Download Prokaryotic cell

Cells
The 3 Basic Parts of all Cells
1. Plasma Membrane
• Controls what enters & exits the cell
2. Cytoplasm
• Entire contents of cell between P.M. and
nucleus
• Where most metabolic activity occurs
3. Nucleus or Nuclear Area
• Contains DNA, the genetic material
– Phospholipids form a two-layer sheet
• Called a phospholipid bilayer, with the heads facing
outward and the tails facing inward
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 structurally simpler than
eukaryotic cells
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
• Containing the cell’s DNA, which directs
cellular activities
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
• Processes toxins and drugs in liver cells
• Stores and releases calcium ions in muscle
cells
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
• Produce proteins that are secreted,
inserted into membranes, or transported in
vesicles to other organelles
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
– Stacks of membranous sacs receive and modify ER
products then ship them to other organelles or the
cell surface
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
• Lysosomes in
white blood cells
destroy bacteria
that have been
ingested
• 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 which
uses the chemical energy in food to make ATP for
cellular work
Mitochondrion
Outer
membrane
Intermembrane
space
Inner
membrane
Cristae
Matrix
TEM 44,880
Figure 4.14
8. Cytoskeleton & related structures • a network of protein fibers
• help organize its structure and activities
Fig 4.17
Tubulin subunit
Actin subunit
Fibrous subunits
25 nm
7 nm
Microfilament
10 nm
Intermediate filament
Microtubule
– Microfilaments of actin
• Enable cells to change shape and move
– Intermediate filaments
• Reinforce the cell and anchor certain organelles
– 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 locomotor appendages
that protrude from certain cells
– Tight junctions
• can bind cells together into leakproof sheets
– Anchoring junctions
• link animal cells into strong tissues
– 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
Please do the activities at the following 2 sites:
http://learn.genetics.utah.edu/conte
nt/begin/cells/insideacell/
http://learn.genetics.utah.edu/conte
nt/begin/cells/scale/
Plant Cell –
Fig. 4.6b
Plant cells also have:
1. Vacuole
• stores water, solutes, waste
• Important for growth and rigidity
2. Chloroplasts
• Site of photosynthesis: conversion of light to
ATP which drives formation of sugars
3. Cell wall
• Protects, supports
**Plant cells do not have lysosomes
Vacuoles function in the general maintenance of the cell
– lysosomal and storage functions
Nucleus
Chloroplast
Colorized TEM 8,700
Figure 4.12
Central
vacuole
Chloroplasts convert solar energy to chemical energy
– found in plants and some protists
– 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
• Are connected by plasmodesmata - connecting
channels
Figure 4.22
Walls of two
adjacent plant
cells
Vacuole
Plasmodesmata
Layers of one
plant cell wall
Cytoplasm
Plasma membrane