Transcript Document 7175075

Structure and Function
The cell is the smallest unit of life that
can carry out all the functions of a
living thing.
History of the Discovery of Cells
 1500’s: microscope (m.s.) invented by
Dutch eyeglass makers (opticians)
• 1665: Robert Hooke (English)
saw empty “cells” or rooms when
he observed cork under a m.s.
Hooke’s drawing of cork as seen
through his microscope.
• 1674: Anton van Leeuwenhoek (Dutch) used hand-held
m.s.’s to observe organisms and living cells in pond
water and blood.
A picture he drew using
his microscope. What
do you think it is?
Fly eye!
• 1820’s: Rene Dutrochet
(French) concluded that
various parts of
organisms (liver, bone,
etc.) are made of cells.
• 1830’s: Robert Brown (Scottish) discovered the nucleus,
or center of the cell.
 1830’s: Felix Dujardin (French)
discovered cytoplasm, or the clear,
jelly-like material in the cell.
• 1838: Matthias Schleiden (German) said that all
plants and plant parts are made of cells.
1839: Theodor Schwann (German) said that all animals
and animal parts are made of cells. (He later said ALL
organisms are made of cells.)
• 1858: Rudolf Virchow (German) said that all cells
come from preexisting cells.
1970: Lynn Margulis
 Proposes the idea
that organelles
were once freeliving cells
Cell theory
developed by Schleiden, Schwann, and
Virchow, consists of three principles:
 Cells are the basic units of all life.
 All organisms are made of one or
more cells.
 All cells come from preexisting cells.
Exceptions of Cell Theory:
 Where did first cell come from?
(Remember Theory of Evolution explanation.)
 Virus particles have a protein coat and
nucleic acid core. They have both living and
nonliving characteristics and do not have all
the parts of a complete cell.
HIV
Hepatitis C
West Nile
FLU
SARS
There are two basic types of living things:
 multicellular: organism
made of many cells
 unicellular: organism
made of one cell
How cells vary:
Shape is related to function.
Nerve cells can be one
meter long, but very thin.
Mycoplasms: smallest
cells cause respiratory
diseases
The largest is an
unfertilized ostrich
egg.
Two types of cells
 eukaryotes: have a
nucleus surrounded
by a membrane (all
cells except bacteria)
 prokaryotes: have no
definite nucleus
(bacteria)
Pro = No: PROKARYOTIC CELLS HAVE NO NUCLEUS!
Basic Cell Structures
 A cell must
have three: cell
membrane,
nucleus, and
cytoplasm.
Cell Membrane
 thin layer of lipid (fats) and protein that
controls what enters and leaves cell
•made of phospholipids (glycerol, two fatty acids, and phosphate
group) and protein molecules embedded in the lipid layer.
•cell membranes are fluid (lipids and proteins are always in motion)
forming “mosaics” (called fluid mosaic model)
Cytoplasm

material between the cell
membrane and the nucleus
• made of water and organic compounds
organelles (cell parts) “float” in it
• contains cytoskeleton: network of fibers and
tubes extending throughout cytoplasm that gives
support and helps anchor organelles. It also helps
cells change shape.
Nucleus
 contains chromosomes: most of
the cell’s genetic material. All
organisms have a specific
number.
 Contains nucleolus: makes
ribosomes, which in turn help make
proteins in the cell.
surrounded by a nuclear envelope,
or lipid bilayer.
Ribosomes
 make proteins from amino acids. They
float in cytoplasm or are bound to
membranes. Made by the nucleolus.
Endoplasmic reticulum (ER)
- network of membranes that produce and
TRANSPORT materials for the cell.
 smooth ER has NO
 rough ER has
ribosomes on it
ribosomes on its surface
- It makes lipids, processes
- It helps in making
carbohydrates, and
protein secreted by the
modifies chemicals that
cell and new cell
are toxic to the cell.
membranes.
Golgi apparatus (also called
Golgi complex or Golgi bodies):
 flat, membranebound sacs
where chemicals
are sorted,
packaged, and
transported to
other places.
Mitochondria
 the “powerhouse” of the
cell
- Changes food
compounds into a
usable form of energy
(ATP: adenosine
triphosphate) for the
cell
Lysosomes
 sacs that have
digestive enzymes
to break down
large molecules of
carbs, proteins,
lipids, and old
organelles no
longer useful.
Vacuole
 membrane-bound
organelle used for
storage.
There is a large,
central one in plant
cells (helps to
maintain their shape)
There are many small
ones in animals.
Types of Movement
 cilia: tiny, hair-like particles
(ex. paramecium)
 flagella: large, whip-like tail (ex.
human sperm)
Cell Diversity
1. Plant Cells
• have a cell wall, a
tough, rigid outer
covering that protects
the cell and helps
maintain its shape.
• Cell walls are also
found in fungi, algae,
and bacteria
• chloroplasts help make sugars during photosynthesis.
• They also contain chlorophyll, the green pigment in plants.
large central vacuole
2. Animal Cells
 have cytoskeleton
but no cell wall for
support
 do NOT contain
chloroplasts may
have
 many very small
vacuoles
Cells and Their Environment
- semipermeable membrane lets certain molecules pass
through and keeps others out. Cells have this!
1. Passive transport
is the movement of
a substance across a
cell membrane
WITHOUT the input
of energy.
NO ENERGY!
2. Osmosis is the diffusion of water molecules only.
NO
ENERGY!
3. Diffusion, the most
common form of
passive transport, is
the movement of
substances from areas
of HIGH
concentration to areas
of LOW concentration.
NO ENERGY!
USES ENERGY (ATP)!
4. Active transport uses cellular energy to move substances
across a cell membrane. molecules move from LOW
concentration to HIGH concentration
- helps organisms maintain homeostasis
Bulk Movement
used to transport large molecules across membrane
 Exocytosis takes materials OUT of
the cell.
Endocytosis carries materials INTO the cell.
Pinocytosis (cell “drinking”) is when liquids are moved into
the cell.
Phagocytosis (cell “eating”) is when solids are moved into the cell.
It’s how some organisms (ex. amoeba) get their food.
Effect of Solution Concentrations
 Hypertonic: the concentration of solutes outside is higher
than it is inside the cell.
 Isotonic: the concentration of solutes outside the cell is equal
to that inside the cell. It should be the state of a normal cell.
 Hypotonic: the concentration of solutes outside is lower than
it is inside the cell.
1. very hypotonic: the cell has burst due to the large amount
of water entering it.
Let’s take a quiz!!
How many parts can you name?
Now, Check your answers!
Is this a plant or animal cell?
2.
3.
4.
Plant Cell
One large vacuole
2.
3.
4.
Is this a plant or animal Cell?
A.
D.
E.
B.
F.
C.
G.
Animal Cell
Let’s Check Your Answers!
A. Nucleus
B. Mitochondria
C. Cell Membrane
D. Smooth ER
E. Golgi Body
F. Rough ER
G. Lysosome