cell metabolism
TRANSCRIPT
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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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CatabolicCatabolism 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 ReactionsMetabolic 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 RespirationOccurs in three series of reactions
1. Glycolysis2. Citric acid cycle3. Electron transport chainProduces
• 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 ETC—they 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 ETC’s found in each mitochondria, which can number in the 100’s 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
4-21
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Carbohydrate StorageExcess glucose stored as
• glycogen (primarily by liver and muscle cells)• fat• converted to amino acids
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Regulation of Metabolic Pathways
Turned off when their product is in
strong supply
Works by supply and demand
4-23
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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
PhenylketonuriaPKU
• enzyme that breaks down the amino acid phenylalanine is missing• build up of phenylalanine causes mental retardation• treated by diets very low in phenylalanine