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Cellular Metabolism
Chapter 4
Introduction
Metabolism is many chemical reactionss Metabolism breaks down nutrients and
releases energy= catabolism Metabolism builds molecules to store
energy= anabolism
Anabolism
Eg. Dehydration synthesis
Anabolism
Peptide bonds link amino acids
Catabolism
Breaking larger molecules into smaller ones Eg: hydrolysis
Enzymes regulate all chemical reactions in cells
When a product is made Which product is made How much product is made How quickly the product is made
Enzyme Characteristics
Catalysts Reactions occur 1,000,000 times faster with
enzymes Not part of reaction
Not changed or affected by reaction Used over and over
Made of protein End in “-ase”
Enzyme and Substrate
DNA (Deoxyribonucleic acid)
Blue prints of enzymes Blueprints of proteins Deciphering genes, chromosomes, DNA.
How do they relate?
DNA
Genetic code This code instructs cells how to synthesize
enzymes and protein molecules. Portion of DNA with information for
making a particular protein is a GENE All of the DNA in a cell makes up the
genome
Human Genome
2% of the human genome encodes protein Rest controls when and where genes are
used Also many repetitive DNA sequences- we
don’t know what for. Completed in 2003
DNA replication
During cell division, DNA must be copied New cell receives a copy of the DNA
Bonds between base pairs of the double strands break
Review of Nucleic Acids
Contain C, H, O, N, P Function: energy carriers
ATP Function: genetic systems
DNA, RNA Determine what
proteins are made Structure: nucleotides
bonded together to form long chains
Nitrogen bases
RNA – 4 possible Adenine - A Cytosine - C Guanine - G Uracil – U
DNA – 4 possible Adenine – A Cytosine – C Guanine – G Thymine - T
Base Pairs
Nitrogen bases of the nucleotides occur in pairs Hold the 2 strands of DNA together
4 nitrogen bases in DNA Bonding is specific
A – T T – A C – G G – C
Sequence determines the order of amino acids in a protein
DNA Replication
DNA separates Each chain links itself to
DNA nitrogen bases Forms two new strands
of DNA
Protein Synthesis
HOW TO MAKE A PROTEIN? Need to find the correct order of amino
acids to build a protein.
Protein Synthesis - Transcription
DNA separates Each chain links itself to
RNA nitrogen bases (Transcription)
4 nitrogen bases in RNA Bonding is specific
A – U U – A C – G G – C
Forms a single strand of RNA
mRNA tRNA
Mutations may occur
RNA
Messenger RNA- carries the genes’ message out of the nucleus
Transfer RNA- correctly aligns amino acids to form proteins
Protein Synthesis - Translation
RNA “translates” genes’ messages
RNA moves out into cytoplasm mRNA binds to a
ribosome tRNA binds to specific
amino acids Carries them to mRNA
Amino acids bond together Form a protein
Summary of Replication, Transcription, Translation
Metabolism in Cells requires
Energy - ATP Aerobic respiration uses oxygen
Glucose enters cells Broken into smaller sugar molecules Occurs in cytoplasm
Yields 2 ATP These smaller sugar molecules are further metabolized
Enter mitochondria Series of chemical reactions yields 34 ATP
Aerobic Respiration
Metabolism in Body Cells (cont’d)
Anaerobic respiration occurs when oxygen is not present
Glucose enters cells Broken into smaller sugar molecules in cytoplasm
Yields 2 ATP
Fats and proteins are also used to make ATP
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