Transcript Chapter 6 Cells

Chapter 7
Cell Structure
and Function
The discovery of
cells was
dependent on the
invention of the
microscope
The Cell Theory
1. All organisms (bacteria, protists, fungi,
plants, animals) are made of cells.
2. Cells are the basic unit of structure and
function of living things.
3. All cells come from preexisting cells.
Important Scientists
• Hooke discovered
and named cells
Early Microscopes = Light Microscopes, where
light reflects off an object. Usually cannot see
most organelles with these.
Van Leeuwenhoek’s
Microscope
Original
Copy
An old German
Microscope
Stains add contrast. Some can
identify chemical types
Acid-secreting cells of
Rattlesnake Venom
Glands
From:
Zoologischer Anzeiger - A Journal of Comparative
Zoology
Volume 245, Issues 3–4, 24 November 2006,
Pages 147–159
Bioweapons synthesis and storage: The venom
gland of front-fanged snakes ☆
Stephen P. Mackessy, , Louise M. Baxter
School of Biological Sciences, University of
Northern Colorado, 501 20th St., CB 92,
Greeley, CO 80639-0017, USA
Fluorescent Stains
Human height
1m
Length of some
nerve and muscle
cells
0.1 m
Chicken egg
1 cm
Unaided eye
Microscopes
are almost always
needed to see a
cell.
Frog egg
Old terminology:
micron
Most plant and
animal cells
10 µm
Nucleus
Most bacteria
1 µm
Mitochondrion
100 nm
Smallest bacteria
Viruses
Ribosomes
10 nm
Proteins
Lipids
1 nm
Small molecules
Atoms
Electron microscope
Size: 1-100
micrometers
(= µm)
100 µm
Light microscope
1 mm
Electron Microscopes Today
(Note Problem: Cells are not alive)
SEM = Scanning
See surface
See 3-D
TEM = Transmission
Thin Section; see through
See 2-D
Important Scientists
• Schleiden determined
that all plants are
made of cells.
• Schwann determined
that all animals are
made of cells.
Important Scientists
Van Leeuwenhoek
discovered that
microorganisms live in a
huge variety of sources
(pond water, rivers, his
mouth).
Virchow claimed that
all cells come from
preexisting cells.
The Two Cell Types
Prokaryotes
and
Eukaryotes
Prokaryotes = Bacteria and BlueGreen Algae
CHARACTERISTICS
• Simple
• Coffee bean size
• No membrane-bound
organelles but do have
ribosomes (rRNA)
• Have DNA, but not in a
nucleus
Organelle = “little organ”
Bacteria Types
Cocci (round) Bacillus (rod)
Spirillum (spiral)
What good are bacteria?
• Autotrophs
– Produce oxygen
• Fix nitrogen
– So plants can take it in. We need nitrogen to make
DNA & proteins
•
•
•
•
Recycle nutrients
Form antibiotics
Help in digestions and formation of vitamins
Production of cheese and yogurt
Eukaryotes
Characteristics
– More complex
– Larger compared to
prokaryotes
– Cell membrane; plants
and fungi ALSO have
cell walls
– Membrane bound
organelles
– DNA in nucleus
Eukaryotes
Organelles are
important in
keeping noncompatible
reactions apart,
yet allowing them
to happen at the
same time =
DIVISION OF
LABOR
The Basic Animal Cell
=
Nucleus + Cytoplasm
(Cytoplasm =
organelles + cytosol)
Plasma Membrane
Controls what goes
in and out.
A phospholipid
bilayer.
Embedded proteins
involved in
transport.
Carbohydrate side
chains involved
in cell-to-cell
recognition.
Endocytosis and Exocytosis
How larger particles get into and out of a cell
Is this green
particle inside
the cell?
Basic Plant
and fungi
cells also
have cell
walls for
support
and
protection
Walls are
typically
made of
cellulose
(plants) or
chitin
(fungi).
NUCLEUS
Nuclear envelope
Nucleolus
Chromatin
Rough endoplasmic
reticulum
TYPICAL
Smooth endoplasmic
PLANT
reticulum
Ribosomes
CELL
Central vacuole
Golgi
apparatus
Microfilaments
Intermediate
filaments
Microtubules
Mitochondrion
Peroxisome
Chloroplast
Plasma
membrane
Cell wall
Plasmodesmata
Wall of adjacent cell
CYTOSKELETON
Nucleus
Contains chromosomes which are
DNA wrapped around protein
spools.
• Recall that DNA has the code that tells the
cell what proteins (enzymes) to make.
• Uncoiled chromosomes are called
chromatin
Also contains nucleoli = areas
where rRNA and tRNA are
made.
Surrounded by a nuclear envelope
that has pores in it.
Vacuoles
Found in plant cells; store
water, digestive enzymes,
salts, pigments, etc.
For support.
Vesicles
Found in all cells. Store
digestive enzymes or
other chemicals,
transport chemicals,
Lysosomes
Contain enzymes to break
down food brought in by
endocytosis; can also break
down own molecules and
organelles for recycling.
Cytoskeleton
A network of
protein fibers
that help the
cell keep its
shape and
helps things
move around
(like a
freeway).
Some help
the cell move.
Cilia
Short flagella, often arranged
in rows, that help the cell
move. Typically hundreds.
Primary Cilia
Some are chemosensitive,
some pressure sensitive.
Function in cell signaling,
cellular development, and
responsible for many diseases.
Ribosomes
The site of protein synthesis
Endoplasmic Reticulum
A system of tubes
Rough ER:
Lipid components of the cell
membrane are made here.
Proteins destined for export, or to
become part of the cell
membrane, or digestive enzymes
are modified here.
Smooth ER:
Lipid components of the cell
membrane are also made here.
Involved in the detoxification of
drugs.
Golgi Apparatus
Where proteins
from the ER are
further refined
and packaged
for either
storage in the
cell or final
transport out of
the cell.
Mitochondria
Break down food to produce
ATP. This process is called
cellular respiration
Chloroplasts
“Solar Power Plants.” They
capture light energy and
convert it to chemical energy
(sugar). This process is called
photosynthesis.
NOTE: Both have their own DNA