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