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Biology > Topic 1A: Biological Molecules > Flashcards

Topic 1A: Biological Molecules Flashcards

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1
Q

What is a monomer?

A

A small, basic molecular unit that can join to form a polymer.

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2
Q

What is a polymer?

A

A large, complex molecule made up of long chains of monomers joined together.

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3
Q

What is condensation?

A

A reaction to join molecules releasing a molecule of water.

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4
Q

What is hydrolysis?

A

A reaction to split up molecules requiring a molecule of water.

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5
Q

What monomer to polymer reaction makes carbohydrates?

A

Monosaccharides –> di/polysaccharides

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6
Q

Name 4 monosaccharides

A
  • Alpha glucose
  • Beta glucose
  • Galactose
  • Fructose
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7
Q

What is the structure of alpha glucose?

A

H H
OH OH

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8
Q

What is the structure of beta glucose?

A

H OH
OH H

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9
Q

What is the structure of galactose?

A

OH OH
H H

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10
Q

What is the structure of fructose and how is that different to the other monosaccharides?

A

It is a pentose sugar.

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11
Q

What is a disaccharide?

A

2 monosaccharides joined together

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12
Q

Name the three disaccharides and what they are made up of.

A
  • Glucose + glucose –> maltose
  • Glucose + galactose –> lactose
  • Glucose + fructose –> sucrose
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13
Q

Draw the bonding of maltose
What is the name of the bond made?

A

Lose H from one glucose and OH from the other, now connected by a central O.
Glycosidic bond.

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14
Q

What is a polysaccharide?

A

More than 2 monosaccharides joined together.

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15
Q

Starch
- What is it used for?
- Which monosaccharide is it made of?
- What 2 polymers is it made up of?

A
  • Energy store in plants.
  • Alpha glucose
  • Amylose + amylopectin
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16
Q

Starch
- How does its structure make it good for storage?

A

Amylose - unbranched chains, helical –> compact for storage
Amylopectin - branched chains –> allow enzymes in easily to break down molecules
Large molecule –> can’t leave cells
Insoluble –> doesn’t affect water potential of the cell.

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17
Q

Glycogen
- What is it used for?
- Which monosaccharide is it made of?

A
  • Energy storage in animals.
  • Alpha glucose
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18
Q

Glycogen
- How does its structure make it good for storage?

A
  • Extremely branched –>stored energy can be released easily
  • Compact –> good for storage
  • Large molecule –> can’t leave cells
  • Insoluble –> doesn’t affect the water potential of cells
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19
Q

Cellulose
- What is it used for?
- Which monosaccharide is it made of?

A
  • Structural support in plants
  • Beta glucose
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20
Q

Cellulose
- How does its structure make it good for its function?

A
  • Long unbranched, straight chains
  • Cellulose chains linked by hydrogen bonds to form strong fibres called microfibrils
  • Strong fibres provide the structural support for cells
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21
Q

What is the difference between saturated and unsaturated fatty acids?

A
  • Saturated –> no C=C
  • Unsaturated –> one or more C=C
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22
Q

What makes up a triglyceride?

A

3 fatty acids + 1 glycerol –> triglyceride + 3H2O

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23
Q

What is the general form of a fatty acid?

A

Central C with =O, an OH group and an R hydrocarbon tail.

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24
Q

Draw the bonding of a triglyceride
Name the bonds used

A
  • Lose H off OH side of glycerol and an OH off each fatty acid.
  • O left over on glycerol bonds directly to C from fatty acid.
  • Joined by -COO ester bond.
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25
Q

What is the function of triglycerides and how are they structured for this?

A
  • Energy store –> hydrocarbon tails have lots of chemical energy which is released when broken down.
  • Hydrophobic hydrocarbon tails - insoluble in water –> clump as insoluble droplets as tails face in shielded by glycerol heads –> don’t affect water potential of cells.
26
Q

What makes up a phospholipid?

A

1 glycerol + 2 fatty acids + 1 phosphate group

27
Q

Draw the structure of a phospholipid and name the bonds used.

A
  • Glycerol in the middle with fatty acids bonded to one side and phosphate group to the other.
  • Fatty acids bonded from central C to an O to the central C of the glycerol.
  • Phosphate bonded from central P to O to central C of the glycerol.
  • Uses ester bonds -COO
28
Q

What is the function of phospholipids and how are they structured for this?

A
  • Make up the bilayer of cell membranes
  • Hydrophilic heads and hydrophobic tails - form double layer with heads facing out to water
  • Centre of bilayer = hydrophobic –> water soluble substances can’t pass through –> acts as a barrier
29
Q

What is the monomer to polymer reaction to make proteins?

A

Amino acids –> polypeptides (proteins)

30
Q

What is the structure of amino acids?

A
  • Central C
  • Amino group (NH2)
  • Single H
  • Carboxyl group (COOH)
  • Variable group (R)
31
Q

Draw the bonding of a dipeptide
What is the name of the bonds used?

A
  • OH from COOH of amino acid 1 and H from NH2 of amino acid 2 remove to make water.
  • C (with =O) bonds to N of second amino acid
  • Peptide bonds
32
Q

How does the primary structure of a protein form?

A

The sequence of amino acids in a polypeptide chain.

33
Q

How does the secondary structure of a protein form?

A

Hydrogen bonds form between amino acids in the chain to make an alpha helix or a beta pleated sheet.

34
Q

How does the tertiary structure of a protein form?

A

More bonds form (hydrogen + ionic) as well as disulfide bridges between sulphur atoms in cysteine bond together.

35
Q

How does the quaternary structure of a protein form?

A

Only needed with multiple different polypeptide chains and is how they are assembled together.

36
Q

Name 4 functions of proteins?

A
  • Enzymes
  • Antibodies
  • Transport proteins
  • Structural proteins
37
Q

What are fibrous proteins?

A

They provide structure as long parallel polypeptide chains with cross links between them to form long rope-like fibres that are generally insoluble e.g. collagen, silk, keratin.

38
Q

What are globular proteins?

A

Spherical, tightly folded chains that are folded with hydrophobic groups inside and hydrophilic outside so they are mostly insoluble in water e.g. transport proteins, enzymes, hormones.

39
Q

What is the test for lipids?

A
  • Shake the substance with ethanol
  • Pour into water
  • Forms a milky emulsion
40
Q

What is the test for proteins?

A
  • Biuret solution (sodium hydroxide solution + copper (II) sulphate)
  • Blue –> purple
41
Q

What is the test for starch?

A
  • Add iodine in potassium iodide solution
  • Amber –> blue / black
42
Q

What is the test for reducing sugars?
What are reducing sugars?

A
  • All monosaccharides and some disaccharides
  • Add Benedict’s solution and heat
  • Turns blue -> green -> yellow -> orange -> brick red (precipitate)
43
Q

What is the test for non-reducing sugars?

A
  • Need to be broken down to reducing sugars first
  • Add HCl and heat
  • Neutralise with sodium hydrogencarbonate
  • Then do Benedict’s test
44
Q

How does the Benedict’s test work?

A
  • Contains copper sulphate (blue)
  • Reducing sugars reduce it into copper oxide (red)
  • This forms the red precipitate
45
Q

What is a substrate?

A

The substance that binds to the active site of an enzyme to form an E-S-C –> it is converted to product while attached to the enzyme and is then released.

46
Q

What can enzymes do?

A
  • Build things up
  • Break things down
47
Q

What is activation energy?

A

The minimum amount of energy needed for a reaction to occur.

48
Q

What do enzymes do to the activation energy?

A

Lower it –> provide alternate reaction pathway

49
Q

What is the lock and key model of an enzyme?

A
  • Enzyme = lock, substrate = key
  • Must fit exactly - is specific - complimentary shape
  • Active site = fixed shape
50
Q

What is the induced fit model of an enzyme?

A
  • Enzyme = glove, substrate = hand
  • Not exactly complimentary
  • Substrate forces the enzyme’s active site to change shape
  • Enzyme moulds around it
51
Q

What two ways is rate often measured?

A
  • Formation of product / time
  • Disappearance of substrate / time
52
Q

How do enzymes denature?

A
  • Bonds in enzyme are broken or interfered with
  • Changes the tertiary structure of the enzyme
  • Changes enzyme shape –> active site shape changes
  • Substrate no longer fits so cannot bind to an E-S-C
  • Reaction cannot be catalysed
53
Q

How does temperature affect enzyme activity?

A
  • High temp = higher kinetic energy = molecules move more quickly = higher frequency of successful collisions = more frequent E-S-C formation
  • Collisions occur with more energy –> more collisions likely to cause a reaction –> more molecules have activation energy
  • Too high temp = denatures –> molecules vibrate too much breaking bonds
54
Q

How is enzyme activity affected by pH?

A
  • Non optimal / extreme pHs can denature enzymes
  • They disrupt the bonds as the H+ or OH- disrupt it
55
Q

How can you prevent pH interfering in reactions?

A

Use a buffer solution

56
Q

How is enzyme concentration a factor affecting enzyme activity?

A
  • High enzyme conc = higher number of active sites = higher likelihood of E-S-C
  • As long as substrate is available - an inc in enzyme conc makes rate inc linearly with enzyme conc
  • If substrate conc limited –> at a certain point any further inc in enzyme has no affect
  • Substrate becomes the limiting factor
57
Q

How does substrate concentration affect enzyme activity?

A
  • Inc substrate conc = higher rate due to inc liklihood of E-S-C
  • If enzyme conc fixed and substrate continues to increase –> eventually all active sites are full and rate stops increasing
58
Q

How do competitive inhibitors work?

A
  • Inhibitor has a similar shape to substrate –> occupies the active site instead of substrate –> competes with it
  • Concentration of enzyme and concentration of inhibitor determines the effect it has on enzyme activity
59
Q

How do non-competitive inhibitors work?

A
  • Binds to a site that is not the active site –> makes active site change shape so substrate cannot bind
60
Q

What enzyme experiment measures the formation of product?

A
  • Formation of H2O2 in measuring cylinder experiment
  • Trough of water with measuring cylinder full of water upside down in it –> delivery tube leads from cylinder out of the water
  • Boiling tubes with H2O2 and buffer solution –> each put in a water bath of different temperatures with a boiling tube of catalase
  • Wait 5 mins then add catalase to H2O2 and quickly put in the bung with the delivery tube and start a stopwatch
  • Record how much O2 produced in 1 minute using measuring cylinder
  • Repeat at each temp and 3 times for a mean
  • Always use the same volume and concentration of H2O2 and catalase
61
Q

What enzyme experiment measures the breakdown of a substrate?

A
  • Starch and iodine spotting tile one
  • Put a drop of iodine in each well of a spotting tile
  • Mix amylase and starch in a test tube (known volume and concentration of each)
  • Pipette some over iodine in a well at regular intervals e.g. 10s
  • Observe colour change (amber = no starch, blue/black = starch)
  • Test how fast starch is broken down by how quickly the colour changes
  • Repeat with different amylase concentrations and each 3 times for a mean

Biology (18 decks)

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