Exam 2: Lab 7 Digestive Enzymes

Question 1

What do enzymes do?

Answer 1

Proteins do work

Question 2

How do enzymes and substrates in solutions find each other?

Answer 2

random molecular collison

Question 3

how do enzymes and substrates interact?

Answer 3

enzymes + substrates E - S –> E + Product

1. enzymes + substrates
2. form and irriversibly form an enzyme substrate complex
3. would irreversible regenerate the enzyme and create some product

Question 4

What does it mean for an enzyme to be denatured

Answer 4

3-D shape has been changed

Question 5

Do denatured enzymes work?

Answer 5

No. Function is highly dependent on its shape.

Question 6

what can denature an enzyme

Answer 6

• high temperature

- pH

Question 7

Each enzyme has a temperature and pH optimum. What does this mean?

Answer 7

• Function optimally in that range

- outside of range, it will not function optimally

Question 8

Function of saliva

Answer 8

• to moisten food

- released by saliva: salivary amylase enzyme

Question 9

starch

Answer 9

• amylose

- enzyme break it down is amylase

Question 10

in order to absorb food from small intestine to blood

Answer 10

• must break it all the way down into its monomer subunit

- if not shit it out

Question 11

once food is swallowed:

Answer 11

pharynx to esophagus to stomach to small intestine to duodenum

Question 12

mouth has pH of?

stomach has pH of?

Answer 12

• mouth: rough pH of 7 (neutral)

- stomach: rough pH of 2 (acidic)

Question 13

amylase

Answer 13

• enzyme works well with pH of 7 (neutral)
• gets denatured in stomach pH 2 acidic
• gets released in small intestine by duodenum in pancreatic juice called pancreatic amylase

Question 14

function of stomach

Answer 14

• temporary storage of food

- no enzymes to breakdown sugar, fat,

Question 15

enzyme in stomach

Answer 15

• pepsin

Question 16

pepsin

Answer 16

• activated with low pH

- take big protein and it make it small protein, but not break all the way down to individual amino acids

Question 17

small intestines

Answer 17

• key to digestive system
• where vast majority of digestion and absorption occurs
• duodenum: 5% of s.i pancreatic juices released

Question 18

pancreatic juice

Answer 18

• enzymes

- all the enzymes that breakdown food stuff are in juice (pancreatic duct); including pancreatic amylase

Question 19

breakdown digestion:

Answer 19

• all the lipase (fat) and all the protease (protein) released into small intestine get digestion
• break down all other carbohydrates released in duodenum

Question 20

IKI result

- K iodine

Answer 20

• results for breakdown of starch (amylose)
• black original
• if positive breakdown: goes lighter
• if negative/no breakdown: black

Question 21

Benedict’s result for starch breakdown

Answer 21

• look for maltose
• orange positive = there was breakdown of starch
• light blue = no breakdown of starch

Question 22

5 ml amylose + 5 drops amylase (enzyme)
IKI:
Benedicts:

Answer 22

• IKI = dark brown to copper (positive for IKI/all starch broke down) in 6 min
• Benedict’s result = orange/maltose seen/breakdown of starch +)

Question 23

5 ml amylose + 1 drop HCl + 5 drops of amylase
IKI:
Benedicts:

Answer 23

• IKI = Black, no change, no breakdown of starch seen, HCl denatured enzyme
• Benedict’s = negative, no maltose seen, HCl denatured enzyme, no digestion occured

Question 24

5 ml amylose + 2 drop amylase

Answer 24

• IKI = dark purple to copper in 8 min; positive for breakdown; slower due to lower concentration of enzyme
• Benedict’s: positive complete breakdown but slower; saw maltose present

Question 25

5 ml amylose + 5 drop boiled amylase

Answer 25

• IKI = no breakdown, black all the way; temperature denatured enzyme
• Benedict’s = no breakdown, no maltose seen; no digestion occurred due to denatured enzyme

Question 26

5 ml cold amylase + 5 drop cold amylase

then after room temp

Answer 26

• IKI no break down occurred: all black due to cold slows enzymes down but doesn’t break it down
• after room temp:
  1. IKI = all sugar broken down; copper all the way
  2. Benedict’s = positive, saw maltose; cold slow enzyme down.

Question 27

Protein digestion experiment: with egg

- positive result

Answer 27

• 37 C = room temp
• 1 drop HCl
• 5 ml pepsin
• HCl (low pH) activates pepsin to break down protein in room temperature otherwise any changes from that, no breakdown occurs.
• if temp change 0 C
• if no enzymes (H20)
• if base added Na+OH
• If no HCl added (H20)