Cellular Metabolism

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Cellular Metabolism
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Introduction

• Cells are the site of metabolic reactions
• Maintain life
• Enzyme controls each of the reactions
• Specific type of protein

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Metabolic Reactions

• Anabolic building up larger molecules from
  smaller ones
• Materials for cell growth and repair
• Catabolic breakdown of larger molecules into
  smaller ones
• Release energy

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Anabolism

• Dehydration Synthesis -OH and H from separate
  molecules are removed forming H2O
• join sugar molecules into chains forming glycogen
• Triglycerides in adipose cells
• Proteins from amino acids
• Peptide bonds

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Dehydration Synthesis
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Catabolism

• Hydrolysis decomposes carbohydrates, lipids, and
  proteins
• Splits water molecules
• C12H22O11 H2O ? C6H12O6 C6H12O6
• Sucrose water glucose fructose
• Occurs during digestion
• Carbohydrates ? monosaccharides
• Fats ? glycerol fatty acids
• Proteins ? amino acids
• Nucleic acids ? nucleotides

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Hydrolysis
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Control of Metabolic Reactions

• Most reaction require energy and a temperature
  greater than the bodys
• Enzymes promote chemical reactions
• Proteins that lower activation energy
• Energy needed to begin a reaction
• Catalysts
• Never consumed ? exist in small quantities

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Enzymes

• Substrate particular chemical enzymes act on
• Catalaseenzyme hydrogen peroxidesubstrate
• Active Site site on an enzyme where substrate
  binds
• Lock and key
• Very specific

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Insulin Degrading Enzyme
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Enzyme Reaction

• ES? ES ? EP ? EP
• S Substrate
• E Enzyme
• P Product
• Reaction Rate increases with increased substrate
  concentration

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Factors that Alter Enzymes

• Denature protein structure fall apart and
  becomes nonfunctional
• Too high temperatures
• Radiation
• Electricity
• pH changes
• Certain chemicals
• Arsenic and Cyanides

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Denatured Enzyme
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Energy for Metabolic Reactions
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Energy

• The capacity to change or move matter
• Ability to do work
• Heat
• Light
• Sound
• Electrical energy
• Mechanical energy
• Chemical energy

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Release of Chemical Energy

• Chemical energy is held in bonds and released
  when bonds are broken
• Oxidation cell burning glucose
• Burning requires a large amount of energy to
  begin
• Enzymes lower the activation energy
• Most of the energy escapes as light or heat
• Carry molecules capture about half of the energy
• Remaining energy, heat, help maintain body
  temperature

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Glycolysis

• 1st step in cellular respiration
• Cytoplasm or cytosol
• Anaerobic Doesnt require oxygen
• Energy is used to synthesize 2 ATP
• 6-C glucose ?2 3-C pyruvic acid molecules

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Aerobic Pathway

• Requires oxygen
• Occurs in the mitochondria
• Products CO2 H2
• CO2 diffuses out the cell
• H2 combine with O2 to form H2O
• Produces more 34 ATP

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ATP vs. ADP

• ATP adenosine triphosphate
• 3 phosphates
• Fully charged battery
• Break last phosphate off ? release energy
• ADP adenosine diphosphate
• 2 phosphates
• Partially charged battery
• Energy phosphate ? store energy

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Metabolic Pathway

• Anabolic and catabolic reaction happen in
  particular sequence
• Enzymes that control the reaction rates must also
  act in a specific sequence
• Enzymes are positioned in the exact sequence as
  that of the reaction

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Pathways

• Carbohydrates cellular energy source
• Cellular respiration
• Glycolysis? Citric Acid Cycle? Electron Transport
  Chain
• Half of the energy(E) ? ATP remaining E? heat
• Lipid phospholipids, cholesterol, triglycerides
• 2x E gram per gram than carb. And protein
• Beta Oxidation form ketone bodies that can be
  used in the citric acid cycle
• Acetone

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Protein Pathway

• Amino acids are absorb and transported by the
  blood to cells
• Amino acids are reunited into cell parts
• Deamination amino acids have N removed
• Used in citric acid cycle
• By product urea
• liver

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Metabolic Pathways
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Nucleic Acids and Protein Synthesis
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Genetics

• In the nucleus, DNA is housed
• information from parent to child
• Gene
• instruction for proteins
• Enzymes and control metabolic processes

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Karyotype
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DNA Molecule

• Double Helix
• Nucleotides
• Sugar phosphate backbone
• Nitrogenous bases in the middle
• A,T,G,C
• 2 strands bonded by H-bonds
• A pairs with T, and G pairs with C
• One DNA molecule millions of base pairs long

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Genetic Code

• DNA specific nucleotide sequence
• Specifies a specific amino acid
• RNA molecules transfer information to cytoplasm

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RNA

• Single stranded
• Contain uracil instead of thymine
• Contain ribose instead of deoxyribose
• mRNA messenger, carries a copy of a single gene
• rRNA composes ribosomes
• tRNA transfers amino acids

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Protein Synthesis

• Transcription
• Single genes are coped into mRNA
• Sent into the cytoplasm to a ribosome

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Transcription
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Protein Synthesis

• Translation
• At ribosome, mRNA is read by codons, 3 bases
• Amino acids are brought to the ribosome by the
  tRNA
• Anticodons on the tRNA must match the codons on
  the mRNA
• mRNA UUA CGC AUC GAU
• tRNA AAU GCG UAG CUA
• Amino acid released from tRNA form a chain and
  then a protein

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DNA Synthesis

• Each cell needs a copy of DNA
• During interphase, the DNA is replicated
• The double helix unzip
• Hydrogen bonds break
• Bases are brought in to each strand
• Semiconservative each DNA molecule contains a
  new and an old strand of DNA

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DNA Replication