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Chapter 25
Metabolism andEnergetics
replacement / repairrecycling / breakdowncell growth / divisionstore nutrientsspecial jobs (secretion/contraction,…)
chemical reactions:
the sum of all the chemical reactions taking place inan organism
(Cell)Metabolism
(a cell)
Catabolism
Anabolism
breakdown of organic substances(release energy)
synthesis of new organic substances
fig. 25-1
Cellular respiration
glucose + 02 H20 + CO2 + ATP
Cellular respiration
glycolysisTriCarboxylicAcid cycle (TCA)Electron Transport System (ETS)
3 subpathways:
3 subpathways
each individual stepeach chemical structurethe names of each enzyme
glucose glucose-6-phosphateglucokinase
+ ATP + ADP
3 subpathways
beginning and endnet gain for eachimportant intermediatesimportant byproductsother features ??
fig. 25-3
O2?
Glycolysis
breakdown glucose (C6)
produce 2 pyruvate (C3)net gain 2 ATP
2 NADH (coenzyme)
(anaerobic)
pyruvate
NAD andCoEnzyme A (CoA)
acetyl-CoA+ CO2
+ NADH
(x 2)
yield
irreversible
fig. 25-4
Tricarboxylic acid cyclecitric acid cycle
reb’s cycleoxaloacetate
fig. 25-4b
32
4 6
5
4
TCA yield
2 CO2
ATP3 NADH1FADH2
x 2
4 CO2
2 ATP6 NADH2 FADH2
cumm.yield
6 CO2
4 ATP8 NADH2 FADH2
2 NADH glycolysis
TCA
Electron Transport Systemand
Oxidative Phosphorylation(production of ATP using O2)
2 H2 + O2 2 H2O
Figure 25-5
Slide 5
cytochromes
fig. 25-6
Cellular respiration
glucose + 02 H20 + CO2 + ATP
glucose + 6 02 6 H20+ 6 CO2+ 36 ATP
Can cells produce glucose?
Yes, but…
not just “undoing” glycolysis
pyruvate acetyl-CoAirreversible
gly
coly
sis
glu
coneogenesis
fig. 2-15
fig. 2-15
fig. 2-15
fig. 2-15
C=CC C
H H
C=CC H
H C
cis-
trans-
beta oxidation
remove C-C fragmentsas acetyl-CoA
TCA cycle, ETS
16 ATP
18 C chain (stearic acid)
X
9 C-C fragments
16 ATPeach C-C
9 C-C fragmentseach 18 C chain
9 x 16 = 144 ATP 18 C fatty acid
18 C chain
9 x 16 = 144 ATP
x ?? ATP/glucose
3 X 36 = 108 ATP 18 C - glucose
18 C - fatty acid
36
= ? glucose molecules3
fig. 25-8
Lipid synthesis
acetyl-CoA many
cholestrol, steroids, …
Lipid synthesis
acetyl-CoA manyDHAP glycerol
fig. 25-3
Lipid synthesis
acetyl-CoA manyDHAP glycerolsome lipids are essential
we can’t make themwe have to ingest them
linoleic acid, linolenic acid
Lipid transport
(not soluble in H2O)
FFA (free fatty acids)
carried by albuminmost abundant blood plasma protein)
Lipid transportFFA (free fatty acids)
Lipoproteins -lipid-protein complexescoated by phospholipids
and protein
Classification: LDL’s HDL’s
Cholesterol:
is necessary
component of membranesprecursor for steroid hormonescan be made by our cells
but,…too much is unhealthyobtained from saturated fats
fig. 25-?
LDL low density lipoprotein
•contain cholesterol•carry it to peripheral tissues•If levels of cholesterol are
high is can accumulate in places like arterial walls
(atherosclerosis)
•transport excess cholesterolback to liver
HDL high density lipoprotein
Slide 10
fig 25-9b
factors affecting [cholesterol]
•genetics•age•physical condition•diet
< 200 mgdl
totalcholesterol
pg. 929
Protein metabolism
General info:
100,000 to 140,000linear arrays of amino acids20 different amino acids
(similarities)
O OHC |
H C N
amino acid
O OHC |
H C NH2
|R
amine
carboxylicacid
amino acid
variable
O OHC |
H C
amino acid
protein catabolism
NH2
Deamination
produces NH4+
(ammonium ion)
urea cycle
NH2H2N
C||O
2 NH3 + CO2
+H2O
Proteins and energy production
•more difficult to break up than carbohydrates or lipids
•byproduct (NH4+) is toxic
•they serve very important roles
fig. 25-10
PKU phenylketouria
Phe Tyr
phenylalaninehydoxylase
inborn errors of metabolism
PKU phenylketouria
PKU phenylketouria
Protein synthesis:
20 amino acids
10 we can “make” 8 we can’t “make” 2 we can’t “make” enough
Protein synthesis:
20 amino acids (aa’s)
10 non-essential 8 2
essential
protein deficiency
Nucleus
DNA mRNA protein
transcription translation
RNA polymeraserRNA, tRNAribosomes
nucleus cytoplasm
fig. 3-12 translation
to make proteins, all amino acids must be available
…protein deficiency diseases
If your diet is “short” any essential amino acids,…
pellagramarasmuskwashiorkor
kwashiorkor
low protein in blood (hypotonic)fluid moves into tissuesedema (swelling)
fig. 25-12
Nutrient requirement for different tissues is different:
liver:adipose tissue:
skeletal muscle:neural tissue:
other peripheral t.:
Nutrient requirement for different tissues is different:
liver:adipose tissue:
skeletal muscle:neural tissue:
other peripheral t.:
can do almost everything
make/break carbs, fats, proteins
Nutrient requirement for different tissues is different:
liver:adipose tissue:
skeletal muscle:neural tissue:
other peripheral t.:
stores triglycerides
Nutrient requirement for different tissues is different:
liver:adipose tissue:
skeletal muscle:neural tissue:
other peripheral t.:
stores glycogen
Nutrient requirement for different tissues is different:
liver:adipose tissue:
skeletal muscle:neural tissue:
other peripheral t.:must have steady supply of glucose[glucose] 100 mg/100 ml
(100 mg %)
Nutrient requirement for different tissues is different:
liver:adipose tissue:
skeletal muscle:neural tissue:
other peripheral t.:low reserves, but can use other molecules
interrelationship among “compartments”
absorptive state
postabsorptive state
following a meal~4 hours
must use internal reserves
postabsorptive state
(conserve glucose) liver breaks down lipids/aa
breakdown acetyl CoA
ketonebodies(ketosis)
blood pH(ketoacidosis)
carb restriction/starvationuncontrolled diabetes mellitus
Food pyramid and groups
guidelines fig. 25-13
proteins
complete contain all essential aa’s
incomplete deficient in at least one of the essential aa’s
nitrogen
found in:
each amino acid of every proteineach nucleotide of DNA and RNAcreatine (muscle cell energy)porphyrin (Hb)
nitrogen
We can‘t store it:
must be recycledor
ingested
nitrogen
balance:
more is being absorbedthan excreted
+
growth, pregnancy, atheltics
less is being absorbedthan excreted
-
dangerous
Minerals
inorganic ions
e.g., Na+, K+, Ca++, Cl-,
maintain osmotic concentrationsmaintain membrane potentialsco-factors in reactions
bulk (g/day) trace mg/day
Table 25-3
Table 25-4
Vitamins
fat soluble
water soluble
A, D, E, K
B’s, C, niacin, folic acid, biotin
Table 25-4
fat soluble
ADEK
visionabsorption of Ca, Ph (bone)
?blood clotting
Vitamins
Table 25-4
water soluble
B2
B5
niacinfolateC
FADacetyl-CoANADaa, nucleic acid metab.collagen synthesis
Vitamins
(coenzymes)
Table 25-5
too little
or
too much
Vitamins
water soluble?
fat solublevitamin toxicity
deficiencies
Energy
released when chemical bonds are broken
calorie
energy needed to raise 1 kg of H2O 1° C
Calorie(kilocalorie)
energy needed to raise 1 g of H2O 1° C
Energy
measure the number of Calories used:
metabolic rate
basal metabolic rateBMR
BMR
minimum amount of energy used by an awake, alert person
influenced by:
agegenesphysical conditionbody weight
BMR
how to measure?
O2 consumptionT4 assay
BMR
intake of energy(calories consumed)
Calories used(BMR, work)
weight = same
=
BMR
intake of energy
(calories consumed)
Calories used
(BMR, work)
weight = increase
>
BMR
intake of energy(calories consumed)
Calories used(BMR, work)
BMR
intake of energy(calories consumed) Calories used(BMR, work)
weight = decrease
<
Weight control
Calorie counting
and
Exercise
Appetite
complexpoorly understood
stretch receptors in guthormones (CCK, leptin)psychological, social, etc…
Thermoregulation
cellular respiration heat
98.6° F37° C
Thermoregulation
heat environment
radiationconductionconvectionevaporation
like heat from sun
transfer through contact
lose to air around body
cools surface
Thermoregulation
heat loss(to environment)
heat gain(from metabolism)
control centers in
hypothalamus
Thermoregulation
too warm? heat loss(to environment)
heat-loss center
peripheral vasodilationsweat gland secretionincrease respiration
Thermoregulation
too cool?
heat loss(to environment)
heat-gain center
prevent hypothermia
heat gain(from metabolism)
Thermoregulation
too cool?
heat loss(to environment)
vasoconstriction to peripherysuperficial versus deepcountercurrent exchange
fig. 25-14
Thermoregulation
too cool?
heat-gain center
shivering muscles produce heat
non-shivering hormones
heat gain(from metabolism)
epinephrine, TSH
Thermoregulation
infants
loose heat quicklycan’t shiverhave “brown” fat
Thermoregulation
fever (pyrexia)
temperature maintained at elevated level