Biological molecules q's

Question 1

name the covalent bond between 2 adjacent amino acids in a chain of amino acids

Answer 1

peptide bond

Question 2

name the type of reaction involved in breaking a bond and describe what happens in this reaction

Answer 2

hydrolysis
water is added

Question 3

describe how an enzyme , such as pepsin, breaks down a substrate

Answer 3

• substrate shape complementary to active site
• substrate fits into active site of enzyme
• induced fit
• forms ESC
• destabilising of bonds in substrate
• then forms enzyme-product complex
  -product leave active site

Question 4

a change to a procedure that would increase validity of an investigation

Answer 4

-equal vol (in each tube)
- add buffer

Question 5

student suggest to repeat investigation at least twice. how could this improve the investigation?

Answer 5

• improves reliability
• assess spread of results
• allows calculation of mean

Question 6

pepstatin acts as a competitive inhibitor of pepsin. What can you conclude about the structure of pepstatin

Answer 6

• similar shape to substrate
• complementary shape to part of active site

Question 7

what lipid contains only the elements C, H, O

Answer 7

Triglyceride
cholesterol

Question 8

what lipid is insoluble in water

Answer 8

triglyceride
phospholipid
cholesterol

Question 9

what lipid contains ester bonds

Answer 9

triglyceride
phospholipid

Question 10

what lipids is important in membrane structure

Answer 10

phospholipids
cholesterol

Question 11

describe how to do the emulsion test for lipids and how a positive result would be identified

Answer 11

• mix ethanol and water
• goes cloudy

Question 12

how might the lipid content of mycoprotein differ from food that comes from animals

Answer 12

less overall lipid
no saturated fat
more unsaturated fat

Question 13

feature of primary level of protein structure

Answer 13

peptode bonds

Question 14

features in secondary level not in primary level of protein structure

Answer 14

hydrogen bonds
the initial folding of the polypeptide chain

Question 15

features in tertiary level not 2nd, 1st of protein structure

Answer 15

• the overall 3D shape
• Ionic bonds

Question 16

features found only in quaternary level of protein structure

Answer 16

alpha and beta subunits

Question 17

describe the ofrmation of a hydrogen bond between two molecules of water and explain why water can form these bonds

Answer 17

• water is polar
• h bond formed between O and H of adjacent molecules
• between H delta +ve and O delta -ve

Question 18

why is the ability of water to act as a solvent important for the survival of organisms

Answer 18

• medium for metabolic reactions
• allows ionic compound to separate
• transport
• organisms can absorb minerals
• able to dilute toxic substances

Question 19

state the name given to the sequence of an amino acid in a protein molecule

Answer 19

primary structure

Question 20

draw a general structure of an amino acids molecule

Answer 20

H2NCHRCOOH

Question 21

State one property of collagen that makes it a useful component of blood vessel walls

Answer 21

strength
toughness
insolubility

Question 22

describe the structure of the collagen molecule

Answer 22

• peptide bonds between amino acids
• every 3rd amino acids is glycine
• coil/helix
• left- handed helix
• glycine allows closeness/twisting of polypeptide chains
• 3 polypeptie chains
• H bonds betwen polypeptide
• no hydrophilic groups on outside of molecule
• adjacent molecules joined by crosslinks
• crosslinks being staggered
• fibril

Question 23

state on function of haemoglobin

Answer 23

transport of O2

Question 24

Describe ways in which the strcuture of Hb differs from that of collagen (C)

Answer 24

• Hb contains a prosthetic group (haem), C doesnt
• Hb globular
• Hb hydrophoblic groups on inside/hydrophilic group on outside
• Hb 4 subunits
• Hb subuits are diff types
• Hb alpha helix
• Hb proportion of glycine similar to that of other amino acids