Quiz 5 1.Which figure depicts an animal cell placed in a solution hypotonic to the cell? 2.T/F The fluid mosaic model describes the cell membrane like

Quiz 5

1. Which figure depicts an animal cell placed in a solution hypotonic to the cell?

2. T/F The fluid mosaic model describes the cell membrane like a peanut butter sandwich with jelly beans stuck in it.

3. When releasing energy from ATP a chemical reaction occurs that changes ATP to ADP. What is the difference between ATP and ADP?

4. The functions of a cell membrane include signal transduction, transport of molecules, and enzymatic reactions. These functions are all carried out by the proteins or the lipids in the membrane?

5. T/F ATP synthase is an enzyme in the inner membrane of a mitochondrion. It makes/synthesizes ATP as chlorine ions flow through it.

a. b. c.

Quiz 56. Cells undergo cellular respiration to make a form of energy that the cell

can use. This energy is released from cellular respiration in the form of

a) ATP

b) DNA

c) Light

d) Oxygen

7. T/F The overall equation for cellular respiration is:

C6H12O6 (Glucose) + 6O2 6CO2 + 6H2O + Energy (ATP)

8. Does fermentation or respiration produce more ATP?

9. Humans get their energy from the carbon dioxide they inhale.

10.Will fermentation occur in the presence of sufficient oxygen?

AN OVERVIEW OF PHOTOSYNTHESIS

Copyright © 2009 Pearson Education, Inc.

7.1 Autotrophs are the producers of the biosphere

Autotrophs are living things that are able to make their own food without using organic molecules derived from any other living thing

– Autotrophs that use the energy of light to produce organic molecules are called photoautotrophs

– Most plants, algae and other protists, and some prokaryotes are photoautotrophs


– Chemoautotrophs- synthesize all necessary organic compounds from heat methane and sulfur, live in hostile environment like deep sea vents

http://en.wikipedia.org/wiki/File:Nur04506.jpg


– Examples of photosynthetic organisms: leaves from higher plants by colonies of photosynthetic purple bacteria (left) and cyanobacteria (right).

– Note the different colors

– Why all the different colors? Shouldn’t they all be green because they have green chloroplasts?


"The World & I" (March 1998, pg 158-165) Vermaas

Structure of chloroplast – location of photosynthetic reactionse

Leaf cross section

Vein

Mesophyll

StomataCO2 O2

ChloroplastMesophyll cell

Outermembrane

Intermembranespace

5 µm

Innermembrane

Thylakoidspace

Thylakoid

GranumStroma

1 µm


The ability to photosynthesize is directly related to the structure of chloroplasts

– Chloroplasts are organelles consisting of photosynthetic pigments, enzymes, and other molecules grouped together in membranes

– These photosynthetic pigments are called chlorophylls and carotenoids


7.2 Photosynthesis occurs in chloroplasts in plant cells

Chloroplasts are the major sites of photosynthesis in green plants

– Chlorophyll, an important light absorbing pigment in chloroplasts, is responsible for the green color of plants

– Energy for photosynthesis is provided by light, which is absorbed by pigments (primarily chlorophylls and carotenoids)

– Chlorophylls absorb blue and red light and carotenoids absorb blue-green light

– Green and yellow light are not effectively absorbed by photosynthetic pigments in plants; therefore, light of these colors is either reflected by leaves or passes through the leaves

– This is why plants are green


What would happen if put a plant in red light? Blue light? Green light? Which would grow the best or undergo photosynthesis more easily?

Light - further explanation

White light and light from the sun contain all colors of the visible spectrum mixed together

You can separate all of these wavelengths so you can see them with a prism

Objects appear to be certain colors because of interactions with light

Because some wavelengths are being absorbed and some are not – transmitted to our eye where we perceive them

Photosynthetic Pigments: The Light Receptors

Pigments are substances that absorb visible light

Different pigments absorb different wavelengths

Wavelengths that are not absorbed are reflected or transmitted

Leaves appear green because chlorophyll reflects and transmits green light

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Fig. 10-7

Reflectedlight

Absorbedlight

Light

Chloroplast

Transmittedlight

Granum

In short

Plants use all kinds of light but the yellow/green light

The best light is actually red or blue


– Why all the different colors? Shouldn’t they all be green because they have green chloroplasts?



7.6 Reflection and absorbtion

– Other photosynthetic organisms, such as cyanobacteria (formerly known as blue-green algae) and red algae, have additional pigments (called phycobilins or bacteriochlorophyll) that absorb and reflect other colors of the spectrum

– Which colors are being absorbed and reflected by the purple colonies? The orange colonies?



So we know light is important for plants.

What else?

C02 and H20

C02 and H20 are brought to the plant through:

Stomata are tiny pores in the leaf that allow carbon dioxide to enter and oxygen to exit

Veins in the leaf deliver water absorbed by roots


This gives us the left hand side of the equation for photosynthesis


Carbon dioxidePhotosynthesis

H2OCO2

Water

+ 66

Lightenergy

Common sense:All plants need to be watered and placed in a lighted area.

The only other element they need is access to is CO2

Just like respiration, photosynthesis is a redox reaction

This implies the transfer of electrons between the reactants and the products of the photosynthetic equation

Much like in respiration the electron is passed along in a manner like a bucket brigade

The electron originates with water

Let’s break water downH20

Oxygen

H+

e-

7.4 Photosynthesis is a redox process, as is cellular respiration

Photosynthesis, like respiration, is a redox (oxidation-reduction) process

– Water molecules are split apart by oxidation, which means that they lose electrons along with hydrogen ions (H+)

– Then CO2 is reduced to sugar as electrons and hydrogen ions are added to it

– Compare to respiration


7.4 Photosynthesis is a redox process, as is cellular respiration

In photosynthesis, electrons gain energy by being boosted up an energy hill

– Light energy captured by chlorophyll molecules provides the boost of energy for the electrons

– As a result, light energy from the sun is converted to chemical energy, which is stored in the chemical bonds of sugar molecules


The complete equation




CO2 receives the H+ and e- to make glucoseThis leaves oxygen gas behind

Carbon dioxide

C6H12O6

Photosynthesis

H2OCO2 O2

Water

+ 66

Lightenergy

Oxygen gasGlucose

+ 6

Actually, photosynthesis occurs in two metabolic stages

Light reactions and the Calvin cycle

THE LIGHT REACTIONS: CONVERTING SOLAR ENERGY

TO CHEMICAL ENERGY


Light reaction in a nutshell

H+ ions reduce NADP+ to NADPH, which is an electron carrier similar to NADH

– NADPH is temporarily stored and then shuttled into the Calvin cycle where it is used to make sugar

– Finally, the light reactions generate ATP


In the light reactions, light energy is converted in the thylakoid membranes to chemical energy and O2

– Water is split to provide the O2 as well as electrons

Light Reactions

What goes in . . .

NADPH, ATP, and O2 are the products of the light reactions

What goes in . . .

What comes out . . .

NADPH and ATP are sent to the Calvin Cyclewhere they are converted to ADP and NADP+

ADP and NADP+ then return to re-enter the light reactions and start the process again.

7.6 Visible radiation drives the light reactions

Sunlight contains energy called electromagnetic energy or radiation

– Visible light is only a small part of the electromagnetic spectrum, the full range of electromagnetic wavelengths

– Electromagnetic energy travels in waves, and the wavelength is the distance between the crests of two adjacent waves


7.7 Photosystems capture solar power

The energy released could be lost as heat or light, but rather it is conserved as it is passed from one molecule to another molecule


Chlorophyllmolecule

Excited state

Ground state

Heat

Photon

Photon(fluorescence)

e–

7.7 Photosystems capture solar power

The energy is passed from molecule to molecule within the photosystem

– Finally it reaches the reaction center where a primary electron acceptor accepts these electrons and consequently becomes reduced

– This solar-powered transfer of an electron from the reaction center pigment to the primary electron acceptor is the first step of the light reactions


7.8 Two photosystems connected by an electron transport chain generate ATP and NADPH

During the light reactions, light energy is transformed into the chemical energy of ATP and NADPH

– To accomplish this, electrons removed from water pass from photosystem II to photosystem I and are accepted by NADP+

– The bridge between photosystems II and I is an electron transport chain that provides energy for the synthesis of ATP


7.9 Chemiosmosis powers ATP synthesis in the light reactions

Interestingly, chemiosmosis is the mechanism that not only is involved in oxidative phosphorylation in mitochondria but also generates ATP in chloroplasts

– ATP is generated because the electron transport chain produces a concentration gradient of hydrogen ions across a membrane


NADPH

Photosystem II

e–

Millmakes

ATP Ph

oto

n

Photosystem I

ATP

e–e–

e–

e–

e–

e–

Ph

oto

n

Light absorbed by chlorophyll

Energy from light causes electron to jump to a higher

energy state

Electron transport chain produces H+

gradient and ATP

Light absorbed by another chlorophyll

Energy from light causes electron to jump to a higher energy state

Electron is donated to

NADP+

1

5

4

3

2

6

Can humans be as smart as plants?

Plants take light energy and convert it to chemical energy

If humans could harness the sun like plants do, there is enough solar power reaching the earth to provide all of our energy needs 10,000 times over. "The total power needs of the humans on Earth is

approximately 16 terawatts." (A terawatt is a trillion watts.) "In the year 2020 it is expected to grow to 20 terawatts. The sunshine on the solid part of the Earth is 120,000 terawatts. From this perspective, energy from the sun is virtually unlimited." Eicke Weber, director of the Fraunhofer Institute for Solar Energy Systems, in Freiburg, Germany


How to harness the sun

“There are two main ways to harness it. The first is to produce steam, with a field of flat, computer-guided mirrors, called heliostats, that focus sunlight on a receiver on top of an enormous "power tower." The second way is to convert sunlight directly into electricity with photovoltaic (PV) panels made of semiconductors such as silicon.”

How do photovoltaic panels work?

-National Geographic. Plugging into the Sun. September 2009.

How is this similar to light reactions in chloroplast?

Future advancements

People are trying to make conductors and emitters of electrons into a paint that you could put onto your house

Right now solar panels are expensive and only 10-20% efficient – moving to make them more efficient (some @ 40%) but still inexpensive

Make it storable to use at night or cloudy days

– We are not done yet

– ATP is the end goal in respiration, but glucose is the end goal in photosynthesis


Now back to photosynthesis

Reviewing Concepts


The complete equation




CO2 recieves the H+ and e- to make glucoseThis leaves oxygen gas behind

Carbon dioxide

C6H12O6

Photosynthesis

H2OCO2 O2

Water

+ 66

Lightenergy

Oxygen gasGlucose

+ 6

NADPH

Photosystem II

e–

Millmakes

ATP Ph

oto

n

Photosystem I

ATP

e–e–

e–

e–

e–

e–

Ph

oto

n

Light absorbed by chlorophyll

Energy from light causes electron to jump to a higher

energy state

Electron transport chain produces H+

gradient and ATP

Light absorbed by another chlorophyll

Energy from light causes electron to jump to a higher energy state

Electron is donated to

NADP+

1

5

4

3

2

6

Note: water is split to replenish e- supply

ATP is the end goal in respiration, but glucose is the end goal in photosynthesis

What goes in . . .

What comes out . . .

NADPH and ATP are sent to the Calvin Cyclewhere they are converted to ADP and NADP+

ADP and NADP+ then return to re-enter the light reactions and start the process again.

THE CALVIN CYCLE: CONVERTING CO2 TO SUGARS


7.10 ATP and NADPH power sugar synthesis in the Calvin cycle

The Calvin cycle makes sugar within a chloroplast

– To produce sugar, the necessary ingredients are atmospheric CO2, ATP, and NADPH, which were generated in the light reactions

– Using these three ingredients, an energy-rich, three-carbon sugar called glyceraldehyde-3-phosphate (G3P) is produced

– A plant cell may then use G3P to make glucose and other organic molecules


CO2

ATPNADPH

Input

CALVINCYCLE

G3POutput: Glucose

G3PCellularRespiration (50%)

CelluloseStarchOther organiccompounds

2 G3P make 1 glucose

7.11 Review: Photosynthesis uses light energy, CO2, and H2O to make food molecules

The chloroplast, which integrates the two stages of photosynthesis, makes sugar from CO2

– All but a few microscopic organisms depend on the food-making machinery of photosynthesis

– Plants make more food than they actually need and stockpile it as starch in roots, tubers, and fruits


NADP+

NADPH

ATP

CO2

+

H2O

ADPP

Electrontransport

chainsThylakoidmembranes

LightChloroplast

O2

CALVINCYCLE

(in stroma)

Sugars

Photosystem II

Photosystem I

LIGHT REACTIONS

RuBP

3-PGA

CALVIN CYCLE

Stroma

G3P Cellularrespiration


CO2

ATPNADPH

Input

CALVINCYCLE

G3POutput: Glucose

G3PCellularRespiration (50%)


2 G3P make 1 glucose

Plants undergo photosynthesisand respiration

Photosynthesis stores energy into sugars and respiration will release that energy

Antioxidants fighting ROS (reactive oxygen species)

ROS form as a natural byproduct of cellular respiration

Are deployed to kill invading microorganisms

– About 0.1-2% of electrons passing through the electron transport oxygen is instead prematurely and incompletely reduced to give the superoxide radical(O2

-) and not water




ATP

H+

Intermembranespace

O2

H2O

12

Innermitochondrialmembrane

H+NAD+

H+

H+

H+

H+

H+

H+

H+

H+

H+

H+

H+

H+

Mitochondrialmatrix

Electronflow

Electroncarrier

Proteincomplexof electroncarriers

NADH

FADH2FAD

ATPsynthase

PADP +

Chemiosmosis

+ 2

Electron Transport Chain

If too much damage is caused to its mitochondria by ROS, a cell will kill itself

Antioxidants



ROS are ions or molecules that that are highly reactive due to the presence of unpaired valence shell electrons. ROS form as a natural byproduct of cellular respiration. Can damage cells.


Tentative negative effects of oxidative damage

Limiting lifespan – more ROS has been proven to cause worms to age prematurely

Cancer

Brain diseases (stroke, Alzheimer's, Parkinson’s)

Heart disease

In order for your body to fight these negative effects, it needs antioxidants

What are antioxidants? Where are they found?

One class of antioxidants are carotenoids found in fruits and vegetables

Photosynthetic pigments – these are the pigments we have been talking about in this chapter

Remember? They absorb light to excite electrons

What are antioxidants? Where are they found?

In general, processed foods contain fewer antioxidants than fresh and uncooked foods, since the preparation processes may expose the food to oxygen and use up the antioxidant potentail of the food


Eat your fruits and vegetables

Good sources of antioxidants

People who do have a lower risk of heart disease and some neurological diseases

Some evidence that particular types of vegetables, and fruits in general, probably protect against a number of cancers

These observations suggest that antioxidants might help prevent these conditions

Antioxidant supplements

However, a large analysis of 68 reliable antioxidant supplementation experiments involving a total of 232,606 individuals concluded that consuming additional beta-carotene from supplements is unlikely to be beneficial, may even be harmful

Health food companies now sell formulations of antioxidants as dietary supplements and these are widely used

These supplements may include specific antioxidant chemicals,

Resveratrol (from grape seeds)

"ACES" products that contain beta carotene (provitamin A), vitamin C, vitamin E and Selenium,

Take home message

Although some levels of antioxidant vitamins and minerals in the diet are required for good health, there is considerable doubt as to whether antioxidant supplementation is beneficial, and if so, which antioxidant(s) are beneficial and in what amounts?

Global Warming

7.13 CONNECTION: Photosynthesis moderates global warming

The greenhouse effect results from solar energy warming our planet

– Gases in the atmosphere (often called greenhouse gases), including CO2, reflect heat back to Earth, keeping the planet warm and supporting life

– However, as we increase the level of greenhouse gases, Earth’s temperature rises above normal, initiating problems


Atmosphere

Sunlight

Some heatenergy escapesinto space

Radiant heattrapped by CO2

and other gases

Global temperatures have flatlined since 2001 despite rising greenhouse gas concentrations, and a heat surplus that should have cranked up the planetary thermostat.


Carbon Dioxide Levels in the Atmosphere

This graph shows the levels of CO2 in the atmosphere measured at Hawaii’s Mauna Loa Observatory over the last 40+ years—the longest measurement of its kind..

Mauna Loa Atmospheric Carbon Dioxide

300

310

320

330

340

350

360

370

380

390

1955 1965 1975 1985 1995 2005

Years

CO

2 (

pp

m)

Keeling, C.D. and T.P. Whorf. 2005. Atmospheric CO2 records from sites in the SIO air sampling network. In Trends: A Compendium of Data on Global Change. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tenn., U.S.A.


Interpreting DataHere’s a magnified view of 5 years of data on CO2 levels. What do you think is the most likely cause for the cycles you see in this data?

1) The differing amounts of CO2 produced by plant during daylight and night hours.

2) Volcanic emissions

3) Seasonal differences in CO2 uptake by photosynthesizers.


320

322

324

326

328

330

332

334

1970 1971 1972 1973 1974 1975

YearsC

O2

(p

pm

)


AnswerHere’s a magnified view of 5 years of data on CO2 levels. What do you think is the most likely cause for the cycles you see in this data?

3) Seasonal differences in CO2 uptake by photosynthesizers.


320

322

324

326

328

330

332

334

1970 1971 1972 1973 1974 1975

YearsC

O2

(p

pm

)


Interpreting DataThe data indicates that carbon dioxide levels are rising.


300

310

320

330

340

350

360

370

380

390

1955 1965 1975 1985 1995 2005

Years

CO

2 (

pp

m)


Biology and SocietyThis graph shows a correlation between Global surface temperature and atmospheric carbon dioxide. The temperature increase and the carbon dioxide increases are real—but direct correlation is difficult to prove. The U.S. has not signed the international Kyoto agreement that sets aggressive goals to reduce carbon dioxide emissions. Do you think we should have direct evidence before taking aggressive action?

Disagree Agree Strongly A B C D E Strongly


Biology and SocietyThis graph shows a correlation between Global surface temperature and atmospheric carbon dioxide. The temperature increase and the carbon dioxide increases are real—but direct correlation is difficult to prove. The U.S. has not signed the international Kyoto agreement that sets aggressive goals to reduce carbon dioxide emissions. Do you think we had better start right now to curb carbon dioxide emissions?

Disagree Agree Strongly A B C D E Strongly

Documents

Quiz 5 1.Which figure depicts an animal cell placed in a solution hypotonic to the cell? 2.T/F The fluid mosaic model describes the cell membrane like