BIO 1140 - Cell Energy Generation

Question 1

What does Photosynthesis involve?

Answer 1

Photosynthesis involves light and gas exchange.

Question 2

Where does Photosynthesis occur?

Answer 2

Photosynthesis occur in chloroplasts
- two membranes

Question 3

What are Chlorophyll-Containing Thylakoid membranes?

Answer 3

Contains light-capturing + ATP generating systems

Question 4

What is a Granum?

Answer 4

Single thylakoid stack
- Grana for plural

Question 5

What are the Two Pathways of Photosynthesis?

Answer 5

1. The light reaction
2. The carbon-fixation reaction

Question 6

What is the Light Reaction?

Answer 6

convert light energy into chemical energy in the form of ATP and the reduced electron carrier NADPH.
- Takes place in thylakoid membrane

Question 7

What is the Carbon-Fixation Reaction?

Answer 7

The carbon-fixation reactions (light-independent reactions) use ATP, NADPH and CO2 to produce carbohydrates.
- takes place in stroma (“matrix” of chloroplast)

Question 8

How is Light Energy absorbed?

Answer 8

Light energy is absorbed by pigments in photosynthesis

Question 9

What are Pigments?

Answer 9

Molecules that absorb wavelength in the visible spectrum are called pigments.

Question 10

What are the Three common Photosynthetic Pigments?

Answer 10

Chlorophyll a, chlorophyll b and beta-carotene are common photosynthetic pigments in plants.

Question 11

What is Light?

Answer 11

A form of electromagnetic radiation
- has a dual nature

Question 12

What is the Dual Nature of Light?

Answer 12

1. It propagates in waves but has particle-like behaviors.
2. Particles of light are described as packets of energy called photons.

Question 13

What is the relation between amount of energy in Electromagnetic Radiation and the Wavelength?

Answer 13

The amount of energy in electromagnetic radiation is inversely proportional to its wavelength
- the shorter the wavelength, the greater the energy

Question 14

What happens when Light energy is absorbed by molecules?

Answer 14

When a molecule acquires the energy of the photon, it is raised from a ground state (with lower energy) to an excited state with higher energy.

Question 15

Is Green Light absorbed?

Answer 15

No, Chlorophyll A and B don’t absorb green light
- leaves are green because it is reflected

Question 16

What happens when a Beam of White light falls on a pigment?

Answer 16

When a bean of white light falls on a pigment , certain wavelengths are absorbed.

Question 17

What happens to the remaining Wavelength that are not absorbed?

Answer 17

The remaining wavelength are scattered or transmitted and make the pigment appear to us as colored.

Question 18

What is the Structure of Chlorophyll?

Answer 18

Chlorophyll’s structure allows it to absorb energy from light
- consists of a complex ring structure and a hydrocarbon tail
- The hydrocarbon tail anchors the chlorophyll in the hydrophobic region of a membrane in the chloroplast thylakoid

Question 19

What is a Photosystem?

Answer 19

A photosystem is a complex of proteins and pigments in the thylakoid membrane.
- Antenna system
- Reaction center

Question 20

How do the Antenna System and Reaction Center work together?

Answer 20

Pigments in the antenna system absorb light energy and transfer it to chlorophyll a in the reaction center.

Question 21

What is the Movement of Electrons in a Photosystem?

Answer 21

Electrons from chlorophylls in the reaction center are transferred to an electron acceptor

Electrons are transported through the thylakoid membrane

Question 22

What role does Water have in the Reaction Centre?

Answer 22

Water molecules are split to provide electrons for chlorophylls in the reaction center

Question 23

Where are Protons transferred to?

Answer 23

Transferred from stroma to the interior of thylakoids during electron transport
- Moves from [high] to [low]

Question 24

What is the role of Movement of Electrons?

Answer 24

The movement of electrons in thylakoid membrane powers the production of both ATP and NADPH.

Question 25

How is the Energy of Electrons boosted in Photosystem 1?

Answer 25

Electrons energy is boosted in photosystem I and transferred to NADP+ - adds energy to electrons from PSII - energy of light increase energy of electrons

Question 26

What are the Products of the Light Reaction?

Answer 26

The light reactions of photosynthesis lead to the production of: - ATP - NADPH - O2

Question 27

What is Chemiosmosis?

Answer 27

Both mitochondria and chloroplasts use chemiosmosis to generate ATP - The movement of protons through special channels to produce a proton gradient - Membrane-based mechanisms use the energy provided by food or sunlight to generate ATP

Question 28

What are the Similarities of Chemiosmosis in Mitochondria and Chloroplasts?

Answer 28

1. Before ATP produced, a chemical gradient of H+ is present 2. Complex collection of proteins uses electrons to pump H+ from one side to another 3. Same ATP synthase used to create ATP 4. Membrane-based mechanisms

Question 29

What are the differences of Chemiosmosis in Mitochondria and Chloroplasts?

Answer 29

Mitochondria: 1. Electron from NADH 2. H+ pump: matrix to intermembrane space 3. 1/2 O2 + 2 H+ 2e -> H2O 4. O2 is oxidizing reagent (becomes reduced) Chloroplast: 1. Electron from H2O 2. H+ pump: Stroma -> Thylakoid space 3. H2O -> 2 H+ + 2e + 1/2 O2 4. Water is Oxidized

Question 30

How is ATP synthesized?

Answer 30

ATP is synthesized using chemical gradient of protons - Photosynthesis and oxidative phosphorylation = ETC + chemiosmosis Chloroplast: - Uses energy from sun to generate H+ gradient Mitochondria: - Uses energy from oxidation of food to generate H+ gradient

Question 31

What is the First Stage of Photosynthesis?

Answer 31

a series of photosynthetic electron-transfer reactions produce ATP and NADPH in the process, electrons are extracted from water and oxygen is released as a by-product.

Question 32

What is the Second Stage of Photosynthesis?

Answer 32

carbon dioxide is assimilated (fixed) to produce sugars and a variety of other organic molecules.

Question 33

What does Carbon Fixation use?

Answer 33

Carbon fixation uses ATP and NADPH to convert CO2 into sugar

Question 34

What does Carbon Fixation involve?

Answer 34

Carbon fixation involves the formation of a covalent bond that attaches CO2 to ribulose 1,5-bisphosphate. - The carbon-fixation cycle consumes ATP and NADPH to form glyceraldehyde 3-phosphate.

Question 35

What does the production of 1 glyceraldehyde 3-phosphate require?

Answer 35

Production of 1 glyceraldehyde 3-phosphate requires 3 CO2, 9ATP and 6NADPH

Question 36

What are the Three Stages of Carbon Fixation (Calvin) Cycle?

Answer 36

1. Carbon fixation stage 2. reduction + sugar production 3. Regeneration and ribulose 1-5 bisphosphate

Question 37

What are the Products of Calvin Cycle used for?

Answer 37

The products of Calvin cycle are used in other metabolic pathways - Some glyceraldehyde 3-phosphate (G3P) enters glycolysis and is converted into pyruvate (in mito) - Some glyceraldehyde 3-phosphate (G3P) enters gluconeogenesis to form glucose (in chloro)

Question 38

How does Light stimulate the Calvin Cycle?

Answer 38

Light-induced pH changes in the stroma activate some Calvin cycle enzymes. Light-induced electron transport reduces disulfide bridges in four of the Calvin cycle enzymes, thereby activating them.

Question 39

What do Corn, Nuts, and Peas all contain?

Answer 39

Corn, nuts, and peas all contain rich stores of starch and fats - Some plant seeds serve as important foods for humans. - These stored starch and fats provide the plant embryo in the seed with energy and building blocks for biosynthesis.

Question 40

What are Enzymes?

Answer 40

Enzymes are biological catalysts. - Nearly all of them are proteins.

Question 41

What is the Classification of Enzymes based on?

Answer 41

- classified based on the type of biochemical reaction they catalyze - The name of the class describes the type of reaction they catalyze. - The suffix –ase is commonly used to indicate that a molecule is an enzyme