UNIT 1- Biological Molecules Flashcards
how are biological molecules evidence of evolution
all organisms share the same carbon based compounds which suggest animals and plants have a common ancestor
what is a polymer
a polomer is a large complex molecule made up of repeating units of monomers
what is a monomer
monomers are small basic molecular units that can from a polymer
how are polymers made
condensation reactions between monomers
how are polymers turned into monomers
hydrolysis reaction breaking the chemical bond using a water molecule
what are the three monosaccharides
glucose, fructose and galactose
what bond forms between monosaccharides
glycosidic bond
what are the three disaccharides and what are they made from
lactose - galactose and glucose
maltose- a-glucose
sucrose- glucose and fructose
how do you test for reducing sugars
- add benedicts solution
- heat solution in water bath to a boil
- blue to brick red
how do you test for non reducing sugars
- do the benedicts test and get a negative result
- add dilute hcl and heat to a boil
- add sodium hydrogencarbonate (NaHCO3)
- carry out benedicts again and should go blue to brick red
what is a polysaccharide
two or more monosaccharides are joined by condensation reactions to from glycosidic bonds
why is the structure of starch important to its function
amylose is coiled and long so it can store lots of energy in a small area
amlopectin is long and branched so enzymes can work on the branches quickly and glucose can be released quickly
starch is also insoluble which means it doesnt effect water potential so it doesnt cause water to enter plant cells and cause them to swell.
what is the structure of starch and what are the properties involved
startch is made up of two polysaccharides of alpha glucose amylose and amylopectin
amylose- long, unbranched , coiled due to glycosidic bonds
amylopectin- long , branched
what are the three polysaccharides
starch, glycogen and cellulose
what is the structure of glycogen
made up of alpha glucose and has lots of side branches
what is the structure of cellulose
long, unbranched chains of beta glucose in long straight chains linked togther by hydrogen bonds to from microfibrils
why is the structure of glycogen important to its function
bracnhes mean that stored glucose can be released quickly and its also very compact so can fit lots in a small space so not as heavy so animals dont have to carry lots of weight
why is the structure of cellulose important to its function
the stong microfibrils that are formed provides structural support for cells in cell walls
what is the test for starch
add iodine dissolved in potassium iodide and it should go from browny orange to dark blue
what are the two types of lipids
triglycerides and phospholipids
what is the structure of a triglyceride
has one molcule of glycerol with three fatty acids attatched to it
how are triglycerides formed
triglycerides are formed by condensation reactions and an ester bond is formed between the glycerol and fatty acid
what is the structure of phospholipids
they have one glycerol 2 fatty acids and a phosphate group
what are the properties of triglycerides that help its function
triglycerides are used as energy storage molecules and they have long hydrocarbon tails which contain a lot of energy in a small area
they are also insoluble so they dont affect water potential of the cell and cause water to enter the cells by osmosis
the triglycerides bundle together as insoluble droplets in cells because of the hydrophobic tails
how does the structure of a phospholipid help with its function
phospholipids have hydrophobic tails and hydrophyllic heads so they from a bilayer in water and prevent water soluble substances passing through a membrane
what is the test for lipids
the emulsion test
1. shake the substance with ethanol for a minute
2. pour into water
3. a milky white emulsion will form
how are proteins made
amino acids from a peptide bond to from a polypeptide chain in a condensation reaction which joins with another polypeptide chain to form a protein
what is the primary structure of a protein
the sequence of amino acids in the polypeptide chain
what is the secondary structure of a protein
hydrogen bonds from between the amino acids in the chain and this makes a coil into a-helix or a fold into a beta pleated sheet
what is the tertiary structure of a protein
the coiled of folded chain of amino acids is coiled and folded further and hydrogen, ionic bonds form and disulfide bridges
when do disulfide bridges form
Formed between 2 sulphur atoms on neighbouring R groups.
what is the quaternary structure of a protein
polypeptide chains are assembled together to form the final 3D structure
what is the structure/properties of an enzyme
usually roughly spherical due to tight folding in polypeptide chains
they are soluble and often have roles in metabolism
what is the structure of anitbodies
made up of two short polypeptide chains and two long polypeptide chains bonded together.
what is the protein structure of a channel protein
channel proteins contain hydrophillic and hydrophobic amino acids which cause the protein to fold up and form a channel for molecules to transport across
what is the protein structure of a structural protein like
long polypepride chians lying parallel to each other with cross links between them.
what is collagens protein structure like and how does it help with its function
three polypeptide chains tightly coiled together which makes it strong so it can be a good supportive tissue in animals
what is the test for proteins
the biuret test
1. add NaOH
2. add copper (ii) sulphate solution
3. colour change from blue to lilac
why are enzymes specific
their tertiary structure
what is activation energy
the minimum amount of energy required for a reaction to start
what are the 2 ways enzymes lower activation energy
If two substrate molecules need to be joined being attatched at the active site holding them close together it will reduce repulsion between molcules so they can bond more easily
If the enzyme is catalysing a breakdown rection fitting a substrate into an active site puts strain on bonds in the substrate so it breaks up more easily
what is the induced fit model
the substrate doesnt only have to be the right shape to fit the active site it has to make the active sit change shape in the rigth way as well
what would happen if the tertiary structure of an enzyme changed
the active site would change shape which means the substrate would no longer be complimentary so a substrate-enzyme complex will be formed so the enzyme cant do its function
what can alter the tertiary structure of an enzyme
pH, temperature and mutation
how can you measure enzyme activity
how fast the product is made
how fast the substrate is broken down
how does tempertaure effect the rate of enzyme reactions
a higher tempertaure measn more kinetic energy which means faster molecules which means more frequent collisons so more successful reactions
if the temperature gets too high the vibrations break some of the bonds so enzyme shape changes resulting in active site changing shape so substrate no longer fits
how does pH effect the rate of enzyme reactions
the OH- ions and H+ ions found in alkalis and acids can disrupt ionic bonds and hydrogen bonds that hold enzymes tertiary structure in place
how does substrate concentrarion effect the rate of enzyme reactions
the higher the conc. the faster the reactiion as there are moore substrate molecules so more collisions between enzymes and substrates
however when it reaches a saturation point when all of the enzymes active sites are occupied it makes no difference
how does enzyme concentration effect the rate of enzyme reactions
the more enzyme molecules the more likely a substrate is to collide with one and form an enzyme substrate complex
but if the amount of substrate is limited then there comes a point where theres more enzyme molcules that substrate so adding more nezyme has no further effect as the chance of it colliding with few of the substrate left is so low
what are teh two types of enzyme inhibitor
competitive and non competitive
what do competitive inhibitors do
they bind to the avtive sit but no reaction takes place so they block the active site so no substrate molecules can bind
what do non-competitive inhibitor do
bind to the enzyme at an allosteric site and it causes the active site to chnage shape so the substrate moleucles can no longer bind to it
how do nucleotides join together
reaction?
between what?
bond name?
condenstation reactions between the phosphate group of one nucleotide and the sugar of another to from a phosphodiester bond
what is the structure of DNA and how does it help with its function
double helic structure with polynucleotides
coiled up vert tightly so lots of genetic information in a small space
what bond forms between bases and what bases pair up
hydrogen bonds from between them
A-T
G-C
what is the structure of RNA like
single polynucleotide strand and shorter
has ribose sugar
uracil instead of thymine
compare DNA and RNA
DNA is double stranded and RNA is single
DNA has a deoxyribose sugar RNA has ribose sugar
DNA has the bases A,T,C,G RNA has A,U,C,G
DNA is longer RNA is relatively short
what did meselson and stahl do
- two samples of bacteria were groen frommant generations one in ligtht nitrogen and heavy nitrogen and as the bacteria reproduced they took up nitrogen gradually became part of the bacteria’s DNA
- a sample of DNA was taken from each batch of bacteria and spun in a centrifuge. the DNA from heavy nitrogen settled lower down the centrifuge then the DNA from light nitrogen bacteria because its heavier
- the bacteria grown in heavy nitrogen broth were taken out and put in light nitrogen. the bacteria were left for one round of DNA replication and then another sample was taken out and spun in the centrifuge
- the DNA settled out in the middle showing that the DNA moleucle contained a mixture of heavy and light nitrogen
what reaction occurs when a cell needs energy from ATP and what is it catalysed by and what are the products
a hydrolysis reaction when a phospate bond is broken and energy is released catalysed by ATP hydrolase
ATP—> ADP + Pi
what is phospholorolation
adding a inorganic phosphate to another compound to make it more reactive
what happens in photosynthesis and respiration to ADP and Pi
they are resthynesised in a condensation reaction and is catalysed by the enzyme ATP synthase
what are the 4 reasons why water is vital to living organisms
water is a metabolite in loads of important metabolic reactions like condensation and hydrolysis reactions
water is a good solvent because its polar which measn it can dissolve ions and transport them
water helps with temp control and it has a high latent heat of vapourisation and a high specific heat capacity
water molecules are very cohesive which helps water transport in plants
what is the role of iron ions
iron ions are in haemoglobin and is what binds to the pxygen and becomes Fe3+ from Fe2+
what is the role of hydrogen ions
control the pH of solutions so play a big role in enzyme reactions
what is the role of sodium ions
are involved in the co-transport of amino acids and glucose
what is the role of phosphate ions
in DNA and RNA and ATP
used in phosphorylation to make other compounds more reactive
