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Energy in the cell

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					Energy in a Cell

All Cells Need Energy
 Cells

need energy to do a variety of work:  Making new molecules.  Building membranes and organelles.  Moving molecules in and out of the cell.  Movement.

Where Does A Cell Get Energy?
is broken down to a form the cell can use.  Extra energy is stored in an ATP molecule, a nucleotide.
 Food

What Is ATP?
 ATP

– adenosine triphosphate is a molecule made up of an adenine, ribose, and 3 phosphate groups.
Adenine

Ribose

How Does ATP Work?
Energy is stored in the bond between the second and third phosphate group.  When the bond is broken, energy is released and ADP is formed.

Adenine

Ribose

ATP – Energy Currency
•

•

Within a cell, formation of ATP from ADP and phosphate occurs over and over, storing energy each time. As the cell uses energy, ATP breaks down repeatedly to release energy and form ADP and phosphate.

Making Energy
 Cells

make energy in two ways:  Photosynthesis – takes place in the chloroplasts.  Respiration – takes place in the mitochondria.

Photosynthesis
 Autotrophs

make their own food by trapping light energy and converting it to chemical energy (carbohydrates).

Photosynthesis
 Using

light from the sun, plants combine water and carbon dioxide to make sugar . C6H12O6 + 6O2
Products

Equation: 6CO2 + 6H2O + energy
Reactants

 General

Photosynthesis
2

Reactions  Light Reactions  Calvin Cycle

Photosynthesis
 Light

Reactions – Light energy is converted to chemical energy to split hydrogen from water.  Takes place in the grana of the chloroplasts (the coinlike stacks of sacs).  Byproducts are oxygen, NADPH, and ATP.

Photosynthesis
 Calvin

Cycle – ATP and NADPH from the light reactions are used along with CO2 to form a simple sugar (glucose).  Takes place in the stroma of the chloroplasts (the liquid filling).  Byproducts are C6H12O6 (glucose), ADP, and NADP+ (which return to the light

Sunlight

O2
NADP+ ADP

ATP

H2 O
NADPH

CO2

CHLOROPLAST

Chemosynthesis
autotrophs can convert inorganic substances to energy.  Most are adapted to live in conditions where there is no oxygen.  Marshes.  Lake sediments.  Digestive tracts of mammals.  Deep in the ocean.
 Some

Respiration
process of breaking down food molecules to release energy.  Occurs in the mitochondria.  Two types:  Aerobic – requires oxygen.  Anaerobic – requires an absence of oxygen.
 The

Respiration
 Two

types of anaerobic respiration:  Fermentation – occurs when bacteria break down plants (vegetables and fruit) and release alcohol or vinegar.  Lactic Acid Fermentation – occurs in muscles – a buildup of lactic acid causes soreness.

Respiration
 Steps
 Glycolysis

Acid Cycle  Electron Transport Chain

 Citric

Respiration
 Glycolysis

– glucose is split to form pyruvate.  Takes place in the cytoplasm of the cell.  ATP is a byproduct.

Respiration
 Citric

Acid Cycle – pyruvate is used to build citric acid (a carbon compound), which is broken down to release ATP.  Takes place in the cristae (the folded membrane in the mitochondrion).  CO2 is released, and NADH carries hydrogen ions to the electron transport chain.

Respiration
 Electron

Transport Chain – hydrogen ions are stripped of their energy, and large amounts of ATP are formed.  Takes place in the inner membrane of the mitochondrion.  The used ions are combined with oxygen to form H2O.

Heat O2 H2O CO2 Glucose Pyruvate
Electron Transport System

ATP

NAD+

NADH

ATP MITOCHONDRION

ATP

Sunlight Heat

Photosystem II

PhotoSystem I

O2 H2O

Electron Transport System

ATP

NADP+ ADP

ATP

NADPH

NAD+

NADH

Calvin Cycle

CO2
Citric Acid Cycle

Glycolysis

ATP

Glucose ATP

Pyruvate

CHLOROPLAST

MITOCHONDRION

Sunlight
Heat

Photosystem II

PhotoSystem I

O2 H2O

Electron Transport System

ATP

NADP+ ADP

ATP

NADPH

NAD+

NADH

Calvin Cycle

CO2
Citric Acid

Glycolysis Glucose Pyruvate

Cycle

ATP

CHLOROPLAST

ATP

MITOCHONDRION


				
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