Biological molecules

Question 1

what is a condensation, hydrolysis and polymerisation reaction ?

Answer 1

1) this is a process by which two molecules are joined together and a chemical bond is formed with removal of water.
2) the process by which a molecule is split and chemical bonds are broken with the addition of water.
3) process by which small monomers are joined together to form a polymer

Question 2

what are important biological properties of water

Answer 2

liquid solvent
density
cohesion and surface tension
high latent heat of vaporisation
high specific heat capacity

Question 3

what are carbohydrates?

Answer 3

group of molecules containing C, H and O only

Question 4

name the three hexose monosaccharide

Answer 4

glucose
frutose
galactose
all have C6H12O6 as formula

Question 5

name the type of bond formed when two monosaccharides reacts

Answer 5

1,4 or 1,6 glycosidic bonds

Question 6

name 3 dissaccharides

Answer 6

glucose + glucose= maltose
glucose+ fructose= sucrose
glucose + galactose= lactose

Question 7

describe the structure and function of starch

Answer 7

insoluble: no osmotic effect on cells
large: does not diffuse out of cells
- amylose
* 1,4 glycosidics bonds
- helix with intermolecular h-bonds=compact

amylopectin
-1,4 or 1,6 glycosidic bonds
branched= many terminal ends for hydrolysis into glucose

Question 8

describe the structure and function of glycogen

Answer 8

1,4 and 1,6 glycosidic bonds
branches =many terminal ends for hydrolysis
compact
insoluble

Question 9

describe the structure and function of cellulose

Answer 9

polymer of beta-glucose
straight chain and unbranched molecules
alternate glucose rotate 180

Question 10

test for lipids in a sample

Answer 10

• dissolve solid sample in ethanol
• add equal volume of water and shake
• positive result: milky white emulsion

Question 11

how are triglycerides formed?

Answer 11

condensation reaction between -COOH from fatty acids and -OH from glycerol

Question 12

difference between saturated and unsaturated fatty acid

Answer 12

saturated
-has no C=C 
-found in animal fat
-solid at room temp. high melting point
-straight chain molecules
unsaturated
-kinked molecules has fewer contact points
-found in plant oils
-liquid at room temp, lower melting points
-has C=C bonds

Question 13

related the structure of triglyceride to their function

Answer 13

• less dense than water=used for buoyancy
• insoluble hydrocarbon chains= it has no effect on -water potential of cells so it could be used as water proof
• slow heat conductor= thermal insulator

Question 14

describe the structure and function of phospholipids

Answer 14

amphilipathic molecule: glycerol + 2 hydrophobic fatty acids + 1 hydrophilic phosphate head.

• forms phospholipid bilayer in water =components of cell membrane
• tails can splay outwards=water proofing

Question 15

Compare phospholipid and triglycerides

Answer 15

• both have glycerol backbone
• both may be attached to a mixture of saturated, monounsaturated and polysaturated fatty acids.
• both contains C, H, O
• both formed by condensation reaction

Question 16

Contrast

Answer 16

Phospholipids

• 2 fatty acids, 1 phosphate group
• hydrophilic head and hydrophobic tail
• used primarily in membrane formation

Triglycerides

• 1 glycerol + 3 fatty acids
• entire molecule is hydrophobic
• used primarily as storage

Question 17

Are phospholipids and triglycerides polymers

Answer 17

No they aren’t made from small repeating units

They are macromolecules

Question 18

Why is water a polar molecule

Answer 18

Because O is more electronegative than H so it attracts electron density in the covalent bond more strongly

Question 19

Why us water important for organisms

Answer 19

• Solvent for polar molecules during metabolic reactions
• enables organism to avoid fluctuations in core temperatures
• cohesion-tension of water molecules are useful in transpiration stream

Question 20

What are inorganic ions and where are they found in the body?

Answer 20

These are ions that do not contain carbon atoms

•they are found in cytoplasm and extracellular fluids in high or low concentrations

Question 21

Explain the role of H+ ions in the body

Answer 21

Interacts with h-bonds and ionic bonds in tertiary structures of proteins which cause then to denatured

Question 22

Role if fe2+ in the body

Answer 22

Binds to porphyrin ring to form hae group in haemoglobin

Question 23

Explain the role of Na+ ions in the body

Answer 23

Helps in nervous transmission

Involved in regulation of osmotic pressure, control if water levels in body fluid

Question 24

Explain role of phosphate ions in the body

Answer 24

Component of DNA ATP NADP cAMP and phospholipids