Biological molecules Flashcards

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1
Q

what is an isomer

A

They have the same number of atoms but in a different arrangement

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2
Q

How are polysaccharides formed

A

Condensation reaction of two monosaccharides

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3
Q

STARCH

A

It is polysaccharide
Amylose - Straight chain of alpha glucose with alpha 1-4 glycosidic bonds - unbranched and is wound and wound into a helix due to hydrogen bonding
Amylopectin - Branched molecule - held togather by 1-4 glycosidic bonds and every 25th glucose molecule it has a alpha 1-6 glycosidic bond.

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4
Q

Describe the structure of a cellulose molecule and explain how cellulose is adapted
for its function in cells.

A
  1. made from β-glucose;
  2. joined by condensation / removing molecule of water / glycosidic bond;
  3. 1 : 4 link specified or described;
  4. “flipping over” of alternate molecules;
  5. hydrogen bonds linking chains / long straight chains;
  6. cellulose makes cell walls strong / cellulose fibres are strong;
  7. can resist turgor pressure / osmotic pressure / pulling forces;
  8. bond difficult to break;
  9. resists digestion / action of microorganisms / enzymes;
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5
Q

GLYCOGEN

A

It is a storage polysaccharide
Found mostly in the muscle and the liver
Branches more frequent than amylopectin
Polymer of alpha glucose

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6
Q

Properties of polymer

A
  1. Insoluble in water
  2. Osmotically inert
  3. Compact
    ( Not sweet and not crystallisation)
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7
Q

Lipids

A

Glycerol and three fatty acids
esterification
There are saturated and unsaturated fatty acids

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8
Q

Phospholipids

A

One of the fatty acids of the triglyceride is substituted by a phosphate containing group

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9
Q

functions of lipids

A

source of energy-
Insulation - poor conductors of heat and are stored in adipose tissue
Saltore connection- Speeds it up and is found in the mylein sheeth around axon and it is an electrical
indicator
Protection- surrounds our organs
Waterproofing- wax cuticle -lipids are insoluble in water and useful for waterproofing

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10
Q

Structure of Triglycerides

A

High ratio of energy storing carbon-hydrogen bonds to carbon atoms and excellent source of energy.
Have low mass to energy ratio, good storage molecules and stored in small volume - reduced mass for animals for movement
non-polar osmotically inert
Releases water when oxidised therefore prevent desiccation

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11
Q

Structure of Phospholipids

A

bi-layer due to hydophillic and hydrophobic end
Phospholipid structure and allows glycoprotiens to form by combing with carbohydrates and glycoprotiens are v.important in cell recognition.

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12
Q

Protiens

A

General structure L-R
Amine group, carbon hydrogen with r group, carboxyl group.
If the :
R=H - glycine
R= CH3 - alanine
R= CH2SH - cysteine
dipeptide - 2 amino acid and forms a peptide bond

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13
Q

Lipid TEST

A
  1. Dissolve in alcohol, then add water;

2. White emulsion shows presence of lipid.

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14
Q

The movement of the woodlice in low relative humidity is an advantage to their survival.
Explain how.

A

1.Low humidity results in more woodlice moving;
So increased movement increased chance of leaving dry / unfavourable
environment so reduce water loss / reduce evaporation;

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15
Q

Complete the table to show two ways in which the structure of a hemicellulose
molecule differs from the structure of a cellulose molecule.

A

hemicellulose shorter / smaller than cellulose / fewer carbons;
hemicellulose from pentose / five-carbon sugars and cellulose from
hexose / glucose / six-carbon sugars;

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16
Q

Use your knowledge of protein structure to explain why enzymes are specific and may be affected by non-competitive inhibitors. (5)

A
  1. each enzyme / protein has specific primary structure / amino acid sequence;
    2 folds in a particular way / has particular tertiary structure giving an active site with a unique structure;
    3 shape of active site complementary to / will only fit that of substrate; maximum of three marks for inhibition, points 5 - 8
    4 inhibitor fits at site on the enzyme other than active site;
    5 distorts active site;
    6 so substrate will no longer fit / form enzyme-substrate complex