Download Cell Wall Robert Brown

A Tour of the Cell
• Anton Van
Leeuwenhoek
(1600’s)
• Credit for the
first
microscope
• Looked at
pond water
and saw “wee
beasties”
Robert Hooke
• Observed plant
stems, wood, and
cork (1600’s)
• Saw all the tiny
chambers and
called them CELLS
• What cell part did
Hooke observe?
• Cell Wall
Robert Brown (1833)
• Observed that cells had a dark structure
within plant cells
• Brown observed the nucleus and stated that
all cells have nuclei (at this time no one
knew that the nucleus has DNA)
Matthias Schleiden (1838)
• Stated that all plants
are made of Cells
• Made many
observations of plants
around the area
Theodor Schwann (1839)
• Stated that all animals are made of
Cells
• Observed many animal tissues
Rudolf Virchow (1855)
• Stated that all cells come from
pre-existing cells
• Cells arise from the division of
pre-existing cells
The Cell Theory
Microscopes Provide
the Windows to the
World of the Cell
The Cell Theory
• All living things
are composed of
cells
• Cells are the basic
unit of structure
and function in
living things
• All cells come
from pre-existing
cells
A Prokaryotic Cell
Figure 7.1 The size range of cells
The Size
Range of
Cells
Cell Sizes
Average Animal Cell – 15 microns
Average Plant Cell – 40 microns
Average Eukaryotic Cell :10-100
microns
Average Prokaryotic Cell: 1-10
microns
An Electron Microscope
Geometric Relationships Explain Why Most Cells Are
Microscopic
Overview of an Animal Cell
Human Cheek Cells
Overview of a Plant Cell
Onion Epithelial Cells
Animal Cell’s Cell Membrane
Cell or Plasma Membrane
•“Fluid Mosaic” Model
• Lipid Bilayer (made of
phospholipids)
•Proteins embedded
throughout
•Semi-permeable or
Selectively Permeable
Cell Wall
• provides support to the
perimeter of plant cells, some
protists, and bacterial cells
The Plasma Membrane
The Nucleus and Its Envelope
Nuclear
Envelope/Membrane
•Double Membrane that
surrounds the nucleus
•Lined with pores
•Supported by nuclear
lamina
Nucleolus
•Inside the nucleus
•Site of ribosome and
rRNA synthesis
Ribosomes
Endoplasmic Reticulum (ER)
Endoplasmic Reticulum
(ER)
•Rough ER
•Intercellular transport of
materials, particularly
proteins; site where proteins
leave ribosomes and are
chemically modified
Smooth ER
• breaks down toxic
substances,
• regulates Ca levels,
• synthesizes steroids and
other lipids
The Golgi Apparatus
Golgi Apparatus
•Modifies proteins and
other substances from
the ER for export from
the cell
Lysosomes
Lysosomes
•Digest cellular waste
and foreign substances
•Breakdown of lipids,
carbohydrates, and
proteins
The Formation and Functions of Lysosomes
• Relationships among organelles of
the endomembrane system
1
Nuclear envelope is
connected to rough ER,
which is also continuous
with smooth ER
Nucleus
Rough ER
2
3
Membranes and proteins
produced by the ER flow in
the form of transport vesicles
to the Golgi
Smooth ER
cis Golgi
Nuclear envelop
Golgi pinches off transport
Vesicles and other vesicles
that give rise to lysosomes and
Vacuoles
Plasma
membrane
trans Golgi
Figure 6.16
4 Lysosome available
for fusion with another
vesicle for digestion
5 Transport vesicle carries
6 Plasma membrane expands
proteins to plasma
membrane for secretion
by fusion of vesicles; proteins
are secreted from cell
Peroxisomes
•Contain an assortment of
enzymes that perform such
roles as detoxification of
alcohol, breaking down of
fatty acids
•Produces H2O2 in the
process
Peroxisomes
The Chloroplast, Site of
Photosynthesis
Plastids
•May be called
chromoplasts or leukoplasts
•Store starch, fat or
contain pigments such
as chlorophyll or
carotenoids to capture
energy from the sun
The Mitochondrion
Mitochondrion
Site of cellular respiration
and synthesis of ATP,
a source of chemical energy
for the cell
The Plant Cell Vacuole
Vacuoles
•Store water, salts,
proteins, carbohydrates,
or enzymes
The Cytoskeleton
Cytoskeleton
•Protein strands that give
the cell its shape and size
•Helps organize the location
of organelles and their
activities
There are three main types
of fibers the make up the
cytoskeleton:
1) Microtubules
2) Microfilaments
3) Intermediate Filaments
Microtubules
•Are made of the protein
tubulin
•Shape and support the cell
•Are responsible for the
separation of chromosomes
during cell division
Centrosome Containing a Pair of Centrioles
Centrioles
•Appear during mitosis in
animal cells; are composed
of nine sets of triplet
microtubules in a ring
Centrosome
•Area from which the
centrioles radiate during
mitosis
Figure 7.24 Ultrastructure of a eukaryotic flagellum or cilium
Ultrastructure of a Cilium
or flagellum
Cilia and Flagella
•In eukaryotes, a specialized
arrangement (“9 + 2”) of
microtubules is responsible for
the beating of flagella and
cilia
•The protein, dynein, is
responsible for the movement
How Dynein “Walking
Moves Cilia and
Flagella
A Comparison of the Beating of Flagella and
Cilia
The microtubule assembly
of a cilium or flagellum is
anchored in the cell by a
Basal Body, which is
structurally identical to a
centriole.
Sea Urchin Sperm
Microfilaments and Motility
Microfilaments also aid in
•Cell motility (Ex: pseudopodia)
•Cell division (cleavage furrow
formation)
•Cytoplasmic Streaming
A Structural Role of Microfilaments
Microfilaments
•Made of the protein actin
•Located in the cytoplasm
of most eukaryotic cells
•Works with myosin to
cause muscle cell
contractions
Intermediate Filaments
•Anchor nucleus and other
organelles
•Reinforces cell shape
•Make up nuclear lamina
that lines the interior of
the nuclear envelope
Plant Cell Walls
Intercellular Junctions in Animal Tissues
Extracellular matrix (ECM)
1)What are the two major
types of electron
microscopes?
2) All cells are classified as
either _______ or _____.
3) Under the microscope,
bacteria are typically
measured in ___________
(units).
4) Two similarities between
plant and animal cells are. .
.. two differences are . . ..
5) The term used to
describe the fact that the
cell membrane allows some
materials in and keeps others
out is. . .
6) The lipid bilayer of the
cell membrane is made of:
1)The organelle that
packages proteins for
export from the cell is the
. . .
2) Cellular respiration occurs
in the ___________ and
energy is made in the form
of ________.
3) The major difference between a
prokaryotic and eukaryotic cell is
that a prokaryotic cell lacks a/an:
4) The oldest cells on earth are
______ cells. They evolved . . . .
years ago.
What characteristic of the cell
membrane allows some molecules
into the cell and keeps other out?
The primary purpose of the cell
wall is..
The cell membrane is composed
primarily of. .
Why is the cell membrane
referred to as a “fluid mosaic
model”?
Since some molecules can pass
through the cell membrane and
others cannot it is termed. .
If a molecule is too big to get
through the cell membrane, it must
enter through _________ channels.
The centers of protein synthesis in
the cell are the _________.
Describe the role of the
cytoskeleton in the cell.
Name two different things
stored by vacuoles.