Chapter 4 Cellular Processes

Cellular Energy

Cells Use Energy Maintain homeostasis To perform all cellular processes To make energy-storing molecules When they stop using energy, they are dead Maintain homeostasis To perform all cellular processes To make energy-storing molecules When they stop using energy, they are dead

Energy Relationships Energy is a one time commodity – every time it is used some escapes and becomes unusable More energy is needed to build an energy-storing molecule than is stored in the molecule. Energy is a one time commodity – every time it is used some escapes and becomes unusable More energy is needed to build an energy-storing molecule than is stored in the molecule.

How do organisms obtain their food? Autotrophs –“auto” = self –“troph” = nourishment Heterotrophs –“hetero” = others Autotrophs –“auto” = self –“troph” = nourishment Heterotrophs –“hetero” = others

Autotrophs Make their own food –They capture light energy and convert it into sugar –Ex: plants, algae, and some bacteria. Make their own food –They capture light energy and convert it into sugar –Ex: plants, algae, and some bacteria.

Heterotrophs Depend on other organisms for their energy source –Ex: humans, animals, fungi, and most bacteria. Depend on other organisms for their energy source –Ex: humans, animals, fungi, and most bacteria.

ATP – Adenosine Triphosphate Most energy sources (fats, carbohydrates) are large and must be broken down into smaller units (sugar – glucose) ATP stores energy in a usable form for all living organisms The bonds between the three phosphate groups are unstable high-energy covalent bonds Most energy sources (fats, carbohydrates) are large and must be broken down into smaller units (sugar – glucose) ATP stores energy in a usable form for all living organisms The bonds between the three phosphate groups are unstable high-energy covalent bonds

ATP

Energy Production When the bonds are broken, a large amount of energy is released (an exothermic reaction) and is available for use in any cellular function that requires energy (an endothermic reaction). ATP  ADP + P + Energy When the bonds are broken, a large amount of energy is released (an exothermic reaction) and is available for use in any cellular function that requires energy (an endothermic reaction). ATP  ADP + P + Energy

ATP adenosine triphosphate Phosphates 123 Adenosine

ATP Production ADP and P can be reused to form ATP with the proper enzymes and adequate supply of energy ADP + P + Energy  ATP ADP and P can be reused to form ATP with the proper enzymes and adequate supply of energy ADP + P + Energy  ATP

12 Adenosine ADP adenosine diphosphate Phosphates

ATP-ADP Cycle

4A – 2 PHOTOSYNTHESIS The process of taking light energy and converting it into stored chemical energy

The sun is the source of energy for living things!

Photosynthesis Reaction Reaction converting light energy into stored chemical energy 6 CO H 2 O + light energy  C 6 H 12 O O 2 (Carbon (water) (glucose) (oxygen) dioxide) Reaction converting light energy into stored chemical energy 6 CO H 2 O + light energy  C 6 H 12 O O 2 (Carbon (water) (glucose) (oxygen) dioxide)

Green plants and algae perform this energy transformation in large enough quantities to provide stored chemical energy for most living organisms

Photosynthesis is important because… 1) It converts solar energy into usable chemical energy 2) It produces oxygen 1) It converts solar energy into usable chemical energy 2) It produces oxygen

Light Absorption Different wavelengths of visible light are seen by the human eye as different colors. The color we see is actually the color reflected. Different wavelengths of visible light are seen by the human eye as different colors. The color we see is actually the color reflected.

Chlorophyll a Primary catalyst of photosynthesis Green pigment in the grana of chloroplasts Becomes activated by light energy Primary catalyst of photosynthesis Green pigment in the grana of chloroplasts Becomes activated by light energy

Chlorophyll a Chlorophyll a is a blue green pigment – it reflects the blues and greens and absorbs the reds and violets

Chlorophyll b Is a yellow green pigment – that absorbs some of the same pigments as chlorophyll a as well as some of the blues not absorbed by chlorophyll a and reflects some of the yellow greens that chlorophyll a absorbs

Absorption Spectrum

The Process of Photosynthesis Requires sunlight and water Occurs in the grana of the chloroplast Produces: Oxygen, ATP and NADPH (electron carrier that stores energy for later use) Requires sunlight and water Occurs in the grana of the chloroplast Produces: Oxygen, ATP and NADPH (electron carrier that stores energy for later use) The Light-Dependent Phase

Light is NOT required Occurs in the stroma of the chloroplast Also called:“Dark phase,” “synthetic phase,” “Calvin cycle,” “carbon fixation cycle” Is dependent upon the products of the light phase (ATP and NADPH) and CO 2 from the atmosphere Light is NOT required Occurs in the stroma of the chloroplast Also called:“Dark phase,” “synthetic phase,” “Calvin cycle,” “carbon fixation cycle” Is dependent upon the products of the light phase (ATP and NADPH) and CO 2 from the atmosphere Photosynthesis: The Process Light-Independent Phase

Conditions for Photosynthesis Proper wavelengths of light Sufficient absorption of carbon dioxide Proper temperatures Proper amount of water Proper wavelengths of light Sufficient absorption of carbon dioxide Proper temperatures Proper amount of water

Chemosynthesis: Other autotrophs A few bacteria use inorganic chemicals (i.e. ammonia or sulfur) to obtain energy Ex. Symbiotic bacteria in tubeworms in hydrothermal vents convert chemical energy in sulfur into usable energy A few bacteria use inorganic chemicals (i.e. ammonia or sulfur) to obtain energy Ex. Symbiotic bacteria in tubeworms in hydrothermal vents convert chemical energy in sulfur into usable energy

Cellular Respiration

The breakdown of a food substance into usable cellular energy in the form of ATP

Summary Kinetic energy (sun) C 6 H 12 O 6 stored chemical energy (C 6 H 12 O 6 ) = photosynthesis

Summary C 6 H 12 O 6 stored chemical energy (C 6 H 12 O 6 ) = cellular respiration ready-to-use chemical energy ( )

Cellular Respiration Aerobic –Requires oxygen, is the opposite of photosynthesis, combines oxygen with sugar to release energy, carbon dioxide and water Anaerobic –Does not require oxygen

Aerobic Cellular Respiration

C 6 H 12 O 6 + O 2 H 2 O + CO 2 + energy (ATP)

The Process of Cellular Respiration Glycolysis Citric Acid Cycle (Krebs Cycle) Hydrogen and Electron Transport System

Glycolysis All types of cellular respiration begin with glycolysis. Does not require oxygen Occurs in the cytoplasm

Glycolysis Breakdown of glucose into pyruvic acid, H +, and electrons 2 net ATP

Aerobic Cellular Respiration The products from glycolysis are sent to the mitochondria.

Aerobic Cellular Respiration 1. Citric Acid Cycle (Krebs Cycle) = Pyruvic acid is broken down into citric acid. −Pyruvic acid  Acetyl CoA −Acetyl CoA  Citric acid

2. Hydrogen and Electron Transport System −Occurs in the cristae of the mitochondria Aerobic Cellular Respiration

2. Hydrogen and Electron Transport System −At the end of the chain, H combines with oxygen to form water. −Oxygen is the rate-limiting factor. Aerobic Cellular Respiration

Energy Facts Aerobic Cellular Respiration results in the net gain of 36 ATP molecules.

Glycolysis Citric Acid Cycle H + & e- transport system Reactants Products Location ATP Cytoplasm Mitochondria (matrix) Mitochondria (cristae) Mitochondria (cristae) Glucose Pyruvic acid; H + ; e- Pyruvic acid CO 2 ; H + ; e- H + ; e- 2 net 32

Anaerobic Respiration Breakdown of food (glucose) without oxygen “Cellular fermentation”

2 Types of Fermentation 1) Alcoholic fermentation – pyruvic acid + NADH  alcohol + CO2 + NAD+ Ex: yeast 2) Lactic Acid fermentation – pyruvic acid + NADH  lactic acid + NAD+ Ex: produced in your muscles during rapid exercise when the body cannot supply enough oxygen to the tissue

Energy Facts Cellular fermentation supplies no ATP energy beyond glycolysis.

Energy Facts Cellular fermentation supplies no ATP energy beyond glycolysis. Cellular fermentation results in the net gain of 2 ATP molecules.

Cellular Respiration

Comparison of Photosynthesis and Cellular Respiration FunctionEnergy CaptureEnergy release LocationChloroplastsMitochondria Reactants Carbon dioxide and water Glucose and oxygen Products Glucose and Oxygen Carbon dioxide and water Equations6CO 2 + 6H 2 O + energy  C 6 H 12 O 6 + 6O 2 6O 2 + C 6 H 12 O 6  6CO 2 + 6H 2 O + energy

Match the following: ____1. Organisms that make their own foodA. Chloroplasts ____2. Site of photosynthesisB. Aneorobic ____3.Process occurs in a mitochondrionC. Aerobic ____4.C 6 H 12 O 6 D. Glucose ____5. Process does not require oxygen E. ATP ____6. Process requires oxygenF. Kreb’s cycle ____7.Adenosine diphosphateG. Glycolysis ____8.Energy storing moleculeH. Energy ____9. The anaerobic process of splitting glucose and forming two molecules of pyruvic acid I. ADP ____10. The ability to do work J. Autotrophs

WORD BANK 2 ATP 2 ATP 36 ATP 6 NADH 2 FADH Electron transport chain Mitochondrion Cytoplasm Fermentation Glycolysis Glucose Pyruvate Lactic acid Kreb's Cycle