Transcript video slide - Mr. Patrick Wagner's Teacher Web Site

The Cell
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Overview: The Importance of Cells
All organisms are made of cells.
The cell is the simplest collection of
matter that can live (grow, metabolize,
reproduce, make adjustments).
Light Microscopes are used to view
cells like this one
RELT
50 µm
Differences in Cells
1. Size:
--smallest @ 0.25μm
Mycoplasma hominis
--largest @ 0.75 mm
Thiomargarita
namibiensis
162,000X
The “sulfur pearl of Namibia”
Chaos chaos (1-5 mm)
Siphonous green algae (1m long)
A human egg cell
= 100 µm
Vs.
human sperm cell
= 5 µm
2. Number
--unicellular (Bacteria, Protists like ameba & algae)
--multicellular (Plants, Animals, Fungi, & some Protists)
3. Kind/type
A. Prokaryote means
“before kernal”
OR
B. Eukaryote means
“true kernal”
Which one has a nucleus inside?
4. Plants vs. Animals (lab)
Prokaryote
1. No nucleus (do have DNA)
2. Size: 0.1 to 10 µm
3. No membrane bound
organelles
4. Single circular chromosome
5. Unicellular
6. Simple life cycle; usually
reproduce asexually
7. Kingdoms– include
Eubacteria & Archaebacteria
8. Evolved 4 billion yrs. ago
Eukaryote
1.True nucleus (enclosed in a
membrane)
2. Size: 10-100 µm
3. Have membrane-bound
organelles
4. Multiple complex chromosomes
5. Unicellular or Multicellular
6. Complex life cycle that includes
mitosis & meiosis; usu. sex. repro.
7. Kingdoms– include Protists,
Animals, Plants and Fungi
8. Evolved 2 bya
See p. 472
Pili: used to attach to other cells
Nucleoid: region where the
cell’s DNA is located (NOT
In a membrane)
Ribosomes: organelles that
synthesize proteins
Cell membrane:
Encloses the cytoplasm
Cell wall: rigid structure outside
the plasma membrane
One circular
chromosome
(a) A typical
rod-shaped bacterium
Figure 6.6 A, B
0.5 µm
Flagella: used for
locomotion
(b) A thin section through the
bacterium Bacillus coagulans
(TEM)
Parts of the Cell
 3 main locations
1. Cell (plasma) membrane +/- cell wall
2. Nucleus (or nucleoid)
3. Cytoplasm (insides of the cell)
1. The cell membrane (next topic)
 Functions as a selective barrier by allowing
movement of nutrients & waste in & out
Outside of cell
Carbohydrate side chain
Inside of cell
0.1 µm
(a)
TEM of a plasma
membrane.
Phospholipids
Proteins
(b) Structure of the plasma membrane
2. The Nucleus: Genetic Library of the Cell
 The nucleus contains most of the genetic info
<3.2 billion vs. 5 million (or 0.1%) nucleotide base
pairs (A-T or C-G) in human cells vs. E. coli>
 The nuclear envelope w/ pores encloses the nucleus,
separating its contents (nucleolus, chromatin) from the
cytoplasm
How are these cells different from
the previous slide?
 Nucleoid region in a ___ karyote
3. CYTOPLASMIC ORGANELLES (“tiny organs”)
A. Ribosomes=not membrane-bound
 Are particles made of ribosomal RNA & protein.
 All cells (pro and eukaryote) must have!
 The smallest and most numerous organelle.
 Weighing in at around
150,000 atoms, the ribosome
is the engine of life itself, an
intricate cellular gizmo that
executes the last piece of how
information goes from DNA
to RNA to protein. The
ribosome transforms mRNA
into the proteins that brickby-biological-brick (= amino
acids) build bacteria, birds, &
biochemists.
from HHMI
Ribosomes: found in all cells because….
they act as protein factories (sites of protein synthesis).
RER
Free ribosomes
Bound
ribosomes
Large
subunit
TEM >
Diagram of a ribosome
0.5 µm
Small
subunit
B. Endoplasmic Reticulum:
Biosynthetic Factory
 continuous w/ nuclear envelope
 Two kinds:
 1. Smooth ER (SER) that lacks ribosomes
 2. Rough ER (RER) w/ ribosomes
Smooth ER
Nuclear
envelope
Rough ER
ER lumen
Ribosomes
Transport vesicle
Smooth ER
Rough ER
200 µm
The functions of Smooth ER include
--synthesizing lipids
(testes/ovaries)
--detoxifying poisons
(liver cells)
SER in the liver
Functions of Rough ER
 The RER
Has bound ribosomes so it …
Produces proteins for transport by vesicles to
other parts of the cell like …
C. The Golgi Apparatus:
Receiving, Packaging, Shipping Center
Receives the transport vesicles produced
by the RER
Looks like stack of flattened empty
pancakes
 Function =modifies the products of RER
Relationship betw. organelles of inner membrane system
1
Nuclear
envelope is
connected to RER,
which is continuous
with SER
Nucleus
Nuclear envelop
Rough ER
2
Transport vesicles
“blip” off of ER
carrying contents to
GA
Smooth ER
cis Golgi
Golgi modifies molecules
Lysosome containing enzymes
Plasma
membrane
trans Golgi
Transport vesicle carries proteins to
cell membrane for secretion
 1. Code travels from nucleus to RER
 2. Ribosomes use code to make raw protein
which then travels quickly thru ER
 3. Goes to Golgi where it is modified
 4. Transported to Cell membrane for secretion
D. Vacuoles
 membrane-bound sacks in the
cytoplasm = storage containers
 In plant cells (larger), they hold water &
starch.
 In animal cells, they are like little ziploc
baggies; storage containers for food,
H2O & waste.
Central Vacuoles
 Are found in plant cells to hold reserves of
starch and water
Central vacuole
Nucleus
Cell wall
Chloroplast
5 µm
Figure 6.15
What organism would have lots of these?
E. Lysosomes: Digestive Compartments
Nucleus
Membrane-bound
sacs w/ hydrolytic
enzymes + acid
used to digest all
kinds of macromolecules.
Ex: amylase, pepsin
1 µm
Lysosome
Lysosome w/
hydrolytic
enzymes
Food vacuole Hydrolytic
enzymes digest
fuses with
food particles into…
lysosome
Digestive
enzymes
Cell membrane
Food vacuole
Energy Converting Organelles
F. Mitochondria are enclosed by two membranes (a
smooth outer & an inner folded membrane)
Mitochondrion
Intermembrane space
Outer
membrane
Ribosomes
Inner
membrane
Mitochondrial
DNA
Figure 6.17
100 µm
Mitochondria
 Function: “burn” glucose to produce
energy in the form of ATP
 Have their own ribosomes and DNA! What
does that mean?
The Mitochondrion
“Thread
Grainy”
Mr. W has
many of us
guys in his
running
muscle
cells!
G. Plastids
Found in plants and algae
Contain pigments so they can
photosynthesize
2 kinds
1.) Chloroplasts: Capture Light Energy
 Contain chlorophyll (“more like… borophyll”)
Chloroplast
Ribosomes
Chloroplast
DNA
Inner &outer
membranes
1 µm
Chloroplasts
 Have two membranes
 Use light to convert CO2 & H2O into glucose
 Possess their own ribosomes & DNA!
2.)Chromoplasts contain other pigments
 Autumn leaves anyone?
Non-membrane bound organelles
H. Cytoskeleton=network of fibers extending throughout
the cytoplasm that supports + organizes structures and
activities in the cell
Microtubule
Microfilaments
0.25 µm
Figure 6.1
10 µm
I. Centrioles
 Only in animal cells
Centrosome
 Used for dividing the
nucleus (mitosis)
Microtubule
Centrioles
0.25 µm
Microtubules
J. Cilia and Flagella
 Are locomotor appendages of some cells (protein
extensions from the cell used for movement)
A Cross-Section of a Cilium
The Cell: A Living Unit Greater Than
the Sum of Its Parts
5
µm
Cells rely on the
integration of
structures &
organelles to
function. Here a
white blood cell
needs what cell
parts to recognize,
ingest, and destroy the bacteria?