Biological Molecules Flashcards
what are carbohydrates made from?
carbon
hydrogen
oxygen
Types of simple carbohydrates?
monosaccharides
disaccharides
type of complex carbohydrates?
polysacharrides
examples of monosaccharides and their chemical formula?
glucose C6H12O6
fructose C6H12O6
galactose C6H12O6
ribose C5H10O5
triose C3H6O3
monosaccharides equation
Cn H2n On
disaccharides formula
C12 H22 O11
what are isomers?
molecules with the same formula but different structures
what is a Glycosidic bond?
a bond formed between two monosaccharides.
what are the importance of monosaccharides:
sources of energy (glucose)
able to be transported in solution in animals (as glucose in blood)
the equation fro the production of maltose
GLUCOSE + GLUCOSE -. MALTOSE (malt sugar) + WATER
the equation fro the production of sucrose
GLUCOSE + FRUCTOSE SUCROSE (cane sugar) + WATER
the equation fro the production of lactose?
GLUCOSE + GALACTOSE LACTOSE (milk sugar) + WATER
how are Disaccharides formed?
Monosaccharides join together in condensation reactions. A glycosidic bond between them forms and water is removed.
what happens to disaccharides in the presence of water?
they are hydrolysed into monosaccharide monomers. Within cells, these reactions are catalysed by specific enzymes.
what is a Condensation reaction?
joins two molecules together with the formation of a chemical bond and involves the elimination of a water molecule
what are Polysaccharides?
polymers formed by combining monosaccharides together, by glycosidic during condensation reactions. They’re large, insoluble molecules ,suitable as storage
Examples of polysaccharides
- Starch
- Cellulose
- Glycogen
how is starch formed?
joining 200 – 100000 α glucose molecules by glycosidic bonds in a series of condensation reactions.
what are the 2 components of starch
- amylose
- amylopectin
amylose structure?
long , unbranched chain ,that is tightly coiled allowing lots of glucose to be sorted in small place (compact)
amylopectin structure?
branched polymer which increases surface area for enzymes to release sugars for respiration
what does amylase digest?
amylose
amylopectin
The main role of starch is energy storage, something its structure is especially suited for:
- insoluble – doesn’t affect water potential
- large & insoluble – doesn’t diffuse out of cells.
- COMPACT – lots can be stored in a small space.
- Branched form so glucose monomers are released rapidly
is starch found in animal cells?
NEVER found in animal cells. Another polysaccharide serves the same role, called glycogen.
glycogen structure
shorter chains and highly branched. this allows more sugar to be released quickly. its storage in animals, stored as small granules, in muscles & liver
how does the structure of glycogen lead to its function?
branched - increases surface area for rapid hydrolysis back to glucose
insoluble - wont affect water potential
why is cellulose different from starch and glycogen?
it is formed from β glucose molecules, rather than α glucose molecules.
what is the structure of cellulose?
straight, unbranched chains, inverted to another, are called micro fibrils. hydrogen bonds form cross-links between chains giving strength and rigidity
cellulose use in plants?
cellulose cell wall prevents the cell from bursting as water enters by osmosis. It exerts inward pressure that stops water. stems & leaves turgid to increase surface area for photosynthesis.
what is a Hydrolysis reaction?
breaks a chemical bond between 2 molecules & involves the use of a water molecule.
what are starch and glycogen cellulose polymers of
Starch & glycogen are polymers of α-glucose & cellulose is a polymer of β-glucose.
what is hydrogen bonding
electrons within a molecule aren’t evenly distributed, but tend to spend more time at one position. This region is more negatively charged than the rest of the molecule
testing for carbohydrates?
- crush / grind the solid and mix strongly with water
- add benedicts reagent
- heat / boil (<80)
- result is a colour change from blue to brick red
quantitative benedicts test result?
green - low conc
yellow - medium conc
brick red - high conc
what test is for non reducing sugars (e.g. sucrose)
- use a fresh sample
- add HCL (still crush and mix)
- boil , this will hydrolyze sucrose into glucose & fructose
- add sodium hydrogen carbonate to neutralize (cant do Benedicts Test in an acidic solution)
- repeat benedicts test,+ results indicates sucrose in og solution
starch
monomers?
bonds between them?
alpha glucose
1-4 glycosidic bonds in amylose
1-4 & 1-6 in amylopectin
starch structure?
made of 2 polymers
amylose - unbranched helix
amylopectin - branched molecule
starch function?
location?
store of glucose
plant cells (e.g. chloroplast)
cellulose
monomers?
bond between them?
beta glucose
1-4 glycosidic bonds
Making dilutions equation
C1 V1 = C2 V2
What test tests for lipids?
The emulsion test
How do you carry out the emulsion test?
1) dissolve the sample in ethanol (its another non-polar substance)
2) mix well/strongly
3)add water, mix again
4) the presences of a milky emulsion shows that lipids are present
What is a triglyceride?
Type of lipid that consists of 3 fatty acid tails connected to glycerol.
It has an ester bond by a condensation reaction that occurs 3 times to make it
What is the difference between saturated and unsaturated
Unsaturated is a carbon- carbon double bond
What is a phospholipid?
Are found in plasma membranes. They form a bilayer, as long as there is an aqueous solution on either side
Contains phosphate, glycerol and 2x fatty acid tails
What is a nucleus acid?
Are information carrying molecules. They are all polymers of nucleotides
What is a DNA’s Pentose sugar and what are there bases?
It’s pentose sugar is deoxyribose
The bases are: adenine, cytosine, thymine and guanine
What is a RNA’s Pentose sugar and what are there bases?
The sugar is ribose
The bases are adenine, uracil , cytosine and guanine
Other differences in DNA vs RNA are:
- dna is a double helix, stable and a long molecule
- RNA is a single stranded, unstable, shorter molecule
What forms can RNA be found as:
- mRNA - used in protein synthesis
- tRNA - involved in protein synthesis
- rRNA - part of ribosomes
What bonds are in polymerisation?
- phosphodiester bonds , formed by condensation reaction
- hydrogen bonds, between complementary base pairs A-T C-G
what enables accurate replication of the DNA molecule?
double helix structure of Dna and the complementary base pairing
what is semi-conservative replication
in each of the 2 new DNA molecules, one of the polynucleotides strands is from the original molecule, and the other is a new one
what are the stages of semi-conservative replication
- DNA helicase breaks the hydrogen bonds between polynucleotide strands, unwinding the double helix
- this exposes the bases on nucleotides to bind to their complementary bases
- DNA polymerase joins these new nucleotides together with phosphodiester bonds, from in the new nucleotide strand from each og template
meselson and stahl experimetn
- agar in a Petri dish with 14. had another with N15
- grew bacteria for a couple of generations on these dishes
- took a sample of bacteria from each & spun it in a centrifuge tube
- N14- high band indicating it was light DNA. N15- had a low band, heavier DNA
- took some bacteria from N15 and grew it on a new petri dish with N14
- grew for 1 generation, made one bit of DNa
- ended up with heavy DNa. found that when it replicated the DNa had 1 og strand and 1 heavy strand
- they found this out by spinning the sample in the centrifuge- band was in the middle
test fro proteins
biuret reagent being added to the sample
a color change from blue to purple is positive
what is the monomer of a polypeptide
amino acid
how many levels are there to a proteins structure
4
what is the primary structure of a protein
the sequence of amino acids
what is the secondary structure of a protein
where it forms localized hydrogen bonds between amino acids. this forms two characteristic shapes
- alpha helix
- beta pleated sheet
what is the tertiary structure of a protein
the 3 dimensional folding involving hydrogen and ionic bonds, and disulphide bridges (interactions across the whole polypeptide). this gives the polypeptides its specific shape
what is the quaternary structure of a protein
this is where a protein consists of two or more polypeptide chains
do all proteins denature
yes
when does denaturation occur
when hydrogen bonds and ionic bonds are broken, changing the tertiary structure of the protein. it is permanent
what are enzymes made of
proteins
what are enzymes
globular proteins that act as biological catalysts. this means that they speed up the rate of chemical reactions, by reducing the activation energy, but aren’t used up in the reaction
what is the induced fit theory
the enzyme and substrate are almost complementary but when the substrate enters the active site, interactions between the substrate and amino acids cause the shape of the active site to change a little to become complementary to the substrate
what are enzyme reactions affected by?
- temperature
- pH
- concentration
effect of temperature on enzyme reactions?
1st stage
as the temp increases so does the kinetic energy, so there are more successful collisions between the enzyme & substrate
effect of temperature on enzyme reactions?
2nd stage
optimum temperature
effect of temperature on enzyme reactions?
3rd stage
the enzyme denatures so the hydrogen and ionic bonds arte broken which changes the tertiary structure of the active site, and the substrate is no longer complimentary
effect of pH on enzyme reactions?
either side of the optimum ph., the enzyme denatures, because the hydrogen and ionic bonds break, changing the tertiary structure of the active site, and the substrate so its no longer complimentary
effect of concentration on enzyme reactions?
1st stage
as you increase the substrate concentration you increase the rate of reaction as there are more successful collisions so the substrate concentration is limiting
effect of conc. on enzyme reactions?
2nd stage
the substrate concentration is no longer limiting as increasing it does not increase the rate of reaction. enzyme concentration may be limiting as all active sites may be in use
what are the two types of enzyme inhibitors?
- competitive inhibitors
- non competitive inhibitors
what are competitive inhibitors
similar shape to the substrate, so they can fit into the enzymes active site temporarily. this means they block access for the substrate
do competitive inhibitors form an enzyme substrate complex?
no, as they are only temporary
what are non competitive inhibitors
an inhibitor that are complementary to an allosteric site on the enzyme
how do non competitive inhibitors work?
when the non competitive inhibitor binds it changes the tertiary structure of the active site so it is no longer complementary to the substrate. this effect is temporary as the inhibitor is only attached temporarily (however there are some exceptions)
does the enzyme become denatured when the non competitive inhibitor binds to it
the enzyme does not become denatured, as denaturation is permanent and this is only temporary
what is chromatography?
separates molecules e.g. amino acids, according to their solubility in a solvent
if a chemical is very soluble where will it travel?
it will travel further up the paper
how to work out the RF value
a / b
how do you make a concentrated sample for chromatography?
add a drop of solution to the origin line allow it to dry and repeat to concentrate the sample
what are exopeptidases
exopeptidases hydrolyze peptide bonds at the ends of polypeptides releasing either: amino acids or a dipeptide
what are endopeptidases?
endopeptidases hydrolyze peptide bonds within a polypeptide, giving a larger surface area fro exopeptidase to function
What is ATP and what does it contain?
ATP is a nucleotide derivative, used as a short term energy store
It contains: adenine, ribose, 3x phosphate groups
What hydrolyses ATP
The enzyme ATP hydrolase will hydrolyse the bend between phosphates 2 and 3 leaving adenosine diphosphate (ADP) and Pi (phosphate)
What happens during the hydrolysis of ATP
The reaction releases lots of energy that can be used n other reactions within cells. The Pi can be used to phosphorylase other compounds as well.
What happens during respiration and photosynthesis?
ATP synthase can remake ATP by the condensation of ADP + Pi
What are inorganic ions
Can occur in a solution throughout the body of organisms. They are charged atoms or group of atoms
structure of a water molecule
the oxygen is slightly negative and the hydrogen is slightly positive. This makes it polar
for this reason you get weak hydrogen bonds forming between water molecules
properties of a water molecule
- its a metabolite
- good solvent
- relatively high heat capacity
- relatively high latent heat of vaporization
- cohesive
why is water a metabolite
used in hydrolysis and made in condensations reactions
why is water a good solvent
polar substances dissolve easily in water. it allows gases, enzymes, waste products e.g. ammonia & urea, to diffuse
why does water have relatively high heat capacity
it takes a lot of energy to raise the temperature of water. it can act as a buffer
- help’s with homeostasis - keeps constant body temperature
- supports aquatic organisms
why does water have a relatively large latent heat of vaporization
it takes a lot of energy to turn liquid water into water vapour. due to lots of weak hydrogen bonds
- its important for sweating and as a mechanism for temperature regulation
why is water cohesive
the hydrogen bonds that form between water molecules allows transpiration in plants, it also provides surface tension (which is important for organisms that live under water). it supports columns of water
The importance of H+ ion
The higher the conc of H+ the lower the ph, enzyme reactions wryly on the maintenance of ph levels
The importance of iron ion
Found in haemoglobin, the iron binds to the oxygen to allow transportation around the body
The importance of sodium ion
Used in co-transport of both glucose and amino acids
The importance of phosphate ion
Found in nucleotides and ATP
Have a same number and type of amino acids, but different tertiary structures. Explain why
- hydrogen an ionic bonds form in different places
- Different sequence of amino acids
What is the monomer?
Repeating units which larger molecules are made from
triglyceride structure related to their properties
- lots of energy storing carbon-hydrogen bonds so they are an energy store
- low mass to energy ratio, lots of energy being stored in small volume. animals have less mass to move around
-large, non-polar lipids are insoluble so storage doesn’t affect water potential - release water when oxidised so are a water source for organism
what happens when phospholipids come into contact with water
form micelles
phospholipids structure related to their properties
- aq environment means a bilayer is formed
- form glycolipids with carbs on the cell surface membrane for cell recognition
what is a buffer solution?
maintains an approximately constant pH, despite dilution or addition of small amounts of acid or base.
