Download 7th-cells-and-heredity-unit-1-lesson-2-chemistry-of-life

th
7
Science
Cells and Heredity (Module A)
Unit 1 Lesson 2
Unit 1 Lesson 2 Chemistry of Life
THE BASICS!
• Element: a substance that cannot be broken down into a simpler
substance.
• Atom: smallest unit of an element that maintains the properties of
that element
• Molecule: a group of atoms held together by chemical bonds
• Some made up of only one type of atom. (N2)
• Most made up of two or more types of atoms. (H20)
• Compound: substance made up of atoms of two or more different
elements (joined by chemical bonds.)
• have different properties than the elements that make them.
• most molecules found in cells are compounds.
Copyright © Houghton Mifflin Harcourt Publishing Company
Is it a
molecule?
Is it a
compound?
What elements How many
are present?
atoms are
present?
O2 – oxygen
Yes
No
O
2
O – oxygen
No
No
O
1
CO2 – carbon
dioxide
Yes
Yes
C and O
3
No
No
He
1
Yes
C, H and O
24
No
H
1
He – helium
C6H12O6 - sugar Yes
H - hydrogen
No
Q: Can something be a molecule without being a compound?
A: yes (example?)
Q: Can something be a compound without being a molecule?
A: no
Q: Can something be an atom without being a compound or a molecule?
A: yes, but it does not happen in nature veryCopyright
often© Houghton Mifflin Harcourt Publishing Company
Molecules of Life!
• Lipid: is a fat molecule
• Mainly used for storing energy
• Comes from oils, some fish
•Protein: made up of smaller molecules called amino acids.
• Used to build and repair body structures
• Enzymes (a type of protein) help chemical processes happen
in cells.
• Found in meat, beans, nuts
Copyright © Houghton Mifflin Harcourt Publishing Company
Molecules of Life!
• Carbohydrates: include sugars, starches, and
fiber.
• Used 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
• Nucleic acids: molecules that carry information in cells.
• Nucleotides- smaller molecules that make up nucleic
acids.
• DNA is a nucleic acid that carries information that cells
need to make other molecules.
One important lipid in the cell is a
phospholipid (it contains phosphorus)
• Head is attracted to water; tail
repels water.
• Much of a cell’s membrane is
made of a double layer of
phospholipids
• This helps regulate molecules
entering and leaving the cell.
Copyright © Houghton Mifflin Harcourt Publishing Company
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.
Copyright © Houghton Mifflin Harcourt Publishing Company