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a level biology > biological molecules > Flashcards

biological molecules Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

how are biological molecules evidence of evolution

A

all organisms share the same carbon based compounds which suggest animals and plants have a common ancestor

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2
Q

what is a polymer

A

a polomer is a large complex molecule made up of repeating units of monomers

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3
Q

what is a monomer

A

monomers are small basic molecular units that can from a polymer

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4
Q

how are polymers made

A

condensation reactions between monomers

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5
Q

how are polymers turned into monomers

A

hydrolysis reaction breaking the chemical bond using a water molecule

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6
Q

what are the three monosaccharides

A

glucose, fructose and galactose

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7
Q

what bond forms between monosaccharides

A

glycosidic bond

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8
Q

what are the three disaccharides and what are they made from

A

lactose - galactose and glucose
maltose- a-glucose
sucrose- glucose and fructose

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9
Q

how do you test for reducing sugars

A
  1. add benedicts solution
  2. heat solution in water bath to a boil
  3. blue to brick red
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10
Q

how do you test for non reducing sugars

A
  1. do the benedicts test and get a negative result
  2. add dilute hcl and heat to a boil
  3. add sodium hydrogencarbonate
  4. carry out benedicts again and should go blue to brick red
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11
Q

what is a polysaccharide

A

two or more monosaccharides are joined by condensation reactions to from glycosidic bonds

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12
Q

why is the structure of starch important to its function

A

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.

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12
Q

what is the structure of starch and what are the properties involved

A

startch is made up of two polysaccharides of alpha glucose amylose and amylopectin

amylose- long, unbranched , coiled due to glycosidic bonds

amylopectin- long , branched

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12
Q

what are the three polysaccharides

A

starch, glycogen and cellulose

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13
Q

what is the structure of glycogen

A

made up of alpha glucose and has lots of side branches

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14
Q

what is the structure of cellulose

A

long, unbranched chains of beta glucose in long straight chains linked togther by hydrogen bonds to from microfibrils

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14
Q

why is the structure of glycogen important to its function

A

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

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15
Q

why is the structure of cellulose important to its function

A

the stong microfibrils that are formed provides structural support for cells in cell walls

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16
Q

what is the test for starch

A

add iodine dissolved in potassium iodide and it should go from browny orange to dark blue

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17
Q

what are the two types of lipids

A

triglycerides and phospholipids

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18
Q

what is the structure of a triglyceride

A

has one molcule of glycerol with three fatty acids attatched to it

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19
Q

how are triglycerides formed

A

triglycerides are formed by condensation reactions and an ester bond is formed between the glycerol and fatty acid

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20
Q

what is the structure of phospholipids

A

they have one glycerol 2 fatty acids and a phosphate group

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20
Q

what are the properties of triglycerides that help its function

A

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

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21
Q

how does the structure of a phospholipid help with its function

A

phospholipids have hydrophobic tails and hydrophyllic heads so they from a bilayer in water and prevent water soluble substances passing through a membrane

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21
Q

what is the test for lipids

A

the emulsion test
1. shake the substance with ethanol for a minute
2. pour into water
3. a milky white emulsion will form

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22
Q

how are proteins made

A

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

23
Q

what is the primary structure of a protein

A

the sequence of amino acids in the polypeptide chain

24
Q

what is the secondary structure of a protein

A

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

25
Q

what is the tertiary structure of a protein

A

the coiled of folded chain of amino acids is coiled and folded further and hydrogen, ionic bonds form and disulfide bridges

26
Q

when do disulfide bridges form

A

Formed between 2 sulphur atoms on neighbouring R groups.

26
Q

what is the quaternary structure of a protein

A

polypeptide chains are assembled together to form the final 3D structure

27
Q

what is the structure/properties of an enzyme

A

usually roughly spherical due to tight folding in polypeptide chains

they are soluble and often have roles in metabolism

28
Q

what is the structure of anitbodies

A

made up of two short polypeptide chains and two long polypeptide chains bonded together.

28
Q

what is the protein structure of a channel protein

A

channel proteins contain hydrophillic and hydrophobic amino acids which cause the protein to fold up and form a channel for molecules to transport across

29
Q

what is the protein structure of a structural protein like

A

long polypepride chians lying parallel to each other with cross links between them.

30
Q

what is collagens protein structure like and how does it help with its function

A

three polypeptide chains tightly coiled together which makes it strong so it can be a good supportive tissue in animals

31
Q

what is the test for proteins

A

the biuret test
1. add NaOH
2. add copper (ii) sulphate solution
3. colour change from blue to lilac

32
Q

why are enzymes specific

A

their tertiary structure

33
Q

what is activation energy

A

the minimum amount of energy required for a reaction to start

33
Q

what are the 2 ways enzymes lower activation energy

A

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

34
Q

what is the induced fit model

A

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

35
Q

what would happen if the tertiary structure of an enzyme changed

A

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

36
Q

what can alter the tertiary structure of an enzyme

A

pH, temperature and mutation

37
Q

how can you measure enzyme activity

A

how fast the product is made

how fast the substrate is broken down

38
Q

how does tempertaure effect the rate of enzyme reactions

A

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

39
Q

how does pH effect the rate of enzyme reactions

A

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

40
Q

how does substrate concentrarion effect the rate of enzyme reactions

A

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

41
Q

how does enzyme concentration effect the rate of enzyme reactions

A

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

42
Q

what are teh two types of enzyme inhibitor

A

competitive and non competitive

43
Q

what do competitive inhibitors do

A

they bind to the avtive sit but no reaction takes place so they block the active site so no substrate molecules can bind

44
Q

what do non-competitive inhibitor do

A

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

45
Q

how do nucleotides join together
reaction?
between what?
bond name?

A

condenstation reactions between the phosphate group of one nucleotide and the sugar of another to from a phosphodiester bond

46
Q

what is the structure of DNA and how does it help with its function

A

double helic structure with polynucleotides
coiled up vert tightly so lots of genetic information in a small space

46
Q

what bond forms between bases and what bases pair up

A

hydrogen bonds from between them
A-T
G-C

47
Q

what is the structure of RNA like

A

single polynucleotide strand and shorter
has ribose sugar
uracil instead of thymine

47
Q

compare DNA and RNA

A

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

48
Q

what did meselson and stahl do

A
  1. 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
  2. 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
  3. 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
  4. the DNA settled out in the middle showing that the DNA moleucle contained a mixture of heavy and light nitrogen
49
Q

what reaction occurs when a cell needs energy from ATP and what is it catalysed by and what are the products

A

a hydrolysis reaction when a phospate bond is broken and energy is released catalysed by ATP hydrolase

ATP—> ADP + Pi

50
Q

what is phospholorolation

A

adding a inorganic phosphate to another compound to make it more reactive

51
Q

what happens in photosynthesis and respiration to ADP and Pi

A

they are resthynesised in a condensation reaction and is catalysed by the enzyme ATP synthase

52
Q

what are the 4 reasons why water is vital to living organisms

A

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

53
Q

what is the role of iron ions

A

iron ions are in haemoglobin and is what binds to the pxygen and becomes Fe3+ from Fe2+

54
Q

what is the role of hydrogen ions

A

control the pH of solutions so play a big role in enzyme reactions

55
Q

what is the role of sodium ions

A

are involved in the co-transport of amino acids and glucose

56
Q

what is the role of phosphate ions

A

in DNA and RNA and ATP
used in phosphorylation to make other compounds more reactive

a level biology (5 decks)

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