Photosynthesis Revised.ppt

(1)

Photosynthesis

(2)

(3)

Autotrophs

Plants and some

Plants and some

other types of

organisms that

contain

chlorophyll

chlorophyll are _are

able to use

able to use light _light energy from the energy from the

sun

sun to produce to produce food.

(4)

Autotrophs

•

Autotrophs

include

organisms

that

make their own

food

•

Autotrophs can

use the sun’s

energy directly

(5)

Heterotrophs

• Heterotrophs Heterotrophs are organisms are organisms

that can NOT that can NOT

make their own make their own

food food

(6)

Energy

• Energy Takes Many Energy Takes Many

Forms such as

Forms such as light, _light, heat, electrical,

heat, electrical,

chemical, mechanical chemical, mechanical

• Energy can be changed Energy can be changed from

from one form to one form to another

another

• Energy can be stored in Energy can be stored in chemical bonds & then

chemical bonds & then

released later

(7)

ATP – Cellular Energy

• Adenosine Triphosphate_{Adenosine Triphosphate}

• Contains two, high-energy phosphate Contains two, high-energy phosphate bonds

bonds

• Also contains the nitrogen base adenine Also contains the nitrogen base adenine & a ribose sugar

(8)

ADP

• Adenosine Diphosphate_{Adenosine Diphosphate}

• ATP releases ATP releases energyenergy, a , a free free phosphate,

phosphate, & _&ADP_ADP when cells take _{when cells take}

energy from ATP

(9)

Sugar in ADP & ATP

•

Called ribose

•

Pentose

sugar

(10)

Importance of ATP

Principal

Compound

Used To

Store

Energy

In

Living

(11)

Releasing Energy From ATP

• ATP is constantly being _{ATP is constantly being}used and _{used and}

remade by cells remade by cells

• ATP provides all of the energy for ATP provides all of the energy for cell activities

cell activities

• The high energy phosphate bonds The high energy phosphate bonds can be

can be BROKEN_BROKEN to _torelease energy_{release energy}

• The process of releasing ATP’s _{The process of releasing ATP’s}

energy & reforming the molecule

(12)

Releasing Energy From ATP

• Adding_Adding A _A

Phosphate Group

Phosphate Group

To ADP stores

Energy in ATP

• RemovingRemoving A A

Phosphate Group Phosphate Group From ATP From ATP Releases Energy Releases Energy

& forms ADP

Lose

(13)

Cells Using Biochemical Energy

Cells Use ATP For:

• Active transport • Movement

• Photosynthesis

• Protein Synthesis • Cellular respiration • All other cellular

(14)

More on ATP

Very Well

•

ATP Is

NOT

Good At

Energy Storage

(15)

Glucose

•

Glucose is a

monosaccharide

•

C

₆₆

H

₁₂₁₂

O

₆₆

•

One Molecule of glucose

Stores

90 Times

More

Chemical Energy Than

One Molecule of ATP

(16)

History of

Photosynthesis &

(17)

Photosynthesis

• Involves the Use Of light _{Involves the Use Of light}

Energy to convert

Energy to convert Water (HWater (H₂₂0)0) and

and Carbon Dioxide (CO_{Carbon Dioxide (CO}₂₂)₎ into _into

Oxygen (O

Oxygen (O22)) and and High Energy High Energy

Carbohydrates

Carbohydrates (sugars, e.g. _{(sugars, e.g.}

Glucose) & Starches

(18)

Investigating Photosynthesis

•

Many Scientists Have

Contributed To

Understanding Photosynthesis

•

Early Research

Focused On

The

Overall Process

•

Later Researchers

Investigated The Detailed

Chemical Pathways

(19)

Early Questions on Plants

Several Centuries Ago, The

Question Was:

Does the increase in mass

(20)

The Photosynthesis

Equation

(21)

Pigments

• In addition to water, carbon dioxide, and light energy,

photosynthesis requires

Pigments

• Chlorophyll is the

primary light-absorbing pigment in autotrophs

(22)

Light and Pigments

• Energy From The Sun

Enters Earth’s Biosphere As Photons

•

Photon = Light Energy

Unit

• Light Contains A Mixture Of Wavelengths

•

Different Wavelengths

(23)

Light & Pigments

• Different pigments_{Different pigments} absorb _absorb

different

different wavelengthswavelengths of light of light

• Photons of light Photons of light “excite”“excite” electrons electrons in the plant’s pigments

in the plant’s pigments

• Excited electrons carry the Excited electrons carry the absorbed energy

absorbed energy

• Excited electrons move to _{Excited electrons move to}

HIGHER

(24)

Chlorophyll

There are 2 main types

of chlorophyll

molecules:

Chlorophyll a

Chlorophyll b

A third type,

A third type, chlorophyll chlorophyll c

c, is found in , is found in dinoflagellates

(25)

Chlorophyll a and b

(26)

Chlorophyll a

•

Found in all

plants, algae, &

cyanobacteria

•

Makes photosynthesis possible

•

Participates

directly

in the

Light Reactions

•

Can

accept energy

from

chlorophyll b

(27)

Chlorophyll b

•

Chlorophyll b is an

accessory pigment

•

Chlorophyll b acts

indirectly

in photosynthesis by

transferring the light it

absorbs to chlorophyll

a

•

Like chlorophyll a, it

absorbs red & blue light

and

(28)

The Biochemical

(29)

It Begins with Sunlight!

(30)

Photoautotrophs Absorb Light

Energy

(31)

Inside A Chloroplast

(32)

Structure of the Chloroplast

•

Double membrane

organelle

•

Outer membrane

smooth

•

Inner membrane

forms stacks

of connected sacs called

thylakoids

•

Thylakoid stack is called the

granun

(grana-plural)

•

Gel-like material around grana

called

(33)

Function of the Stroma

•

Light Independent

reactions occur here

•

ATP used

to make

carbohydrates like

glucose

•

Location of the

Calvin

Cycle

(34)

(35)

Thylakoid membranes

• Light DependentLight Dependent reactions occur reactions occur here

here

• Photosystems are made up of Photosystems are made up of clusters of chlorophyll molecules

clusters of chlorophyll molecules • Photosystems are Photosystems are embedded in embedded in

the thylakoid membranes

the thylakoid membranes

• The two photosystems are:The two photosystems are:

Photosytem I_{Photosytem I}

(36)

Photosynthesis Overview

(37)

Energy Carriers

• Nicotinamide Adenine Dinucleotide _{Nicotinamide Adenine Dinucleotide}

Phosphate

Phosphate (NADP(NADP++))

•

NADPH

= =

Reduced

Form

•

Picks Up

2 high-energy

electrons and H

++

from the Light

Reaction to form NADPH

•

NADPH

carries energy to be

passed on to another molecule

(38)

NADPH

(39)

•

Occurs across the

thylakoid

membranes

•

Uses light energy

•

Produce

Oxygen

from water

•

Convert

ADP to ATP

•

Also convert

NADP

++

into the

energy carrier

NADPH

Light Dependent Reactions

(40)

Light Dependent Reaction

(41)

Light Dependent Reaction

(42)

Photosystem I

•

Discovered

First

•

Active in the final stage of

the Light Dependent Reaction

•

Made of 300 molecules of

Chlorophyll

•

Almost completely chlorophyll

a

(43)

Photosystem II

•

Discovered

Second

•

Active in the beginning stage

Of the Light Dependent

Reaction

•

Contains about

equal amounts

of chlorophyll a and

chlorophyll b

(44)

Photosynthesis Begins

Photosystem

II absorbs light energy

Electrons are energized

and passed

to the

Electron Transport Chain

Lost electrons are replaced from

the splitting of water

into 2H

+, +,

free electrons, and Oxygen

2H

+ +

pumped across thylakoid

membrane

(45)

Photosystem I

High-energy electrons

High-energy electrons are _are

moved to Photosystem I

through the Electron

Transport Chain

Energy is used to

Energy is used to transport H_{transport H}++

from stroma to inner

thylakoid membrane

thylakoid membrane

NADP+ converted to NADPH NADP+ converted to NADPH

when it picks up 2 electrons &

H+

(46)

Phosphorylation

Enzyme in thylakoid

membrane called

ATP

Synthase

As H+ ions passed through

thylakoid membrane,

enzyme binds them to ADP

Forms

(47)

(48)

Light Reaction Summary

Reactants:

•

H

₂₂

O

•

Light Energy

Energy Products:

•

ATP

(49)

Light Independent Reaction

•

ATP & NADPH

from light

reactions used as energy

•

Atmospheric

C0

₂₂

is used

to

make sugars

like glucose and

fructose

•

Six-carbon Sugars made

during the

Calvin Cycle

(50)

The Calvin Cycle

(51)

The Calvin Cycle

• Two turnsTwo turns of the Calvin Cycle of the Calvin Cycle are required to make one

are required to make one

molecule of glucose

• 3-CO_3-CO₂₂ molecules enter the cycle molecules enter the cycle to form several

to form several intermediate _intermediate compounds (PGA)

compounds (PGA)

• A 3-carbon molecule called A 3-carbon molecule called Ribulose Biphosphate

Ribulose Biphosphate (RuBP) is (RuBP) is used to regenerate the Calvin

used to regenerate the Calvin

cycle

(52)

(53)

Factors Affecting the Rate

of Photosynthesis

•

Amount of

available water

•

Temperature

•

Amount of

available light

energy

(54)