Lesson 2: Photosynthesis and Cellular Respiration

Lesson 2: Photosynthesis and Cellular Respiration

Learning Target: Explain the roles of photosynthesis and cellular respiration in the cycling of matter and energy.

What is chemistry?

• Chemistry is the study of properties, composition, and structure of substances (defined as elements and compounds), the transformations they undergo, and the energy that is released or absorbed during these processes.

Things to remember...

• Atoms are the simplest units of matter.

• Bonded atoms make molecules.

• Different types of atoms bonded together make compounds.

• You can tell what elements make up a molecule or compound by looking at its formula.

Chemical reactions are constantly happening in every cell of your body.

• The new molecules formed are used as matter and energy for life processes.

• Metabolism, digestion, muscle contractions, emotions....

What is a chemical reaction?

• A process in which atoms are rearranged to produce new substances.

• The starting substances are called REACTANTS.

• The substances formed by the reaction are called PRODUCTS.

Multiple Choice

What are the reactants in this chemical equation?

• Water and Oxygen

• Glucose and Oxygen

• Water and Carbon Dioxide

• Carbon Dioxide and Glucose

During a chemical reaction bonds between atoms may be FORMED or BROKEN.

• Energy is RELEASED when new bonds are formed.

• Energy is NEEDED to break bonds.

• Matter and energy are CONSERVED during reactions.

Chemical equations show the RELATIONSHIP between the reactants and products of a chemical reaction.

• Reactants --> Products

Multiple Choice

Where is energy stored in molecules?

• inside of the atoms that are involved in the compound

• in the chemical bonds between atoms

Multiple Choice

Which is an example of a chemical reaction?

• melting an ice cube

• shredding a piece of paper

• dissolving sugar in water

• burning a candle

Multiple Choice

What is the difference between a chemical change and a physical change?

• a physical change creates completely new substances

• a chemical change produces completely new substances

Carbon-based molecules are the building blocks of living things.

• Carbon can form many bonds with many other atoms, and even itself.

• All animal and plant cells are powered by energy that comes from carbon-based molecules.

Carbohydrates

• AKA "Starch", which is a complex chain of sugar molecules.

• "Simple vs. Complex Carbohydrates"

• Plants store their energy molecules as starch.

• Animals use starch for energy by breaking it down into simpler sugars, or store it for later.

Open Ended

Why do carbon-based molecules, like sugar, contain so much energy?

Proteins

• Proteins are responsible for most of the work performed in cells, including transport, growth, and repair.

• Some are used for structure, chemical messengers/hormones, cell identification, and even pigmentation

• Some are needed for chemical reactions to take place

Lipids ("fats")

• Animals store energy as fat

• cushion and protect the body

• maintain body temperature

• Seedlings use lipids in seeds for energy to stay alive while dormant and start their growth

We're going to take a closer look at the process of photosynthesis.

What is photosynthesis?

A series of CHEMICAL REACTIONS in which the cells producers- including plants, algae, and some bacteria - use ENERGY from the SUN to make food molecules, called SUGARS.

Carbon dioxide molecules combine with water molecules to form sugar molecules and oxygen molecules.

The sugars can be used immediately by the plant (as energy) or they can be stored for later use.

Where do plants store their starch? (Lab time!!)

Where does photosynthesis take place?

Leaf cells have organelles called CHLOROPLASTS.

These are where photosynthesis takes place.

Chlorophyll is the green pigment that absorbs the sun's energy.

Oxygen and sugar are the "waste" products of photosynthesis.

• Make your own model showing the movement of energy and matter through the leaf by the process of photosynthesis.

The products of photosynthesis become the REACTANTS for cellular respiration.

Cellular Respiration

A process that uses oxygen to release the energy stored in food molecules.

Much of the energy released is used to make ATP, an energy storage molecule.

Without ATP, organisms cannot grown, reproduce, or repair tissues.

Cellular respiration takes place in the mitochondria of cells.

That's why they're the "powerhouse" of the cell!

Glycolysis

Each sugar molecule gets broken down into smaller molecules.

This occurs in the cytoplasm.

The smaller molecules get broken down even more INSIDE the mitochondria.

Energy is released throughout the whole process.

Water and carbon dioxide are also produced by cellular respiration.

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