chapter 25 metabolism and energetics. replacement / repair recycling / breakdown cell growth /...

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