Docsity
Docsity

Prepare for your exams
Prepare for your exams

Study with the several resources on Docsity


Earn points to download
Earn points to download

Earn points by helping other students or get them with a premium plan


Guidelines and tips
Guidelines and tips

Metabolism and Enzymes: Understanding the Flow of Energy in Living Organisms, Slides of Biology

Explore the role of metabolism and enzymes in converting food into energy, the importance of endergonic and exergonic reactions, and the mechanisms that regulate enzyme activity. Learn about the properties of enzymes, naming conventions, and the lock and key and induced fit models.

Typology: Slides

2012/2013

Uploaded on 01/30/2013

maalolan
maalolan 🇮🇳

4.5

(8)

123 documents

1 / 47

Toggle sidebar

This page cannot be seen from the preview

Don't miss anything!

bg1
Metabolism & Enzymes
Docsity.com
pf3
pf4
pf5
pf8
pf9
pfa
pfd
pfe
pff
pf12
pf13
pf14
pf15
pf16
pf17
pf18
pf19
pf1a
pf1b
pf1c
pf1d
pf1e
pf1f
pf20
pf21
pf22
pf23
pf24
pf25
pf26
pf27
pf28
pf29
pf2a
pf2b
pf2c
pf2d
pf2e
pf2f

Partial preview of the text

Download Metabolism and Enzymes: Understanding the Flow of Energy in Living Organisms and more Slides Biology in PDF only on Docsity!

Metabolism & Enzymes

From food webs to the life of a cell

energy

energy

energy

Metabolism

• Chemical reactions of life

  • forming bonds between molecules
    • dehydration synthesis
    • synthesis
    • anabolic reactions
  • breaking bonds between molecules
    • hydrolysis
    • digestion
    • catabolic reactions That’s why they’re called anabolic steroids!

Examples

 dehydration synthesis (synthesis)

 hydrolysis (digestion)

H 2 O

H 2 O

enzyme

enzyme

Chemical reactions & energy

• Some chemical reactions release energy

  • exergonic
  • digesting polymers
  • hydrolysis = catabolism

• Some chemical reactions require

input of energy

  • endergonic
  • building polymers
  • dehydration synthesis = anabolism

digesting molecules= LESS organization= lower energy state

building molecules= MORE organization= higher energy state

Endergonic vs. exergonic reactions

exergonic endergonic

**- energy released

  • digestion**
    • energy invested
    • synthesis

- ∆ G

G = change in free energy = ability to do work

+ ∆ G

What drives reactions?

• If reactions are “downhill”, why don’t they just

happen spontaneously?

  • because covalent bonds are stable bonds Why don’t stable polymers spontaneously digest into their monomers?

starch

Activation energy

• Breaking down large molecules requires

an initial input of energy

– activation energy

– large biomolecules are stable

– must absorb energy to break bonds

cellulose (^) energy CO2 + H 2 O + heat

Reducing Activation energy

• Catalysts

  • reducing the amount of energy to start a reaction Pheeew… that takes a lot less energy!

reactant

product

uncatalyzed reaction

catalyzed reaction

NEW activation energy

Catalysts

• So what’s a cell got to do to reduce

activation energy?

– get help! … chemical help… ENZYMES

∆ G

Call in the ENZYMES!

Enzymes vocabulary

substrate

  • reactant which binds to enzyme
  • enzyme-substrate complex: temporary association

product

  • end result of reaction

active site

  • enzyme’s catalytic site; substrate fits into active site

substrate

enzyme

products

active site

Properties of enzymes

• Reaction specific

  • each enzyme works with a specific substrate
    • chemical fit between active site & substrate
      • H bonds & ionic bonds

• Not consumed in reaction

  • single enzyme molecule can catalyze thousands or more reactions per second - enzymes unaffected by the reaction

• Affected by cellular conditions

  • any condition that affects protein structure
    • temperature, pH, salinity

Lock and Key model

  • Simplistic model of enzyme

action

  • substrate fits into 3-D structure of enzyme’ active site - H bonds between substrate & enzyme
  • like “key fits into lock”

In biology… Size doesn’t matter… Shape matters!

Induced fit model

• More accurate model of enzyme action

  • 3-D structure of enzyme fits substrate
  • substrate binding cause enzyme to change shape leading to a tighter fit - “conformational change” - bring chemical groups in position to catalyze reaction