BIOII Chapter 4: Cellular Metabolism
POWERPOINT OUTLINE
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4.1: Introduction Metabolic Processes:
All chemical reactions that occur in the body
There are two types of metabolic reactions:
Anabolism- Larger molecules are made from smaller ones- Requires energy
Catabolism- Larger molecules are broken down into smaller ones- Releases energy
Q1 GIVE AN EXAMPLE OF BOTH AN ANABOLIC AND CATABOLIC CHEMICAL REACTION
Anabolism
Anabolism provides the materials needed for cellular growth and repair
Dehydration Synthesis
Type of anabolic process - Produces water
Used to make polysaccharides, triglycerides, nucleic acids & proteins
Q2 DEHYDRATION SYNNTHESIS IS ALSO KNOWN AS? WHY?
Catabolism
Catabolism breaks down larger molecules into smaller ones
Hydrolysis: A catabolic process Used to decompose carbohydrates, lipids, and
proteins
Water is used to split the substances- Reverse of dehydration synthesis
4.3: Control of Metabolic Reactions
Enzymes Control rates of metabolic reactions
Lower activation energy needed to start reactions
Most are globular proteins with specific shapes Not consumed in chemical
reactions Substrate specific Shape of active site determines substrate
Q3 HOW DO ENZYMES LOWER ACTIVATION ENERGY?
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
Enzyme names commonly: Reflect the substrate Have the suffix – ase
Examples: sucrase, lactase, protease, lipase
Q4 WHAT DOES A PHOSPHORYLLASE DO?
Cofactors and Coenzymes
Cofactors - Make some enzymes active- Non-protein component
Ions or coenzymes- Coenzymes- Organic molecules that act as cofactors- Vitamins
Factors That Alter Enzymes
Heat
Electricity
Radiation
Chemicals
Q5 HOW DO HEAT AND pH ALTER ENZYME FUNCTION
Changes in pH
Regulation of Metabolic PathwaysLimited number of regulatory enzymes- Negative feedback
4.4: Energy for Metabolic Reactions
Energy is the capacity to change something; it is the ability to do work
Common forms of energy:
Heat
Electrical energy
Light
Mechanical energy
Sound
Chemical energy
ATP Molecules
Each ATP molecule has three parts:
When the bond is broken, energy is
An adenine molecule
transferred
A ribose molecule
When the bond is broken, ATP
Three phosphate molecules in a
becomes ADP
chain
ADP becomes ATP through
Third phosphate attached by highphosphorylation
energy bond
Phosphorylation requires energy
release from cellular respiration
Q6 DIAGRAM THE CONVERSION OF ATP TO ADP BELOW
4.5: Cellular Respiration - A Series Of
Reactions:
Glycolysis
“Prep” steps or intermediate steps
Citric acid cycle (aka TCA or
Kreb’s Cycle)
Electron transport system
Glycolysis
Series of ten reactions
Breaks down glucose into 2
pyruvic acid molecules
Occurs in cytosol
Cellular Respiration
Produces: Carbon dioxide, Water, ATP
(chemical energy), Heat
Includes:
Anaerobic reactions (without O2) produce little ATP
Aerobic reactions (requires O2) produce most ATP
Anaerobic phase of cellular
respiration
Yields two ATP molecules per
glucose molecule
NADH delivers hydrogen atoms to electron transport system if oxygen is available
ADP is phosphorylated to become ATP
Two molecules of pyruvic acid are produced
Two molecules of ATP are generated
Q7. WHERE DOES GLYCOLYSIS OCCUR?
Anaerobic Reactions
If oxygen is not available: FERMENTATION OCCURS
Electron transport system cannot accept new electrons from NADH
Pyruvic acid is converted to lactic acid
Glycolysis is inhibited
Q8 IN ANIMALS WHAT IS THE OUTPUT OF FERMENTATION?
Aerobic Reactions- If Oxygen Is Available:
Pyruvic acid is used to produce acetyl CoA
Citric acid cycle begins
Electron transport system functions
Carbon dioxide and water are formed
34 molecules of ATP are produced per each glucose molecule
Q9 GIVE 3 EXAMPLES OF HOW ATP IS USED TO DO CELLULAR WORK
Carbohydrate Storage
Carbohydrate Storage
Carbohydrate molecules from foods can
Excess glucose stored as:
enter:
Glycogen (primarily by liver and
Catabolic pathways for energy production
muscle cells)
Anabolic pathways for storage
Fat: Converted to amino acids
Q10 DIAGRAM GLYCOGEN IN THE ADJACENT SPACE
Summary of Catabolism of Proteins, Carbohydrates, and Fats
Q11 WHAT HAPPENS TO PROTEINS THAT ARE CATABOLIZED
4.6: Nucleic Acids and Protein Synthesis
Instruction of cells to synthesize proteins comes from a nucleic acid, DNA
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 –used to translate a sequence of nucleotides of DNA into a sequence of amino
acids
Q12 HOW MANY GENES DO HUMANS HAVE AND PRIMARILY WHAT IS THEIR FUNCTION
Structure of DNA
Two polynucleotide chains – double-stranded
Hydrogen bonds hold nitrogenous bases
together
Bases pair specifically (A-T and C-G)
Forms a helix
DNA wrapped about histones forms chromatin
Chromosomes are condensed chromatin
Animation: DNA Structure
DNA Replication
Hydrogen bonds break between bases
Double strands unwind and pull apart
New nucleotides pair with exposed
bases
Controlled by DNA polymerase
Q13 WHAT IS THE DIFFERENCE BETWEEN ADENOSINE AND ADENOSINE TRIPHOSPHATE
DNA Replication
Genetic Code- Specification of the correct sequence of amino acids in a polypeptide chain
Each amino acid is represented by a triplet code
RNA Molecules- single-stranded- ribose - uracil instead of thymine
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
Q14 WHAT ARE 3 MAJOR DIFFERENCES BETWEEN DNA AND RNA
RNA Molecules
Messenger RNA (mRNA):
Delivers genetic information from nucleus to the cytoplasm
Single polynucleotide chain
Formed beside a strand of DNA
RNA nucleotides are complementary to DNA nucleotides (exception – no thymine in RNA;
replaced with uracil)
How Translation Works -Protein Synthesis
The transfer RNA molecule for the last amino acid added holds the growing polypeptide
chain and is attached to its complementary codon on mRNA. A second tRNA binds
complementarily to the next codon, and in doing so brings the next amino acid into position
on the ribosome. A peptide bond forms, linking the new amino acid to the growing
polypeptide chain. The tRNA molecule that brought the last amino acid to the ribosome is
released to the cytoplasm, and will be used again. The ribosome moves to a new position at
the next codon on mRNA. A new tRNA complementary to the next codon on mRNA brings
the next amino acid to be added to the growing polypeptide chain.
Q15 RNA HAS THE ABILITY TO ACT LIKE AN ENZYME TO CATALYZE REACTIONS. GIVE
AN EXAMPLE
Nature of Mutations
Mutations – change in genetic information
Result when: Extra bases are added or
deleted
Bases are changed
May or may not change
the protein
Protection Against Mutation
Repair enzymes correct the
mutations
Inborn Errors of Metabolism
Occurs from inheriting a mutation
that then alters an enzyme
This creates a block in an
otherwise normal biochemical
pathway