Transcript ATP

CHAPTER 4: CELL METABOLISM
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METABOLIC PROCESSES
all chemical reactions that occur in the body
Two (2) types :
Anabolism
• Larger molecules are
made from smaller
ones
• Requires energy
Catabolism
• Larger molecules are
broken down into smaller
ones
• Releases energy
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CONTROL OF METABOLIC REACTIONS
Enzymes
• Control rates
• Not consumed in chemical reactions
• Substrate specific:
Shape of active site determines substrate
Substrate molecules
Product molecule
Active site
Enzyme
molecule
(a)
Enzyme-substrate
complex
(b)
(c)
Unaltered
enzyme
molecule
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ENZYME ACTION
Metabolic pathways
• Series
of enzyme-controlled reactions leading to
formation of a product
• Each new substrate is the product of the
previous reaction
Substrate
1
Enzyme A
Substrate
2
Enzyme B
Substrate
3
Enzyme C
Substrate
4
Enzyme D
Product
• Enzyme names commonly reflect the substrate
• Have the suffix – ase
• Examples: sucrase, lactase, protease, lipase
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Cofactors
• Make some enzymes active
• Non-protein component
• Ions or coenzymes
Coenzymes
• Organic molecules that act as cofactors
• Vitamins
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FACTORS THAT ALTER ENZYMES
• Heat
• Radiation
• Electricity
• Chemicals
• Changes in pH
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RELEASE OF CHEMICAL ENERGY
• Chemical
bonds are broken to release
energy
• We burn glucose in a process called
oxidation (combustion)
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4.5: CELLULAR RESPIRATION
Occurs in a series of reactions:
1. Glycolysis
2. Citric acid cycle (TCA or Kreb’s Cycle)
3. Electron transport system
4. Produces ATP
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Includes:
• Anaerobic reactions (without O2) –
produce little ATP
• Aerobic reactions (requires O2) –
produce most of ATP needed
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SUMMARY OF CELLULAR RESPIRATION
Glycolysis
no O2
High-energy electrons (e–)
2 ATP
Glycolysis
Cytosol
6-C sugar  2 3-C sugars
2 ATP
1
Glucose
Pyruvic acid
Pyruvic acid
Citric Acid Cycle
2
High-energy electrons (e–)
CO2
Mitochondrion
Produces acetyl coenzyme A (CoA)
2 turns of cycle
3
2 ATP
O2
Acetyl CoA
Citric acid
Oxaloacetic acid
Citric acid
cycle
High-energy electrons (e–)
2 CO2
2 ATP
Electron Transport Chain
Electron
transport
chain
4
34 ATP formed
32–34 ATP
2e– and 2H+
O2
H2O
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SUMMARY OF
CATABOLISM
Breakdown of large
macromolecules
to simple molecules
Food
Proteins Carbohydrates Fats
Amino acids
Simple sugars
Glycerol Fatty acids
(glucose)
Glycolysis ATP
Pyruvic acid
Formation of
CoA and 2 ATP
Acetyl coenzyme A
Citric
acid
cycle
Complete oxidation,
production of most
of the ATP
CO2
ATP
High energy electrons carried
by NADH and FADH2
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Electron
transport ATP
chain
2e– and 2H+
–NH2
½ O2
H2O
Waste products
CO2
4.6: Nucleic Acids and
Protein Synthesis
• Genetic information – instructs cells how to
construct proteins; stored in DNA
• Gene – segment of DNA that codes for one protein
• Genome – complete set of genes
• Genetic Code – method used to translate a
sequence of nucleotides of DNA into a
sequence of amino acids
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TYPES OF RNA MOLECULES
Messenger RNA (mRNA):
Making of mRNA (copying of DNA) is transcription
Transfer RNA (tRNA):
• Carries amino acids to mRNA
• Carries anticodon to mRNA
• Translates a codon of mRNA into an amino acid
Ribosomal RNA (rRNA):
• Provides structure and enzyme activity for ribosomes
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4.7: CHANGES IN GENETIC INFORMATION
Only about 1/10th of one percent of the human
genome differs from person to person
Inborn Errors of Metabolism
• Occurs from inheriting a mutation that
alters an enzyme
• Creates a block in a biochemical pathway
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NATURE OF MUTATIONS
Mutations – change in genetic information
May or may not change the protein
Code for
glutamic
acid
Result when:
Repair enzymes:
correct mutations
P
T
P
S
Direction of “reading” code
• Extra bases are
added or deleted
• Bases are changed
P
P
S
A
S
C
P
S
(a)
T
S
T
P
Code for
valine
Mutation
C
S
(b)
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ANIMATION: HOW ENZYMES WORK
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ANIMATION: DNA STRUCTURE
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ANIMATION: DNA REPLICATION
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ANIMATION: STAGES OF TRANSCRIPTION
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ANIMATION: HOW TRANSLATION WORKS
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ANIMATION: PROTEIN SYNTHESIS
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