Cell Structure and Function
Chapter 7
The discovery of cells
Anton van Leewenhoek-given
credit for inventing the first
microscope
Robert Hooke-first used the word cell

He was looking at cork cells
 Robert
Brown-discovered the nucleus
 Mathias
Schleiden- all plants are made of cells
 Theodor
Schwann-all animals are made from
cells
 Rudolf
Virchow-studied reproduction in cells and
found all cells come from other cells
Cell Theory



all living things are made up of cells
cells come from other cells
cells are the basic unit of life
There are 2 types of cells:
prokaryotic and eukaryotic cells
 Prokaryotic
cells-do not have a nucleus, the DNA
is free in the cell. Prokaryotic cells are very small
and do not have most cell structures.
 Example: bacteria cells
 Eukaryotic
cells-contain a nucleus which holds
the DNA together. They have many cell
structures and are much larger cells.
 Example: all other cells (plants, animals, fungi)
Major cell structures:
 Cell
membrane-holds cell together, controls
what enters and leaves
 made
of 2 layers of lipids
 proteins embedded throughout
 Nucleus-means
”center”, usually appears darker,
acts as control center


surrounded by a nuclear envelope
contains DNA which is our
genetic information
 Cytoplasm-all
the material between the cell
membrane and the nucleus


It is a jelly like material
It holds all the cell organelles in place but still allows
movement
 Cell
wall-found in plants, most bacteria and
fungi.


Provides support and protection for the cell
Made of cellulose (a combination of sugar and
protein)
 Nucleolus-found
ribosomes
inside the nucleus, it makes the
 Cytoskeleton-framework
support and strength
 microtubules-hollow
inside cell for
tubes made of protein,
form the centrioles
 microfilaments-long thin fibers, movement and
support
 cilia-short
hair like structures on outside of cell for
movement
 flagella-long hair like structures on outside of cell for
movement
 Ribosomes-small
proteins

bead like structures that make
may be free or attached to ER
 ER-endoplasmic


reticulum-folded membrane
forms a canal for materials to leave cell
Smooth-no ribosomes attached
Rough-has attached ribosomes
 Golgi
apparatus-look like flattened sacs, modify
and package materials to leave cell
 Lysosomes-small
sacs with enzymes that digest
food , foreign material or the entire cell when it
wears out
 vacuoles-sacs
that hold waste, food, water:
storage centers


plants have 1 large one in the center
animals have several small ones
 Chloroplast-contain
chlorophyll


the green pigment
produce sugar from sunlight
found in plant cells only
 Mitochondria-power
for energy
 certain
house: breaks down food
cells, like brain and muscle cells, may
have thousands
 centriole-found
only in animal cells, help the cell
to divide, cell has two
Plant cell
 Have
a cell wall
 Have chloroplasts
 Do not have
centrioles
 Have one large
vacuole
 Do not have
lysosomes
Animal Cell
 Do
not have a cell wall
 Do not have
chloroplasts
 Have centrioles
 Have several small
vacuoles
 Have lysosomes
Movement through the cell
membrane
o
o
o
o
The environment of the cell is liquid inside
and out.
The liquid contains dissolved materials
(solutes)
These materials are always in motion
This motion is random but follows the rule of
moving from high to low concentrations.
Methods of movement:
o
Passive-no energy is required by the cell.
o
o
Diffusion-the random movement of
materials from high to low concentration.
It continues until equilibrium is reached
Osmosis-the movement of water across a
membrane from high to low
concentration.
Facilitated diffusion
o carrier proteins found in the cell
membrane transport material across the
membrane
o
still moving from high to low
Active transport
o movement that requires energy
o
Endocytosis- moving material into the cell
o
phagocytosis- Greek for “eat”, cell engulfs large
particles, vacuole forms around food
o
o
o
example- white blood cell eating bacteria in the body
Pinocytosis- Greek for “drink”. The cell surrounds a
large amount of water and forms a vacuole.
Exocytosis-moving materials out of the cell
o
a vacuole moves to the cell membrane, it opens and
material is pushed out
Specialization of cells
 Unicellular
organisms-the cell is the entire
organism. It carries on all life functions.
 Multicellular
organisms-cells are
interdependent on each other.
o
They have specialized to do different jobs.
 Specialization-cells
organism
 Examples1.
2.
carry out different jobs for the
Pancreas cells make the protein insulin so they
have a lot of ribosomes and ER
Respiratory cells have cilia and make mucus to
keep foreign material out of lungs
Levels of organization in
multicellular organisms:
cells
muscle cell
muscle cell
tissue
muscle tissue
muscle tissue
organ
stomach
heart
system
digestive
circulatory