Cellular RespirationCellular Respiration

I. How do living things turn I. How do living things turn food into energy?food into energy?

How it begins in humans:How it begins in humans:1. The nervous system senses 1. The nervous system senses

that nutrients are needed and that nutrients are needed and excretes chemical signals that excretes chemical signals that increase appetite.increase appetite.

2. The organism eats food, and 2. The organism eats food, and the food is broken down into the food is broken down into simple molecules in the simple molecules in the digestive system (metabolism).digestive system (metabolism).

3. Nutrients such as 3. Nutrients such as carbohydrates carbohydrates and proteins are and proteins are transported through intestinal transported through intestinal membranes into the circulatory membranes into the circulatory system.system.

I. How do living things turn I. How do living things turn food into energy?food into energy?

I. How do living things turn I. How do living things turn food into energy?food into energy?

4. Blood carries nutrients to cells.4. Blood carries nutrients to cells.

5. Nutrients are transported into cells. 5. Nutrients are transported into cells. Sugar is transported into the cell with the Sugar is transported into the cell with the help of a molecule called insulin. help of a molecule called insulin.

I. How do living things turn I. How do living things turn food into energy?food into energy?

Once sugar enters the cell, the cell Once sugar enters the cell, the cell must convert it to usable energy. The must convert it to usable energy. The process of converting nutrients into process of converting nutrients into ATP is called ATP is called cellular respiration.cellular respiration.

Do plants carry out cellular Do plants carry out cellular respiration? _____________respiration? _____________

I. How do living things turn I. How do living things turn food into energy?food into energy?

Yes! Yes!

ALL LIVING THINGS ALL LIVING THINGS CARRY OUT CARRY OUT CELLULAR CELLULAR RESPIRATION! RESPIRATION!

(Even plants)(Even plants)

II. Where is this II. Where is this happening?happening?

Cellular respiration takes place in Cellular respiration takes place in specialized organelles called specialized organelles called mitochondriamitochondria. Typical animal cells have . Typical animal cells have 1000 to 2000 mitochondria per cell. 1000 to 2000 mitochondria per cell.

II. Where is this II. Where is this happening?happening?

Mitochondria are Mitochondria are specialized for energy specialized for energy conversion. The inner conversion. The inner membrane of membrane of mitochondria is highly mitochondria is highly convoluted, forming folds convoluted, forming folds called cristae. Inside the called cristae. Inside the membrane are proteins membrane are proteins that carry out cellular that carry out cellular respiration.respiration.

Why do mitochondria have so many folds Why do mitochondria have so many folds in their membranes? in their membranes?

________________________________________________________________________________

III. So how does it happen III. So how does it happen exactly?exactly?

1.1. GlycolysisGlycolysis - Happens in the cytoplasm of the cell. - Happens in the cytoplasm of the cell. One glucose molecule is split into 2 molecules of One glucose molecule is split into 2 molecules of pyruvate pyruvate - - During this processDuring this process, 2 ATP are made. , 2 ATP are made.

Hydrogen atoms are also removed from the Hydrogen atoms are also removed from the glucose molecule by NAD+, and NADH is formed.glucose molecule by NAD+, and NADH is formed.

2. Transition reaction2. Transition reaction - Pyruvate is transported into - Pyruvate is transported into the mitochondria, where it is converted to a the mitochondria, where it is converted to a molecule called molecule called acetyl CoAacetyl CoA. During this process, 2 . During this process, 2 NADH molecules are made.NADH molecules are made.

1. 1.

2. 2.

III. So how does it happen III. So how does it happen exactly?exactly?

3. Krebs cycle3. Krebs cycle – Happens in the matrix of – Happens in the matrix of the mitochondria. In the presence of the mitochondria. In the presence of oxygen, acetyl CoA is converted to carbon oxygen, acetyl CoA is converted to carbon dioxide. In the process, dioxide. In the process, 2 ATP are made2 ATP are made. . Other molecules called FADH2 and NADH Other molecules called FADH2 and NADH are made. are made. Carbon dioxide is given off as waste.Carbon dioxide is given off as waste.

4. Electron transport chain4. Electron transport chain – Happens in – Happens in the inner membrane. Consists of a series of the inner membrane. Consists of a series of carrier molecules which pass electrons from carrier molecules which pass electrons from a high-energy compound to a final low-a high-energy compound to a final low-energy electron acceptor (oxygen). Energy energy electron acceptor (oxygen). Energy is released during these oxidation-reduction is released during these oxidation-reduction reactions to produce reactions to produce 32 ATP.32 ATP. Water is also Water is also released as waste.released as waste.

3. 3.

4. 4. electron transport chainelectron transport chain

III. So how does it happen III. So how does it happen exactly?exactly?

How many total ATP molecules How many total ATP molecules are made from one glucose are made from one glucose molecule? ___________molecule? ___________

IV. What is ATP used for?IV. What is ATP used for?Everything! Any cell Everything! Any cell process that requires process that requires energy requires ATP. energy requires ATP. Cells use ATP to Cells use ATP to transport materials transport materials around the cell, around the cell, construct building construct building blocks of the cell, blocks of the cell, communicate with communicate with other cells, and do other cells, and do many many other many many other jobs.jobs.

V. What if there’s no V. What if there’s no oxygen around? Can cells oxygen around? Can cells

still get energy from still get energy from nutrients?nutrients?

Yes! When conditions are anaerobic Yes! When conditions are anaerobic (no oxygen), cells can still break (no oxygen), cells can still break down sugar and make ATP. down sugar and make ATP.

This process is called This process is called fermentation. fermentation.

V. What if there’s no V. What if there’s no oxygen around? Can cells oxygen around? Can cells

still get energy from still get energy from nutrients?nutrients?

Fermentation is not very efficient, Fermentation is not very efficient, though, because only though, because only 2 ATP2 ATP are are made for every molecule of glucose. made for every molecule of glucose.

The final product of fermentation is The final product of fermentation is either either alcoholalcohol (like yeast make) or (like yeast make) or lactate (which can make your lactate (which can make your muscles sore).muscles sore).

To Summarize:To Summarize:

CC66HH1212OO66 + O + O22 CO CO22 + H + H22O + O + ATPATP