Chapter 8 Cellular Energy *Photosynthesis *Cellular Respiration Cellular Energy Cellular Energy

Chapter 8Chapter 8

Cellular Energy

*Photosynthesis*Photosynthesis*Cellular Respiration*Cellular Respiration

ENERGY - is ENERGY - is

the ability to do workthe ability to do work

ALLALL ORGANISMS – ORGANISMS –

need and use energy!!!!need and use energy!!!!

Where do organisms get Where do organisms get the energy that they the energy that they

need?need?

it comes from it comes from food, however, food, however,

the ultimate the ultimate source of most source of most of our energy of our energy

is the SUNis the SUN

Law of ThermodynamicsLaw of Thermodynamics

Energy cannot be created or Energy cannot be created or destroyed, but it can be converted destroyed, but it can be converted into other formsinto other forms

MetabolismMetabolism

The sum of a cell’s chemical reactionsThe sum of a cell’s chemical reactions Metabolism = Catabolism + AnabolismMetabolism = Catabolism + Anabolism

Catabolism: to break down Catabolism: to break down Ex: cellular respirationEx: cellular respiration

Anabolism: to build up Anabolism: to build up Ex: photosynthesisEx: photosynthesis

*This results in a continuous flow of energy within *This results in a continuous flow of energy within an organism.an organism.

organisms meet their energy needs organisms meet their energy needs in different waysin different ways

AUTOTROPHSAUTOTROPHS – plants, some bacteria & – plants, some bacteria & protistsprotists

produce their own food produce their own food chemoautotrophs go through chemoautotrophs go through

chemosynthesischemosynthesis photoautotrophs go through photoautotrophs go through

photosynthesisphotosynthesis

HETEROTROPHSHETEROTROPHS – fungi, animals, some – fungi, animals, some bacteria & protists cannot produce their own bacteria & protists cannot produce their own foodfood must obtain energy from the foods they must obtain energy from the foods they

consumeconsume

ENERGYENERGY energy comes in many forms – light, heat, electricity, energy comes in many forms – light, heat, electricity,

nuclear, kinetic,…nuclear, kinetic,…

Some organisms consume foods in order to get the Some organisms consume foods in order to get the

stored energy out of themstored energy out of them

ATPATP cellular activities require the use of energycellular activities require the use of energy one of the main chemical compounds that cells use one of the main chemical compounds that cells use

to store energy is ATP (adenosine triphosphate) to store energy is ATP (adenosine triphosphate)

ATP consists of :ATP consists of : 1. a N-containing part – called adenine1. a N-containing part – called adenine 2. a 5-Carbon sugar - called ribose2. a 5-Carbon sugar - called ribose 3. three phosphate groups (P and O)3. three phosphate groups (P and O)

Metabolic Pathway of ATP and ADP form a cycle of releasing and absorbing energyform a cycle of releasing and absorbing energy

ATP

ADP

releases Energy

requires (absorbs) energy

ATP and GlucoseATP and Glucose most cells have only a small amount of ATP most cells have only a small amount of ATP

(enough to last for a few seconds of activity)(enough to last for a few seconds of activity)

more is made as needed by using the stored more is made as needed by using the stored energy (glycogen)energy (glycogen)

2 processes of 2 processes of great importancegreat importance that enable living things to that enable living things to

meet their energy needs – meet their energy needs –

1. 1. PHOTOSYNTHESISPHOTOSYNTHESIS – –

the production of organic the production of organic compounds compounds

2. 2. CELLULAR RESPIRATIONCELLULAR RESPIRATION – – the break down of organic the break down of organic

compoundscompounds

PHOTOSYNTHESISPHOTOSYNTHESIS

CELLULARCELLULAR

RESPIRATIONRESPIRATION

ATP- ADP CYCLEATP- ADP CYCLE

Light EnergyLight Energy

Chemical Energy Chemical Energy (organic compounds)(organic compounds)

ATP’sATP’s

ADP’s + P groups + ADP’s + P groups + energy (that can be used energy (that can be used to do cellular activities)to do cellular activities)

Photosynthesis

process by which a cell captures light energy (photons) and uses it to make food

(usually carbohydrates, like glucose)

photosynthesis occurs in photoautotrophs: plants algae some bacteria (prokaryotes)

PHOTOSYNTHESISPHOTOSYNTHESIS - process in which - process in which water, carbon dioxide, and light water, carbon dioxide, and light energy are converted into oxygen and energy are converted into oxygen and organic compounds organic compounds

the ORGANIC COMPOUNDS the ORGANIC COMPOUNDS made made during during photosynthesis are usually photosynthesis are usually

carbohydratescarbohydrates (sugars and (sugars and starches)starches)

PHOTOSYNTHESISPHOTOSYNTHESIS – general equation – general equation

6 CO6 CO22 + 6 H + 6 H22O + light (energy) CO + light (energy) C66HH1212OO6 6 + 6 O+ 6 O22

What are the reactants?What are the reactants?

What are the products? What are the products?

Where does the light energy come from?Where does the light energy come from?

Where does the HWhere does the H22O come from?O come from?

Where does the COWhere does the CO2 2 come from?come from?

Photosynthesis - OverviewPhotosynthesis - Overview

most photosynthetic organisms are most photosynthetic organisms are eukaryotes, therefore, eukaryotes, therefore,

photosynthesis photosynthesis

occurs inside the occurs inside the

CHLOROPLASTCHLOROPLAST

prokaryotes lack chloroplasts, prokaryotes lack chloroplasts,

in these organisms, photosynthesis in these organisms, photosynthesis

occurs in the cytoplasmoccurs in the cytoplasm

PIGMENTSPIGMENTS

ALLALL photosynthetic organisms contain photosynthetic organisms contain PIGMENTSPIGMENTS (light absorbing (light absorbing substances)substances)

the principal photosynthetic pigment is the principal photosynthetic pigment is (green) CHLOROPHYLL (green) CHLOROPHYLL

in addition to chlorophyll there are other in addition to chlorophyll there are other pigments called pigments called ACCESSORY PIGMENTSACCESSORY PIGMENTS (ex. Carotenoids)(ex. Carotenoids)

Chloroplast StructureChloroplast Structure

chloroplasts contain disc like chloroplasts contain disc like structures calledstructures called

THYLAKOID DISKSTHYLAKOID DISKS

these are arranged in stacks these are arranged in stacks called called GRANAGRANA

PIGMENTSPIGMENTS are found inside are found inside the thylakoid disks the thylakoid disks

a fluid called a fluid called STROMASTROMA surrounds the thylakoid surrounds the thylakoid disksdisks

PHOTOSYNTHESISPHOTOSYNTHESIS – –

consists of 2 major sets of reactionsconsists of 2 major sets of reactions

1. LIGHT DEPENDENT REACTIONS1. LIGHT DEPENDENT REACTIONS

2. LIGHT INDEPENDENT REACTIONS 2. LIGHT INDEPENDENT REACTIONS

(or CALVIN CYCLE)(or CALVIN CYCLE)

What do the names indicate What do the names indicate

about these reactions?about these reactions?

Light Light Dependent Dependent ReactionsReactions

(occur in thylakoid disk (occur in thylakoid disk containing chlorophyll)containing chlorophyll)

Light Light Independent Independent Reactions Reactions (occur in stroma)(occur in stroma)

Light dependent reaction:Light dependent reaction:What are the reactants? products?What are the reactants? products?

Light independent reaction (Light independent reaction (Calvin Cycle)?)?

What are the reactants? products?What are the reactants? products?

Alternative PathwaysAlternative Pathways

Used when water and/or carbon dioxide are Used when water and/or carbon dioxide are not present or in insufficient amountsnot present or in insufficient amounts

2 types:2 types: The CThe C44 pathway pathway

Sugar cane, cornSugar cane, corn The CAM pathwayThe CAM pathway

Pineapple, cacti, orchidsPineapple, cacti, orchids

Factors Affecting PhotosynthesisFactors Affecting Photosynthesis

availability of wateravailability of water availability of carbon availability of carbon

dioxidedioxide temperaturetemperature light intensitylight intensity

Biochemical (Metabolic) Biochemical (Metabolic) PathwayPathway

PHOTOSYNTHESISPHOTOSYNTHESIS

CELLULARCELLULAR

RESPIRATIONRESPIRATION

ATP- ADP CYCLEATP- ADP CYCLE

Light EnergyLight Energy

Chemical Energy Chemical Energy (organic compounds)(organic compounds)

ATP’sATP’s

ADP’s + P groups + energy ADP’s + P groups + energy (that can be used to do cellular (that can be used to do cellular

activities)activities)

Cellular Respiration

process that releases energy (in the form of ATP’s)

from food (organic compounds)

All living things undergo some form of cellular respiration, but remember living things differ so this process may differ

There are 2 possible ways in which a cell can There are 2 possible ways in which a cell can accomplish cellular respiration and harvest energy accomplish cellular respiration and harvest energy from food….from food….

(aerobic) (aerobic) CCellular Respiration = oxidative respiration= oxidative respiration

ororFermentation (anaerobic Fermentation (anaerobic

respiration)respiration)

*both start with the same first step*both start with the same first stepGLYCOLYSISGLYCOLYSIS

(aerobic) Cellular Respiration or (aerobic) Cellular Respiration or Oxidative RespirationOxidative Respiration

releases energy (in the form of ATP’s)

from food (organic compounds)

~in the presence of oxygen~

3 steps of 3 steps of (aerobic) (aerobic) Cellular RespirationCellular Respiration

1. Glycolysis1. Glycolysis

2. Kreb’s Cycle 2. Kreb’s Cycle

3. Electron Transport Chain3. Electron Transport Chain

1. Glycolysis1. Glycolysis

occurs in the cytoplasmoccurs in the cytoplasm anaerobic anaerobic ““splitting of glucose” into pyruvic acid (pyruvate) splitting of glucose” into pyruvic acid (pyruvate) net gain of 2 ATP and 2 pyruvatenet gain of 2 ATP and 2 pyruvate

2. Kreb’s Cycle2. Kreb’s Cycle

occurs in mitochondrion (of eukaryotes) occurs in mitochondrion (of eukaryotes) aerobic aerobic breaks down pyruvic acidbreaks down pyruvic acid produces COproduces CO22 and a net gain of 2 ATP and a net gain of 2 ATP

3. Electron Transport Chain3. Electron Transport Chain

occurs in mitochondria(of eukaryotes) occurs in mitochondria(of eukaryotes) aerobic aerobic uses electrons to release energy and produce ATPuses electrons to release energy and produce ATP produces Hproduces H22O and up to 34 ATPO and up to 34 ATP

How many ATP’s from How many ATP’s from (aerobic) (aerobic) Cellular RespirationCellular Respiration??

Glycolysis (2)Glycolysis (2)

Kreb’s Cycle (2)Kreb’s Cycle (2)

Electron Transport Chain (maximum 34)Electron Transport Chain (maximum 34)

possible 38 ATP’spossible 38 ATP’s

the actual number of ATP’s varies from cell to cellthe actual number of ATP’s varies from cell to cell most eukaryotic cells produce 36 ATP’smost eukaryotic cells produce 36 ATP’s

General Equation for General Equation for (aerobic) Cellular Respiration(aerobic) Cellular Respiration

C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP (energy)

What are the reactants?What are the reactants?

What are the products?What are the products?

if no oxygen is present….. if no oxygen is present…..

glycolysis is followed by glycolysis is followed by fermentationfermentation

Fermentation (anaerobic respiration) Fermentation (anaerobic respiration) releases energy (in the form of ATP) releases energy (in the form of ATP)

from food (organic compounds) from food (organic compounds)

~in the absence of oxygen~~in the absence of oxygen~

2 steps of 2 steps of FermentationFermentation

(anaerobic respiration)(anaerobic respiration)

1. Glycolysis1. Glycolysis

2. Fermentation2. Fermentation

1. Glycolysis1. Glycolysis

occurs in the cytoplasmoccurs in the cytoplasm anaerobic anaerobic ““splitting of glucose” into pyruvic acid (pyruvate) splitting of glucose” into pyruvic acid (pyruvate) net gain of 2 ATP and 2 pyruvatenet gain of 2 ATP and 2 pyruvate

2. Fermentation2. Fermentation

occurs in the cytoplasmoccurs in the cytoplasm anaerobic anaerobic the break down of pyruvic acid in the absence of the break down of pyruvic acid in the absence of

oxygenoxygen net gain of 0 ATPnet gain of 0 ATP

How many ATP’s from How many ATP’s from FERMENTATION?FERMENTATION?

Glycolysis (2)Glycolysis (2)Fermentation (0)Fermentation (0) possible 2 ATPpossible 2 ATP

* fermentation is not nearly as efficient in releasing * fermentation is not nearly as efficient in releasing energy from food as is (aerobic) Cellular Respiration energy from food as is (aerobic) Cellular Respiration

2 common types 2 common types of Fermentationof Fermentation

LACTIC ACID FERMENTATIONLACTIC ACID FERMENTATION converts pyruvic acid into lactic acidconverts pyruvic acid into lactic acid process used to make yogurt, cheese, sour cream occurs in some fungi and some bacteria occurs in skeletal muscle cells of animals = lactic

acid or sore muscles

2 common types 2 common types of Fermentationof Fermentation

ALCOHOLIC FERMENTATIONALCOHOLIC FERMENTATION converts pyruvic acid into ethanol (ethyl alcohol)converts pyruvic acid into ethanol (ethyl alcohol) process used in the making of bread and alcoholic

beverages - wine, beer,… occurs in yeasts, some bacteria, some plants ethanol is added to gasoline to make gasoholethanol is added to gasoline to make gasohol

Visualizing Cellular RespirationVisualizing Cellular Respiration

Let’s see the process again…Let’s see the process again…

Photosynthesis Photosynthesis and and

Cellular Respiration Cellular Respiration are a metabolic (biochemical) pathwaysare a metabolic (biochemical) pathways

BECAUSEBECAUSE…..…..

The products of photosynthesis The products of photosynthesis are used as the reactants in are used as the reactants in cellular respirationcellular respiration

The products of cellular The products of cellular respiration are used as the respiration are used as the reactants in photosynthesisreactants in photosynthesis

Cellular Respiration Virtual LabCellular Respiration Virtual Lab