Module 8 - Cellular Energy

Question 1

What is energy?

Answer 1

The ability to do work

Question 2

What are thermodynamics?

Answer 2

The study of the flow and transformation of energy in the universe

Question 3

What is the first law of thermodynamics?

Answer 3

The law of conservation of energy - energy cannot be created or destroyed, only converted from one form to another.

Question 4

What is the second law of thermodynamics?

Answer 4

Energy cannot be converted without the loss of usable energy. Increase in entropy.

Question 5

What is entropy?

Answer 5

The measure of disorder, or unusable energy, in a system.

Question 6

What is metabolism?

Answer 6

All of the chemical reactions in a cell

Question 7

What is a metabolic pathway?

Answer 7

A series of chemical reactions in which the product of one reaction is the substrate for the next reaction.

Question 8

What are the two metabolic pathways and what is the difference?

Answer 8

Catabolic pathways release energy by breaking down larger molecules into smaller molecules and anabolic pathways use energy (created by catabolic pathways) to build larger molecules from smaller molecules.

Question 9

What is photosynthesis?

Answer 9

The anabolic pathway in which light energy is converted to stored chemical energy by converting carbon dioxide plus water into sugars plus released oxygen.

Question 10

What is cellular respiration?

Answer 10

A catabolic pathway in which organic molecules are broken down to release energy. Oxygen breaks down organic molecules, producing carbon dioxide and water.

Question 11

What is adenosine triphosphate?

Answer 11

ATP is the most important biological molecule that provides chemical energy. Most abundant energy-carrier molecule in cells. A nucleotide made of an adenine base, a ribose sugar, and three phosphate groups.

Question 12

What is ATP’s function?

Answer 12

Releasing energy when the bond between the second and third phosphate groups forming adenosine diphosphate (ADP) and a free phosphate group. Lots of conversions between ADP and ATP happen in energy reactions in the cell.

Question 13

What is the chemical equation for photosynthesis?

Answer 13

6CO2 + 6H2O → C6H12O6 + 6O2

Question 14

What are the two phases of photosynthesis?

Answer 14

Light-dependent reactions and the light-independent reactions (Calvin Cycle)

Question 15

What are thylakoids?

Answer 15

flattened, saclike membranes arranged in stacks in the chloroplast. Where light-dependent reactions take place

Question 16

What are grana?

Answer 16

The stacks of thylakoids

Question 17

What is the stroma?

Answer 17

The fluid filled space outside the grana. Where light-independent reactions take place.

Question 18

What are pigments?

Answer 18

LIght absorbing colored molecules found in the thylakoid membranes.

Question 19

What are the major light-absorbing pigments in plants?

Answer 19

Chlorophyll a and b (absorb most strongly in the violet blue region and reflect green light) and carotenoids (absorb light mainly in the blue and green regions and reflect yellow, orange, and red regions.)

Question 20

What is NADPH?

Answer 20

An energy storage molecule.

Question 21

What are the steps of the electron transport chain?

Answer 21

1. light energy excites electrons in photosystem II
2. Light energy causes a water molecule to split, releasing an electron into the electron transport system, a hydrogen ion into the thylakoid space, and the release of oxygen as a waste product.
   3.Excited electrons move from photosystem II to an electron acceptor molecule
3. Electron acceptor molecule transfers the electrons along a series of electron carriers to photosystem I
4. Photosystem I transfers the electrons to a protein called ferrodoxin (in the presence of light only) Electrons lost by photosystem I are replaced by electrons shuttled from photosystem II
5. Ferrodoxin transfers the electrons to the electron carrier NADP+ forming NADPH.

Question 22

What is chemiosmosis?

Answer 22

The mechanism by which ATP is produced as a result of the flow of electrons down a concentration gradient.

Question 23

What is the Calvin cycle?

Answer 23

The second phase of photosynthesis in which energy is stored in organic molecules such as glucose. (light independent)

Question 24

What are the steps of the Calvin cycle?

Answer 24

1. Six carbon dioxide molecules combine with six 5-carbon compounds to form twelve 3-carbon molecules called 3-phosphoglycerate.
2. Chemical energy stored in ATP and NADPH is transferred to the 3-PGA molecules to form high energy molecules called glyceraldehyde 3-phosphates (G3P). ATP supplies the phosphate groups and NADPH supplies hydrogen ions and electrons.
3. Two of the G3P molecules leave the cycle to be used for the production of glucose and other organic compounds
4. Rubisco converts the remaining ten G3P molecules into 5-carbon molecules called ribulose 1, 5-bisphosphonates.
5. These combine with new carbon dioxide molecules and start over.

Question 25

What is the difference between aerobic processes and anaerobic processes?

Answer 25

Aerobic processes require oxygen
Anaerobic do not require oxygen

Question 26

What are the three main steps of aerobic respiration?

Answer 26

1. Glycolysis
2. Krebs Cycle
3. Electron transport chain

Question 27

What is glycolysis?

Answer 27

The process that breaks down glucose in the cytoplasm. Two molecules of ATP and two molecules of NADH are formed for each molecule of glucose that is broken down.

Question 28

What are the substeps of glycolysis?

Answer 28

1. Two phosphate groups, derived from two molecules of ATP, are joined to glucose. (some energy is required to start the reactions)
2. The 6-carbon molecule is broken down into 3-carbon compounds.
3. Two phosphates are added and electrons and hydrogen ions combine with two NAD+ molecules to form two NADH molecules.
4. The two 3-carbon compounds are converted into two molecules of pyrovate and four molecules of ATP are produced.

Question 29

What is the Krebs cycle?

Answer 29

The series of reactions in which pyruvate is broken down into carbon dioxide, AKA the tricarboxylic acid cycle, AKA the citric acid cycle.

Question 30

What are the steps of the Krebs cycle?

Answer 30

1. Acetyl CoA combining with a 4-carbon compound to form a 6-carbon compound called citric acid.
2. Citric acid is broken down releasing two molecules of carbon dioxide and generating one ATP, three NADH, and one FADH2
3. Acetyl CoA and citric acid are generated and the cycle continues.

Question 31

What are the steps of the electron transport chain?

Answer 31

(occuring in the mitochondria)
1. Ten NADH molecules and the two FADH*2 molecules from the Krebs cycle releasing electrons.
2. These electrons move along the mitochondrial membrane frome one protein to another.
3. Hydrogen positive ions are released into the mitochondrial matrix and are pumped into the intermembrane space through proteins in the inner mitochondrial membrane. Increase in concentrantion of hydrogen ions in the intermembrane space
4. Because of the concentration difference, the hydrogen ions diffuse down their concentration gradient back across the inner mitochondrial membrane and into the mitochondrial matrix through the ATP synthase.
5. ADP is converted into ATP
6. Oxygen is the final electron acceptor in the electron transport system in cellular respiration. The hydrogen ions and electrons are transferred to oxygen to form water.

Question 32

What is fermentation?

Answer 32

The anaerobic pathway that follows glycolysis (when NAD+ is used up. AKA anaerobic respiration. It occurs in the cytoplasm and regenerates the cell’s supply of NAD+ while producing a small amount of ATP.

Question 33

What are the two types of fermentation?

Answer 33

Lactic acid fermentation and alcohol fermentation

Question 34

What is the difference between the two fermentations?

Answer 34

Lactic acid - enzymes convert the pyruvate made during glycolysis to lactic acids
Alcohol - occurs in yeast and some bacteria, pyruvate is converted to ethyl alcohol and carbon dioxide.

Question 35

What does a high lactic acid concentration cause in muscle cells.

Answer 35

Fatigue and soreness.