+ All Categories
Home > Documents > Enzymes A cell’s toolbox (Ch 6.4). progress of reaction low high energy content of molecules...

Enzymes A cell’s toolbox (Ch 6.4). progress of reaction low high energy content of molecules...

Date post: 18-Jan-2016
Category:
Upload: reginald-hicks
View: 219 times
Download: 0 times
Share this document with a friend
Popular Tags:
18
Enzymes A cell’s toolbox (Ch 6.4)
Transcript
Page 1: Enzymes A cell’s toolbox (Ch 6.4). progress of reaction low high energy content of molecules products reactants activation energy without catalyst activation.

EnzymesA cell’s toolbox (Ch 6.4)

Page 2: Enzymes A cell’s toolbox (Ch 6.4). progress of reaction low high energy content of molecules products reactants activation energy without catalyst activation.

progress of reactionlow

high

energycontent

ofmolecules

products

reactants

activation energywithout catalyst

activation energywith catalyst

Page 3: Enzymes A cell’s toolbox (Ch 6.4). progress of reaction low high energy content of molecules products reactants activation energy without catalyst activation.

• An enzyme is a protein that

• catalyzes a chemical reaction in living cells.

• is not consumed in the reaction.

Page 4: Enzymes A cell’s toolbox (Ch 6.4). progress of reaction low high energy content of molecules products reactants activation energy without catalyst activation.

Enzyme structure

allostericregulatory site

Many enzymes have bothactive sites and allostericregulatory sites.

Page 5: Enzymes A cell’s toolbox (Ch 6.4). progress of reaction low high energy content of molecules products reactants activation energy without catalyst activation.

3 Substrates, bondedtogether, leave enzyme;enzyme ready for newset of substrates.

active siteof enzyme

enzyme

1 Substrates enteractive site in aspecific orientation.

2 Substrates and activesite change shape,promoting reactionbetween substrates.

Page 6: Enzymes A cell’s toolbox (Ch 6.4). progress of reaction low high energy content of molecules products reactants activation energy without catalyst activation.

Lactase

Lactose (milk sugar) is a

disaccharide.

Lactase breaks lactose down into two

monosaccharides, which can be absorbed in the

small intestine.

Page 7: Enzymes A cell’s toolbox (Ch 6.4). progress of reaction low high energy content of molecules products reactants activation energy without catalyst activation.

Why would the genetic “error” causing lactose tolerance (the ability to drink milk all your life) be selected for in some parts of the world and not in others?

Page 8: Enzymes A cell’s toolbox (Ch 6.4). progress of reaction low high energy content of molecules products reactants activation energy without catalyst activation.

Amylase

Amylase breaks ________ (amylose)

apart into monosaccharides

Iodine turns black when ______ is

present. How does the test in this picture

demonstrate amylase activity?

Page 9: Enzymes A cell’s toolbox (Ch 6.4). progress of reaction low high energy content of molecules products reactants activation energy without catalyst activation.

Pepsin Pepsin is a protease which breaks apart _______ chains into

smaller chains or single _____ ______.

Page 10: Enzymes A cell’s toolbox (Ch 6.4). progress of reaction low high energy content of molecules products reactants activation energy without catalyst activation.

allostericregulatormolecule

An allosteric regulatormolecule causes the activesite to change shape, so thesubstrate no longer fits.

Allosteric inhibition

A competitive inhibitor moleculeoccupies the active site andblocks entry of the substrate.

Competitive inhibition

Enzyme regulation

Page 11: Enzymes A cell’s toolbox (Ch 6.4). progress of reaction low high energy content of molecules products reactants activation energy without catalyst activation.

Regulation controls enzyme pathways.

If one enzyme in the chain were missing, could the end product, G, be made?

If Product G came from another source, such as from consumed food, what would be its effect on

this system?

Page 12: Enzymes A cell’s toolbox (Ch 6.4). progress of reaction low high energy content of molecules products reactants activation energy without catalyst activation.

Regulation may be through competitive or non-competitive inhibition.

Page 13: Enzymes A cell’s toolbox (Ch 6.4). progress of reaction low high energy content of molecules products reactants activation energy without catalyst activation.

MTHFR gene: methylenetetrahydrofolate reductase

enzyme.

Located on the p arm of chromosome 1 in humans, this gene codes for an enzyme involved in the methylation of folic acid, a necessary B vitamin. Methylated (folate) and non-methylated (folic acid) forms are found in leafy greens, beans, and whole grains.

Page 14: Enzymes A cell’s toolbox (Ch 6.4). progress of reaction low high energy content of molecules products reactants activation energy without catalyst activation.

MTHFR is just one enzyme among many that convert certain nutrients into usable forms

and convert waste into non-toxic forms.

Page 15: Enzymes A cell’s toolbox (Ch 6.4). progress of reaction low high energy content of molecules products reactants activation energy without catalyst activation.

• Lack of the MTHFR enzyme causes buildup of homocysteine and/or folic acid, which can cause damage to the heart, blood vessels, and thyroid over time.

• Homocysteine is normally converted to glutathione, one of the body’s chief antioxidants. People with a defective MTHFR enzyme lose the protection of this important antioxidant.

More information on the MTHFR gene on:

•http://www.stopthethyroidmadness.com/mthfr/

•http://ghr.nlm.nih.gov/gene/MTHFR

Page 16: Enzymes A cell’s toolbox (Ch 6.4). progress of reaction low high energy content of molecules products reactants activation energy without catalyst activation.

pH influences enzyme activity

enzymeactivity

acidic

pepsin

salivaryamylase

basicpH

If you ate a lot of antacids, could that affect your digestion? Why?

Page 17: Enzymes A cell’s toolbox (Ch 6.4). progress of reaction low high energy content of molecules products reactants activation energy without catalyst activation.

enzymeactivity

Enzyme activityincreases

temperature

Maximum activity atoptimal temperature.

High temperaturesdistort enzymestructure.

Temperature influences enzyme activity

What is one reason why high fevers can be dangerous?

Page 18: Enzymes A cell’s toolbox (Ch 6.4). progress of reaction low high energy content of molecules products reactants activation energy without catalyst activation.

Recap

• Enzymes are proteins that catalyze chemical reactions in living systems.

• Each enzyme does one job, but does that job over and over again. This is referred to as enzyme specificity.


Recommended