16. Energy Generation in Mitochondria and Chloroplast

Question 1

Cells require a constant supply of energy

Two basic reactions responsible for life:

Answer 1

• Photosynthesis
• Oxidative Catabolism

Question 2

Photosynthesis

Answer 2

6CO₂ + 6O₂ ——> C₆H₁₂O₆ + 6O₂

• Uses energy from sunlight to reduce carbon from atmospheric CO₂ to sugar
• O₂ produced as a by-product

Question 3

Oxidative Catabolism

Answer 3

C₆H₁₂O₆ + 6O₂ ——> 6CO₂ + 6H₂O

• Oxidizes carbon from sugar to release energy to power metabolism
• CO₂ produced as a by-product.

Question 4

ATP

Answer 4

main source of energy for many reactions in cells in eucaryotes ATP produced.

• during glycolysis ( small amount)
• in mitochondria ( most of ATP production)
• in chloroplast ( plants and green algae

Question 5

The process of ATP production-

Answer 5

chemiosmotic coupling - in mitochondria and chloroplast, in cell membrane of many bacteria

Question 6

Breakdown of food

Answer 6

Digestion

Question 7

Digestion-

Answer 7

Enzymatic hydrolysis of macromolecules digestive tract/organelles.

Question 8

Digestion

Glycolysis

Answer 8

• partial oxidation of glucose to pyruvate in the cytosol
• does not require oxygen
• basis of anaerobic metabolism

Question 9

Digestion

Citric Acid Cycle

Answer 9

In the matrix of mitochondria

-requires oxygen

Question 10

digestion

oxidative Phosphorylation

Answer 10

• driven by electron transport across the inner mitochondrial membrane
• generates ATP
• requires oxygen

Question 11

Glycolysis

Answer 11

Partial oxidation of glucose (6 carbon) to pyruvate ( 3 Carbon)

• does not require oxygen
• occurs in steps- allow energy to be efficiently captured
• Production of ATP and NADH

Question 12

Net results of glycolysis

Answer 12

2 molecules of pyruvate

2 molecules of ATP

2 molecules of NADH

Question 13

Oxidation of Pyruvate

in mitochondrial matrix

Answer 13

Pyruvate —> acetyl CoA + CO₂

Sources of pyruvate:

Yglycolysis

Yamino acids

Question 14

A, B, C-

Answer 14

pyruvate dehydrogenase complex

Question 15

Oxidation of Pyruvate

Net result:

Answer 15

1 NADH

Question 16

Citric Acid Cycle

in mitochondrial matrix

Answer 16

Oxidation of acetl CoA to CO₂

Fatty acids also oxidized to acetyl CoA

Question 17

Citric Acid Cycle-

Answer 17

Net results :

3 NADH

1GTP

1 FADH₂

Question 18

Glycolysis and Citric Acid Cycle-

generation of precursors for biosynthesis

Answer 18

• Sugars
• amino acids
• nucleotides
• Lipids
• produced during glycolysis and citric acid cycle are used as the precursors for synthesis of many macromolecules.

Question 19

Mitochondrion

Answer 19

Double membrane organelle of varable size and shape that provides a site for:

• Oxidation of pyruvate–> acetyl CoA + NADH
• Oxidation of fatty acids—-> acetyl CoA + NADH + FADH₂
• Citric acid cycle —–> NADH + FADH₂ +GTP
• Oxidative phosporylation

Question 20

Mitochondrion

Answer 20

Main site of energy production in eucaryotic cells.

vry efficient:

• glycolysis harvest less than 10% of the total free energy potentially avaiable from the glucose (2 ATP molecules produced per gllucose molecule)
• in mitochondria- ~ 30 ATP molecules produced for each glucose molecule.

Question 21

Mitochondria

contain:

Answer 21

• thier own DNA and RNA
• Complete transcription and translation machinery ( ribosomes)
• present in large numbrs (~2000 in hepatocytes)
• can be extremely motile or stationary
• stay in close location to a site high ATP consumption ( close to the contractile apparatus in muscle cells, wrapped tightly around the base of the motile flagellum)
• defects in mitochondrial function - serious effects on the body function (especially affected are tissues with high energy need e.g. muscles and nervous tissue; MERRF - myoclonic epilepsy and ragged red fiber disease - mutation in one of mitochondrial tRNA genes —> decrease in synthesis of electron transport proteins)