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Chapter 1 Sec. 1 Discovering Cells
I.
Cells are the basic unit of structure and
function in all living things.
II. First sightings of cells
a. Was not possible until the discovery of
the microscope (around 1590).
i. Microscopes make small things look
larger by focusing light through
lenses. If more than one lens, called a
compound microscope.
ii. They changed everyone’s
understanding of living things.
b. Robert Hooke
i. Looked at cork slices and described
the millions of cells.
c. Anton van Leeuwenhoek
i. First to see many one celled animals,
including bacteria.
III. The cell theory
a. A theory is not an educated guess. It is a
well-tested statement that explains a
wide range of observations.
b. Cell theory says
i. All living things are made of cells
ii. Cell are the most basic structure of
living things
iii. All cells are produced from other cells
IV. How a light microscope works
a. Magnification
i. The ability to make things look larger
ii. The convex lenses bend the light
iii. The second lens gets a magnified
image and magnifies it further.
iv. The power of a microscope is the
power of the lenses multiplied.
b. Resolution
i. Ability to clearly distinguish the parts
of the image. Means same as
sharpness.
V. Electron microscopes
a. Use electrons (a part of atoms) to create
image, instead of light, so have much
better resolution than ordinary
microscopes.
Chapter 1 Sec. 2 Looking inside cells
I.
Cell wall
a. A rigid layer of non-living material
surrounding plant cells only
b. Made of cellulose (wood is mostly
cellulose)
II.
Cell membrane
a. All cells, plants and animals, have a
membrane
b. It has openings (pores) that control what
goes in or out of the cell
III. Nucleus
a. The “brain” or control center of the cell
which controls everything that happens
b. Nuclear membrane
i. Works just like the cell membrane
c. Chromatin
i. Strands that contain all of the
genetic material, which has
instructions for everything the cell
does
d. Nucleolus
i. A small body where ribosomes are
made.
IV.
Organelles in the cytoplasm
a. The cytoplasm is a clear, thick, gel-like
fluid that makes up most of the cell. The
organelles do most of the work in the cell.
b. Mitochondria
i. Rod shapes bodies that produce the
energy cells need to function.
Muscles have many mitochondria.
c. Endoplasmic reticulum
i. Passageways that move stuff from
one part of the cell to another.
d. Ribosomes
i. Where proteins are made.
ii. Proteins control most of what and who
we are
e. Golgi bodies
i. Help the endoplasmic reticulum to
move materials throughout the cell
f. Chloroplasts
i. Green bodies in plants only
ii. Turn sunlight into food for the cell
g. Vacuoles
i. Water-filled sacs that also hold food
and other stuff needed by the cell
ii. When plants look limp, it’s because
their vacuoles are empty
h. Lysosomes
i. A chemical factory that breaks down
food and old, unused cell parts.
V.
Bacterial cells
a. Much smaller and much simpler than plant
or animal cells
b. Human skin cell 10X as big as a bacteria
c. Have cell wall/membrane and ribosomes
d. Genetic material is loose in the cell.
e. None of the other organelles
VI.
Specialized cells
a. Ranging from very long nerve cells,
muscles, bone, to small round blood cells.
Chapter 1 Sec. 3 Chemical compounds in cells
I.
Elements and Compounds
a. Element is a substance that cannot be
broken down into smaller substances.
b. Atom is the smallest unit of an element
c. Compounds are two or more elements
chemically combined
i. Properties are different from the
elements that make them up
d. Molecules are the smallest unit of a
compound
II.
Organic & inorganic
a. Living things are based on (and made up
of) carbon-based compounds. Nearly
everything with carbon in it is organic
i. Exceptions include coal, diamonds, and
carbon dioxide.
b. Other compounds are called inorganic.
c. Carbohydrates, proteins, lipids, and
nucleic acids are all organic.
III. Carbohydrates
a. Made of carbon, oxygen, and hydrogen.
b. Sugars and starches are common examples
c. Fruits and many vegetables are made of
sugars.
d. Starches are complex sugars that store
better
i. Like potatoes , wheat, & rice
ii. Your body breaks them down into
sugar (glucose) that you can burn
IV.
Proteins
a. Large organic molecules
b. Protein structure
i. Made from amino acids. There are
only 20 amino acids, but can be
combined thousands of ways
ii. Cannot make proteins w/o amino acids
c. Enzymes
i. A protein that speeds up (or lowers
the temperature) of chemical
reactions in living things
ii. Life would not be possible w/o
enzymes
V.
Lipids
a. Fats, oils, & waxes are all lipids
b. Another energy rich source
c. A more efficient way to store energy than
in carbohydrates
d. Cholesterol is a lipid. You need some, but
too much builds up in blood vessels and
causes heart attacks.
VI.
Nucleic acids
a. Carry the instructions necessary for life
b. Have you heard of DNA? That stands for
dioxy (2 oxygens) ribo nucleic acid
VII. Water & living things
a. Water is 2/3 of your body
b. Most chemical reactions in your body only
take place if compounds are dissolved in
water
c. Maintains cell size and shape
d. Helps maintain a constant temperature
Chapter 1 Sec. 4 Cell in its environment
I.
Cell membrane as a gatekeeper
a. Selectively permeable which means it
lets some things through and keeps others
out
b. 3 ways are diffusion, osmosis & active
transport
II.
Diffusion – molecules in motion
a. Is the main mechanism used by cells
b. It is the process of moving from high
concentration to lower concentration
i. Concentration is the amount of
something in a given volume
c. Think about how perfume spreads
d. What causes it?
i. The higher the concentration, the
closer molecules are to each other.
ii. Closer means more collisions, which
push them apart
iii. The molecules keep spreading out
until they are evenly distributed
e. Diffusion in cells
i. If there is a higher concentration
outside the cell of something that the
membrane will let through, it will
diffuse into the cell
ii. Like oxygen in water
III. Osmosis – the diffusion of water
a. A special kind of diffusion, only for water
IV.
Active transport
a. Diffusion/osmosis are passive transport,
which means doesn’t require any energy
b. Sometimes cells need to move something
inside, even though the concentration
inside is already higher than outside. This
requires energy and is called active
transport
c. Transport proteins
i. Protein picks up molecule and moves it
through the cell membrane (in or out)
d. Transport by engulfing
i. Surrounds something, then pinches
off that part of the membrane to
form a vacuole
V.
Why are cells small?
a. The bigger it is, the further some of the
cytoplasm is from the membrane. It would
take too long to move stuff into or out of
cytoplasm far away.