Energy In A CellEnergy In A Cell

Photosynthesis Cellular Respiration

The Need for Energy

• 1. All cells use energy for life processes.• 2. Where do cells get energy? Food• 3. What is the original energy source for

most organisms? Sun– Autotrophs-make their own food from the

sun’s energy. Ex: Plants– Heterotrophs-organisms unable to make their

own food; they depend on other organisms for a source of food. Ex: animals, fungi

Sun

Autotroph

Heterotroph

• Energy for Life Processes– There are 2 stages in the passage of energy from

the sun to the cells:• Stage 1: Photosynthesis

» The process of plants

taking CO2 from the

atmosphere along with

water from the soil to

produce O2 gas and

glucose» This process converts

sunlight into chemical

energy.

Energy for Life Process Cont.

• Stage 2 Cellular Respiration– The process of taking oxygen gas from the atmosphere and

glucose from food molecules to produce CO2, H2O, and energy in the form ATP.

– **This process occurs in the mitochondria and the cytoplasm of cells.**

– This process does not occur in prokaryotes, since they do not have mitochondria.

Cellular Cellular Respiration takes Respiration takes in food to give us in food to give us

energy!! This energy!! This player really player really

needed ENERGY!needed ENERGY!

State Test Question

• Many cell processes cannot directly use the energy from food. Which organelles covert food energy to a form that can be used by the cell?

a) Endoplasmic reticulum

b) Golgi body

c) Ribosomes

d) Mitochondria

Energy For Life Processes Cont.

– Most organisms depend on cellular respiration and photosynthesis to provide energy directly or indirectly.

– The alternation of photosynthesis and cellular respiration results in the continuous recycling of CO2 and O2.

• ATP (Adenosine Triphosphate)- Stores Energy– ATP is found in all living things, and it is able to

absorb energy and release it when needed by a cell.– There are 3 parts of the ATP molecule:

1. Adenine-a nitrogen containing molecule

2. Ribose-a 5-carbon sugar

3. 3 phosphate groups

*The adenine combines with ribose to form adenosine.*

State Test Question

Energy from food sources drives the production of ATP. Why is this molecule essential in all living cells?

a) It is the main energy source for most cellular processes.

b) It is the basis of DNA.c) It is a structural component found in cell

walls.d) It is required for osmosis and diffusion.

– Some related terms:• AMP (Adenosine Monophosphate)- identical to ATP

except it has 1 phosphate group.• ADP (Adenosine Diphosphate)- identical to ATP

except it has 2 phosphate groups• ATP (Adenosine Triphosphate)- The bond holding

together the last 2 phosphates is a high-energy bond. When the bond is broken, a tremendous amount of energy is released for use by the cell. After the bond is broken, the remaining molecule holds only two phosphate groups. It is now called ADP. ADP can absorb energy, use this energy to add another phosphate, and become ATP again. ATP allows the cell to use its energy a little at a time.

A – P ~ P~P A – P ~ P ~ P A – P ~ + Energy

ATP ADP + Energy

Note: When a bond is broken, energy is released. When cells break down food molecules, some of the energy in the molecules is released as heat. Much of the remaining energy is stored temporarily in molecules of ATP.

High Energy Bond

*Energy is stored in high energy bonds

BOOM!

State Test Question

ATP is continuously regenerated from ADP when energy released by cellular respiration is used in an endergonic reaction.

Energy stored in food is released when—• chemical bonds are broken.• atomic nuclei are split.• elements combine.• electrons are produced.

State Test Question

ATP is called the energy currency for cells because it—

a) is a constantly renewing source of energy.

b) is the ultimate source of energy on Earth.

c) is the exchange molecule for energy transfers.

d) provides energy for exergonic reactions.

State Test Question

The process of breaking down ATP to ADP is termed—

a) fermentation.

b) an exergonic reaction.

c) an endergonic reaction.

d) a synthesis reaction.

State Test Question

Energy for most cellular processes is obtained by breaking a bond between which two components of ATP?

a) Phosphate and nitrogen

b) Phosphate and carbon

c) Phosphate and adenosine

d) Phosphate and phosphate

State Test Question

Which of the following is needed to transfer and release energy?

a) Calcium

b) Phosphate

c) Nitrate

d) Potassium

State Test Question

Energy stored in food is released when—

a) chemical bonds are broken.

b) atomic nuclei are split.

c) elements combine.

d) electrons are produced.

• Photosynthesis: Photosynthesis provides energy for almost all life.– Equation:

• 6CO2 + 6H2O+ sunlight C6H12O6 + 6O2

– Photosynthesis Occurs in 2 Phases:• Phase 1 is the light reaction• Phase 2 is the dark reaction (The Calvin Cycle)

• Phase 1. The light reaction:– Stage 1: Energy is captured from sunlight.

• Pigment molecules in the thylakoids of chloroplasts absorb light energy, energy transferred to electrons in the chlorophyll

• Stage 2: Light energy is converted to chemical energy• Excited electrons that leave chlorophyll molecules are used to

produce new molecules that temporarily store chemical energy, including ATP. AN excited electron jumps to a nearby molecule in the thylakoid membrane

• Then the electron is passed through a series of molecules along the thylakoid membrane like a ball being passed down a line of people. The series of molecules through which excited electrons are passed along a thylakoid membrane are called electron transport chains.

• While one electron transport chain provides energy used to make ATP, a second electron transport chain provides energy used to make NADPH

State Test Question

The light-dependent reactions of photosynthesis use the Sun’s energy to produce—

a) glucose.

b) chemical energy.

c) carbon dioxide.

d) water.

• The light reaction (Stage 1 and 2) produces the O2 gas and the energy ATP+NADPH for the Dark reaction-Calvin cycle.

State Test Question

In the light-dependent phase of photosynthesis, energy from the Sun is used to drive the production of which of the following molecules?

a) Proteins

b) Carbohydrates

c) ATP

d) ADP

State Test Question

The process of photosynthesis produces sugar, water and—

a) hydrogen gas.

b) nitrogen dioxide gas.

c) carbon dioxide gas.

d) oxygen gas.

State Test Question

The glucose produced during photosynthesis is an example of a—

a) lipid.

b) monosaccharide.

c) protein.

d) nucleic acid.

State Test Quesiton

When excess sugar is produced in a plant, the plant will—

a) release the sugar into the soil.

b) convert the sugar into minerals.

c) store the sugar by forming larger molecules.

d) burn the leaves of the plant as it releases energy.

State Test Question

Because most plants are able to undergo photosynthesis, they do NOT—

a) require carbon dioxide.

b) store energy for later use.

c) undergo cellular respiration.

d) depend on other organisms for energy.

State Test Question

Photosynthesis begins when sunlight causes chlorophyll molecules to—

a) produce sugars.

b) absorb carbon dioxide.

c) emit oxygen.

d) emit electrons.

State Test Question

In photosynthesis, light energy from the Sun is stored in the bonds of—

a) lipids.

b) carbohydrates.

c) proteins.

d) enzymes.

State Test Qustion

What are the raw materials for photosynthesis?

a) CO2 and H2O

b) H2O and O2

c) C6H12O6 and O2

d) C6H12O6 and H2O

• Phase 2: The Dark Reaction: Calvin Cycle– CO2 enters the leaf through hundreds of small pores. – A three-carbon sugars is used to make organic

compounds-including carbohydrates such as sucrose and starch in which energy is stored for later use. So, this excess

sugar is stored for use later.– ***The dark reaction-Calvin cycle produces the organic

compound C6H12O6-glucose

State Test Question

What are the main products of photosynthesis?

a) Glucose and oxygen

b) Glucose and water

c) Carbon dioxide and water

d) Water and ATP

State Test Question

During photosynthesis, energy from the sun is trapped in—

a) chemical bonds.

b) the nuclei of atoms.

c) enzymes.

d) Golgi bodies.

Cellular Respiration– The process of taking O2 gas from the atmosphere

and glucose from food molecules to produce CO2, H2O and energy in the form of ATP. Cellular Respiration produces ATP. Food molecule are broken down to release the energy in their bonds. Glucose is the energy source for cellular respiration. Respiration occurs in the cytoplasm; glycolysis) in the mitochondria (Citric Acid Cycle/ Krebs’ Cycle.)

Takes in Oxygen

Takes in Glucose from food molecules

Gives off Carbon Dioxide

Gives off water

Releases energy in the from of ATP

Cellular Respiration

• Metabolic process that require oxygen are called aerobic.

• Metabolic process that do NOT require oxygen are called anaerobic meaning “without air”.

• A. Equation: C6H12O6 + 6O2 6CO2 + 6H2O + ATP

Aerobic respiration = oxygen

Sore muscles = anaerobic respiration

Cellular Respiration

State Test Question

Most organisms exhibit aerobic respiration which requires—

a) oxygen.

b) carbon.

c) nitrogen.

d) hydrogen.

State Test Question

In which of the following places would you most likely find anaerobic organisms?

a) Freshwater streams or rivers

b) The intestinal tract of animals

c) Warm, humid habitats

d) Cold, dry habitats

• Cellular Respiration (Aerobic Respiration with Oxygen) Occurs in 2 phases:– Phase 1 is Glycolysis (Anaerobic)– Phase 2 is the Citric Acid Cyle/Kreb’s Cycle

(Aerobic)

• Phase I: Anaerobic• Named: Glycolysis means the splitting of

glucose– Oxygen is NOT directly involved in this step– Occurs in the cytoplasm of cells– The process of breaking down glucose begins with

glycolysis, producing 2 molecules of ATP for each molecule of glucose broken down.

– Glycolysis breaks down 1 glucose into 2 pyruvic acid.– Produces 2 ATPs

• At the end of glycolysis if O2 is NOT present, anaerobic respiration (without oxygen) takes place.

• At the end of glycolysis if O2 is present aerobic respiration (with oxygen) takes place (Citric Acid Cycle)

• Phase II: Aerobic– Citric Acid Cycle (Kreb’s Cycle)

• Completes the breakdown of glucose• Occurs in the mitochondria of cells• In this reaction, pyruvic acid is changed to acetic

acid. Then acetic acid forms citric acid.– Results: Carbon dioxide is released

2 ATP are produced

State Test Question

Which organelle performs cellular respiration?

a) Lysosome

b) Ribosome

c) Chromosome

d) Mitochondria

– 2. Electron Transport Chain– This process is considered aerobic (with oxygen),

because oxygen is the final electron acceptor in the chain

– This reaction accepts electrons and hydrogen ions which are passed along, and energy is released.

• Results: Oxygen is the final electron acceptor.

34 ATP are produced• At the end of the cellular respiration, glycolysis has

produced 2 ATPs• The citric acid cycle has produced 2 ATPs• The electron transport chain has produced 34 ATPs• For aerobic respiration, a total of 36 ATPs• Cellular Respiration makes a total of 38 ATPs

Electron

Electron

Electron

State Test Question

• Both plant and animal cells have the ability to—

a) make glucose.

b) move.

c) reproduce.

d) release oxygen.

• Anaerobic respiration (without oxygen): Anaerobic respiration occurs when oxygen is NOT present. This process is called fermentation, and is used by organisms to produce energy without oxygen. Yeast cells undergo alcoholic fermentation when oxygen is not present. Animals produce lactic acid when oxygen is not available; this is called lactic acid fermentation This process occurs in our muscles cells during strenuous activity. The body cannot supply enough oxygen to the muscle cells to keep up with ATP production. When lactic acid forms and builds up fatigue sets in.

Anaerobic respiration (Alcoholic fermentation)

Lactic Acid Fermentation (Sore Muscles)

There are 2 types of fermentation:• Alcoholic Fermentation

– Occurs in yeast cells– This process is important to the baking

and wine industry– Products are alcohol (ethanol) and CO2

• Lactic Acid Fermentation- Occurs in some unicellular and organisms and

human muscle cells.- This process is used to produce en-

ergy in muscle cells when no oxygen is available.

- Lactic acid build-up causes muscle soreness

State Test Question

The energy from food that is used to produce ATP from ADP is—

a) released via photosynthesis.

b) stored as radiation energy.

c) released in the Calvin cycle.

d) stored in the bonds of glucose.

State Test Question

As respiration begins, glucose is broken down into pyruvic acid and two molecules of ATP are formed. What will happen next in yeast cells if NO oxygen is available?

a) Krebs cycleb) Photosynthesisc) Alcoholic fermentationd) Lactic acid fermentation

State Test Question

Which of the following BEST describes the purpose of cellular respiration?

a) The production ATP in animals cells

b) The release of energy from glucose molecules inside the cell

c) The diffusion of oxygen into and out of cells

d) The production of amino acids

State Test Question

Which step in aerobic cellular respiration produces the most ATP?

• Glycolysis

• Fermentation

• Krebs cycle

• Electron transport chain

State Test Question

The aerobic process in cellular respiration uses the products of glycolysis in a series of enzyme-catalyzed reactions in the mitochondria to release CO2. This process is called—

a) photosynthesis.b) the Calvin cycle.c) the Krebs cycle.d) fermentation.

Comparison of Photosynthesis and Cellular Respiration

• Photosynthesis– 1. CO2 and H2O are

materials used– 2. Takes place in cells

that contain chlorophyll.

– 3. Photosynthesis builds sugars

– 4. Glucose and oxygen are products– 5. Produces 2 ATP’s

• Cellular Respiration– 1, CO2 and H2O are

end products– 2. Takes place in all

living cells– 3. Breaks down

sugars– 4. Glucose and

Oxygen are materials used

– 5. Pro- duces 38 ATP’s

• ****The end products of aerobic respiration are the starting materials of photosynthesis

C6H12O6 + O2 CO2 + H2O + ATP

CO2 + H2O C6H12O6 + O2

Light Energy

Cellular Respiration

Photosynthesis

State Test Question

In which of these processes does the Sun’s energy play a direct role?

a) Entropy

b) Glucose synthesis

c) Anaerobic respiration

d) Cellular respiration

State Test Question

Which of the following statements is false?a) Cellular respiration is a metabolic process that

releases energy that is stored in the bonds of glucose in the form of ATP.

b) Photosynthesis is a two-part reaction that uses the Sun’s energy to produce glucose from carbon dioxide and water.

c) ATP acts as the energy currency of cells by giving up two phosphate molecules in an electron transfer.

State Test Question

Which process supplies the energy needed to produce ATP in the Cell?

a) Cellular respiration

b) Diffusion

c) Protein synthesis

d) Osmosis

State Test Question

Which of the reactions would result in the Greatest release of energy?

a) 2H2O→ 2H2 + O2

b) ADP + phosphate → ATP

c) ATP → ADP + phosphate

d) 6CO2 + 6H2O → C6H12O6 + 6O2