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AQA A Level biology > biological molecules > Flashcards

biological molecules Flashcards

(61 cards)

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1
Q

what 3 elements make up carbohydrates?

A

carbon, hydrogen and oxygen

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2
Q

what 3 structures do carbohydrates exist in?

A

monosaccharides, disaccharides and polysaccharides.

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3
Q

monosaccharides

A

small chain molecules, soluble

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4
Q

examples of monosaccharides

A

glucose, galactose and fructose

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5
Q

disaccharides

A

2 monosaccharides

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6
Q

3 types of disaccharides

A

maltose (2 glucose)
sucrose (glucose + fructose)
lactose (glucose + galactose)

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7
Q

what are polysaccharides?

A

they are polymer containing many monosaccharides linked by glyosidic bonds.

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8
Q

features of glucose

A

it is a hexose (6 carbon) sugar.

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9
Q

formula of glucose

A

C6H12O6

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10
Q

are monosaccharides reducing sugars?

A

Yes, they all are, as they can donate an electron to another chemical.

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11
Q

what happens when a reducing sugar is in water?

A

the ring open up to display a free ketone or aldehyde group, this donates an electron and thus reduces the Benedict’s solution.

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12
Q

what is a condensation reaction?

A

joining of molecules to form chemical bonds, excluding water
it allows the formation of disaccharide molecules and eventually polysaccharide molecules.

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13
Q

how are polysaccharides formed?

A

through a condensation reaction

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14
Q

what are polysaccharides used for?

A

used as energy stores and as structural components of cells.

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15
Q

examples of polysaccharides

A

starch and cellulose in plants, and glycogen in animals.

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16
Q

features of starch

A

found in plants
helical structure
compact, can be hydrolysed back into alpha glucose for respiration
insoluble, cannot effect water potential

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17
Q

starch test

A

add iodine, if present turns blue-black

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18
Q

feature of glycogen

A

highly branched with 1-4 and 1-6 glycosidic bonds
broken down for respiration, storage molecule
animal cells, polymer of alpha glucose

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19
Q

features of cellulose

A

polymer of beta glucose
hydroxyl groups can form hydrogen bonds with other molecules
forms fibrils, provides strength for plant cell walls
straight chained 1-4 glycosidic hydrogen bonds

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20
Q

Benedict’s test for reducing sugars

A

reducing sugars= monosaccharides
1. test tube, add blue Benedict’s reagent, heat
2. reducing sugar goes brick red, negative stays blue
3. add Hal, boil to hydrolyse non-reducing sugar, add sodium hydrogen carbonate, do Benedict’s test again, positive result= non-reducing sugar

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21
Q

features of lipids

A

main functions= insulation, energy storage, protection

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22
Q

types of lipids

A

triglycerides (known as true fats or natural fats) and also waxes, steroids and cholesterol.

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23
Q

test for lipids

A

dissolve sample with ethanol
add water
lipid present= cloudy white emulsion

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24
Q

features of triglycerides

A

condensation of 3 fatty acids + 1 glycerol (forms ester bonds)
high ratio of C-H to C-C bonds= energy storage
metabolic water source (high ratio H-O atoms)
insoluble, no affect of water potential
low mass

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25
features of phospholipids
1 fatty acids by a phosphate containing group polar molecule phosphate continuing group is hydrophilic due to negative charge fatty acid chain= hydrophobic form a bilayer to polar ends (membrane)
26
what is glycerol made up of?
three carbon atom, each has a hydroxyl group (OH) attached to it, hydrogen atoms occupy the remaining positions.
27
types of fatty acids
saturated, mono-saturated and polyunsaturated.
28
saturated fatty acids have?
no double bond between carbon atoms
29
mono-saturated fatty acids have?
one double bond between carbon atoms
30
polyunsaturated fatty acids have?
more than one double bond between carbon atoms, causes the molecule to bend and they can therefore pack together so closely, making them liquid at room temperature (oils).
31
features of amino acids
monomers from which proteins are made
32
what does a condensation reaction between 2 amino acid make?
dipeptide
33
what do many amino acids form?
polypeptide
34
features of protein structure
primary= sequence of amino acids secondary= folding of sequence of amino acids into a-helices or b-pleated sheets, hydrogen bonds hold them together tertiary= helices of sheets fold to form specific 3D structure quaternary= more than 1 polypeptide chain, can bind to a prosthetic/ non-protein group.
35
Biuret test
add Biuret reagent to sample positive= purple precipitate negative= solution remains blue
36
features of enzymes
are proteins catalyse reactions by lowering activation energy
37
induced fit model
substrate not complementary to active site induces complementary change to active site substrate binds forming enzyme-substrate complex
38
enzyme specificity
tertiary structure of active sit is extremely specific only complementary substrates can bind to active site to form complex
39
effect of temp on enzyme activity
incr. slowly then rapidly, molecules gain kinetic energy optimum temp at peak after, rate decreases, enzyme denatures as H bonds broken changes tertiary structure of active site
40
effect go pH on enzyme activity
similar trend to temp imbalance of H+ and OH- ions can disrupt tertiary structure
41
effect on enzyme conc.
ready incr. then amount of substrates becomes limiting factor
42
effect of substrate conc.
steady incr. then amount of active sites becomes limiting factor
43
features of competitive enzyme inhibition
competitive inhibitor (structurally similar to normal substrate), can also bind bad as normal substrate cannot so no complex formed incr. in substrate conc. helps decrease effect of competitive inhibition
44
features of non-competitive enzyme inhibition
enzymes can have other sites (allosteric), non-competitive bind here causes tertiary structure of active site to change permanently substrate no longer complementary, cannot bind, no complex formed
45
what is DNA
deoxyribonucleic acid holds genetic info 2 polynucleotide chains (double helix)
46
what is RNA
ribonucleic acid transfers genetic info from DNA to ribosomes 1 short polynucleotide chain (single helix)
47
nucleotide structure
DNA + RNA are polymers of nucleotides so POLYNUCLEOTIDES have a phosphate group, pentose and nitrogenous base
48
DNA bases
adenine, thymine, guanine, cytosine
49
RNA bases
adenine, racism guanine, cytosine
50
condensation of 2 nucleotides makes...
dinucleotide
51
what is semi-conservative DNA replication
one strand comes from original DNA (acts as template), other from newly synthesised strand ensures genetic continuity between generations of cells
52
steps of semi-conservative replication
1. DNA helices unwinds the double helix by breaking hydrogen bonds between complementary bases on the polynucleotide strand, forming 2 template strands 2. new DNA nucleotides are attracted to exposed bases on template strands and base pairing occurs 3. DNA polymerase joins adjacent nucleotides 5' to 3' to form phosphodiester bonds
53
evidence for semi-conservative replication
Meselson Stahl experiment= 2 test tubes with E-coli, one with 14N, other with 15N let DNA grow from this then added together to grow for one generation took 3 test tubes; 14N, 15N, 14+15N, spun in centrifuge shows both sets of DNA were incorporated
54
structure of ATP
nucleotide derivative
55
ATP hydrolysis and synthesis is...
reversible hydrolysis= ADP +Pi synthesis is ADP + Pi= ATP
56
the forwards reaction of ATP is...
catalysed by ATP hydrolase uses water to break off a phosphate
57
the backwards reaction of ATP is...
a condensation reaction catalysed by ATP synthase
58
Pi can...
phosphorylate other compounds to make them more reactive
59
properties of ATP
releases small amounts of energy at a time cannot leave the cell immediate source of energy soluble
60
feature of water
dipolar molecule
61
properties of water
important metabolite important solvent in which metabolic reaction occur relatively high heat capacity (amount of energy required to raise by 1 degree) relatively ;are latent heat of vaporisation (cooling effect) strong cohesion between water molecules provides surface tension allows water molecules to attach to each other (cohesion) important in formation of water columns

AQA A Level biology (8 decks)

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