Biological Molecules Flashcards

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1
Q

What are the 3 main functions of carbohydrates?

A
  • Storage of energy
  • Release of energy
  • Cellular structures (cellulose cell wall of plant cells)
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2
Q

Why is glucose called a hexose sugar?

A

Monosaccharide that contains 6 carbon atoms

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3
Q

What’s the difference between alpha and beta glucose?

A

ABBA (OH group)
Alpha Below
Beta Above

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4
Q

What is an isomer?

A

Molecules with the same chemical formula but different arrangements of their atoms

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5
Q

What are the 2 other hexose sugars?

A

Fructose and galactose

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6
Q

What is a property of monosaccharides?

A

Soluble in water
Due to small size so easily dissolve in cell and are easily transported in the bloodstream

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7
Q

Alpha glucose + alpha glucose =

A

Maltose

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8
Q

Glucose + fructose =

A

Sucrose

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9
Q

Glucose + galactose =

A

Lactose

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10
Q

What’s the name of the bond between the 2 sugars in a disaccharide?

A

Glycosidic

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11
Q

How can disaccharides be broken back down to monosaccharides?

A

Hydrolysis reaction
(Breaking of the glycosidic bond by chemically inserting water)

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12
Q

Properties of polysaccharides eg starch (ICE)

A
  • INSOLUBLE so don’t affect osmosis
  • COMPACT so can be stored in small placed in the cell/can store a lot in one area
  • EASILY HYDROLYSED to release the glucose for respiration
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13
Q

Give 4 examples of polysaccharides

A
  1. STARCH (storage in plants)
  2. GLYCOGEN (storage in animals)
  3. CELLULOSE (structural in plants)
  4. CHITIN (structural in animals)
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14
Q

Are storage polysaccharides alpha or beta glucose?

A

Alpha

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15
Q

Are structural polysaccharides alpha or beta glucose?

A

Beta
(Beat it and it will keep its shape)

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16
Q

What 2 molecules make up starch?

A

Amylose and amylopectin

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17
Q

Describe the structure of amylose

A

Straight chained, helical polymer containing alpha 1-4 glycosidic bonds

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18
Q

Describe the structure of amylopectin

A

Branched polymer containing alpha 1-4 and alpha 1-6 glycosidic bonds

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19
Q

Where is glycogen stored?

A

Liver and muscle cells

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20
Q

Describe the structure of glycogen

A

Highly branched polymer containing alpha 1-4 and alpha 1-6 glycosidic bonds

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21
Q

Describe the structure of cellulose

A
  • Beta glucose monomers joined by 1-4 glycosidic bonds
  • Each adjacent beta glucose monomer rotated 180
  • Forming straight chains
  • Hydrogen bonds form between OH groups of straight chains
  • Many straight chains joined together by many hydrogen bonds forms a strong microfibril
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22
Q

What are the properties of chitin?

A
  • lightweight
  • waterproof
  • very strong

(Forms exoskeleton of arthropods eg insects)

23
Q

What 2 components are triglycerides made up of?

A

Glycerol
Fatty acids

24
Q

What is the name of the bond that links triglycerides and phospholipids?

A

Ester bond

25
Q

What’s the formula of glycerol?

A

C3H8O3

  H   H   H H - C - C - C - H    OH OH OH
26
Q

General structure of fatty acid

A

Carboxyl group (COOH)
Hydrocarbon chain (CH2)
Methyl group (CH3)

27
Q

What’s the difference between a saturated and unsaturated fatty acid?

A

Saturated has no carbon to carbon double bonds whereas unsaturated has carbon to carbon double bonds

28
Q

Draw condensation reaction that takes place during the formation of a triglyceride from glycerol and three fatty acids

A

Page 18 in BM booklet

29
Q

What do low density lipoproteins do?

A

LDLs contain and transport saturated fats and cause harm. Fatty material can block major arteries and cause a heat attack.

30
Q

What do high density lipoproteins do?

A

HDLs contain and transport unsaturated fats and carry harmful fats away to liver for disposal. Higher proportion of HDL in blood lowers the risk of heart disease.

31
Q

What are 3 properties of lipids?

A

> INSOLUBLE in water but soluble in organic solvents eg ethanol
Fats are solid at room temp eg butter
Oils are liquid at room temp eg olive oil

32
Q

State the 6 functions of lipids

A

> Energy storage
Protection of vital organs from impact
Thermal insulation
Buoyancy
Metabolic water
Waterproofing (cuticle of plant, exoskeleton of insects)

33
Q

What is the structure of a phospholipid?

A

A glycerol, two fatty acids and a phosphate group

34
Q

Which part of the phospholipid is hydrophilic?

A

Polar head group.
The fatty acid tails are hydrophobic.

35
Q

What are phospholipids an important component of?

A

Cell membranes

36
Q

What are the 3 groups in an amino acid?

A

Amino group (H2N), variable ‘R’ group, carboxyl group (COOH)

37
Q

There are 20 amino acids found in nature. How to they differ from each other?

A

Different variable groups

38
Q

Draw a diagram to illustrate the condensation reaction that takes place during the formation of a dipeptide from 2 amino acid monomers

A

Page 23 of NB

39
Q

What is the bond between 2 amino acid monomers in a dipeptide called?

A

Peptide bond

40
Q

What is the primary structure of a protein?

A

The number and sequence of amino acids in a polypeptide chain

41
Q

What is the secondary structure of a protein?

A

The primary structure of the polypeptide coils to form either an alpha-helix or a beta-pleated sheet.
Most common is alpha-helix which is held in spiral shape by HYDROGEN bonds.
Beta-pleated sheet (flat zigzag structure) also stabilised by hydrogen bonds.

42
Q

What is the tertiary structure of a protein?
(And how they’re held in place)

A

Where the secondary structure folds to give complex 3D shapes.
Held in shape by bonds or interactions that form between R groups of some amino acids in the polypeptide chain.

43
Q

What bonds hold together the tertiary structure of a protein?

A
  • Hydrogen (form between O and OH)
  • Ionic bonds (between oppositely charged R groups)
  • Disulphide bridges (between S atoms)
  • Hydrophobic interactions (on inside of the protein)
  • Hydrophilic interactions (on outside of protein)
44
Q

What is the quaternary structure of a protein?

A

When more than one polypeptide chain each with a tertiary structure combine. Sometimes associated with non-protein groups called prosthetic groups. Eg haemoglobin

45
Q

What are the 2 classifications of proteins?

A

Fibrous proteins and globular proteins

46
Q

What makes fibrous proteins effective at carrying out STRUCTURAL functions?

A
  • Tough
  • Non-specific
  • Insoluble
47
Q

What are the properties of globular proteins?

A
  • Compact and folded into spherical molecules
  • Have a specific shape
  • Soluble in water
48
Q

How do you test for proteins?

A
  • Add a few drops of biuret reagent to protein solution
  • Shake gently
  • Blue —> purple
49
Q

How do you test for reducing sugars eg glucose?

A
  • Add a few drops of Benedict’s reagent to test sample
  • Heat in water bath
  • Blue —> brick red
    May be graduated between green, yellow orange or brick-red
    Semi-quantitative
50
Q

How do you test for non-reducing sugars?

A

If negative result was found initially with Benedict’s and boil test:
- Add HCl to test sample and heat in water bath (hydrolyse any glycosidic bonds)
- Add bicarbonate of soda to neutralise
- Add Benedict’s reagent and heat in water bath
- Blue —> brick red

51
Q

How do you test for starch?

A
  • Add a few drops of iodine solution
  • Orange —> blue/black
52
Q

How do you test for lipids?

A
  • Mix test sample with an equal volume of ethanol
  • Add mixture to an equal volume of water and shake
  • Cloudy white emulsion will form
53
Q

What is cohesion?

A

Water molecules sticking together as a result of the formation of hydrogen bonds

54
Q

What are the 7 properties of water?

A
  1. Surface tension
  2. Universal solvent (excellent transport medium)
  3. Metabolite
  4. High specific heat capacity
  5. High latent heat capacity
  6. Density
  7. Transparency