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Biology Year 12 > 3.1 Biological Molecules > Flashcards

3.1 Biological Molecules Flashcards

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1
Q

What is a monomer ?

A

The smaller units from which larger molecules are made.

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2
Q

What is a Polymer?

A

Molecules made from a large number of monomers joined together.

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3
Q

What is a condensation reaction?

A

Joins two molecules together with the formation of a chemical bond and the elimination of a water molecule

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4
Q

What is a hydrolysis reaction ?

A

Breaks a chemical bond between two molecules and involves the use of a water molecule.

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5
Q

What is a monosaccharide?

A

The monomers from which larger carbohydrates are made

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6
Q

What type of bond forms between two monosaccharides during a condensation reaction

A

Glycosidic bond

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7
Q

What is a disaccharide

A

Formed by the condensation reaction of two monosaccharides

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8
Q

What is a polysaccharide?

A

Formed by the condensation of many glucose units

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9
Q

What does glucose + glucose make

A

Maltose

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10
Q

What does glucose + galactose make

A

Lactose

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11
Q

What does glucose + fructose make

A

Sucrose

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12
Q

What is the test for starch?

A

1) Small sample of food is placed on a spotting tile
2) Drop of iodine solution is added
3) If the food sample turns from orange to blue-black , starch is present

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13
Q

What are the features of starch

A
  • Made from alpha glucose monomer
  • 1-4 glycosidic bonds in amylose
  • 1-6 glycosidic bonds in amylopectin
  • It’s a store of glucose
  • It’s found in plant cells (chloroplast)
  • Amylose = unbranched helix
  • Amylopectin = branched molecule
  • Helix can compact to a fit a lot of glucose in small spaces.
  • Branched structure increases surface area for rapid hydrolysis back into glucose .
  • Insoluble so won’t affect water potential
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14
Q

What are the features of cellulose ?

A
  • Made from beta glucose
  • 1-4 glycosidic bonds
  • Provides structure for cell wall
  • Found in cell wall of plants.
  • Long , straight chains
  • Held in parallel by H+ bonds to form fibrils and micro fibrils
  • Many hydrogen bonds provide collective strength
  • Insoluble so won’t affect water potential
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15
Q

What are the features of glycogen ?

A
  • Made from alpha glucose
  • 1-6 glycosidic bonds
  • Store of glucose
  • Found in animals in the muscle and liver cells
  • A highly branched molecule
  • Branched increases surface area for rapid hydrolysis back into glucose.
  • Insoluble so won’t affect water potential
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16
Q

What are the two types of lipids .

A

Phospholipids and triglycerides

17
Q

What are some roles of lipids

A

Insulation e.g thermal insulation
Energy
Waterproofing - insoluble in water
Protection

18
Q

What is a saturated bond

A

Contains Only one single carbon bond

19
Q

What is an unsaturated bond

A

Contains double carbon , carbon bonds

20
Q

What happens to,unsaturated fatty acids

A

The double bond causes the molecule to bend . Therefore cannot pact closely together so they’re liquid at room temperature

21
Q

What is the structure of a triglyceride

A

Three fatty acids combined with a glycerol
Each fatty acid forms an ester bond with glycerol in a condensation reaction
Fatty acid = RCOOH

22
Q

What are properties of triglycerides relating to its structure

A
  • High ratio of energy storing carbon hydrogen bonds to carbon atoms so it’s an excellent source of energy
  • Low mass to energy ratio so it’s a good storage molecule
  • Insoluble in water so doesn’t affect water potential
  • Release water when oxidised therefore provide an important source of water
23
Q

What is the structure of a phospholipid ?

A

One of the fatty acid molecules is replaced by a phosphate molecule
It has 2 fatty acids , one phosphate and one glycerol
Has a hydrophilic head which is attracted to water
Has a hydrophobic tail which orients itself away from water
Polar molecules

24
Q

What are the properties of phospholipids relating to its structure

A

Polar - form a bilayer within cell surface membranes
Hydrophilic phosphate heads help to hold at the surface of the cell surface membranes
Phospholipid structure allows to form glycolipids by combining with carbohydrates within the cell surface membrane
Glycolipids are important in cell recognition

25
Q

What is the test for lipids

A

1) take a completely dry test tube
2) to 2cm^3 of the sample being tested , add 5c ^3 of ethanol
3) shake the tube thoroughly to dissolve any lipid in the sample
4) Add 5cm^3 of water and shake gently
5) A milky - white emulsion indicates presence of a lipid

26
Q

What is an amino acid

A

Monomers from which proteins are made

27
Q

What bond forms between 2 amino acids in a condensation reaction

A

Peptide bonds

28
Q

How are dipeptides formed

A

Condensation reaction of two amino acids

29
Q

How are polypeptides formed

A

Condensation reaction of many amino acids

30
Q

What is the primary structure of protein

A

The sequence of amino acids in a polypeptide chain forms the primary structure of any protein. These are connected by peptide bonds

31
Q

What is the secondary structure of protein

A

Form weak bonds called hydrogen bonds
This causes the long polypeptide chain to be twisted into a 3D shape , alpha helix .
NH group is positive
C=O group is negative

32
Q

Properties of hydrogen bonds in protein

A

Between slightly positive hydrogen and another slightly negative atom e.g oxygen
Numerous but easily broken

33
Q

What are the properties of ionic bonds in protein structure

A

Between negative carboxyl groups and positive amino groups that aren’t involved in peptide bonds
Weaker than disulfide bonds but easily broken by changes in PH

34
Q

What are the properties of disulfide bridges bonds in proteins

A

Between sulphur atoms
Fairly strong and not easily broken

35
Q

What is the tertiary structure of proteins

A

An alpha helix pc the secondary protein structure can be twisted and folded to give a more complex 3D structure

36
Q

WhT is the quaternary structure of a protein

A

Combination of a number of different polypeptides chains and associated non protein groups into a large complex protein molecule e.g. haemoglobin

37
Q

What is the test for proteins

A

1) Place a sample of the solution to be tested in a test tube and add an equal volume of sodium hydroxide solution at room temperature
2) Add a few drops of Buiret reagent to the sample
3) A purple or,lilac coloration indicates presence of a protein
If no change , solution remains blue

38
Q

What is the test for reducing sugars

A

1) Add 2cm^3 of the food sample to be tested in a test tube , if it’s not in a liquid grind it up in water
2) Add an equal volume of Benedict’s reagent
3) Heat up mixture in a gently boiling water bath for 5 minutes

39
Q

What is the test for non reducing sugars

A

1) if solution doesn’t change colour , add another 2cm^3 of food sample to 2cm^3 of HCl and place in a boiling water bath for 5 mins
2) Slowly add some sodium hydrogen carbonate solution to the condensation test tube to neutralize the acid
3) retest resulting solution with Benedict’s reagent and in a boiling water bath for 5 mins
4) if non reducing sugar was present , solution should turn orange to brown

Biology Year 12 (6 decks)

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