Cell mtblsm

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Cell Metabolism
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Cell Respiration (Metabolism)

• Cellular Respiration- is a metabolic process used
  to obtain energy from organic compounds or food
• can run under aerobic and anaerobic conditions.
• catabolic pathway.
• occurs in the cytoplasm and mitochondria
• 3 main steps Glycolysis and the Kreb Cycle, also
  known as the citric acid cycle and tricarboxylic
  acid cycle, and the ETC (electron transport chain)

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Cellular Metabolism
Metabolism all chemical reactions that occur in
the body
Two types of metabolic reactions
Anabolic

• Catabolic

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Goal of Cell Respiration-Make ATP
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Anabolic
Anabolism provides the substances needed for
cellular growth and repair

• Dehydration synthesis
• type of anabolic process
• used to make polysaccharides, triglycerides, and
  proteins- produces water

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Catabolic
Catabolism breaks down larger molecules into
smaller ones

• Hydrolysis
• used to decompose carbohydrates, lipids, and
  proteins
• water is used
• reverse of dehydration synthesis

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Control of Metabolic Reactions
Enzymes- all are proteins

• lower activation energy
• not consumed in chemical reactions
• substrate specific
• Controlled through feedback inhibition

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Do not make anything happen that could not happen
on its own Enzymes can be reused over and
over Same enzymes catalyses the forward and
reverse reactions. They are very specific
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Control of Metabolic Reactions

• Metabolic pathways
• series of enzyme-controlled reactions leading to
  formation of a product

• Enzyme names commonly
• reflect the substrate
• have the suffix ase
• sucrase, lactase, protease, lipase

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Control of Metabolic Reactions

• Cofactors
• make some enzymes active
• ions or coenzymes

• Coenzymes
• organic molecules that act as cofactors
• vitamins

• Factors that alter enzymes
• heat
• radiation
• electricity
• chemicals
• changes in pH

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Energy for Metabolic Reactions

• Energy
• ability to do work or change something
• heat, light, sound, electricity, mechanical
  energy, chemical energy
• involved in all metabolic reactions

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Cellular Respiration

• Occurs in three series of reactions
• Glycolysis
• Citric acid cycle
• Electron transport chain

• Produces
• carbon dioxide
• water
• ATP (chemical energy)
• heat

• Includes
• anaerobic reactions (without O2) - produce
  little ATP
• aerobic reactions (requires O2) - produce most
  ATP

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Glycolysis

• There are 10 steps and all require specific
  enzymes to catalyze them
• Goal- Produce pyruvate for use in the Krebs Cycle
• NADH used in ETC

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Citric Acid Cycle

• begins when acetyl CoA combines with oxaloacetic
  acid to produce citric acid
• citric acid is changed into oxaloacetic acid
  through a series of reactions
• cycle repeats as long as pyruvic acid and oxygen
  are available
• Makes 2 ATP 6 NADH and 2 FADH2
• BP- 4 CO2

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The Goal is the production of NADH and FADH2 for
use in the ETCthey are electron carriers
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ETC

• So far only 4 of the 38 ATP that will be produced
  have been, all by substrate level
  phosphorylation.
• The remaining will be produced by the ETC.
• The majority of the ATP produced comes from the
  energy carried in the electrons of NADH (and
  FADH2) that were produced by the Krebs Cycle. 6
  NADH and 2 FADH2
• The energy in these electrons is used in the ETC
  to power the synthesis of ATP.
• There are thousands of ETCs found in each
  mitochondria, which can number in the 100s
  depending on the cell type.

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Oxygen if the Final Electron AcceptorWhy do we
Breath??
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Summary of Catabolism of Proteins, Carbohydrates,
and Fats
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Carbohydrate Storage

• Excess glucose stored as
• glycogen (primarily by liver and muscle cells)
• fat
• converted to amino acids

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Regulation of Metabolic PathwaysTurned off when
their product is in strong supplyWorks by
supply and demand
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Nucleic Acids and Protein Synthesis
Gene segment of DNA that codes for one protein
Genome complete set of genes
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The Central Dogma

• It is all about Proteins!!!
• DNA contains the information needed to build
  these life giving proteins in a code on segments
  called genes.
• One gene can code for more than one protein?

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Structure of DNA

• two polynucleotide chains
• hydrogen bonds hold nitrogenous bases together
• bases pair specifically (A-T and C-G)
• forms a helix
• DNA wrapped about histones forms chromosomes

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RNA Molecules
mRNA rRNA tRNA
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Protein Synthesis (Transcription and Translation)

• 1st the DNA strand is used as a template to build
  a molecule of RNA called mRNA that can leave the
  nucleus taking the instructions for the protein
  to ribosome for assembly.
• 2nd during translation the information contained
  in the RNA molecule is used to determine the
  sequence of amino acids needed to build a
  protein.
• Order DNA - RNA protein - trait.

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Translation
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Overview Protein Synthesis
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DNA Replication
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Mutations
Mutations change in genetic information

• Result when
• extra bases are added or deleted
• bases are changed

May or may not change the protein
Some good some bad
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Clinical Application
Phenylketonuria PKU

• enzyme that breaks down the amino acid
  phenylalanine is missing
• build up of phenylalanine causes mental
  retardation
• treated by diets very low in phenylalanine