molecules there are in a solution, the more likely they are to collide with a substrate with sufficient energy to form an E-S complex
as a result, increasing the enzyme concentration increases the rate of reaction
however, if the amount of substrate becomes limiting, increasing enzyme concentration will have no effect on the rate of reaction
draw a graph showing the curves of a normal enzyme and competitive inhibitor graph with substrate concentration on the x-axis and rate of reaction on the y-axis + explain it
the competitive inhibitor curve will reach the almost same max rate of reaction as the normal curve, just slower- some of the active sites are occupied by the inhibitor, as substrate concentration increases, there will be less inhibition of the active sites so more substrates can bind to the active site, meaning max rate is almost reached
draw a graph showing the curves of a normal enzyme and non-competitive inhibitor graph with substrate concentration on the x-axis and rate of reaction on the y-axis + explain it
the line initially increases because there are some active sites unaltered by the inhibitor. the inhibitor changes the shape of the active site so the substrate is no longer complementary and e-s complexes can’t form, so even when substrate concentration increases, the rate never reaches the maximum and the line plateaus
draw and label a DNA nucleotide
always say deoxyribose sugar instead of just sugar
draw and label an RNA nucleotide
always say ribose sugar instead of just sugar
draw the formation of a dinucleotide
what is the structure of an rna molecule?
a relatively short linear polynucleotide chain, normally single-stranded
why is it important that the 2 polynucleotide chains in dna are antiparallel?
because it ensures only 1 strand is read to make proteins, and in dna replication, the dna polymerase only has a complementary active site to the 3’ end of the molecule (it is labelled with a 5’ end and a 3’ end)
why is semi-conservative dna replication important?
it ensures genetic continuity between generations of cells
what was the experiment meselson and stahl did to prove semi-conservative theory?
they grew e.coli on a medium with the heavy isotope of 15N, as the bases are nitrogenous. the nitrogen atoms the bacteria used to make the new dna would all be of 15N kind (generation 0).
the dna made from the 15N kind was extracted and centrifuged in a test tube (heavier molecules went to the bottom)
the bacteria were then transefrred to a medium with normal 14N and after the bacteria divided once in 14N, the dna was taken and centrifuged (generation 1).
so on so forth
they were right as semi-conservative replication meant the new dna would have a mix of the og and a new strand of the new nitrogen
draw the structure of atp
adenine, ribose, 3 phosphate groups
draw a diagram showing the condensation and hydrolysis of atp
how is a water molecule polar (opposite charges at either end)?
the oxygen atom is slightly negative and the hydrogen atoms are slightly positive
