BABS1201 Lecture Notes - Lecture 6: Photosystem I, Cellular Respiration, Carbon Fixation

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rubysalmon926

28 May 2018

School

UNSW, UNSW Sydney

Department

Biotechnology & Biomolecular Sciences

Course

BABS1201

Professor

All

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Photosynthesis

Nutrition

• Autotrophs: produce organic molecules from CO2 and other inorganic molecules from the

environment

• Heterotrophs: obtain organic molecules through other organisms

Photosynthesis

• Photoautotrophs: organisms that synthesise organic molecules from carbon dioxide and water

• Comprised of two process:

o Light reaction (photo)

o Calvin cycle (dark reaction, synthesis)

• Chloroplasts

o Structure

▪ Outer membrane

▪ Inner membrane

▪ Stroma - dense fluid enclosed by the membrane

▪ Thylakoids - membranous sacs

▪ Thylakoid space - space within the thylakoid

▪ Grana - stacks of thylakoids

▪ Chlorophyll - located within the thylakoid membranes

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Photosynthesis

Light reaction

• Reactants: H2O, NADP+, ADP

• Products: O2, NADPH, ATP

o Water is split    

o   

o     

• Light energy is converted to chemical energy ATP and NADPH

• NADP+ - nicotinamide adenine dinucleotide phosphate (an electron acceptor)

Light

• Electromagnetic radiation

• Travels in waves

• Visible light - wavelength - 380-750nm

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Photosynthetic pigments

• Pigment: substances that absorb visible light

• Absorbs red and violet wavelengths, reflects green wavelengths

• Carbon dioxide + water

• Carbon dioxide diffuses into the plant through small pores

• CO2 diffuses into the cell and into the chloroplast where photosynthesis takes place

• Chloroplasts use energy from light to transform carbon dioxide and water into sugar

and oxygen

Light reactions

• Occurs in flattened membranous sacs called thylakoids

• Where light energy is converted to chemical energy

•

• Within the thylakoids

• Photosystems - (the two green structures) large complexes of protein and chlorophyll

▪ Captures light energy

• Electron transport chain (ETC) - (purple structures) - connects the two photosystems

▪ Three mobile electron carriers - transport electrons between the complexes

▪ Photosystem II - absorbs light energy, exciting electrons that enter the ETC

• Electrons are replaced with electrons stripped from water, creating

oxygen as a by-product

• Electrons flow down to the ETC, releasing energy that is used to pump

hydrogen ions (positive charges) into the thylakoid

▪ Photosystem I - light energy excites electrons

• Electrons are transported by the electron carrier molecule

• Captured by the electron carrier molecule NADPH

▪ The high concentration of hydrogen ions inside the thylakoid powers ATP

synthase, producing ATPs

• Light reactions produced two energy products - ATP and NADPH - powers the production of

sugar in the Calvin cycle

Calvin Cycle (C3 cycle)

• Takes place in the stroma - the thick fluid of the chloroplast

• At the beginning of the cycle, CO2 combine with molecules called RuBP

• The resulting molecules go through a series of reactions powered by ATP and NADPH

- producing sugar molecules glyceraldehyde-3-phosphate (G3P)

• Most of the G3Ps are rearranged back into RuBPs that will begin the Calvin cycle

again

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Document Summary

Nutrition: autotrophs: produce organic molecules from co2 and other inorganic molecules from the environment, heterotrophs: obtain organic molecules through other organisms. Photosynthesis: photoautotrophs: organisms that synthesise organic molecules from carbon dioxide and water, comprised of two process, light reaction (photo, calvin cycle (dark reaction, synthesis, chloroplasts, structure, outer membrane. Stroma - dense fluid enclosed by the membrane: thylakoids - membranous sacs, thylakoid space - space within the thylakoid, grana - stacks of thylakoids, chlorophyll - located within the thylakoid membranes. Light reaction: reactants: h2o, nadp+, adp, products: o2, nadph, atp, water is split 2(cid:1841) 2++(cid:1841)2, (cid:1840)(cid:1842)+++ (cid:1840)(cid:1842, (cid:1842)+(cid:1842) (cid:1842) Light energy is converted to chemical energy atp and nadph: nadp+ - nicotinamide adenine dinucleotide phosphate (an electron acceptor) Light: electromagnetic radiation, travels in waves, visible light - wavelength - 380-750nm. Light reactions produced two energy products - atp and nadph - powers the production of sugar in the calvin cycle.

Related Questions

Question 1 The membrane structures inside the chloroplast are called the ______, while the fluid surrounding the stacks of membrane is called the ______.
a. stroma; thylakoid
b. thylakoid; cytosol
c. thylakoid; stroma
d. thylakoid; matrix
e. matrix; thylakoid

Question 2 What is considered the ultimate source of energy for living things on Earth?
a. the sun
b. electrons
c. green plants
d. oxygen
e. ATP

Question 3 Why do most plant leaves appear green?
a. They contain a lot of starch which has a green color.
b. They have chloroplasts which absorb green light for photosynthesis.
c. During the light reaction phase carbon dioxide is converted to oxygen which emits green light.
d. They have chloroplasts which absorb all colors of light except for green, which is reflected.
e. During the dark reaction phase water is converted to oxygen which emits green light.

Question 4 Plants perform only photosynthesis, not respiration. True False

Question 5 What is the primary purpose of the light reactions of photosynthesis?
a. to create oxygen gas
b. to produce glucose
c. to convert solar energy to chemical energy (in the form of ATP and NADPH) to power the dark reactions
d. to remove carbon dioxide gas from the atmosphere
e. to create water

Question 6 The light dependent reactions occur in the:
a. mitochondrial membrane.
b. mitochondrial matrix.
c. stroma.
d. thylakoid membrane.
e. cytosol.

Question 7 The energy to run the dark reactions of photosynthesis is produced _________.
a. by the CO2 initially used in the dark reactions.
b. during glycolysis
c. during the light reaction phase
d. during the Krebs cycle
e. during anaerobic respiration

Question 8 Which of the following substances could be totally eliminated and not interfere with the process of photosynthesis?
a. O2
b. H2O
c. light
d. CO2

Question 9 What product(s) do plants produce during photosynthesis that is/are used by humans and other animals?
a. carbon dioxide
b. carbon dioxide and water
c. glucose and oxygen
d. glucose
e. oxygen

Question 10 Only plants can carry out photosynthesis. True False

Question 11 During the light reactions of photosynthesis, ...
a. oxygen is produced from H2O.
b. glycolysis occurs.
c. the Krebs cycle occurs.
d. CO2 is combined into glucose.
e. ATP is broken down to ADP + P

Question 12 The reactants of photosynthesis are:
a. sugar.
b. sugar and water.
c. O2 and CO2
d. O2 and sugar.
e. CO2 and water.

Question 13 During the dark reaction phase of photosynthesis in plants...
a. ATP is created.
b. H+ ions are moved into the stroma from the matrix.
c. molecules of CO2 are combined into sugar.
d. H2O is split into oxygen and H+.
e. solar energy is converted to chemical energy.

coffeelion96

The complete set of reactions carried out by an organism is called:

a. anabolism

b. catabolism

c. metabolism

Value: 2

The breakdown of starch is broken down to glucose is an example of:

a. anabolism

b. catabolism

c. metabolism

Value: 3

For the following statement, determine which description best describes the process: DNA is synthesized from free nucleotides.

a. anabolism

b. catabolism

c. metabolism

Value: 4

Fill in the blank: Catabolic reactions result in the synthesis of molecules of .............via cellular respiration. This is then used to power anabolic reactions.

Value: 5

The energy in organic molecules is released in a series of steps because:

a. it is not possible to release it in a single step.

b. more total energy is released in multiple steps than would be released in a single step

c. less total energy is released in multiple steps than would be released in a single step.

d. more energy can be harvested for cellular use in multiple steps than from a single step.

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photosynthesis

1-The light reaction of photosynthesis does not include

a. chemiosmosis

b. oxygen liberation

c. glucose synthesis

d. electron transport

Value: 2

Photosynthesis takes place in the membranes of small sacs called

a. thylakoids

b. photosystems

c. stroma

d. photons

Value: 3

During what stage of photosynthesis is O2 produced?

a. the light-dependent reactions involving photosystems I and II

b. carbon fixation

c. the Krebs cycle

d. O2 is not produced during photosynthesis

Value: 4

The pigment molecules responsible for photosynthesis are located in the

a. mitochondria

b. cytoplasm of the cell

c. stroma of the chloroplast

d. thylakoid membrane of the chloroplast

Value: 5

During what stage of photosynthesis are ATP and NADPH converted to ADP + Pi and NADP+?

a. the light-dependent reactions

b. the light-independent reactions

c. both of the above

d. none of the above

Value: 6

What energy-rich organic compound is produced as a result of the Calvin cycle?

a. ATP

b. NADPH

c. glucose

d. H2O

Value: 7

During photosynthesis, photons raise electrons to higher energy levels. These excited electrons belong to what compound?

a. water

b. ATP

c. chlorophyll

d. electron transport chain

Value: 8

Which of the following statements accurately describes the relationship between photosynthesis and cellular respiration?

a. photosynthesis occurs only in autotrophs; cellular respiration occurs only in heterotrophs

b. photosynthesis uses solar energy to convert inorganics to energy-rich organics; respiration breaks down energy-rich organics to synthesize ATP

c. photosynthesis involves the oxidation of glucose; respiration involves the reduction of CO2

d. the primary function of photosynthesis is to use solar energy to synthesize ATP; the primary function of cellular respiration is to break down ATP and release energy

Review question its 1-12 sorry for the xtra questions in the bottom

1:2D chromatography is so named because ____

A: there are two steps: labeling with a radioactive marker and separation via chromatography

B: two different solutions are used in the paper chromatography

C: the molecules are separated into a linear arrangement, meaning two dimension

D: two different types of radioactive markers must be used

E: the process separates the molecules in two direction, first along the X and then along the Y axis

2: :Which molecule(s) regulate(s) photosynthesis by sensing the metabolic status of the chloroplast and regulating proton flow out of the thylakoid lumen??

A: ATP synthase

B: antenna complex

C: Chrolophyll B

D: carotenoids

E: chlorphyll A

3: When does A CAM plant take in atmospheric CO2?

A: daytime only

B: Summer day

C: winter day

D: nighttime only

E: anytime the calvin cycle is happening

4: Where can you find ATP synthase in a plant cell ?
A; in the thylakoid membrane only

B: in the mitochondial inner membrane

C: both thylakid and inner mitochondria membrane

D: only in the nucleus

E: embedded in the plasma membrane

5: chloroplast kept in the daek can continue to make sugar is provided with

A: NADPH, CO2, and ADP

B: CO2, and ATP

C: NADPH, ATP, and CO2

D: NADPH and ATP

E: water and ATP

7: C3 plants are more susceptible to photorespiration than either C4 or CAM plants. Why do most plants lack the C4 pathway??

A: Switching between C3, C4, and CAM photosynthesis is very difficult for most plants

B: ?Rubisco is more efficient in C3 plants when compared to rubisco of C4 and CAM plants

C: Most plant species do not have vacuoles in their cells to store the malate generated from CO2 taken in during the night.

D; : Photorespiration is not a serious problem for most plants.?

E: There is an energetic cost to C4 and CAM pathways that only makes them advantageous in very hot and/or arid environments.?

8: In Engelmann's classic experiment, why were the oxygen-requiring bacteria clustered around the regions of Spirogyra algae that were bathed in red, blue, and violet light?

A; The bacteria were immobile and that is where Engelmann happened to place them

B; The most energy-rich wavelengths of light are found at the edges of visible and nonvisible light (ultra

violet and infrared)

C; Photosynthesis is most active in those wavelengths of light and thus more oxygen is consumed by the algae in those regions.

D: Photosynthesis is most active in those wavelengths of light and thus more oxygen is produced by the algae in those regions.?

E: : Chlorophyll is green and thus reflects green light.

9: In any experiment, changes to the dependent variable based on the manipulations of the independent variable are measured. When determining the action spectrum of a given plant, what is the independent variable and what is the dependent variable?

A: independent = rate of O2 release in photosynthesis; dependent = wavelength?

B: ?independent = absorption of light; dependent = wavelength

C: independent = wavelength; dependent = rate of O2 release in photosynthesis?

D: independent = wavelength; dependent = absorption of light?

E: independent = rate of O2 release in photosynthesis; dependent = absorption of light

10: Which plant structure is responsible for gas exchange??

A: stromal lamellae

B: grana

C: granastomata?

D: stroma

11: n order to elucidate the Calvin cycle, Calvin and his colleagues used two-dimensional paper chromatography to analyze the presence of different molecules under different conditions. What did they conclude from the accumulation of RuBP when CO2 levels were low??

A: CO2 serves as a non-competitive inhibitor of rubisco.

B: RuBP is the last substrate to react in the Calvin cycle.

C: RuBP only reacts with CO2 when concentrations of ATP are low

D: RuBP is the first substrate to react with CO2

E: ?RuBP only reacts with CO2 in the sunlight.

12: Why isn't oxygen produced by organisms that perform anoxygenic photosynthesis?

A; their membranes lack ATP synthase?

B; They use a different enzyme for the initial reactions of the calvin cycle

C: they use electrons donors other than water

D: their photosystem do not utilize the calvin cycle

E: their chorophyll contains an iron rather than magnesium

A: ?there are two steps: labeling with a radioactive marker and separation via chromatography

B: two different solutions are used in the paper chromatography process?

C: the molecules are separated into a linear arrangement, meaning two dimensions?

D: two different types of radioactive markers must be used?

E: the process separates the molecules in two directions, first along the x axis and then along the y axis?

2:Which molecule(s) regulate(s) photosynthesis by sensing the metabolic status of the chloroplast and regulating proton flow out of the thylakoid lumen??

A: ?ATP synthase

B: the antenna complex?

C: chlorophyll b?

D: carotenoids?

E: chlorophyll a

3: When does a CAM plant take in atmospheric CO2??

A: ?daytime only

B: summer only?

C: ?winter only

D: nighttime only?

?e: anytime the Calvin cycle is occurring

4: Where can you find ATP synthase in a plant cell??

A: ?in the thylakoid membrane only

B: in the mitochondrial inner membrane only?

C: both the thylakoid and inner mitochondrial membranes?

D: only in the nucleus?

E: ?embedded in the plasma membrane

5: Chloroplasts kept in the dark can continue to make sugar if provided with ____.

A: NADPH, CO2, and ADP?

B: CO2 and ATP?

?c: NADPH, ATP, and CO2

D: NADPH and ATP?

E: water and ATP

6: Where does the Calvin cycle occur?

A: thylakoid lumen?

B: cytosol?

C: stroma?

D: stromal lamellae

?e: thylakoid membrane

7: C3 plants are more susceptible to photorespiration than either C4 or CAM plants. Why do most plants lack the C4 pathway??

A: Switching between C3, C4, and CAM photosynthesis is very difficult for most plants.?

B: ?Rubisco is more efficient in C3 plants when compared to rubisco of C4 and CAM plants.

C: Most plant species do not have vacuoles in their cells to store the malate generated from CO2 taken in during the night.?

D: Photorespiration is not a serious problem for most plants.?

E: There is an energetic cost to C4 and CAM pathways that only makes them advantageous in very hot and/or arid environments.?

8: In Engelmann's classic experiment, why were the oxygen-requiring bacteria clustered around the regions of Spirogyra algae that were bathed in red, blue, and violet light??

A:The bacteria were immobile and that is where Engelmann happened to place them.?

B: The most energy-rich wavelengths of light are found at the edges of visible and nonvisible light (ultra violet and infrared).?

?c: Photosynthesis is most active in those wavelengths of light and thus more oxygen is consumed by the algae in those regions.

D; Photosynthesis is most active in those wavelengths of light and thus more oxygen is produced by the algae in those regions.?

?e: Chlorophyll is green and thus reflects green light.

9; In any experiment, changes to the dependent variable based on the manipulations of the independent variable are measured. When determining the action spectrum of a given plant, what is the independent variable and what is the dependent variable??

A: independent = rate of O2 release in photosynthesis; dependent = wavelength?

B: ?independent = absorption of light; dependent = wavelength

C: independent = wavelength; dependent = rate of O2 release in photosynthesis?

D: independent = wavelength; dependent = absorption of light?

E: independent = rate of O2 release in photosynthesis; dependent = absorption of light?

10: Which plant structure is responsible for gas exchange??

A: stromal lamellae?

B: grana?

C: stomata?

?D: stroma

11: In order to elucidate the Calvin cycle, Calvin and his colleagues used two-dimensional paper chromatography to analyze the presence of different molecules under different conditions. What did they conclude from the accumulation of RuBP when CO2 levels were low??

A:	?CO2 serves as a non-competitive inhibitor of rubisco.

?B: RuBP is the last substrate to react in the Calvin cycle.

C: RuBP only reacts with CO2 when concentrations of ATP are low.?

D:	RuBP is the first substrate to react with CO2.?

e:	?RuBP only reacts with CO2 in the sunlight.

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BABS1201 Lecture Notes - Lecture 6: Photosystem I, Cellular Respiration, Carbon Fixation

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