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Biology > 2.1.2 Biological Molecules > Flashcards

2.1.2 Biological Molecules Flashcards

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1
Q

What is a condensation reaction?

A

Monomers are joined together to form a polymer.
Anabolic reaction.
A water molecule is released and a covalent bond formed.

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2
Q

What is a hydrolysis reaction?

A

A reaction that splits polymers.
Water molecule is used.
Covalent bond is broken.

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3
Q

What are the monomers and polymers for proteins?

A

Monomer= Amino acids
Polymer= Polypeptides

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4
Q

What are the monomers and polymers for carbohydrates?

A

Monomer= Monosaccharides
Polymer= Polysaccharides

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5
Q

What are the monomers and polymers for nucleic acids?

A

Monomer= Nucleotides
Polymer= DNA and RNA

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6
Q

What are carbohydrates made from?

A

Carbon, hydrogen and oxygen.

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7
Q

What are the monomers and polymers for nucleic acids?

A

Monomer= Nucleotides
Polymer= DNA and RNA

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8
Q

What is the general formula for monosaccharides?

A

Cn (H20)n

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9
Q

How many carbon atoms can monosaccharides have?

A

3-triose
5-pentose
6-hexose

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10
Q

What are the properties of all monosaccharides?

A
  • Sweet
  • Water soluble
  • Form crystals
  • Reducing sugars
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11
Q

How is glucose suitable for it’s purpose?

A
  • Very small so diffuses across cell membranes easily.
  • Very soluble so is easily transported.
  • Has many bonds so can be broken down quickly to release energy.
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12
Q

What is the difference between alpha and beta glucose?

A

Alpha glucose has the hydroxyl group below the first carbon, Beta has it above.

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13
Q

What are disaccharides?

A

Formed by a condensation reaction of 2 monosaccharides, also produces a water molecule.
The bond formed between them is glycosidic.

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14
Q

Are disaccharides reducing sugars?

A

All apart from sucrose which is non-reducing. Sucrose must be hydrolysed with acid before it will give a positive result to the benedict’s test.

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15
Q

What monosaccharides and disaccharides do you need to know?

A

Fructose and galactose are hexose monosaccharides.

Fructose is a monosaccharide and with glucose it forms sucrose.

Galactose and glucose form lactose.

Ribose and deoxyribose are pentose monosaccharides. Ribose is present in RNA and deoxyribose is present in DNA molecules.

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16
Q

What are polysaccharides?

A

Polymers containing many monosaccharides linked by glycosidic bonds.

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17
Q

How are polysaccharides formed?

A

By condensation reactions

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18
Q

What is the function of starch?

A

Energy storage in plants.

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19
Q

What is starch made from?

A

Amylose and amylopectin, both made from alpha glucose.

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20
Q

What bonds are present in amylose and amylopectin?

A

Amylose and amylopectin have alpha 1-4 glycosidic bonds but amylopectin also has alpha 1-6 glycosidic bonds.
Also has hydrogen bonds within the cokl to hold it’s shape.

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21
Q

Is starch soluble?

A

Amylose is slightly but amylopectin is not therefore starch is not.

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22
Q

What makes amylopectin different from amylose and why is it useful?

A

Amylopectin also has alpha 1-6 glycosidic bonds which is useful as there are more point where glucose can be hydrolysed off to be used with the cell

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23
Q

Why does iodine turn anything with starch blue/black?

A

Iodine molecules become trapped in the coils of the starch to form an amylose-iodine complex, changing the colour to blue/black.

24
Q

What is the function of glycogen?

A

Energy storage in animals.

25
Q

What is the structure of glycogen? Why is this useful?

A

Contains alpha 1-4 glycosidic bonds and lots of alpha 1-6 glycosidic bonds. Lots of branches is useful as it is easier to hydrolyse off glucose molecules for energy (in animals because have a higher metabolic rate).

26
Q

Is glycogen soluble?

A

No, it is insoluble so doesn’t affect osmotic potential.

27
Q

What is the function of cellulose?

A

Involved in structure in plants (cell walls)

28
Q

What is cellulose made from and what bonds does it form?

A

Made from beta glucose with beta 1-4 glycosidic bonds. The monomers alternate their orientation to form straight chains. They have hydrogen bonds between the layers.

29
Q

What is the semi-quantitative test for reducing sugars?

A

Using manufactured reagent strips to test for their presence then compare to a colour-coded chart which relates to a concentration.

30
Q

What is the quantitative test for reducing sugars?

A

Using a colorimeter can determine the amount of glucose by measuring the amount of Cu2+ remaining after the benedicts test.

31
Q

How does a colorimeter work?

A

Measures the amount of ligh transmitted of the amount of light absorbed by a coloured solution to determine how much of the colour is present.

32
Q

What is a serial dilution?

A

A dilution in which the concentration decreases by the same factor each successive step.

33
Q

How do you calculate the final concentration of a serial dilution?

A

Final concentration= dilution factor x initial concentration.

34
Q

Why is water useful in biology?

A
  • A solvent
  • A lubricant
  • A habitat
  • A transport medium
  • A temperature regulator
35
Q

What useful properties does water have?

A
  • High specific heat capacity
  • High latent heat of fusion and evaporation
  • Strong cohesive and adhesive properties
  • Max density at 4 degrees celsius
  • High surface tension
  • Low viscosity
36
Q

What are the features and bonds present in a primary structure protein?

A

It is a sequence of amino acids.
Peptide bonds.

37
Q

What are the features and bonds present in a secondary structure protein?

A

It is an alpha helix and a beta pleated sheet.
It has peptide and hydrogen bonds.

38
Q

What are the features and bonds present in a tertiary structure protein?

A

It has a 3D structure.
It has peptide and hydrogen bonds as well as disulphide bridges, ionic bonds, hydrophobic and hydrophilic bonds between R groups.

39
Q

What are the features and bonds present in a quaternary structure protein?

A

It has two more polypeptides joined together.
It has peptide and hydrogen bonds, disulphide bridges, ionic bonds, hydrophilic and hydrophobic bonds- not just between R groups.
Are either fibrous or globular proteins.

40
Q

Why is water a good habitat?

A
  • It is a solvent which means it can transports nutrients and waste products.
  • High specific heat capacity so it is a stable environment.
  • Cohesion and adhesion creates surface tension for insects to walk on water.
  • Most dense at 4 degrees c so can float.
41
Q

Why is water a good solvent?

A

The small molecules can surround each molecule of solvent. The delta negative atoms of the water are attracted to the delta positive components of the solute (and vice versa).

42
Q

Why is water a good transport medium?

A
  • Polar so can transport substances easily.
  • Cohesion and adhesion means it flows easily because they pull the next molecule along.
  • Low viscosity means it can flow easily.
43
Q

What two groups is a simple amino acid made from?

A

A basic amino group (2 H bonded to 1 N) and an acidic carboxyl group (1 OH bonded to a C and another O double bonded to the C)

44
Q

How do amino acids in plants and animals differ?

A

Plants manufacture aa from nitrate from soil and organic molecules from photosynthesis.
Animals can make non-essential aa but essential aa must come from diet.
Animals can’t store aa as the amino group makes them toxic- deamination occurs in the liver.

45
Q

How are dipeptides formed?

A

With a condensation reaction releasing a water molecule and forming a peptide bond.

46
Q

What is the role of enzymes in protein breakdown?

A

Covalent peptide bonds are strong and must be broken down by protease enzymes.

47
Q

How are lipids used by living organisms?

A

Membranes (E.g. the phospholipid bilayer).
Metabolic water for desert animals.
Hibernation- energy and warmth.
Hormones- steroids.
Buoyancy in large water animals.
Electrical insulation- myelin sheath.
Insulation for warmth (E.g. blubber)

48
Q

What is the structure of lipids?

A

Formed by condensation reactions between fatty acids and an alcohol.
At room temp solid is a fat and liquid is an oil.
Plants tend to store oils, not fats.

49
Q

What are triglycerides?

A

1 glycerol and 3 fatty acid molecules.
Less dense than water so can float.
Non-polar so don’t form H bonds with water so are hydrophobic and insoluble.
Many types of triglyceride.
Tail length varies according to fatty acid used.

50
Q

What is glycerol?

A

A simple molecule made from 3 carbon atoms joined to 3 OH groups.
The 3 OH groups can all condense with fatty acids.

51
Q

What are fatty acids?

A

Contains an acidic OH group.
Have a general formula of R.COOH where R is a hydrocarbon tail of various lengths.
Most have 14-22 carbon atoms.
The tail determines the fatty acid properties (E.g. it’s solubility).

52
Q

What is an unsaturated fatty acid?

A

Has a double bond between 2 carbons. Causes the structure to bend and become fluid.
Melt at a lower room temp- often liquid (E.g. Plant oils).

53
Q

What is esterification?

A

The hydroxyl group of the glycerol reacts with the carboxyl group of the fatty acid, leading to the formation of ester bonds.

54
Q

What are phospholipids?

A

When one of the fatty acids is replaced by a phosphate group (an OH group combines with phosphoric acid).
Molecule has a phosphate head and 2 fatty acid hydrocarbon tails.
Fatty acids tails are hydrophobic.
The phosphate head is charged and therefore polar and hydrophilic.
Often contains a molecule that is also hydrophilic.

55
Q

What is cholesterol?

A

Made of 4 C rings, unlike glycerol and fatty acids.
Found in all biological membranes.
Small and hydrophilic so can pass through the and sit between phospholipid tails in membranes.
Regulates membrane fluidity and strength.
Primarily made in the liver.

56
Q
A

Biology (3 decks)

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