Proteins 1

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Globular proteins

• Usually water soluble, compact, roughly spherical
• Hydrophobic interior, hydrophilic surface
• Globular proteins include enzymes,carrier and
  regulatory proteins

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Fibrous proteins

• Provide mechanical support
• Often assembled into large cables or threads
• a-Keratins major components of hair and nails
• Collagen major component of tendons, skin,
  bones and teeth

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Water-fearing amino acids

• Hydrophobic
• water fearing amino acids
• try to get away from water in cell
• the protein folds

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Its shape that matters!

• Proteins do their jobs, because of their shape
• Unfolding a protein destroys its shape
• wrong shape cant do its job
• unfolding proteins denature
• temperature
• pH (acidity)

unfoldeddenatured
folded
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1. Primary Structure Polypeptide chain
2. Secondary Structure a. ? Helix
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1. Primary Structure Polypeptide chain
2. Secondary Structure a. ? Helix
b. ? Pleated sheet
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Enzymes Helper Protein molecules
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Chemical reactions of life

• Processes of life
• building molecules - ANABOLIC
• Synthesis
• breaking down molecules - CATABOLIC
• digestion

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Its shape that matters!

• Lock Key model
• shape of protein allows enzyme substrate to fit
• specific enzyme for each specific reaction

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Examples of Classification of Enzymes

• Oxidoreductoases
• oxidases - oxidize ,reductases reduce
• Transferases
• transaminases transfer amino groups
• kinases transfer phosphate groups
• Hydrolases
• proteases - hydrolyze peptide bonds
• lipases hydrolyze lipid ester bonds
• Lyases
• carboxylases add CO2
• hydrolases add H2O

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• Apoenzyme the protein part of an enzyme.
• Cofactor a nonprotein portion of an enzyme that
  is necessary for catalytic function examples are
  metallic ions such as Zn2 and Mg2.
• Coenzyme a nonprotein organic molecule,
  frequently a B vitamin.

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• Enzyme activity a measure of how much a reaction
  rate is increased.
• The rate of an enzyme-catalyzed reaction is
  effected by
• Enzyme concentration
• Substrate concentration
• Temperature
• pH

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• The effect of enzyme concentration on the rate of
  an enzyme-catalyzed reaction. Substrate
  concentration, temperature, and pH are constant.

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• The effect of substrate concentration on the rate
  of an enzyme-catalyzed reaction. Enzyme
  concentration, temperature, and pH are constant.

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• The effect of temperature on the rate of an
  enzyme-catalyzed reaction. Substrate and enzyme
  concentrations and pH are constant.

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• The effect of pH on the rate of an
  enzyme-catalyzed reaction. Substrate and enzyme
  concentrations and temperature are constant.

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• Inhibition any process that makes an active
  enzyme less active or inactive.
• Competitive inhibitor any substance that binds
  to the active site of an enzyme thereby
  preventing binding of substrate.
• Noncompetitive inhibitor any substance that
  binds to a portion of the enzyme other than the
  active site and thereby inhibits the activity of
  the enzyme.

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• Enzyme kinetics in the presence and absence of
  inhibitors.

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General Outline
Glucose
Glycolysis
No Oxygen Anaerobic
Oxygen Aerobic
Pyruvic Acid
Transition Reaction
Fermentation
Krebs Cycle
ETS
36-38 ATP
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Steps A fuelmolecule is
energized,using ATP.
Glucose
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3
Step
Glycolysis
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Glucose-6-phosphate
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Fructose-6-phosphate
Energy In 2 ATP
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Fructose-1,6-diphosphate
Step A six-carbonintermediate splits into
two three-carbon intermediates.
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Glyceraldehyde-3-phosphate (G3P)
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Step A redoxreaction generatesNADH.
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1,3-Diphosphoglyceric acid(2 molecules)
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Steps ATPand pyruvic acidare produced.
3-Phosphoglyceric acid(2 molecules)
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Energy Out 4 ATP
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2-Phosphoglyceric acid(2 molecules)
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2-Phosphoglyceric acid(2 molecules)
NET 2 ATP
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Pyruvic acid
(2 moleculesper glucose molecule)
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Transition Reaction
Each pyruvic acid molecule is broken down to
form CO2 and a two-carbon acetyl group, which
enters the Krebs cycle
Pyruvic Acid
Acetyl CoA
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Krebs Cycle Where? In the Mitochondria What?
Uses Acetyl Co-A to generate ATP, NADH, FADH2,
and CO2.
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Reduction and Oxidation OILRIG Gain
or loss of electrons is often in the form of
hydrogen. The hydrogen is then passed to a
coenzyme such as NAD
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Reduction and Oxidation What are some common
cofactors? NAD and FAD
NAD 2 H ? NADH H
FAD 2 H ? FADH2
Remember that H 2 electrons and 2H
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Coupling of Ox and Phos

• The overall reactions of oxidative
  phosphorylation are
• Oxidation of each NADH gives 3 ATP.
• Oxidation of each FADH2 gives 2 ATP.

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Cellular Respiration uses oxygen and glucose to
produce Carbon dioxide, water, and ATP.
Glucose
Oxygen gas
Carbon dioxide
Water
Energy
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Mitochondrion
Double membrane, cristae invaginations of
inner membrane
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Reduction and Oxidation As the electrons move
from carrier to carrier, energy is released in
small quantities.
Electron transport system (ETS)
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Krebs Cycle
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Electron Transport System
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Electron Transport System
For each glucose molecule that enters cellular
respiration, chemiosmosis produces up to 38 ATP
molecules
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Generation of ATP Chemiosmosis
Cells use the energy released by falling
electrons in the ETS to pump H ions across a
membrane Uses the enzyme ATP synthase.
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Review Cellular Respiration

• Glycolysis 2 ATP (substrate-level
  phosphorylation)
• Krebs Cycle 2 ATP
  (substrate-level phosphorylation)
• Electron transport oxidative phosphorylation
  2 NADH (glycolysis) 6ATP
  2 NADH (acetyl CoA) 6ATP 6 NADH
  (Krebs) 18 ATP 2 FADH2 (Krebs) 4
  ATP
• 38 TOTAL ATP/glucose