Cellular Respiration (the big picture)ktp10



Name: ______________________________________

Cellular Respiration - Aerobic & Anaerobic

Like it or not, chemistry continues to sneak itself into our beloved biology course.  This is because what distinguishes living things from nonliving things is the presence of cells. Cells are nothing but bags of chemicals with a multitude of chemical reactions occurring inside them.  And furthermore, all the metabolic activities in cells are being directed by DNA.  Compounds, chemicals, chemical reactions are what produce the structures & functions within the basic units of structure & function for living things (cells).

The process of creating cell energy is known as cellular respiration, a chemical reaction in which the chemical energy in glucose is converted to adenosine triphosphate (ATP). ATP is the cellular energy or “gasoline” for the cell. Although one series of reactions takes place in the cytoplasm, most of the chemical reactions involved in cellular respiration happen in the mitochondrion, which is referred to as the “powerhouse” of the cell. A mitochondrion is shaped perfectly to maximize its efforts. It has folds that increase its surface area.

To perform cellular respiration, living organisms must gain energy in the form of glucose. Animals gain energy from breaking down their food. Animals cannot create their own energy from sunlight. They need to eat another animal or plant. Plants can create their own sugars, but we will discuss that more during photosynthesis. These processes are essential for daily life because it allows the carbon to cycle as carbon dioxide (CO2) and water to be released.

Questions:

1. What is cellular respiration?

2. Exactly why is cellular respiration so important?

3. Where does cellular respiration occur?

4. What raw (beginning) materials are needed for the process of cellular respiration?

5. What are the ending products of cellular respiration?

For the most part, when thinking of organisms that carry-out cellular respiration, it is easier to picture animals. Don’t forget cellular respiration also takes place in plants, fungus, protists, and prokaryotes. No matter the organism, ingested sugars are normally in polymers or large chains. The body must break down the large polymers into single glucose monomers for absorption.

The entire cellular respiration process is split into 3 parts: Glycolysis, Krebs Cycle, and the Electron Transport Chain. Only glycolysis occurs outside the mitochondria. It occurs in the cytoplasm.

Glycolysis: Glycolysis takes place as the first step in cellular respiration. Glycolysis involves the breaking down of glucose molecules from carbohydrates into molecules of pyruvic acid (pyruvate), which will continue on to the Krebs Cycle. This process occurs in the cytoplasm of the cell and can proceed with or without oxygen. The reactions of glycolysis produces, a net gain of 2 ATP molecules, as well as a release of 2 water molecules and 2 NADH molecules (another energy molecule for a later step). The end product of glycolysis, pyruvate, is converted into acetyl CoA as it enters the mitochondrion.

The Krebs Cycle: Again, as pyruvate is being shuttled from the cytoplasm to the interior of the mitochondrion it becomes Acetyl CoA. The Krebs Cycle is an aerobic process, meaning it needs oxygen to function. Two complete turns of the Krebs Cycle must occur to produce: 4 CO2 molecules, 6 NADH molecules, 2 ATP molecules and 2 FADH2 molecules (yet another energy-yielding molecule).

.

The Electron Transport Chain: Most of the energy locked in the original glucose molecule will be released by the electron transport chain. NADH and FADH2 drop off electrons at the "top" of the electron transport chain, where the electrons are passed along the chain of membrane proteins to produce the remaining 32 ATP molecules per 1 molecule of glucose.

Summary the Reactants (IN) and Products (OUT) of each step –

Glycolysis:

Krebs Cycle:

Electron Transport Chain:

Fermentation - an Alternative to Cellular Respiration: While some steps do not require oxygen, cellular respiration, as a whole, can only take place when oxygen is present. For organisms living in anaerobic conditions, complete cellular respiration is not possible. For these organisms, glycolysis is the first and last step of the cellular respiration process. Glycolysis proceeds normally, as in aerobic conditions, producing a net gain of 2 ATP. The two pyruvate molecules as NAD are reduced and recycled. In this way, the cells do not deplete their store of NAD, although they are only able to produce 2 ATP. As a by-product of fermentation, either ethanol (by yeast) or lactic acid (by animals) is produced. This can produce alcohol and muscle cramps!

Review Questions:

1. How do cells capture the energy released by cellular respiration?

A) They produce ATP.

B) They produce glucose.

C) They store it in molecules of carbon dioxide.

D) The energy is coupled to oxygen.

2. Respiration ________, and cellular respiration ________.

A) produces ATP . . . is gas exchange

B) is gas exchange . . . produces ATP

C) produces glucose . . . produces oxygen

D) uses glucose . . . produces glucose

3. Which of the following are products of cellular respiration?

A) oxygen and carbon dioxide

B) energy to make ATP and carbon dioxide

C) oxygen and glucose

D) oxygen and energy to make ATP

4. The overall equation for the cellular respiration of glucose is

A) C5H12O6 + 6 O2 → 5 CO2 + 6 H2O + energy.

B) 5 CO2 + 6 H2O → C5H12O6 + 6 O2 + energy.

C) C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + energy.

D) C6H12O6 + energy → 6 CO2+ 6 H2O + 6 O2.

5. Humans use the calories they obtain from ________ as their source of energy.

A) food

B) water

C) sunlight

D) minerals

6. Which of the following metabolic pathways is common in aerobic and anaerobic metabolism?

A) the citric acid cycle

B) oxidative phosphorylation

C) glycolysis

D) electron transport chain

7. As a result of glycolysis there is a net gain of ________ ATPs.

A) 0

B) 1

C) 2

D) 36

8. Pyruvate

A) forms at the end of glycolysis.

B) is the molecule that starts the citric acid cycle.

C) is the end product of oxidative phosphorylation.

D) is a six-carbon molecule.

9. In yeast cells,

A) lactic acid is produced during anaerobic respiration.

B) lactic acid is produced during glycolysis.

C) alcohol is produced during the citric acid cycle.

D) alcohol is produced after glycolysis.

................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download