Chapter 8 Cellular Energy

8.1 Vocabulary Energy Thermodynamics Autotroph Heterotroph Metabolism Photosynthesis Cellular Respiration Adenosine Triphosphate (ATP) Adenosine Diphosphate (ADP)

Section 1 How Organisms Obtain Energy Standards: 2.2, Objectives: Summarize the two laws of thermodynamics. Compare and contrast autotrophs and heterotrophs. Describe how ATP works in a cell.

Energy Energy – ability to do work. – forms of energy: light, mechanical, thermal, chemical, electrical, sound, potential, kinetic, & more – organisms need a constant source of energy to survive. – Ultimate source of energy  SUN Thermodynamics – study of the flow and transformation of energy in the universe.

Laws of Thermodynamics 1.“Law of Conservation of Energy” - energy cannot be created or destroyed; converted from one form to another. 2.“Entropy Increases” - energy cannot be converted without losing usable energy.

How Organisms Obtain Energy Autotrophs – capture energy from the sun or inorganic substances to produce their own food.  Producers Heterotrophs – cannot make their own food but get nutrients and energy by feeding on others  Consumers

Metabolism Metabolism – all of the chemical reactions that occur within an organism. – Metabolic pathway is a series of reactions in which the product  the reactant (substrate) for the next reaction. Anabolic  use energy; builds large molecules Catabolic  release energy; breaks down large molecules Photosynthesis

Photosynthesis/Cellular Respiration Photosynthesis – light energy from the sun is converted to chemical energy  anabolic Cellular Respiration – organic molecules are broken down to release energy  catabolic

ATP: The Unit of Cellular Energy Adenosine Triphosphate (ATP) –most important biological molecule that provides chemical energy. – Special nucleotide which forms nucleic acids – Most abundant energy-carrying molecule – Found in all types of organisms – Composed of adenine (nitrogen base), a ribose sugar, and 3 phosphate groups

How ATP Functions Bond between the 2 nd & 3 rd phosphate group in ATP breaks  forms adenosine diphosphate (ADP) and a free phosphate group  releases a lot of ENERGY ADP + phosphate group + Energy  ATP (“ATP Synthesis”) energy is stored in the bond

ATP-ADP Cycle

8.2 Vocabulary Chloroplasts Thylakoid Granum Stroma Pigment Calvin Cycle

Section 2 Photosynthesis Standards: 2.2, 2.5, 2.8, 3.1, 3.3 Objectives: Summarize the two phases of photosynthesis. Explain the function of a chloroplast during the light reactions.

Photosynthesis Sunlight (solar energy) chemically converts water and carbon dioxide into chemical energy stored in simple sugars (glucose). Light energy  chemical energy 6 CO H 2 O + Energy  C 6 H 12 O O 2 Used by plants, algae, phytoplankton Occurs in two stages: 1.Light-dependent reaction  requires sun 2.Light-independent reaction  doesn’t require sun; takes place in the dark

Photosynthesis Plants absorb carbon dioxide from the atmosphere through the leaves and water from the soil through the roots. Photosynthesis occurs in chloroplasts.

Chloroplast Structure Chloroplasts have 2 compartments: 1.Thylakoids – flattened saclike membranes that are arranged in stacks. Grana – stacks of thylakoids 2.Stroma – fluid filled space that is outside the grana

Chloroplast Structure Pigments – light absorbing colored molecules found in the thylakoids ‒Major light absorbing pigment is chlorophyll ‒Chlorophyll causes plants to appear green because it reflects green light

Chloroplasts A single chloroplast

Stage One: Light Dependent Reaction During the day, sunlight is absorbed and used to split water  occurs on thylakoid membrane H 2 O H + O 2 – O 2 enters the atmosphere  waste product – H + is used to make energy storing molecules (ATP & NADPH)

Stage Two: Light Independent Reaction Calvin Cycle – second stage of photosynthesis in which energy is stored in organic molecules. – Also called carbon fixation Occurs in the stroma of chloroplasts ATP & NADPH fuel this reaction to take place. Uses CO 2 and the energy from ATP & NADPH to make a carbohydrate called GLUCOSE (C 6 H 12 O 6 ).

Stage Two: Light Independent Reaction

6 CO H 2 O + Energy  C 6 H 12 O O 2

8.3 Vocabulary Mitochondria Anaerobic Process Aerobic Respiration Aerobic Glycolysis Krebs Cycle Fermentation

Section 3 Cellular Respiration Standards: 2.2, 2.3, 2.8, , 4.1 Objectives: Summarize the stages of cellular respiration. Compare alcoholic fermentation and lactic acid fermentation.

Cellular Respiration Organisms obtain energy for cellular metabolic processes (such as active transport, protein synthesis, muscle contraction). Chemical energy in nutrients  chemical energy in ATP C 6 H 12 O O 2  6 CO H 2 O + Energy (ATP) Any food (organic molecule) can be broken down for energy to produce ATP: nutrients + O 2  CO 2 + H 2 O + Energy (ATP)

Cellular Respiration All eukaryotic cells have cytoplasm & mitochondria  work together during cellular respiration. Occurs slowly in two stages: 1.Glycolysis  doesn’t require oxygen (anaerobic) 2.Aerobic Respiration  requires oxygen (aerobic)

Mitochondria Structure 2 membranes (1 outer and 1 inner) Cristae – folded membrane inside Matrix – the aqueous fluid that fills the cristae

Stage One: Glycolysis (doesn’t require oxygen) Glucose is broken down by enzymes into ATP and pyruvic acid molecules  occurs in the cytoplasm.

Stage Two: Aerobic Respiration (requires Oxygen) Part One: Kreb Cycle (or Citric Acid Cycle) – Occurs in the matrix of the mitochondria

Stage Two: Aerobic Respiration (requires Oxygen) Part Two: Electron Transport Chain – Series of reactions ending with H 2 + O 2  H 2 O – Occurs in the cristae of the mitochondria – ADP  ATP – Produces most of the energy storing ATP molecules (34-36 ATP)  used for cellular metabolism

Anaerobic Respiration (NO Oxygen) IF oxygen isn’t available cells produce energy using fermentation (occurs in the cytoplasm). – Fermentation is not efficient and produces less energy (ATP) compared to aerobic respiration. – 2 Types of Fermentation: 1.Lactic Acid Fermentation – glucose  pyruvic acid  lactic acid + Energy – Occurs in muscle cells during vigorous exercise 2.Alcohol Fermentation – glucose  pyruvic acid  alcohol + carbon dioxide + energy – Occurs in yeast and some bacteria

Summary

Photosynthesis & Cellular Respiration