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Biology > Molecules Of Life > Flashcards

Molecules Of Life Flashcards

1
Q

3 examples of monomers

A

Monosaccharides, amino acids and nucleotides

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2
Q

Benedicts test for reducing sugars

A

Add benedicts reagent to a sample and heat it in a water bath
No reducing sugars - blue
Reducing sugars - green, yellow, orange, red

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3
Q

Benedicts test for non reducing sugars

A

Break down into monosaccharides by adding HCl to sample and put in the water bath. Add sodium hydrogencarbonate.

No non reducing sugars - blue
Non reducing sugars - green, yellow, orange, red

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4
Q

How does the structure of starch help it to store glucose

A

Starch is made up of amylose and amylopectin (both polysaccharides of alpha glucose). Amylose is long and unbranched. The glycosidic bonds cause it to coil up and become compact. This makes it good for storage. Amylopectin is long and branched. The branches allow enzymes to break down the glycosidic bonds more easily, releasing glucose quicker.

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5
Q

How does the structure of glycogen relate to its function?

A

Animals store glucose and glycogen. Glycogen contains lots of side branches meaning the enzymes can break down the glycosidic bonds more easily and release glucose more quickly. Glycogen is also compact making it good for storage

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6
Q

Explain the structure of cellulose

A

Cellulose is made of long, unbranched chains of beta glucose. The beta glucose molecules bond to form straight cellulose chains. The cellulose chains are not linked together by hydrogen bonds to form strong fibres called microfibrils. The strong fibres mean cellulose provides structural support for cells

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7
Q

Iodine test for starch

A

Add iodine dissolved in potassium iodide solution to the sample. Turns from orange to blue = starch

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8
Q

Structure of triglycerides

A

3 fatty acids attached to 1 glycerol molecule by an ester bond

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9
Q

The structure of phospholipids

A

1 phosphate group bonded to 1 glycerol molecule. 2 fatty acids bonded to glycerol molecule by ester bond. Phosphate group is hydrophilic head and fatty acids are hydrophobic tail

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10
Q

Role of triglycerides

A

Energy storage because fatty acid tails contain lots of chemical energy
Insoluble in water don’t affect water potential due to hydrophobic tail

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11
Q

Describe phospholipid bilayer

A

Hydrophobic tails face inwards. Hydrophilic head face outwards towards water molecules

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12
Q

Emulsion test for lipids

A

Shake the substance in ethanol for 1 minute then add water. If the liquid turns milky white/cloudy then a lipid is present

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13
Q

Bond between glycerol and fatty acid

A

Ester bond

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14
Q

Bond between amino acids

A

Peptide bond

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15
Q

Primary structure of protein

A

Sequence of amino acids in polypeptide chain

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16
Q

Secondary structure of protein

A

Hydrogen bonds form between amino acids. Alpha helix or beta pleated sheets form

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17
Q

Tertiary structure of protein

A

Hydrogen and ionic bonds for between amino acids. Disulphide bridges form between two molecules of cysteine when they’re close together. Final 3D structure of proteins made of one polypeptide chain

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18
Q

Quaternary structure of protein

A

Way the polypeptide chains are help together. Final 3D structure of proteins made of more than one polypeptide chain

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19
Q

Biuret test for proteins

A

Add sodium hydroxide solution to sample
Add copper sulphate solution
Blue - no protein
Purple - protein

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20
Q

Bond between pentose sugar and phosphate molecule

A

Phosphodiester bond

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21
Q

DNA nucleotide structure

A

Phosphate molecule bonded to a deoxyribose sugar (pentose sugar) by a phosphodiester bond. Nitrogen containing base bonded to the pentose sugar

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22
Q

RNA nucleotide structure

A

Phosphate molecule bonded to a ribose sugar (pentose sugar) by a phosphodiester bond. Nitrogen containing base bonded to the pentose sugar

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23
Q

DNA bases

A

Adenine
Thymine
Cytosine l
Guanine

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24
Q

Complementary base pairs in DNA

A

A T

C G

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25
Q

Bonds between nucleotide bases

A

Hydrogen bonds

26
Q

Always equal amounts of A and T in DNA and equal amounts of C and G in DNA

A 
Can have different amounts of the pairs though e.g. 
30 x A
20 x C
30 x T
20 x G
27
Q

RNA bases

A

Uracil
Adenine
Cytosine
Guanine

28
Q

Complementary base pairs in RNA

A

A U

C G

29
Q

How many hydrogen bonds between the bases A and T

A

2

30
Q

How many hydrogen bonds between the bases C and G

A

3

31
Q

Compare DNA and RNA

A

DNA is double stranded (double helix) and RNA has a single strand
DNAs pentose sugar is a deoxyribose sugar whereas RNA contains a ribose sugar
The bases of DNA are ATCG but the bases of RNA are AUCG
DNA is long but RNA is short

32
Q

By what process is DNA replicated?

A

Semi conservative replication

33
Q

Describe DNA replication

A

The enzyme DNA helicase breaks the hydrogen bonds between the bases in the DNA double helix, causing it to unwind and form two single strands. These single strands act as templates for new strands. Complementary base pairing occurs with free floating DNA nucleotides. DNA polymerase cause hydrogen bonds to form between the bases on the original strands and the new strands during a condensation reaction

34
Q

Why can DNA polymerase only work in the 3’ to 5’ direction

A

The active site of DNA polymerase is only complementary to the 3’ end of DNA meaning it moves in the direction of 3’ to 5’. The new DNA strand is made in the 5’ to 3’ direction

35
Q

Why does the DNA polymerase on each DNA strand move in opposite directions

A

DNA is anitparallel

36
Q

Experiment to prove semi conservative replication

A

Two samples of bacteria grown for generations in two broths. One broth contained heavy nitrogen and the other contained light nitrogen. The bacteria absorbed the nitrogen during DNA replication. Both bacteria DNA samples were spun in a centrifuge. The bacteria containing heavy nitrogen settled lower down than that of the light nitrogen. The bacteria containing heavy nitrogen were put in the broth containing light nitrogen for one replication. The DNA was taken and spun in the centrifuge. It settled in between the heavy and light nitrogen samples from earlier. This showed semi conservative replication, as it was evident the DNA had taken up both the light and heavy nitrogen.

37
Q

What is ATP made of?

A

Adenine bonded to a ribose sugar bonded to three phosphate groups

38
Q

How is energy made via ATP?

A

ATP is broken down into ADP and Pi during a hydrolysis reaction. The breaking of the phosphate bond is what releases the energy. This is catalysed by ATP hydrolase (ATPase)

39
Q

How is ATP resynthesised

A

ADP and Pi
Condensation reaction
Catalysed by ATP synthase

40
Q

Uses of water

A

Metabolite
Solvent
high latent heats of vaporisation - prevent loss of water
high specific heat capacity - buffer
Water molecules are cohesive which helps with water transport

41
Q

Why is water a good solvent

A

Water is polar so the slightly positive hydrogen atoms in the water molecule are attracted to negative ions and the slightly negative oxygen atom is attracted to positive ions. The causes the ions to be surrounded by water molecules, dissolving it

42
Q

What does high latent heat of vaporisation mean?

A

Lots of heat is used to change the substance from a liquid to a gas

43
Q

How does water evaporate

A

Water evaporates when the hydrogen bonds holding water molecules together are broken. This allows the water molecules on the surface of the water to escape into the air as a gas. It takes a lot of energy to break the hydrogen bonds so a lot of energy is used up when water evaporates

44
Q

What property of water helps organisms stay cool?

A

Water has a high latent heat of vaporisation. This is useful because organisms can cool down via water loss through evaporation without loosing too much water (as it takes a lot of energy to lose water). When water evaporates it carries away heat energy from a surface, cooling the surface down

45
Q

What is specific heat capacity?

A

Energy needed to raise the temperature of 1 gram of a substance by 1 degree Celsius

46
Q

Water has a high specific heat capacity. Why is this useful for organisms?

A

Water doesn’t experience rapid temperate changes, keeping the water inside of them at a stable temperature, maintaining a constant internal body temperature

47
Q

What is an anion?

A

Negative ion

48
Q

What is a cation?

A

Positive ion

49
Q

What does alpha glucose look like?

A

OH on bottom

50
Q

What does beta glucose look like?

A

OH in top

51
Q

Bond formed between two monosaccharides

A

Glycosidic bond

52
Q

What do you do if the substance you want to carry out a Benedicts test on is solid?

A

Crush the solid with water then filter out the solid

53
Q

Amino acid structure

A 
R   O
            |   ||
 H2N -C-C-OH
            |
           H
54
Q

Structure of a dipeptide

A 
H   R   O   H   R  O
|     |    ||    |    |   ||
N -C -C -N -C -C -OH
|     |               |
H   H             H
55
Q

Induced fit model

A

Substrate needs to be similar shape to active site but not exactly the same shape. When the substrate binds to the active site, it needs to be able to change the shape of the active site in the right way so that the active site is then complementary in shape to the substrate

56
Q

Don’t ever say that the enzymes are used up

A

All the active sites are occupied

57
Q

How do you estimate the initial rate of reaction from a graph

A

Draw a tangent to the curve at t=0. Do this by positioning the rules so it’s an equal distance from the curve at other sides of where it’s touching it. Tangent needs to start at 0

Calculate the gradient of the tangent
Change in Y divide by change in X

Workout the units. Divide the units of the Y axis by the units of the X axis

58
Q

Why is water a good biological buffer

A

Has a high specific heat capacity

59
Q

Why does sweat form droplets?

A

Water has strong cohesion characteristics which means it has a high surface tension when it comes in to contact with air

60
Q

What is an inorganic ion?

A

An ion that doesn’t contain carbon

61
Q

In haemoglobin, where does the iron(2) bind

A

Oxygen forming iron(3)

Biology (15 decks)

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