Transcript Prokaryotic cell

Ch.3 Cells
The 3 Basic Parts of all Cells
1. Plasma Membrane
2. Cytoplasm
• Entire contents of cell between P.M. and
nucleus
• .
3. Nucleus or Nuclear Area
• Contains DNA, the genetic material
– Phospholipids form a two-layer sheet
Hydrophilic
heads
Water
Hydrophobic
tails
Water
Figure 5.11B
Classes of Cells
•
Two basic types of cells:
1. Prokaryotic cells
2. Eukaryotic cells
Prokaryotic cells are ….
Prokaryotic cell
Colorized TEM 15,000 
Nucleoid
region
Nucleus
Figure 4.3A
Eukaryotic cell
Organelles
Prokaryotic Cell
Pili
Cell wall
Plasma membrane
Nuclear area
Ribosomes
Flagella
Figure 4.3B
Eukaryotic cells
Animal Cell
Fig 4.4A
1. The nucleus is the cellular control center
Chromatin
Nucleolus
Nucleus
Two membranes
of nuclear
envelope
Pore
Figure 4.5
Rough
endoplasmic
reticulum
Ribosomes
2. Smooth endoplasmic reticulum, or smooth ER
• Synthesizes lipids
Smooth ER
Rough ER
Nuclear
envelope
Ribosomes
Figure 4.7
Rough ER
TEM 45,000
Smooth ER
3. Rough endoplasmic reticulum or Rough ER
– Ribosomes on the surface
Transport vesicle
buds off
4
Ribosome
3
1
Secretory
(glyco-) protein
inside transport vesicle
Sugar chain
Figure 4.8
Polypeptide
2
Glycoprotein
Rough ER
4. The Golgi apparatus finishes, sorts, and ships cell
products
Figure 4.9
“Receiving” side of
Golgi apparatus
Golgi apparatus
Golgi
apparatus
New vesicle
forming
“Shipping” side
of Golgi apparatus
Transport
vesicle from
the Golgi
TEM 130,000
Transport
vesicle
from ER
5. Vesicles:
– Membrane-bound “balloons” that transport and
store substances in cells
6. Lysosomes are
sacs of enzymes
• function in
digestion
within a cell
• recycle
damaged
organelles
Fig 4.13
•The various
organelles of
the endomembrane
system are
interconnected
structurally
and
functionally
7. Mitochondria harvest chemical energy from food
– Mitochondria carry out cellular respiration …
Mitochondrion
Outer
membrane
Intermembrane
space
Inner
membrane
Cristae
Matrix
TEM 44,880
Figure 4.14
8. Cytoskeleton & related structures Fig 4.17
Tubulin subunit
Actin subunit
Fibrous subunits
25 nm
7 nm
Microfilament
10 nm
Intermediate filament
Microtubule
– Microfilaments of actin
– Intermediate filaments
– Microtubules give the cell rigidity
• And provide anchors for organelles and act as tracks for
organelle movement
Cilia and flagella move when microtubules bend
Figure 4.18
LM 600
Colorized SEM 4,100
– Eukaryotic cilia and flagella are
– Tight junctions
– Anchoring junctions
– Gap junctions
• allow substances to flow from cell to cell
Tight junctions
Figure 4.18B
Anchoring junction
Gap junctions
Extracellular matrix
Space between cells
Plasma membranes of adjacent cells
Plant Cell –
Fig. 4.6b
Plant cells also have:
1. Vacuole
• stores water, solutes, waste
• Important for growth and rigidity
2. Chloroplasts
3. Cell wall
**Plant cells do not have lysosomes
Vacuoles function in the general maintenance of the cell
Nucleus
Chloroplast
Colorized TEM 8,700
Figure 4.12
Central
vacuole
Chloroplasts convert solar energy to chemical energy
– convert solar energy to chemical energy in sugars
Chloroplast
Stroma
Granum
Intermembrane
space
Figure 4.15
TEM 9,750
Inner and outer
membranes
Plant cells
• have rigid cell walls made of cellulose
Figure 4.22
Walls of two
adjacent plant
cells
Vacuole
Plasmodesmata
Layers of one
plant cell wall
Cytoplasm
Plasma membrane
Chapter 5: How cells Work
Transporting across membranes
• Solvent –
• Solute –
– any molecule dissolved in the liquid.
• Selectively permeable – water can move freely
through the membrane, but the membrane regulates the
passage of solutes
• Diffusion –
• Osmosis – movement of water across a selectively
permeable membrane.
Given a membrane that is permeable to water and glucose:
Which way will water move?
Which way will glucose move?
• Hypertonic – high solute concentration, as
compared to the other side of a membrane
• Hypotonic –
• Isotonic – equal solute concentrations on both
sides of the membrane
Fig. 5.12: Diffusion
Isotonic Solutions
Fig. 5.13
Fig. 5.14
Functions of membrane proteins
Messenger molecule
Receptor
Activated
molecule
Enzymes
Receptors for messages
ATP
Transport of substances
Two types of transport across membranes
1. Passive transport (or Facilitated
diffusion)
– a solute moves through a membrane
transport protein in the direction set by its
concentration gradient
– Small nonpolar molecules such as
– Other larger or polar molecules do not easily diffuse
across the bilayer and transport proteins provide passage
across membranes through a process called facilitated
diffusion
Solute
molecule
Figure 5.15
Transport
protein
2.Active transport
• energy-driven transport proteins move solutes
across membranes against their concentration
gradient.
• Why?
• Mechanism: ATP binds to active transport pump,
causing a change in its shape. The protein now
has energy to pump the solute against its
concentration gradient
Cells expend energy for active transport
Transport
protein
ATP
Solute
1 Solute binding
Figure 5.18
P
ADP
2 Phosphorylation
Protein
changes shape
3 Transport
P
Phosphate
detaches
P
4 Protein reversion
Exocytosis and endocytosis transport large molecules
– To move large molecules or particles into the cell is
endocytosis
Figure 5.19A
Fluid outside cell
Vesicle
Protein
Cytoplasm