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Unit 1 Lesson 2 Chemistry of Life
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Unit 1 Lesson 2 Chemistry of Life
It’s Elementary
What are atoms and molecules?
• All cells (and all matter) are made up of atoms
and molecules.
• An element is a substance that cannot be broken
down into a simpler substance.
• The smallest unit of an element that maintains the
properties of that element is called an atom.
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Unit 1 Lesson 2 Chemistry of Life
What are atoms and molecules?
• What are the six main elements that make up the
human body?
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Unit 1 Lesson 2 Chemistry of Life
What are atoms and molecules?
• A molecule is a group of atoms held together by
chemical bonds.
• Some molecules are made up of only one type of
atom.
• Most molecules are made up of two or more types
of atoms.
Copyright © Houghton Mifflin Harcourt Publishing Company
Unit 1 Lesson 2 Chemistry of Life
What are atoms and molecules?
• A compound is a substance made up of atoms of
two or more elements joined by chemical bonds.
• Most molecules found in cells are compounds.
• Compounds have different properties than the
elements that make them.
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Unit 1 Lesson 2 Chemistry of Life
Cell Fuel
What are some important types of
molecules in cells?
• Organisms use nutrients for energy and as
building materials.
• A lipid is a fat molecule or a molecule that has
similar properties. Lipids have many jobs in cells,
such as storing energy.
• Your cells get lipids from foods such as olive oil
and fish.
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Unit 1 Lesson 2 Chemistry of Life
What are some important types of
molecules in cells?
• A protein is a molecule made up of smaller
molecules called amino acids.
• Protein-rich foods are broken down into amino
acids, which make new proteins to build and
repair body structures.
• Proteins called enzymes help chemical processes
happen in cells.
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Unit 1 Lesson 2 Chemistry of Life
What are some important types of
molecules in cells?
• Carbohydrates are molecules that include
sugars, starches, and fiber.
• Cells use carbohydrates for energy and energy
storage.
• Simple carbohydrates are made of one or a few
sugars linked together. Complex carbohydrates
contain many sugar molecules linked together.
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Unit 1 Lesson 2 Chemistry of Life
What are some important types of
molecules in cells?
• Nucleic acids are molecules that carry
information in cells.
• Nucleotides are the smaller molecules that make
up nucleic acids.
• DNA is a nucleic acid that carries information that
cells need to make other molecules.
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Unit 1 Lesson 2 Chemistry of Life
Waterworks
What are phospholipids?
• A lipid that contains phosphorus is called a
phospholipid.
• The head of a phospholipid molecule is attracted
to water. The tail repels water.
• Much of a cell’s membrane is made of a doublelayer of phospholipids, which regulates molecules
entering and leaving the cell.
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Unit 1 Lesson 2 Chemistry of Life
What are phospholipids?
• What causes a cell membrane to have a doublelayer structure?
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Unit 1 Lesson 2 Chemistry of Life
Why is water important?
• Water moves through a cell membrane by a
process called osmosis.
• Water moves into and out of a cell, from areas of
higher concentration to areas of lower
concentration.
• Too little water in a cell causes it to shrink.
• Too much water in a cell causes it to burst.
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