Transcript Cell Theory: 1. Every living thing is composed of one or more cells

Chapter 4: Cell Structure and
Function
I. Cell Theory:
1. Every living thing is
composed of one or more
cells.
2. The cell is the smallest/simplest
unit of life.
3. Under current conditions, all
cells come from preexisting
cells.
II. Prokaryotic Cells
A. Prokaryotic cells do contain DNA and
ribosomes, but no membrane-bound
organelles or nuclear membrane.
B. Include bacteria and archea (all
unicellular).
C. Single strand of DNA.
Prokaryotic Cell (Label)
ribosomes
In cytoplasm
Fig. 4.27a, p. 74
III. Eukaryotic Cells
• Eukaryotic cells are characterized by the
presence of membrane-bound organelles
and a defined nucleus. Include animals,
plants, fungi, and ‘protists.’
• Organelles: Discrete structures within
eukaryotic cells with specific functions.
Nucleus
Brain of Cell. The nucleus is surrounded by
two lipid bilayers, forming the nuclear
envelope. The nuclear envelope has
numerous pores, allowing certain items to
leave the nucleus. The pores are not
large enough to allow DNA to leave the
nucleus. Also, the nucleus holds the
nucleolus, which is responsible for
making the components of the ribosomes.
Ribosomes
Construction Crew of Cell. Made of two pieces
of RNA, the ribsomes read DNA and
assemble amino acids into proteins.
+
Endoplasmic Reticulum
The UPS of the cell.
Rough ER contains ribosomes, so rough
ER modifies proteins.
Smooth ER is involved with the modification
of lipids rather than proteins.
Golgi Bodies
UPS/related to ER. Hollow tubes that are
involved with processing of lipids and
proteins. Golgi bodies produce vesicles
(membrane-bound sacs) for shipment to
specific locations within a cell.
DNA instructions for
building polypeptide
chains leave the nucleus
and enter the cytoplasm.
The chains (green) are
assembled on ribosomes
in the cytoplasm.
Fig. 4.13, p. 64
Important Vesicles
Lysosomes: Loaded with enzymes to digest
cell components, or even entire cells.
Peroxisomes: Loaded with enzymes to
break down fats and proteins.
Mitochondrion
Powerhouse. The mitochondrion is an organelle with a
double membrane that functions to convert stored
energy such as sugar into useable energy, ATP.
Interestingly, the mitochondrion contains its own distinct
DNA. Glucose to ATP.
Chloroplast
Solar Panel. The inner membrane hold pigments (such as
chlorophyll) that collect light and the conversion to stored energy
occurs within the membrane system. Solar energy is converted to
stored chemical energy (glucose).
Plasma Membrane
The tails are fatty acid chains (hydrophobic) and the
heads contain phosphate groups (hydrophilic). The basic
function of the plasma membrane is to keep the contents
within the membrane separate from the contents outside
of the membrane.
A
B
C
Cytoskeleton
Made of microtubles (hollow tubes made of protein)
and microfilaments (thin ‘ropes’ of twisting two
polypeptide chains together).
tubulin
subunit
37
nm
one
polypeptide
chain
8-12
nm
actin
subunit
25
nm
Fig. 4.19, p. 69
Golgi body
vesicle
central vacuole
rough endoplasm
reticulum (rough ER)
microfilaments
(components of
cytoskeleton)
ribosomes (attached to
rough ER)
ribosomes (free in
cytoplasm)
smooth endoplasmic
reticulum
(smooth ER)
mitochondrion
chloroplast
microtubules
(components of
cytoplasm)
DNA + nucleoplasm
nucleolus
nuclear envelope
NUCLEUS
plasma membrane
cell wall
Fig. 4.8a, p. 59
Three Organelles Unique to Plants:
1.
2.
3.
nuclear enevelope
nucleolus
NUCLEUS
DNA + nucleoplasm
microfilaments
vesicle
microtubules
lysosome
components of
cytoskeleton
rough ER
ribosomes
(attached to
rough ER
and free in
cytoplasm)
smooth ER
plasma
membrane
vesicle
Golgi body
mitochondrion
pair of
centrioles
Fig. 4.8b, p. 59
IV. Cell Movement
A. Cytoskeleton can add/remove amino
acids (important in mitosis).
B. Many extentions = cilia
C. Few extentions = flagellum
V. Cell Junctions
A. Tight Junction:
Cell connections don’t allow materials to
flow past a surface. Proteins extend from
the cell membranes of the neighboring cells,
acting to bring the two cells close together
V. Cell Junctions
B. Adhering Junctions- Muscles cells are
connected but also must be able to flex
and stretch. They are connected with
adhering junctions.
C. Gap Junctions - The nerve cells of your
brain/nervous system have small gaps
between connecting cells.