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A Level Biology > Biological molecules (Topic 1) > Flashcards

Biological molecules (Topic 1) Flashcards

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1
Q

describe a biochemical test to show a solution contains non-reducing sugars

A
  1. perform the reducing sugar test if negative then
  2. heat with acid and neutralise
  3. heat with benedict’s solution
  4. red precipitate formed if present
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2
Q

explain the arrangement of phospholipids in a cell surface membrane

A

hydrophobic tails point away from water and hydrophilic heads point to water

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3
Q

describe how an ester bond is formed in a phospholipid molecule

A

through a condensation reaction between glycerol and fatty acid

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4
Q

state the property of water that helps prevent temperature increase in a cell

A

high specific heat capacity

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5
Q

how does waters high specific heat capacity prevent temperature increase in a cell

A

it buffers change in temperatures

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6
Q

explain how a phosphodiester bond is formed between two nucleotides within a DNA molecule and what catalyses the reaction

A

condensation reaction between phosphate and deoxyribose that is catalysed by DNA polymerase

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7
Q

describe how the separation of the two DNA stands occurs

A

•DNA helicase
•breaks H bonds between base pairs

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8
Q

where is amylase produced

A

pancreas
salivary glands

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9
Q

where is maltase produced

A

small intestine

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10
Q

why does an enzyme only catalyse one reaction

A
  1. active site of enzyme has specific shape
  2. only the substrate can bind to it
  3. to form an enzyme substrate complex
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11
Q

describe how the structure of glycogen is related to its function (4 marks)

A
  1. branched so compact
  2. polymer of glucose so easily hydrolysed
  3. branched so faster hydrolysis
  4. insoluble so not easily lost from cell
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12
Q

what enzyme breaks bonds between amino acids?

A

endopeptidase

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13
Q

all carbohydrates contain the elements….

A

carbon
hydrogen
oxygen

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14
Q

glucose is a _____ sugar

A

hexose

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15
Q

the two types of glucose are….

A

alpha
beta

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16
Q

which type of glucose has the OH group joined above the H?

A

beta

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17
Q

which type of glucose has the OH group joined below the H?

A

alpha

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18
Q

how are disaccharides formed?

A

by joining 2 monosaccharides through a condensation reaction

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19
Q

what bonds are formed when a disaccharide is formed?

A

glyosidic

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20
Q

what is released when disaccharides are formed?

A

water

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21
Q

sucrose is formed from…

A

glucose and fructose

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22
Q

maltose is formed from…

A

two alpha glucose

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23
Q

lactose is formed from…

A

glucose and galactose

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24
Q

what is the test for reducing sugars?

A
  1. heat sample with benedicts reagent
  2. sample forms brick red precipitate
  3. if reducing sugar present
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25
polysaccharides form when...
more than two monosaccharides are joined by a condensation reaction
26
what is amylose formed from?
lots of alpha glucose molecules
27
polysaccharides are broken down by...
hydrolysis
28
plants store excess glucose as....
starch
29
when a plant needs more energy it....
breaks down starch to release glucose
30
starch is a mixture of two polysaccharides which are:
amylose amylopectin
31
is starch soluble in water?
no
32
why is it important for starch to be insoluble in water?
so that it doesn't affect water potential and water doesn't move into the cells via osmosis causing them to swell
33
animals store excess glucose as...
glycogen
34
what are the benefits of glycogen being branched?
stored glucose can be released quickly
35
what is the benefit of glycogen being compact?
good for storage
36
cellulose is made of....
long, unbranched chains of beta glucose
37
cellulose chains are held together by __ bonds. to form strong fibres called....
hydrogen bonds microfibrils
38
cellulose provides....
structural support for cell walls
39
what is the test for starch?
1. add iodine dissolved in potassium iodide solution to the sample 2. if starch is present sample turns from browny-orange to blue-black
40
lipids are made from...
proteins and carbohydrates
41
triglycerides contain...
glycerol 3 fatty acids
42
fatty acids have ____ tails and ______ heads
hydrophobic hydrophilic
43
saturated fatty acids don't have....
double carbon bonds
44
unsaturated fatty acids have.... which cause....
double carbon bonds the chain to kink
45
what kind of reaction forms triglycerides?
condensation reaction
46
phospholipids consist of...
a phosphate group glycerol 2 fatty acids
47
2 properties of triglycerides...
- insoluble in water - long hydrocarbon tails with lots of chemical energy
48
what is the emulsion test for lipids?
1. shake substance with ethanol then pour it into water 2. lipid will show up as a milky solution
49
proteins are made of....
one or more polypeptides
50
amino acid functional groups are
NH2 and COOH
51
dipeptides and polypeptides are formed by...
condensation reactions
52
the bonds between amino acids are called...
peptide bonds
53
primary protein structure is...
the sequence of amino acids in the polypeptide chain
54
secondary protein structure is...
hydrogen bonds form between amino acids to make alpha helix or beta pleated sheet
55
tertiary protein structure is...
hydrogen bonds, ionic bonds and disulfide bridges form to fold and coil them further
56
quaternary protein structure is....
the way polypeptide chains are assembled together
57
what is the test for proteins?
1. add NaOH solution TO THE SMAPLE 2. add copper (II) sulfate solution 3. if present solution turns purple
58
enzymes are...
biological catalysts
59
what are the models for enzyme action?
lock and key induced fit
60
how can you measure enzyme activity?
how fast product is made how fast the substrate is broken down
61
what factors effect enzyme activity?
temperature pH substrate concentration enzyme concentration
62
what are competitive inhibitors?
they bind to the active site of the enzyme so no substrate can bind to the enzyme
63
what are non competitive inhibitors?
molecules that fit onto the molecule away from the active site causing a positive change in the enzymes active site
64
nucleotide consist of...
a phosphate pentose sugar nitrogenous base
65
nucleotide chains join together to form_______ via a ________ reaction. This forms a ________ bond. The chain of phosphates and sugars is known as the ______ backbone
polynucleotides condensation phosphodiester sugar-phosphate
66
the sugar in RNA is...
ribose
67
the sugar in DNA is....
deoxyribose
68
how many hydrogen bonds form between adenine and thymine?
2
69
how many hydrogen bonds form between cytosine and guanine?
3
70
polynucleotide strands run _____ to each other
anti parallel
71
DNA is replicated by.....
semi-conservative repliaction
72
the 4 steps of DNA replication are:
1. DNA helicase breaks H bonds, separating strands 2. Free nucleotides are attracted by complementary bases 3. Condensation reaction catalysed by DNA polymerase 4. Two strands are produced
73
in the experiment which proves semi-conservative replication light nitrogen...
settles at the top of the tube
74
in the experiment which proves semi-conservative replication heavy nitrogen...
settles at the bottom of the tube
75
in the experiment which proves semi-conservative replication the tube...
has one band midway in the tube
76
give the 5 properties of water....
1. its a metabolite 2. has high latent heat of vaporisation 3. resists temp changes 4. is a good solvent 5. strong cohesion between water molecules
77
ATP consists of...
an adenine base a ribose sugar 3 phosphate groups
78
give the reaction for resynthesis of ATP
ADP + P --> ATP catalysed by ATPase
79
give the equation for when energy is broken down
ATP --> ADP + P catalysed by ATP hydrolase

A Level Biology (19 decks)

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