Human Bio Unit 1 - Enzymes

Question 0

Lock and key model

Answer 0

States that each enzyme’s active site is designed for one specific substrate and will only work with that one and no others

Question 1

How does an enzyme speed up a chemical reaction?

Answer 1

It breaks down the substrate

Lowers the activation energy required for the reaction of the product

Question 2

Induced fit model

Answer 2

States enzymes can slightly alter their active sites when needed to fit different substrates

Question 3

Alpha-1-antitrypsin

Answer 3

Inhibits the enzymes elastase and protease so they don’t damage the lungs

Question 4

Detecting glucose in urine

Answer 4

Use two enzymes, glucose oxidase and glucose peroxidase, and a colourless hydrogen-donor fixed on a strip

Strip is dipped into test solution (urine)

Colour develops if glucose is present

Used by diabetics as healthy people don’t have glucose in urine

Question 5

Glucose oxidase

Answer 5

Highly sensitive to low concentration of glucose

Highly specific because it only reacts with glucose

Catalysts the conversion of glucose to hydrogen peroxide

Question 6

Glucose peroxide

Answer 6

Catalyses reaction between colourless hydrogen-donor molecule and hydrogen peroxide

Question 7

Cause of lactose intollerance

Answer 7

Lactase deficiency

Lactose isn’t broken down and moves through body

Fermented in colon (large intestine) by bacteria

This causes the release of fatty acids and carbon dioxide

Question 8

Symptoms of lactose intolerance

Answer 8

Flatulence

Diarrhoea

Stomach cramps

Bloated stomach

Question 9

Acute pancreatitis

Answer 9

Reversible inflammation of the pancreas

Trypsin becomes active before it leaves the pancreas

Trypsin begins to hydrolyse the proteins that make up the pancreas and its cell membrane brakes down

Amylase and lipase escapes into blood stream

Question 10

Diagnosis of acute pancreatitis

Answer 10

Do a blood test

shows high levels of amylase and lipase in blood for up to 3 days

Question 11

Causes of acute pancreatitis

Answer 11

Gallstones

Alcohol

Scorpion bites

Trauma

Question 12

Chronic pancreatitis

Answer 12

Pancreas gradually loses it’s ability to produce digestive enzymes

Food is not digested and not absorbed (malabsorbtion)

Question 13

Diagnosing chronic pancreatitis

Answer 13

Normal levels of amylase and lipase

However low levels of elastase in faeces

Too much fat in faeces because it passes through the gut without being digested

Question 14

Treating pancreatitis

Answer 14

Pancreatic enzyme replacement therapy (PERT)

Required for life in patients with irreversible pancreatic damage (chronic, and cystic fibrosis sufferers)

Take a tablet that contains digestive enzymes that would normally be produced by the pancreas

Question 15

How does the tablet used in Pancreatic enzyme replacement therapy make sure it isn’t effected by the stomach acids too early?

Answer 15

Coated with protective layer

You take an extra tablet that inhibits stomach acid secretion

Question 16

Factors that effect enzyme-substrate reaction rate

Answer 16

pH

Temperature

Enzyme concentration

Substrate concentration

Question 17

How does pH effect enzyme-substrate reaction rate?

Answer 17

Has an optimum pH

High amount of H+ or OH- ions for particular enzyme will alter it’s active site

Small change is reversible

Large change is irreversible because it changes the ionic bonds in the tertiary structure

Question 18

How does temperature effect the enzyme-substrate reaction speed?

Answer 18

Optimum temperature gives it the most energy to move about, making it quicker and increasing chance of collisions

Too high a temperature causes the hydrogen bonds to break, changing the tertiary shape and making them denatured

Too low a temperature and they don’t have the kinetic energy to collide with substrate, will work again if the temperature is raised

Question 19

How does enzyme concentration effect enzyme-substrate reaction rate?

Answer 19

Increase of concentration causes increase of collisions and reaction rate

Plateaus when the concentration becomes too high because there will be active sites empty

Question 20

How does substrate concentration effect enzyme-substrate reaction rate?

Answer 20

If the concentration of enzymes is constant then an increase will cause an increase of collisions and reaction rate

Plateaus when it reaches point of saturation - where all enzymes are working to full capacity

Question 21

Buffers

Answer 21

Maintain constant pH

Soak up hydrogen ions

Stops change of pH when an acid/base is added

Question 22

Structure of enzymes

Answer 22

Tertiary globular proteins

Spherical or globular shape

Each different enzyme has its own sequence of amino acids (variant/R group)

Question 23

Define inhibit

Answer 23

Making something harder to happen

Question 24

Inhibition in enzymes

Answer 24

An enzymes action is slowed down or stopped

Another substance combines with the enzyme-substrate complex

Question 25

Types of inhibitor

Answer 25

Competitive

Non competitive

Question 26

Competitive inhibitor

Answer 26

Structurally the same as substrate

Competes with substrate to bind to active site

Binds to active site forever

Question 27

Non competitive inhibitor

Answer 27

Binds somewhere else than the active site so concentration of substrate doesn’t effect chances of binding

Alters the shape of the active site so substrate doesn’t fit

Question 28

Causes of chronic pancreatitis

Answer 28

Cystic fibrosis

Long term alcohol intake