Respiration

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1

catabolic reaction

which break down large chemicals and release energy

2

anabolic reaction

which build up large chemicals and require energy

3

regulation

the steady-state of the internal environment is known homeostasis and includes regulation by hormones and the nervous system

Irritability is the ability to respond to a stimulus and is part of the regulation.

4

the net reaction of glycolysis

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5

the net reaction of citric acid cycle

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6

Pyruvate degradation can proceed

under anaerobic condition, pyruvate is reduced

Under aerobic condition, pyruvate oxidized in mitochondria

7

Alcohol fermentation

Only in yeast and some bacteria

Pyruvate is converted to ethanol

8

Lactic acid formation

In certain fungi and bacteria and in human muscle cells during strenuous activity.

NAD is regenerated and is used in step 5

9

Cellular respiration

36-38 ATPs are produced

Oxygen is the final acceptor pof electrons

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Stages of the cellular respiration

  1. Pyruvate decarboxylation
  2. The citric acid cycle
  3. Electron transport chain
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Pyruvate decaeboxylation

Pyruvate is decarboxylated in mitochondria ( it loses CO2)

NAD is reduced to NADH

Acetyl group is transferred to coenzyme A to form Acrtyl-CoA

12

Coenzyme A

Coenzyme A is a derivative of pantothenic acid (a B vitamin)

13

Citric acid cycle

Acetyl-CoA(2C) combines with oxaloacetate(4C) to form six carbon citrate

2ATP is produced by substrate-level phosphorylation via GTP intermediate

2acetyl-CoA + 6NAD + 2FAD + 2GDP + 2Pi + 4H2O >>>> 4CO2 + 6NADH + 2FADH2 + 2GTP + 4H + 2CoA

2GTP>>> 2ATP

14

Electron transport chain (ETC)

Occurs on the inside of the inner mitochondrial membrane

During oxidative phosphorylation, ATP is produced when high-energy potential electrons are transferred from NADH and FADH2 to oxygen by a series of carrier molecules located in the inner mitochondrial membrane.

15

Cytochrome

Electron carriers that resemble hemoglobin in the structure of their active site.

The functional unit contains a central iron atom that is capable of undergoing a reversible redox reaction.

16

Carriers mechanism

Electrons are transferred from one carrier to the next, each carrier is reduced as it accepts an electron and is then oxidized when it passes it on to the next carrier.

17

O2 acceptor

2H* + 2e- + 1/2O2>>>> H2O

The last carrier of ETC passes its electron to the final electron acceptor, O2

In addition to electrons, O2 picks up a pair of hydrogen ions from the surrounding medium, forming water

18

Pump of hydrogen

  1. Series of protein complexes (cytochromes) in the cristae of the mitochondria
  2. Electrons are passed through the cytochromes and lose energy
  3. This energy is used to pump hydrogen ions from the matrix to the intermembrane space.
  4. As the hydrogen ions pass through channels in the respiratory enzymes,the energy created used to convert ADP to ATP.
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Number of ATP production

1.Glycolysis

Net 2ATP, 2NADH × 2ATP/NADH. = 6ATP

2. Pyruvate decarboxylation

2 NADH × 3 ATP/NADH = 6 ATP

3. Citric acid

6 NADH × 3ATP/NADH, 2 FADH2 × 2ATP/FADH2, 2GTP × 1ATP/ GTP = 24.

TOTAL 36 ATP

4 ATP is produced by substrate

20

alternate energy source : Carbohydrate

Disaccharides are hydrolyzed into monosaccharides, can convert glucose or glucose intermediate

Glycogen stored in the liver can be converted , when needed, into a glycolytic intermediate

21

alternate energy source : Fat

fat molecules are stored in adipose tissue in the form of triglycerides.

When needed, they are hydrolyzed by lipases to fatty acids and glycerol and carry by blood to other tissues for oxidation.

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How Glycerol enters to glycolysis

Glycerol can be converted into PGAL, a glycolytic intermediate

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How fatty acid enters to glycolysis

Fatty acid must first be activated in the cytoplasm, this process requires two ATP.

ONCE ACTIVATED, it is transported into the mitochondrion and taken through a series of beta-oxidation cycle that convert it into two-carbon fragments which are then converted into acetyl-CoA that can enters the citric acid cycle.

With each round of beta-oxidation of a saturated fatty acid, one NADH and one FADH2a are generated.

24

Fat and glycogen

The amount of glycogen stored in humans is enough to meet the short-term energy needs of about a day

The stored fat reserves can meet the long-term energy needs for about a month.

25

Proteins

The body degrates proteins only when not enough carbohydrate or fat is available.

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Transamination reaction

Most amino acid undergo a transamination reaction in which they lose an amino group to form an alpha-keto acid. The carbon atoms of most amino acids are converted into acetyl-CoA, pyruvatw or one of the intermediate of the citric acid cycle.

These intermediates enter their respective metabolic pathways, allowing cells to produce fatty acids, glucose, or energy in the form of ATP

27

Oxidation deamination

Removes an ammonia molecule from the amino acid.

Ammonia is a toxic substance in vertebrates. Fish can excrete ammonia,whereas insects and birds convert it to uric acid, and mammal convert it to urea for excretion.

28

energy is stored in ATP as high-energy bonds

created by the covalent bonding of three phosphates to adenosine, the hydrolysis of ATP to ADP releases inorganic phosphate and 7 Kcal, hydrolysis of ADP to AMP release additional 7 Kcal