cell process photosynthesis€¦ · cell process photosynthesis. cell process - photosynthesis....

27
CO 7 Cell Process Photosynthesis

Upload: others

Post on 08-Aug-2020

25 views

Category:

Documents


1 download

TRANSCRIPT

Page 1: Cell Process Photosynthesis€¦ · Cell Process Photosynthesis. Cell Process - Photosynthesis. Photosynthesis is used to build carbohydrates (the main energy source of all life.)--

CO 7

Cell Process

Photosynthesis

Page 2: Cell Process Photosynthesis€¦ · Cell Process Photosynthesis. Cell Process - Photosynthesis. Photosynthesis is used to build carbohydrates (the main energy source of all life.)--

Cell Process - Photosynthesis

Page 3: Cell Process Photosynthesis€¦ · Cell Process Photosynthesis. Cell Process - Photosynthesis. Photosynthesis is used to build carbohydrates (the main energy source of all life.)--

Photosynthesis is used to

build carbohydrates (the

main energy source of all

life.)

- - Producers (like plants)

use carbon dioxide and

water to make

carbohydrates; oxygen gas

is released as waste

- - Occurs in the

chloroplasts

- - {Write Equation}

Page 4: Cell Process Photosynthesis€¦ · Cell Process Photosynthesis. Cell Process - Photosynthesis. Photosynthesis is used to build carbohydrates (the main energy source of all life.)--

Chloroplast Structure

- Stroma is the space between the grana

which are stacks of tylakoid membranes

which are full of pigments (quick pic)

Page 5: Cell Process Photosynthesis€¦ · Cell Process Photosynthesis. Cell Process - Photosynthesis. Photosynthesis is used to build carbohydrates (the main energy source of all life.)--

Figure 7.2

Page 6: Cell Process Photosynthesis€¦ · Cell Process Photosynthesis. Cell Process - Photosynthesis. Photosynthesis is used to build carbohydrates (the main energy source of all life.)--

Photosynthetic Pigments – chemicals such as chlorophyll that absorb

various portions of visible light. (Anything green denotes chlorophyll

and is photosynthetic. Chlorophyll is great at absorbing all colors

except green. Green is reflected, which is why it looks green to our

eyes.)

1. Two major photosynthetic pigments are chlorophyll a and chlorophyll b.

2. Both chlorophylls absorb violet, blue, and red wavelengths best.

3. Most green is reflected back; this is why leaves appear green.

Page 7: Cell Process Photosynthesis€¦ · Cell Process Photosynthesis. Cell Process - Photosynthesis. Photosynthesis is used to build carbohydrates (the main energy source of all life.)--

Accessory pigments help

absorb the light colors that

chlorophyll can’t.

- Carotenoids are yellow-

orange pigments which

absorb violet, blue, and

green regions.

- Phycobilins are red-purple

pigments

- When chlorophyll breaks

down and is reabsorbed in

fall, it is pulled out of the

leaves first. This allows the

accessory pigments in

leaves show through.

Page 8: Cell Process Photosynthesis€¦ · Cell Process Photosynthesis. Cell Process - Photosynthesis. Photosynthesis is used to build carbohydrates (the main energy source of all life.)--

Absorption Spectrum - spectrophotometer measures the

amount of light that passes through a sample of pigments (like

crushed green leaves)

Page 9: Cell Process Photosynthesis€¦ · Cell Process Photosynthesis. Cell Process - Photosynthesis. Photosynthesis is used to build carbohydrates (the main energy source of all life.)--

Action Spectrum - measures the rate of photosynthesis

at different wavelengths of light; measured by the rate

oxygen is produced

Page 10: Cell Process Photosynthesis€¦ · Cell Process Photosynthesis. Cell Process - Photosynthesis. Photosynthesis is used to build carbohydrates (the main energy source of all life.)--
Page 11: Cell Process Photosynthesis€¦ · Cell Process Photosynthesis. Cell Process - Photosynthesis. Photosynthesis is used to build carbohydrates (the main energy source of all life.)--

In one sentence summarize what this graph says about wavelengths,

color of light, absorption and photosynthesis.

Page 12: Cell Process Photosynthesis€¦ · Cell Process Photosynthesis. Cell Process - Photosynthesis. Photosynthesis is used to build carbohydrates (the main energy source of all life.)--

Checkpoint

1. What is the relationship between the absorption spectrum and the

action spectrum?

2. How can we measure the rate of photosynthesis?

3. How is the wavelength of light related to the rate of

photosynthesis?

4. A radish plant is grown

using lights of different

colors. Explain the chart.

Page 13: Cell Process Photosynthesis€¦ · Cell Process Photosynthesis. Cell Process - Photosynthesis. Photosynthesis is used to build carbohydrates (the main energy source of all life.)--
Page 14: Cell Process Photosynthesis€¦ · Cell Process Photosynthesis. Cell Process - Photosynthesis. Photosynthesis is used to build carbohydrates (the main energy source of all life.)--

Photosynthetic Reaction

1. In 1930 C. B. van Niel showed that O2 given off by

photosynthesis comes from water and not from CO2.

2. The net equation reads:

Page 15: Cell Process Photosynthesis€¦ · Cell Process Photosynthesis. Cell Process - Photosynthesis. Photosynthesis is used to build carbohydrates (the main energy source of all life.)--

Two Sets of Reactions in Photosynthesis (general detail)

1. Light reactions only happen with light. They are the

energy-capturing reactions that take place in the

thylakoids.

a. Water is split into

oxygen, two H+, and

two free e-

b. The electrons and

hydrogens are sent

to the electron

transport chain

where they are used

to make ATP and

NADPH to power the

Calvin Cycle

c. Oxygen is

released

Page 16: Cell Process Photosynthesis€¦ · Cell Process Photosynthesis. Cell Process - Photosynthesis. Photosynthesis is used to build carbohydrates (the main energy source of all life.)--
Page 17: Cell Process Photosynthesis€¦ · Cell Process Photosynthesis. Cell Process - Photosynthesis. Photosynthesis is used to build carbohydrates (the main energy source of all life.)--

2. Calvin Cycle Reactions

(aka dark reactions)

a. take place in the stroma

in either the light or dark.

b. The NADPH and ATP

from light rxns provide

energy to combine 6CO2

molecules into a six

carbon sugar carb.

Page 18: Cell Process Photosynthesis€¦ · Cell Process Photosynthesis. Cell Process - Photosynthesis. Photosynthesis is used to build carbohydrates (the main energy source of all life.)--

What you should know by now..

1. The equation for photosynthesis. Write it!

2. The structure of a chloroplast. Sketch it!

3. The two reactions of photosynthesis.

Page 19: Cell Process Photosynthesis€¦ · Cell Process Photosynthesis. Cell Process - Photosynthesis. Photosynthesis is used to build carbohydrates (the main energy source of all life.)--

Same Photosynthesis Reactions (in more detail)

- The Light Reactions occur in two systems: Photosystem I

and Photosystem II. These photosystems create the cyclic

and the non-cyclic electron transport chains. The ETC’s are

able to create ATP (c and n-c) and NADPH (n-c only) through

membrane compartments and gradients – (Obviously the

creation of ATP is a complicated process/ I told you

compartmentalization was important! Your HW should help.)

Page 20: Cell Process Photosynthesis€¦ · Cell Process Photosynthesis. Cell Process - Photosynthesis. Photosynthesis is used to build carbohydrates (the main energy source of all life.)--

Non-cyclic ETC – electrons are removed from the water molecule using light energy

at PSII; they are passed down a chain of enzymes where their energy is used to pull

H+ molecules from the stroma into the thylakoid, creating the concentration gradient

needed to drive ATP Synthetase; electrons are then re-charged at PSI and attached

to an NADP+ to make NADPH and sent to power the Calvin cycle.

- Summary- IN: Water and Light. OUT: equal amounts of ATP and NADPH. GEN

DIRECTION: PSII (energy used to pull in H+) PSI recharge NADPH

Calvin Cycle

Cyclic ETC – extra ATP molecules are needed for the Calvin Cycle. The Cy ETC just

creates more ATP. Electrons are charged by PSI, then passed down the ETC where

their energy is used to pull more H+ into the thylakoid to keep the concentration

gradient going and driving ATP. They are then returned to PSI, recharged, and used

the same way all over again. IN: Electrons. OUT: ATP only. GEN DIRECTION: PSI

energy used to pull in H+ PSI again! (cycles!)

ATP Synthetase – this enzyme uses the energy from moving H+ molecules to

recharge ADP to ATP in both ETCs. The ETCs cram the H+ inside the thylakoid

creating an area of a high concentration. The H+ want out and away from that high

concentration. The only way out is through ATP Synthetase. As they move through

ATP Synthetase, the enzyme spins and generates power to recharge ATP. It’s

remarkably like a hydroelectric power plant! Note, membranes and

compartmentalization are HUGE here! It wouldn’t work without them!

Are you still confused? Check out the videos on my website to see it in action.

Page 21: Cell Process Photosynthesis€¦ · Cell Process Photosynthesis. Cell Process - Photosynthesis. Photosynthesis is used to build carbohydrates (the main energy source of all life.)--

Now for the dark reactions…

Summary Statements:

What is the purpose of the Calvin Cycle?

To make sugar from carbon dioxide

Where does the cell get its energy to perform these reactions? From the ATP and

NADPH charged in the light reactions

What is the final product? Glucose (and ADP/NADP+ to be sent back to light rxn)

Why is carbon dioxide necessary? The 6 carbons from 6CO2 molecules become the

6 carbons in one molecule of C6H12O6; process called carbon fixation

Enzyme to know: Rubisco – used to bind the CO2 in carbon fixation; can bind to O2

accidentally if there’s too much around which leads to photorespiration (which is bad)

FORTUNATELY, AP Biology no longer

requires the memorization of every step of

the Calvin Cycle, but you should

understand the beginning and the end and

the purpose.

Page 22: Cell Process Photosynthesis€¦ · Cell Process Photosynthesis. Cell Process - Photosynthesis. Photosynthesis is used to build carbohydrates (the main energy source of all life.)--

Photorespiration- Problem caused when Rubisco bonds to O2 in the Calvin Cycle

instead of CO2 (and you can’t make sugar without carbon); happens

when too much O2 builds up in the leaf; a concern of hot weather

plants who have to keep their stomata (holes to allow gas exchange)

closed to prevent excess transpiration (water evaporation)

- Adaptations to Avoid…

- CAM photosynthesis: temporal (timing) separation of

photosynthesis reactions; close stomata during the day and just do light

reactions, open at night to release O2 build up and bring in CO2 for calvin

cycle; store CO2 and preliminary sugar molecules as an acid overnight,

use the carbon acid during the day to make sugar when energy is

available

- C4 photosynthesis: spatial separation of photosynthesis

reactions; first convert CO2 into a carbon chemical called malate and

move it to cells in darker regions of the leaf for the Calvin cycle; the cells

in the lighter areas do the light reactions while the cells in the darker

regions do the Calvin Cycle

Page 23: Cell Process Photosynthesis€¦ · Cell Process Photosynthesis. Cell Process - Photosynthesis. Photosynthesis is used to build carbohydrates (the main energy source of all life.)--

Factors the Affect Photosynthesis

1. Light Quality (color)- white is best, followed by blue; green is

worst due to pigment absorption

2. Light Intensity (typically, brighter = better)

3. Light Period (longer time in light = better)

4. Carbon Dioxide Availability – more is better

5. Water Availability – more is better

Note: Rate of Photosynthesis can be measured by the amount

of oxygen released OR the amount of CO2 absorbed. More O2

released or CO2 absorbed = more photosynthesis

Page 24: Cell Process Photosynthesis€¦ · Cell Process Photosynthesis. Cell Process - Photosynthesis. Photosynthesis is used to build carbohydrates (the main energy source of all life.)--

Quick Practice

Page 25: Cell Process Photosynthesis€¦ · Cell Process Photosynthesis. Cell Process - Photosynthesis. Photosynthesis is used to build carbohydrates (the main energy source of all life.)--

Quick Practice

thylakoid

O2

stroma

grana

Page 26: Cell Process Photosynthesis€¦ · Cell Process Photosynthesis. Cell Process - Photosynthesis. Photosynthesis is used to build carbohydrates (the main energy source of all life.)--

Pg 129b

Light & H2O

O2

CO2

glucose

ATP

NADPH

ADP

NADP

Page 27: Cell Process Photosynthesis€¦ · Cell Process Photosynthesis. Cell Process - Photosynthesis. Photosynthesis is used to build carbohydrates (the main energy source of all life.)--

A = photosystem II

B = photosystem I

C = H20

D = Electron Transport Chain

E = ATP Synthase

AB = ATP

AC = phospholipids

AD = light (energy)