part 1: atp &photosynthesis - ddtwo

Part 1: ATP &Photosynthesis

Objectives

• Understand the energy carrying

molecules ATP & ADP, their structure and

model their cycle.

• Explain the importance of photosynthesis

to organisms on Earth.

• Recall the equation for photosynthesis.

• Discuss the structure of a chloroplast.

Autotrophs and Heterotrophs

• Autotrophs-Organisms,

plants, which make

their own food.

• Heterotrophs-

Organisms, animals,

that must obtain

energy from the foods

they consume.

Chemical Energy and ATP

–An important chemical compound

that cells use to store and release

energy is adenosine triphosphate,

ATP.

–ATP is used by all types of cells as

their basic energy source.

Chemical Energy and ATP

• ATP consists of:

– adenine

– ribose (a 5-carbon sugar)

– 3 phosphate groups

Adenine

ATP

Ribose 3 Phosphate groups

Chemical Energy and ATP•Storing Energy

– ADP has two

phosphate groups

instead of three.

– A cell can store small

amounts of energy by

adding a phosphate

group to ADP.

Energy

Energy

Chemical Energy and ADP

•Releasing Energy•Energy stored in ATP is released by

breaking the chemical bond between the

second and third phosphates.

P

ADP

2 Phosphate groups

ADP/ATP Cycle

In a Nut shell, ATP

• ATP is consumed in the cell by

energy-requiring processes and can

be generated by energy-releasing

processes. – In this way ATP transfers energy between separate biochemical

reactions in the cell.

• ATP is the main energy source for the

majority of cellular functions. – This includes the synthesis of organic molecules, including DNA

and, and proteins. ATP also plays a critical role in the transport of

organic molecules across cell membranes, for example during

exocytosis and endocytosis.

Energy Transformations

• All organisms need

constant energy

• Ultimate source of energy

for most life is the SUN

• Photosynthesis

– Chloroplasts of plants

– Solar energy is used to

convert water and carbon

dioxide into stored energy

in sugar

PHOTOSYNTHESIS An Overview

• The key cellular process

identified with energy

production is

photosynthesis.

• Photosynthesis is the

process in which green

plants use the energy of

sunlight to convert water

and carbon dioxide into

high-energy carbohydrates

and oxygen.

The Photosynthesis Equation

•The Photosynthesis Equation• The equation for photosynthesis is:

• Reactants Products

• 6CO2 + 6H2O C6H12O6 + 6O2

• carbon dioxide + water sugars +

oxygen

Light

Chloroplast Structure• Majority of chloroplasts are in the leaves

(million per square millimeter).

• Color of chloroplasts and leaves is

determined by chlorophyll (pigment that

collects light energy).

• Chloroplast is surrounded by a double membrane

(inner and outer)

• Inside the chloroplast are stacks of flat membrane

discs called thylakoids

• Stack of thylakoids = granum (multiple stacks are

called grana)

• Liquid portion that surrounds the grana= stroma

• Stomata – pores on

underside of leaf through

which gases pass

Pigments in Thylakoid• Chlorophyll is the main pigment that absorbs sunlight

• Blue and red wavelengths of light are absorbed and

green wavelengths are reflected (hence the green

color of plants)

• There are other pigments called accessory pigments

that can absorb light (red, yellow, orange- you see this

in the fall when the leaves change)

Inside a Chloroplast

•Inside a Chloroplast• In plants, photosynthesis takes place

inside chloroplasts.

Plant

Plant cells

Chloroplast


• Chloroplasts contain thylakoids—saclike

photosynthetic membranes.

Chloroplast

Single

thylakoid


• Thylakoids are arranged in stacks known

as grana. A singular stack is called a

granum.Granum

Chloroplast


• The stroma is the area that surrounds the

Granum. It is like the cytoplasm in a cell. Stroma

Chloroplast

CHECK FOR UNDERSTANDING

What type of organism makes their own food?

What is the main source of Energy on earth?

Where does photosynthesis occur?

What are the overall reactants of photosynthesis?

What are the overall products of photosynthesis?

What pigments are found in a chloroplast?

High Energy Electrons

• High energy electrons

produced by chlorophyll

require carriers to transfer

them (with their energy)

• NADP+ is a carrier

• When full with electrons it is

NADPH

Photosynthesis• 2 Stages:

– Light-dependent reactions

– Light-independent reactions (Calvin Cycle)

Photosystems

• Areas on thylakoids that contain clusters of chlorophyll and protein

• Absorb sunlight

• Generate high energy electrons

• Photosystem II and Photosystem I

LIGHT-DEPENDENTREACTIONS OVERVIEW

• Requires sunlight

• Location: thylakoid membranes

• Reactants: sunlight, water, NADP+

(electron acceptor), ADP• Products: oxygen, NADPH (energy

carrying molecule), and ATP• Main function : generate energy carrying

molecules (ATP and NADPH) for the next stageof photosynthesis

Light Dependent Reactions

• Photosystem II

– Light energy absorbed by

photosystem II produces high

energy electrons

– Water molecules are split to

replace those electrons

(releasing H+ ions and oxygen)


• Electron Transport

Chain

– High-energy electrons

move down the electron

transport chain (to

photosystem I)

– Energy made is used to

pump H+ ions across

the thylakoid membrane

and into the thylakoid

space


• Photosystem I

– Electrons are reenergized in photosystem I

– Second electron transport chain transfers these

electrons to NADP+ to form NADPH

– NADP+ is final electron acceptor


• Hydrogen Ion Movement and ATP Formation

– H+ now highly concentrated in thylakoid space

– H+ move out of thylakoid to get to more negative

area

• Move through ATP synthase which rotates and the

energy is used to convert ADP into ATP

• Called Chemiosmosis

CFU

• What is made in light dependent

reactions?

• What is used in light dependent

reactions?

• Where do these reactions occur?

• What travels into the thylakoid?

CFU continued

• What happens when the H+ build up?

• What makes the ATP?

• What happens to the electrons at the

end of the chain?

• What happens to the ATP and NADPH

made?

LIGHT-INDEPENDENTREACTIONS OVERVIEW

• DOES NOT require sunlight (dark reactions or Calvin cycle)

• Location: stroma

• Reactants: NADPH, ATP, and CO2

• Products: ADP and unhooked phosphate group,NADP+, and glucose

• Main Function: to make glucose

Light-Independent Reactions• occurs in the stroma of the chloroplast

• uses the ATP and NADPH from the light

reactions

• uses CO2 from environment (often called

carbon fixation) to make sugar

• AKA – Calvin Cycle

CO2 Enters the Cycle

• 6 carbon dioxide molecules are taken in

through the stomata (openings in bottom

of a leaf)

• Combine with six 5-carbon molecules to

make twelve 3-carbon compounds

Sugar Production

• Energy from ATP and NADPH convert

the 3-carbon molecules to higher energy

forms

• 2 of the 3-carbon molecules are removed

from cycle to form glucose, starch, and

cellulose

• Remaining 3-carbon molecules (most of

them) are converted back to 5-carbon

forms that started the cycle (to keep it

going)

Sugar Production

• Glucose can be used for energy to make

ATP or it can be converted to

starch/cellulose

• Sugars made also provide carbon

skeleton to interact with elements like

nitrogen, sulfur, and phosphorous to

make other organic molecules

– Amino acids, lipids, or nucleic acids

Chloroplast

LightH2O

O2

CO2

Sugars

NADP+

ADP +

PLight-

dependent

reactions

Calvin

Cycle

–Factors Affecting Photosynthesis • Many factors affect the rate of photosynthesis,

including:

• Water

• Temperature

• Intensity of light

• Water- a shortage can slow or stop photosynthesis

• Temperature-photosynthesis depends on enzymes

that work best between 0o and 35o C. Temps above

or below will slow photosynthesis.

• Intensity of light- increasing light intensity increases

the rate of photosynthesis. The rate will level off.

• Stomata- used for gas exchange.

• Guard cells- control the opening and closing of the

stomata.

CHECK FOR UNDERSTANDING

1. What is used in Calvin Cycle?

2. What is made in Calvin Cycle?

3. Where does the Calvin Cycle occur?

4. What leaves the Calvin Cycle?

part 1: atp &photosynthesis - ddtwo

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