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POWERPOINT® LECTURE SLIDE PRESENTATION
by LYNN CIALDELLA, MA, MBA, The University of Texas at Austin
Additional text by J Padilla exclusively for Physiology 31 at ECC
UNIT 1
4
Energy and
Cellular Metabolism
HUMAN PHYSIOLOGY
AN INTEGRATED APPROACH
DEE UNGLAUB SILVERTHORN
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FOURTH EDITION
Enzymes: Types of Reactions
Types
1. Oxidation-reduction
Description
Energy extraction
+/- electrons or H+
2. Hydrolysis-dehydration Breakdwon/synthesis
+/- water
3. Addition-subtraction+/- or exchange
exchange
function groups to
substrates
4. Ligation
Joins molecules using
ATP
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Chemical Reactions: Overview
Activation energy is the
energy that must be put
into reactants before a
reaction can proceed
A+BC+D
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Figure 4-3
Enzymes: Speed Up Reactions
Enzymes lower the activation energy of reactions
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Figure 4-8
Enzymes: Overview
 Speed up the rate of reactions- they reduce the
activation energy making easier for a reaction to
occur. They may also perform reactions that would
not otherwise take place.
 Isozymes
 Catalyze same reaction but under different conditions such as in different tissue cells
 May be activated, inactivated, or modulated
 Proenzymes and zymogens are synthesized as inactive
and undergo proteolytic reactions to activate
 Coenzymes  usually vitamins, are needed for proper
function, can carry atoms removed at the active site
 Chemical modulators, temperature, and pH also affects
enzyme activity
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ENZYMES
 Metabolism is defined as the many chemical reactions that occur in
organisms
 Few metabolic reactions occur without the assistance of enzymes
 Enzymes are made up of proteins and have the following
characteristics
 They function at an optimal pH and Temperature
 They are denatured or deactivated if exposed to extreme pH and
temperature
 They only bind a specific molecule
 They only perform one specific reaction
 While they change the reactants into new products enzymes
themselves are not changed during a reaction
 They can be re-used multiple times
 They may be permanently or temporarily inhibited
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The Enzyme Substrate Complex
 Enzymes can be recycled
 This is a key characteristic of enzymes
Substrate
(sucrose)
1 Enzyme
available with
empty active site
2 Substrate binds
Active site
to enzyme
Enzyme
(sucrase)
Fructose
Glucose
4 Product
are released
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3
Substrate is
converted to
products
Figure 5.9
Cofactors and competitive Inhibition
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Figure 2-19
Allosteric Modulation
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Figure 2-20a
Physical Regulators
 Temperature- each protein has a adequate temperature for it’s
function. Outside of the range it may be denatured of inactivated.
 pH- each protein has a adequate temperature for it’s function. Outside of
the range it may be denatured of inactivated.
 Concentration of protein –amounts in body vary over time to
control physiological processes
 Up-regulation – programmed production of protein
 Down regulation – programmed removal of protein
 Concentration of ligand – determines the magnitude of the
reponse if the protein concentration is the same.
 Reaction rates – speed up as ligand concentration increases up
until saturation is reached.
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A Review of DNA & RNA Structure

Nucleic Acids are ____? What does DNA stand for? How does DNA compare
to RNA? Why is RNA needed?
Cap
End
Tail
Start of genetic message
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Visual Summary
3.3
Figure 10.17
Nucleotides, DNA, and RNA
 Nucleotides are the monomers of nucleic acids.
 DNA and RNA have different nucleotides .
 In DNA A –T and C-G pair up. There is no pairing in RNA but RNA
nucleotides pair up with DNA nucleotides
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Synthesis: Protein
The major
steps required
to convert the
genetic code of
DNA into
a functional
protein are
done by
enzymes
We have20
different amino
acids made
from 4
nitrogenous
bases
Gene
1 GENE ACTIVATION
Regulatory proteins
Constitutively
active
Regulated
activity
Induction
Repression
2 TRANSCRIPTION
mRNA
3 mRNA PROCESSING
Alternative
splicing
siRNA
Interference
mRNA “silenced”
Processed
mRNA
Nucleus
• rRNA in ribosomes
• tRNA
• Amino acids
4 TRANSLATION
Cytoplasm
Protein chain
5 POST-TRANSLATIONAL
MODIFICATION
Folding and
cross-links
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Cleavage into
smaller peptides
Addition of groups:
• sugars
• lipids
• —CH3
• phosphate
Assembly into
polymeric
proteins
Figure 4-24
Transcription and Translation
 What is the language of
nucleic acids?
 In DNA, it is the linear
sequence of nucleotide
bases
 When DNA is transcribed,
the result is an RNA
molecule
 RNA is then translated into
a sequence of amino acids
in a polypeptide
 Triplets of bases are called
codons and they specify all
of the amino acids
DNA molecule
Gene 1
Gene 2
Gene 3
DNA strand
Transcription
RNA
Translation
Codon
Polypeptide
Amino acid
Figure 10.10
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The Genetic Code
 The genetic code is the set of rules relating nucleotide sequence to amino
acid sequence
 Use the RNA sequence in codons to determine the corresponding amino
acid
Figure 10.11
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Synthesis: Protein
Gene
1 GENE ACTIVATION
Constitutively
active
Regulatory proteins
Regulated
activity
Induction
Repression
2 TRANSCRIPTION
mRNA
Nucleus
Cytoplasm
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Figure 4-24, steps 1–2
Synthesis: Protein
Gene
1 GENE ACTIVATION
Regulatory proteins
Constitutively
active
Regulated
activity
Induction
Repression
2 TRANSCRIPTION
mRNA
3 mRNA PROCESSING
Alternative
splicing
Processed
mRNA
siRNA
Interference
mRNA “silenced”
Nucleus
Cytoplasm
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Figure 4-24, steps 1–3
Synthesis: Protein
Gene
1 GENE ACTIVATION
Regulatory proteins
Constitutively
active
Regulated
activity
Induction
Repression
2 TRANSCRIPTION
mRNA
3 mRNA PROCESSING
Alternative
splicing
Processed
mRNA
siRNA
Interference
mRNA “silenced”
• rRNA in ribosomes
• tRNA
• Amino acids
4 TRANSLATION
Nucleus
Cytoplasm
Protein chain
5 POST-TRANSLATIONAL Folding and Cleavage into Addition of groups: Assembly into
MODIFICATION
• sugars
cross-links smaller peptides
polymeric
• lipids
proteins
• —CH3
• phosphate
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Figure 4-24, steps 1–5
Protein: Transcription
 Transcription
factors bind and
activate promoter
region
RNA
polymerase
RNA
nucleotides
 RNA polymerase
binds and
“unwinds” DNA
 mRNA created
from sense strand
 mRNA is processed
by
 RNA
interference
Newly made
RNA
 Alternative
splicing
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Direction of
transcription
Template
strand of DNA
Figure
10.13a
RNA polymerase
DNA of gene
 Transcription of an
entire gene
Promoter
DNA
Initiation
Terminator
DNA
 Three stages
 Initiation of
transcription
RNA
Elongation
Area shown
in part (a)
 Elongation of
RNA Strand
 Termination of
transcription
Termination
Growing
RNA
Completed RNA
(b) Transcription of a gene
RNA
polymerase
Figure 10.13b
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The Processing of Eukaryotic RNA
DNA
 The eukaryotic cell
processes the RNA after
transcription
 RNA processing
includes
Cap
RNA
transcript
with cap
and tail
Tail
Introns removed
Exons spliced together
 Adding a cap and tail
 Removing introns
Transcription
Addition of cap and tail
mRNA
 Splicing exons together
Coding sequence
Nucleus
Cytoplasm
Figure 10.14
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Translation: The Players
 Translation is the conversion from the nucleic acid
language to the protein language
 There are three types of RNA
 mRNA is messenger RNA, it is created during
transcription
 tRNA is transfer RNA it carries the amino acid and an
anticodon
 rRNA is ribosomal RNA, it forms the units of the
ribosome
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Transfer RNA (tRNA)
 tRNA
Amino acid attachment site
 Acts as a molecular
interpreter
 Carries amino acids
 Matches amino acids
with codons in mRNA
using anticodons
Hydrogen bond
RNA
polynucleotide
chain
Anticodon
Anticodon
Figure 10.15
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Ribosomes
 Ribosomes
 Are organelles that
actually make
polypeptides
 Are made up of
two protein
subunits
Next amino acid
to be added to
polypeptide
Growing
polypeptide
 Contain ribosomal
RNA (rRNA)
tRNA
mRNA
 A fully assembled
ribosome holds
tRNA and mRNA
for use in translation
(b)
Figure 10.16b
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Intiation of Translation
 Translation is divided into
three phases
 Initiation
 Elongation
 Termination
 The first phase brings
together
 The mRNA
 The first amino acid with
its attached tRNA
 The two subunits of the
ribosome
Met
Initiator
tRNA
mRNA
Start codon
1
Small ribosomal
subunit
Large ribosomal
subunit
A site
Initiation
 The process of initiation is
the assembly stage and is
signaled by the codon AUG
that matches the anticodon
UAC
P site
2
Figure 10.18.1
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Formation of a polypeptide chain
Amino acid
 The process of
elongation
 The anticodon of an
incoming tRNA pairs
with the mRNA codon
Polypeptide
P site
Anticodon
mRNA
A site
Codons
 The ribosome catalyzes
bond formation
between amino acids
1 Codon recognition
Elongation
 A tRNA leaves the P
site of the ribosome
2 Peptide bond formation
 The ribosome moves
down the mRNA
New peptide
bond
mRNA
movement
3 Translocation
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Figure 10.19
Termination
RNA Polymerase
1 Transcription
Nucleus
RNA
transcript
DNA
Elongation
continues until
the ribosome
reaches a stop
codon
The stop codon
signals all the
pieces that come
together at
initiation to
disassemble
The end result is
a polypeptide
Intron
2 RNA processing
Amino acid
CAP
Tail
mRNA
Intron
Enzyme
3 Amino acid attachment
Ribosomal
subunits
4 Initiation of translation
Stop codon
Anticodon
Codon
6 Termination
Elongation
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Protein: Transcription and Translation
DNA
1 Transcription
2
mRNA
processing
RNA
polymerase
Nuclear
membrane
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Figure 4-27, steps 1–2
Protein: Transcription and Translation
DNA
1 Transcription
2
mRNA
processing
RNA
polymerase
Nuclear
membrane
3 Attachment of
ribosomal subunits
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Figure 4-27, steps 1–3
Protein: Transcription and Translation
DNA
1 Transcription
2
mRNA
processing
RNA
polymerase
Nuclear
membrane
Amino acid
tRNA
4 Translation
Growing peptide
chain
Incoming tRNA
bound to an
amino acid
Lys
Asp
3 Attachment of
ribosomal subunits
Outgoing
“empty” tRNA
Phe Trp
Anticodon
mRNA
AA G A C C
G AU UU C UG G A A A
Ribosome
Each tRNA molecule attaches at one end
to a specific amino acid. The anticodon of
the tRNA molecule pairs with the appropriate
codon on the mRNA, allowing amino acids to be
linked in the order specified by the mRNA code.
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Figure 4-27, steps 1–4
Protein: Transcription and Translation
DNA
1 Transcription
2
RNA
polymerase
mRNA
processing
Nuclear
membrane
Amino acid
tRNA
4 Translation
Growing peptide
chain
Incoming tRNA
bound to an
amino acid
Lys
Asp
Outgoing
“empty” tRNA
3 Attachment of
ribosomal subunits
Phe Trp
Anticodon
mRNA
AA G A C C
G AU UU C UG G A A A
Ribosome
mRNA
5 Termination
Ribosomal
subunits
Completed
peptide
Each tRNA molecule attaches at one end
to a specific amino acid. The anticodon of
the tRNA molecule pairs with the appropriate
codon on the mRNA, allowing amino acids to be
linked in the order specified by the mRNA code.
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Figure 4-27, steps 1–5
Protein: Post-Translational Modification
 Protein folding
 Creates tertiary
structure
 Cross-linkage
 Strong covalent
bonds  disulfide
 Cleavage
 Addition of other
molecules or groups
 Assembly into
polymeric proteins
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