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biology aqa a-level > topic 1 - biological molecules > Flashcards

topic 1 - biological molecules Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

what are polymers?

A

molecules made up of chains of monomers.

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2
Q

what reaction turns monomers into polymers?

A

condensation reaction.

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3
Q

what reaction turns polymers into monomers?

A

hydrolysis reaction.

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4
Q

what do all carbohydrates contain?

A

carbon (C), hydrogen (H), and oxygen (O).

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5
Q

what bond is formed when two monosaccharides join together?

A

glycosidic bond.

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6
Q

what test is used to test for sugars?

A

the Benedict’s test.

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7
Q

what colour does the solution turn if there are not reducing/non-reducing sugar present?

A

blue (no colour change).

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8
Q

what colour does the solution turn if there are reducing/non-reducing sugars present?

A

green > yellow > orange > brick red

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9
Q

how do you test for reducing sugars?

A

heat a food sample with Benedict’s solution.

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10
Q

how do you test for non-reducing sugars?

A

heat a new sample with diluted hydrochloric acid, and neutralise with sodium hydrogencarbonate. heat again with Benedict’s solution after.

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11
Q

what are some examples of polysaccharides?

A

starch (amylose and amylopectin), glycogen, and cellulose

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12
Q

what test is used to test for starch?

A

the iodine test.

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13
Q

how do you test for starch?

A

add iodine dissolved in potassium iodide to the sample.

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14
Q

what colour does the test sample turn if there is starch present.

A

dark blue-black.

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15
Q

what colour does the test sample turn if there is not starch present?

A

brown-orange (no colour change).

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16
Q

what are lipids made of?

A

fatty acids and glycerol.

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17
Q

what is the structure of triglycerides?

A

3 fatty acids and 1 glycerol molecule.

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18
Q

are triglyceride tails hydrophilic or hydrophobic?

A

hydrophobic.

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19
Q

what is the difference between saturated and unsaturated hydrocarbon tails?

A

saturated tails only have single bonds between carbon atoms, yet unsaturated tails have double bonds between carbon atoms.

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20
Q

what bond is formed when a fatty acid joins to a glycerol molecule?

A

ester bond.

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21
Q

what type of lipid is found in cell membranes?

A

phospholipids.

22
Q

what is the structure of phospholipids?

A

1 glycerol molecule, 1 phosphate group, and 2 fatty acids.

23
Q

are the phosphate groups in phospholipids hydrophilic or hydrophobic?

A

hydrophilic.

24
Q

what test is used to test for lipids?

A

the emulsion test.

25
Q

how do you test for lipids?

A

shake the solution with ethanol for ~1 minute, and then pour into water.

26
Q

what happens to the test solution if there are lipids present?

A

there will be a milky white emulsion present above the solution.

27
Q

what are proteins made of?

A

amino acids.

28
Q

what bond forms between two amino acids forming a dipeptide?

A

peptide bond.

29
Q

what are some functions for proteins?

A

enzymes, antibodies, transport proteins, and structural proteins.

30
Q

what test is used to test for proteins?

A

the biuret test.

31
Q

before testing for proteins, what does the test solution need to be?

A

alkaline. (if not, add drops of sodium hydroxide.)

32
Q

how do you test for proteins?

A

add copper(II) sulfate to the sample.

33
Q

what colour does the test solution turn if there is protein present?

A

purple (can be pale).

34
Q

what colour does the test solution turn if there is not protein present?

A

it stays blue (can be pale).

35
Q

what can affect enzyme activity?

A

temperature, pH level, enzyme concentration, and substrate concentration.

36
Q

which type of inhibitor can greatly affect enzyme activity?

A

non-competitive inhibitors.

37
Q

what does DNA stand for?

A

deoxyribonucleic acid.

38
Q

what does RNA stand for?

A

ribonucleic acid.

39
Q

what is the structure of both DNA and RNA nucleotides?

A

1 phosphate group, 1 pentode sugar, and 1 nitrogen-containing base.

40
Q

what bond forms between polynucleotides?

A

ester bonds (between the sugar on one nucleotide and the phosphate on another nucleotide).

41
Q

in DNA, how many hydrogen bonds do adenine and thymine have while they bond?

A

two.

42
Q

in DNA, how many hydrogen bonds do cytosine and guanine have while they bond?

A

three.

43
Q

what different characteristics do RNA and DNA have?

A

RNA strands are a lot shorter than DNA strands, DNA is double stranded and RNA is single stranded, uracil is a RNA base but thymine is a DNA base, DNA’s sugar is deoxyribose yet RNA’s sugar is ribose.

44
Q

how do DNA strands appear?

A

they appear antiparallel, running from 5’ to 3’ as a double helix.

45
Q

what type of DNA replication occurs in cells before cell division?

A

semi-conservative replication.

46
Q

what is the process of DNA replication?

A

DNA Helicase breaks the hydrogen bonds between strands, making them single strands. free floating nucleotides are attracted to the complimentary base pairs. DNA Polymerase catalyses the condensation reactions between the old and new strand.

47
Q

what is the evidence for semi-conservative replication?

A

Meselson and Stahl’s experiment: samples were taken from the DNA in bacteria in light or heavy nitrogen and spun in a centrifuge; heavy nitrogen sunk to the bottom while light nitrogen. they collected bacteria with heavy nitrogen and placed them in a light nitrogen solution. the results showed that DNA with both would settle at a midpoint.

48
Q

what is the structure of ATP?

A

1 ribose sugar, 3 phosphate groups, and 1 adenine base.

49
Q

how does water help with temperature control?

A

it has a high latent heat of vaporisation and a high specific heat capacity.

50
Q

why is water polar?

A

one side of the molecule has a negative charge, while the other has a positive charge.

51
Q

what are some important inorganic ions and their uses?

A
  • Fe²+: oxygen carried by haemoglobin.
  • H+: pH is calculated by the amount of H+ ions present; the more H+, the more acidic the pH is.
  • Na+: assisting the transport of glucose and amino acids across cell membranes (co-transport).
  • PO₄³-: the bonds between phosphate groups store energy in ATP, and the phosphate groups help form polynucleotides.

biology aqa a-level (8 decks)

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