Download Chapter 7 Body Systems

Chapter 4
Cell Metabolism
B. Souto
Elsevier items and derived items © 2007, 2003, 2000 by Saunders, an imprint of Elsevier Inc.
Slide 1
Introduction

To carry on its functions, the cell must
metabolize its fuel ( raw material) : the CHO,
proteins, and fats.
Elsevier items and derived items © 2007, 2003, 2000 by Saunders, an imprint of Elsevier Inc.
Slide 2
Metabolism

Metabolism the series of chemical reactions
necessary for the use of raw material by the
cell to maintain life.

Anabolism: includes the chemical reactions
that build larger, more complex substances
from simpler substances. Requires an input
of ATP ( review pgs. 26-28)

Catabolism: includes those chemical
reactions that break down larger, more
complex substances into simpler substances.
Energy is released and captured as ATP.
Elsevier items and derived items © 2007, 2003, 2000 by Saunders, an imprint of Elsevier Inc.
Slide 3
Carbohydrates: Structure and
Function
Carbohydrates: classified according to
size and composed of:
1. Monosaccharides ( glucose is the
most important of the 3 –six carbon
simple sugars listed). Ribose and
deoxyribose and 5-carbon
monosaccharides used in the
synthesis of RNA and DNA.
2. Disaccharides ( must be)____ before
being absorbed across the walls of
the digestive tract and used by the
cells.
3. Polysaccharides ( see pg. 51).
Glucose is the
primary source of
energy.
Elsevier items and derived items © 2007, 2003, 2000 by Saunders, an imprint of Elsevier Inc.
Slide 4
Carbohydrates: Structure and
Function cont’d



Glucose can be burned and used immediately as
fuel for energy, stored as glycogen ( primarily in
the liver and skeletal muscle), and burned as fuel
at a later time, or stored as fat and burned as fuel
at a later time.
Glucose can be catabolized anaerobically and
aerobically. Anaerobically, glucose is incompletely
broken down (glycolysis) into lactic acid and
small amounts of ATP. Aerobically, glucose is
broken down completely (citric acid cycle) into
carbon dioxide (CO2) and water (H2O) and large
amounts of energy (ATP).
Glucose can be synthesized from nonglucose
substances such as protein (gluconeogenesis)
when BS gets ↓.
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The Kreb Cycle
Slide 5
Lipids

The most common lipids are triglycerides,
phospholipids, and steroids ( see Table 4-2).


Building blocks fatty acids and glycerol, they
are of an organic nature, longer chains and
have a more complex arrangement
Lipids are used primarily in the synthesis of
membranes ( cells and myelin sheath) and
steroids. A source of energy as well ( huge
amount of ATP).
Saturated vs. Unsaturated fats

The long chains of fatty acids are broken down
into two-carbon units and metabolized by the
enzymes of the citric acid (Krebs) cycle into CO2
and H2O, releasing large amounts of energy.

The extra donut eaten today is worn on your hip
tomorrow! What does this mean?

HDL vs. LDL
What is the correlation between DM and utilizing
of fats for glucose? See Case Study.
Elsevier items and derived items © 2007, 2003, 2000 by Saunders, an imprint of Elsevier Inc.
Slide 6
Protein


The most important organic matter in the body.
Why are proteins Essential to Life?

Participates in every body function.
 Almost every chemical reaction is regulated by
enzymes, which are proteins.
 Most hormones are proteins, Hgb, which delivers O2 to
every cell in the body, is a protein and muscles contract
because of contractile proteins.

Protein is composed of a series of amino acids
linked together by peptide bonds in a specific
sequence. Amino acids “AKA” building blocks of
proteins.

Amino acids (Table 4-3)

Essential amino acids (cannot be
synthesized)

Nonessential amino acids (can be
synthesized by the liver).
Elsevier items and derived items © 2007, 2003, 2000 by Saunders, an imprint of Elsevier Inc.
Slide 7
Protein


Non-essential amino acids are not VITAL to the
body? True or False? Explain.
Define: peptide bond, peptide and polypeptide.
Uses of Proteins:




Proteins are used primarily in the synthesis of
hormones, enzymes, antibodies, plasma
proteins, muscle proteins, hemoglobin, and cell
membranes.
 Proteins are also used as fuel and as raw
material for making glucose (gluconeogenesis).
This is done when BS levels can’t be
maintained by dietary CHO and glycogen
stores ( anorexia/starvations). Not preferred
source of fuel—Why?
There is special handling of protein nitrogen by the
urea cycle. Why?
What could happen if there’s hepatic dysfunction?
What is the significance of the following dx. tests:
BUN & Blood Ammonia level?
Elsevier items and derived items © 2007, 2003, 2000 by Saunders, an imprint of Elsevier Inc.
Slide 8
Protein Synthesis and DNA

DNA (deoxyribonucleic acid)

DNA stores the code for protein synthesis.

DNA is a double-stranded series of nucleotides,
arranged in a twisted-ladder formation.

A nucleotide is composed of a sugar, a phosphate
group, and a base. For DNA, the sugar is
deoxyribose, and the bases are adenine, thymine,
cytosine, and guanine.

The genetic code is stored in a sequence of three
bases.
Elsevier items and derived items © 2007, 2003, 2000 by Saunders, an imprint of Elsevier Inc.
Slide 9
Protein Synthesis
and DNA - cont’d
RNA

The structure of ribonucleic
acid (RNA) is similar to the
structure of DNA, with the
following differences: in RNA
the sugar is ribose; RNA is
single-stranded; and the
RNA bases are adenine,
uracil, cytosine, and guanine.

Two types of RNA include
messenger RNA (mRNA)
and transfer RNA (tRNA).
a. Transcription

Protein Synthesis: five steps
summarized in Figure 4-9.→
b. mRNA in nucleus  cytoplasm (ribosomes)
c. Translation
d. Formation of the peptide bond between the
amino acids
e. The completed protein leaves the ribosome
Elsevier items and derived items © 2007, 2003, 2000 by Saunders, an imprint of Elsevier Inc.
Slide 10
Disorders of Metabolism ( pg. 62)

How do anticancer
drugs affect protein
synthesis?

Misreading the
genetic code:
mutations/drugs

Defective genetic
code (e.g., PKU,
sickle cell anemia)
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Slide 11