Cell Processes

Key Concepts

• Explain how the sun supplies living things with the energy they need.

• Describe what happens during the process of photosynthesis.

• Describe the events that occur during respiration.

• Tell what fermentation is.

Key Terms

• Photosynthesis

• Autotroph

• Heterotroph

• Pigment

• The process by which a cell captures energy in sunlight and uses it to make food.

• An organism that makes its own food.

• An organism that cannot make its own food.

• Colored chemical compounds that absorb light.

Key Terms

• Chlorophyll

• Stomata

• Respiration

• Fermentation

• The main photosynthetic pigment in chloroplasts.

• Small openings in the undersides of leaves where CO2 enters and O2 exits.

• The process by which cells obtain energy from glucose.

• An energy-releasing process that does not require oxygen.

Introduction

• Every living thing needs energy.

• All cells need energy to carry out their functions.– Making proteins– Transporting substances into and out of

the cell

• The sun supplies energy for most living things, directly or indirectly.

Sources of Energy

• Autotroph

• An organism that makes its own food.

• Ex. plants, algae, some bacteria

• Heterotroph

• An organism that cannot make its own food.

• Ex. animals, fungi, some bacteria

Photosynthesis

What is Photosynthesis?

• The process by which a cell captures energy in sunlight and uses it to make food.

• Photo – light

• Synthesis – putting together

Two Stages of Photosynthesis

• Capturing the Sun’s Energy.

• Using Energy to Make Food.

Stage 1: Capturing the Sun’s Energy

• In plants, this energy-capturing process occurs mostly in the leaves.

• Chloroplasts, containing chlorophyll, capture energy from sunlight.

Stage 2: Using Energy to Make Food

• The cell uses the captured energy to produce sugars.

• Water and Carbon Dioxide (raw materials) are needed for this stage.

• The raw materials undergo a complex series of chemical reactions producing sugar and oxygen.

Animation of Photosynthesis

• http://www.growingthenextgeneration.com/agrium-games/Animation/index.htm

The Chemical Equation for Photosynthesis

Simplifying the Equation

• Raw Materials – Water & Carbon Dioxide• Catalyst – Light Energy• Products – Carbohydrates (Sugars) & Oxygen

Respiration

What is Respiration?

• The process by which cells obtain energy from glucose.

• Cells break down simple food molecules such as sugar and release the energy they obtain.

Breathing and Respiration

• Respiration has two meanings.

– “Breathing” – moving air in and out of your lungs.

– “Cellular Respiration” – respiration process that takes place inside cells.

• The connection – “breathing” brings oxygen into the body needed for “cellular respiration” to occur.

Two Stages of Respiration

• Breaking down glucose.

• Breaking down glucose even more.

Stage 1: Breaking Down Glucose Molecules

• This first stage takes place in the cytoplasm of the organism’s cells.

• Oxygen is not involved in this part of the process and only a small amount of energy is released.

Stage 2: Making Small Glucose Molecules Smaller

• This second stage takes place in the mitochondria of the organism’s cells.

• Oxygen is required in these chemical reactions and a great deal of energy is released.

Animation of Respiration• http://www.sumanasinc.com/webcontent/animations/content/cellularrespiration.html

• Click on “The Big Picture”. (You can add subtitles!)

The Chemical Equationfor Respiration

Simplifying the Equation

• Raw Materials – Glucose & Oxygen• Catalyst – Stored Energy• Products – Carbon Dioxide, Water & Energy (ATP)

What’s the Connection?

Photosynthesis and Respiration are Opposites

Fermentation

What is Fermentation?

• Respiration without oxygen!

Fermentation Defined

• An energy-releasing process that does not require oxygen.

• Some single-celled organisms live where there is no oxygen, such as deep in the ocean or in the mud of lakes or swamps.

• The amount of energy released from each sugar molecule is much lower than the amount released during respiration (with oxygen).

Types of Fermentation

• Alcoholic • Lactic Acid

Alcoholic Fermentation

• Yeast and other single-celled organisms break down sugars.

• This is often called alcoholic fermentation because alcohol is one of the products.

• Carbon dioxide and a small amount of energy are also products.

Carbon dioxide in yeast causes bread to rise and causes the bubbles in alcoholic drinks like beer and wine.

Lactic Acid Fermentation• Takes place at times in

your body.

• Muscle cells use up oxygen faster than it can be replaced.

• When cells lack oxygen, fermentation occurs.

• Lactic acid is a product of fermentation within animal cells. – painful sensation in your

muscles– muscles feel weak and sore

Photosynthesis and Respiration

Cell processes that affect the function of the entire organism.