Download some of Chapter 25

Chapter 25
Metabolism and
Energetics
chemical reactions:
replacement / repair
recycling / breakdown
cell growth / division
store nutrients
special jobs (secretion/contraction,…)
(Cell) Metabolism
the sum of all the chemical reactions
taking place in
(a cell)
an organism
Catabolism
breakdown of organic
substances
(release energy)
Anabolism
synthesis of new
organic substances
fig. 25-1
Cellular respiration
glucose + 02
H20 + CO2 + ATP
Cellular respiration
3 subpathways:
glycolysis
TriCarboxylicAcid cycle (TCA)
Electron Transport System (ETS)
3 subpathways
each individual step
each chemical structure
the names of each enzyme
glucokinase
glucose
+ ATP
glucose-6-phosphate
+ ADP
3 subpathways
beginning and end
net gain for each
important intermediates
important byproducts
other features ??
O2?
fig. 25-3
Glycolysis (anaerobic)
breakdown glucose (C6)
produce
net gain
2 pyruvate (C3)
2 ATP
2 NADH (coenzyme)
yield
NAD and
CoEnzyme A (CoA)
pyruvate
acetyl-CoA
irreversible
+ CO2
+ NADH
(x 2)
oxaloacetate
Tricarboxylic acid cycle
citric acid cycle
reb’s cycle
fig. 25-4
3
2
4
6
5
4
fig. 25-4b
TCA yield
2 CO2
ATP
3 NADH
1FADH2
4 CO2
2
ATP
x2
6 NADH
2 FADH2
cumm.
yield
6 CO2
4 ATP
8 NADH
2 FADH2
2 NADH
TCA
glycolysis
Electron Transport System
and
Oxidative Phosphorylation
(production of ATP using O2)
2 H2 + O 2
2 H2O
Slide 5
Figure 25-5
fig. 25-6
Cellular respiration
glucose + 02
glucose + 6 02
H20 + CO2 + ATP
6 H20 + 6 CO2 + 36 ATP
Can cells produce glucose?
Yes, but…
not just “undoing” glycolysis
pyruvate
acetyl-CoA
irreversible
glycolysis
gluconeogenesis
fig. 2-15
fig. 2-15
fig. 2-15
H
H
C=C
C
cis-
H
C
C
C=C
C
H
transfig. 2-15
beta oxidation
remove C-C fragments
as acetyl-CoA
TCA cycle, ETS
16 ATP
18 C chain (stearic acid)
9 C-C fragments
9 C-C fragments
each 18 C chain
9 x 16 = 144 ATP
X
16 ATP
each C-C
18 C fatty acid
18 C chain =3? glucose molecules
x 36
?? ATP/glucose
3 X 36 = 108 ATP
18 C - glucose
9 x 16 = 144 ATP
18 C - fatty acid
fig. 25-8
Lipid synthesis
acetyl-CoA
many
cholestrol, steroids, …
Lipid synthesis
acetyl-CoA
DHAP
fig. 25-3
many
glycerol
Lipid synthesis
acetyl-CoA
many
DHAP
glycerol
some lipids are essential
we can’t make them
we have to ingest them
linoleic acid, linolenic acid
Lipid transport
(not soluble in H2O)
FFA (free fatty acids)
carried by albumin
most abundant blood plasma
protein)
Lipid transport
FFA (free fatty acids)
Lipoproteins lipid-protein complexes
coated by phospholipids
and protein
Classification:
LDL’s HDL’s
Cholesterol:
is necessary
component of membranes
precursor for steroid hormones
can be made by our cells
but,…
too much is unhealthy
obtained 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)
HDL
high density lipoprotein
•transport excess cholesterol
back to liver
Slide 10
fig 25-9b
factors affecting [cholesterol]
•genetics
•age
•physical condition
•diet
total
cholesterol
<
200 mg
dl
pg. 929
Protein metabolism
General info:
100,000 to 140,000
linear arrays of amino acids
20 different amino acids
(similarities)
O
H
OH
C
|
C
N
amino acid
carboxylic
acid
O
OH
C
|
H C NH2
amine
|
R
variable
amino acid
protein catabolism
O
OH
C
|
H C NH2
amino acid
Deamination
produces NH4+
(ammonium ion)
O
||
C
urea cycle
2 NH3 + CO2
H2N
+H2O
NH2
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
inborn errors of metabolism
Phe
phenylalanine
hydoxylase
Tyr
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
essential
2
protein deficiency
Nucleus
rRNA, tRNA
ribosomes
RNA polymerase
DNA
mRNA
transcription
translation
nucleus
cytoplasm
protein
fig. 3-12
translation
to make proteins, all
amino acids must be
available
If your diet is “short” any essential
amino acids,…
…protein deficiency diseases
pellagra
marasmus
kwashiorkor
kwashiorkor
low protein in blood (hypotonic)
fluid moves into tissues
edema (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.:
[glucose] 100 mg/100 ml
(100 mg %)
must have
steady supply
of glucose
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
following a meal
~4 hours
postabsorptive state
must use internal reserves
postabsorptive state
(conserve glucose)
liver breaks down lipids/aa
breakdown
acetyl CoA
carb restriction/starvation
uncontrolled diabetes mellitus
blood pH
ketone
bodies
(ketoacidosis)
(ketosis)
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 protein
each nucleotide of DNA and RNA
creatine (muscle cell energy)
porphyrin (Hb)
nitrogen
We can‘t store it:
must be recycled
or
ingested
nitrogen
balance:
+
more is being absorbed
than excreted
growth, pregnancy, atheltics
-
less is being absorbed
than excreted
dangerous
Minerals
inorganic ions
e.g., Na+, K+, Ca++, Cl-,
maintain osmotic concentrations
maintain membrane potentials
co-factors in reactions
bulk (g/day)
trace mg/day
Table 25-3
Vitamins
fat soluble
A, D, E, K
water soluble
B’s, C, niacin, folic acid, biotin
Table 25-4
Vitamins
fat soluble
A
D
E
K
vision
absorption of Ca, Ph (bone)
?
blood clotting
Table 25-4
Table 25-4
Vitamins
water soluble
B2
B5
niacin
folate
C
(coenzymes)
FAD
acetyl-CoA
NAD
aa, nucleic acid metab.
collagen synthesis
Table 25-5
Vitamins
too little
or
deficiencies
water soluble
?
too much
fat soluble
vitamin toxicity
Energy
released when chemical
bonds are broken
calorie
energy needed to raise
1 g of H2O 1° C
Calorie
energy needed to raise
1 kg of H2O 1° C
(kilocalorie)
Energy
measure the number of
Calories used:
metabolic rate
basal metabolic rate
BMR
BMR
minimum amount of energy used
by an awake, alert person
influenced by:
age
genes
physical condition
body weight
BMR
how to measure?
O2 consumption
T4 assay
BMR
intake of energy
(calories consumed)
=
Calories used
weight = same
(BMR, work)
BMR
weight = increase
BMR
intake of energy
Calories used
(calories consumed)
(BMR, work)
BMR
weight = decrease
Weight control
Calorie counting
and
Exercise
Appetite
complex
poorly understood
stretch receptors in gut
hormones (CCK, leptin)
psychological, social, etc…
Thermoregulation
cellular respiration heat
98.6° F
37° C
Thermoregulation
heat environment
radiation
conduction
convection
evaporation
like heat from sun
transfer through contact
lose to air around body
cools surface
Thermoregulation
control centers in
hypothalamus
heat loss
heat gain
(to environment)
(from metabolism)
Thermoregulation
too warm?
heat loss
(to environment)
heat-loss center
peripheral vasodilation
sweat gland secretion
increase respiration
Thermoregulation
heat loss
(to environment)
too cool?
heat gain
heat-gain center
(from metabolism)
prevent hypothermia
Thermoregulation
heat loss
(to environment)
too cool?
vasoconstriction to periphery
superficial versus deep
countercurrent exchange
fig. 25-14
Thermoregulation
heat gain
too cool?
(from metabolism)
heat-gain center
shivering
non-shivering
muscles produce heat
hormones
epinephrine, TSH
Thermoregulation
infants
loose heat quickly
can’t shiver
have “brown” fat
Thermoregulation
fever (pyrexia)
temperature maintained at
elevated level