Chapter 8 Cellular Energy

Cooperative Activity What do you know about energy?

Energy - what we know Ability to do work Cannot be created or destroyed Can change forms

Some usable energy is lost ! Energy “lost” is converted to thermal energy ( a.k.a. heat) Therefore, Entrophy (unusable energy) increases! When Energy Changes Forms

Stored in chemical bonds Released when bonds are broken Needed to form bonds Energy

All living organisms need energy to live Directly or indirectly all the energy for life comes from the SUN! Why do we care about Energy?

Autotrophs make their own food by converting: Autotrophs & Heterotrophs

Heterotrophs need to ingest food to obtain energy. Autotrophs & Heterotrophs

Review: Chemical Reactions Chemically changing substances Metabolism: sum of all the chemical reactions that occur in our body

Chemical equations show how substances change Reactants  Products Na + Cl  NaCl Review: Chemical Reactions (cont.)

ATP ( Adenosine triphosphate) Portable form of energy “Energy currency” – Delivers energy where needed in cell

Adenosine triphosphate is made of: –Adenine –Ribose sugar –3 phosphate groups ATP

Photosynthesis

How plants convert solar energy into glucose Takes place in chloroplasts

Why is it called photosynthesis? Photo means “light” Synthesis means “to put together” What are we putting together? glucose

Chloroplasts Capture light; found mostly in leaves Contain pigments like chlorophyll Chlorophyll Chloroplast

Chloroplasts & Chlorophyll

Chlorophyll = main pigment Each pigment reflects a different color Accessory Pigments

Accessory Pigments (cont.) Carotene – Orange Xanthophyll – Yellow Anthocyanin – Red

Phases of Photosynthesis 1.Sunlight is converted into ATP (aka light dependent reaction) 2.Calvin Cycle: ATP is converted into glucose (aka light independent or dark reaction)

Photosynthesis: Chemical Equation Reactants 6 CO H 2 O > C 6 H 12 O O 2 Products Light

What affects the rate of photosynthesis? Light Intensity Temperature Water Other

Why do leaves fall off the tree? Chlorophyll breaks down in cold temps No use for leaves so they fall off to save energy Trees hibernate in winter

What’s up with that tree? Why are Japanese Maple trees red? – Anthocyanin Do they perform photosynthesis? – Yes

Cellular Respiration Process of releasing energy stored in the bonds of glucose

Chemical Equation: Reactants  Products C 6 H 12 O O 2  6 CO H 2 O + Energy Cellular Respiration

Two types: -Aerobic – requires oxygen -Anaerobic – no oxygen is required Cellular Respiration

Step 1 – Glycolysis Takes place in cytoplasm Does not require oxygen (Anaerobic)

Glyco – refers to glucose Lysis – means to “cut” Step 1 – Glycolysis

We break down glucose to provide energy for the cell! Step 1 – Glycolysis

During Glycolysis 2 ATP & 2 NADPH (energy- carrier) molecules are produced per glucose molecule. 2 ATP’s needed to start reactions! Step 1 – Glycolysis

4 ATP – 2 ATP = 2 ATP & 2 NADPH (produced) What is the net gain of ATP molecules at the end of glycolysis? ______ Step 1 – Glycolysis

After glycolysis the pathway can go ONE of two ways.

Pathways: Aerobic cellular respiration OR Fermentation

2. Fermentation (Aerobic) Only 2 ATP produced Occurs during rapid & heavy exercise Feel burning sensation in muscles

2 Types of Fermentation: 1. Alcohol fermentation – occurs in yeast and some bacteria

Found in breads and alcoholic beverages! Produces ethyl alcohol Alcohol Fermentation (Aerobic)

2. Lactic acid fermentation – occurs in skeletal muscle and in several microorganisms to produce foods like: cheese, yogurt & sour cream. 2 Types of Fermentation:

Produced during periods of strenuous exercise Lactic acid builds up and muscles feel “sore” 2. Lactic Acid Fermentation (Aerobic)

2. Respiration (Aerobic) Takes place in mitochondria Requires oxygen (aerobic) 34 ATP produced

and the total is… 4 ATP: Glycolysis & Fermentation 36 ATP: Glycolysis & Respiration

Question: Which path do you think is the best for a sprint? Explain

Question: Which path do you think is best for a 20 min run? Explain

~ Cellular Respiration ~ The Chemical Equation Reactants C 6 H 12 O O 2  6 CO H 2 O + ATP Products

Comparing the reactions Photosynthesis 6 CO H 2 O + Light  C 6 H 12 O O 2 Cellular Respiration C 6 H 12 O O 2  6 CO H 2 O + ATP