Transcript Review of Cells

Class Connect Mini-Lesson
Cell Structure
Scientists Responsible for Cell Theory
Anton van Leeuwenhoek
• Microscope (1600)
Robert Hooke
• Cork cells
Robert Brown
• Nucleus
Schleidan
• Plants are made of cells
Schwan
• Animals are made of cells
Rudolf Virchow
• Every cell comes from an already existing cell
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
Cell Theory
All organisms are composed of cells
The cell is the basic unit of the life
New cells arise only from cells that already exist
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
INTRODUCTION TO THE CELL
Microscopes provide windows to the world of the cell
• The light microscope (LM)
– Enables us to see the overall shape and structure
of a cell
Eyepiece
Ocular
lens
Objective lens
Specimen
Condenser
lens
Light
source
Figure 4.1A
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
• Light microscopes
Figure 4.1B
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
LM 1,000
– Magnify cells, living and preserved, up to
1,000 times
• The electron microscope
Figure 4.1C
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
TEM 2,800 
SEM 2,000 
– Allows greater magnification and reveals
cellular details
Figure 4.1D
• Different types of light microscopes
220
1,000
– Use different techniques to enhance contrast
and selectively highlight cellular components
Figure 4.1E
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
Figure 4.1F
Most cells are microscopic
• Cells vary in size and shape
10 m
Human height
100 mm
(10 cm)
Length of some
nerve and
muscle cells
Chicken egg
Unaided eye
1m
10 mm
(1 cm)
Frog egg
100 m
Most plant and
animal cells
10 m
Nucleus
Light microscope
1 mm
Most bacteria
100 nm
Mitochondrion
Mycoplasmas
(smallest bacteria)
Viruses
Ribosome
10 nm
Proteins
Lipids
1 nm
Small molecules
Figure 4.2A
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
0.1 nm
Atoms
Electron microscope
1 m
• The microscopic size of most cells ensures a
sufficient surface area
– Across which nutrients and wastes can
move to service the cell volume
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
• A small cell has a greater ratio of surface area
to volume
– Than a large cell of the same shape
– As volume increases, surface area
increases but at a slower rate.
10 m
30 m
30 m
Figure 4.2B
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
10 m
Prokaryotic cells are structurally simpler than eukar
yotic cells
• There are two kinds of cells
Colorized TEM 15,000 
– Prokaryotic and eukaryotic
Prokaryotic cell
Nucleoid
region
Nucleus
Figure 4.3A
Eukaryotic cell
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
Organelles
• Prokaryotic cells are small, relatively simple cells
– That do not have a membrane-bound nucleus
Prokaryotic
flagella
Ribosomes
Capsule
Cell wall
Plasma
membrane
Nucleoid region (DNA)
Pili
Figure 4.3B
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
Eukaryotic cells are partitioned into functional
compartments
– Distinguished by the presence of a true
nucleus
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
• Membranes form the boundaries of many
eukaryotic cells
– Compartmentalizing the interior of the cell
and facilitating a variety of metabolic
activities
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
• A typical animal cell
– Contains a variety of membranous organelles
Rough
endoplasmic
reticulum
Smooth endoplasmic
reticulum
Nucleus
Flagellum
Not in most
plant cells
Lysosome
Ribosomes
Centriole
Peroxisome
Microtubule
Cytoskeleton
Figure 4.4A
Intermediate
filament
Microfilament
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
Golgi
apparatus
Plasma membrane
Mitochondrion
• A typical plant cell has some structures that an
animal cell lacks
– Such as chloroplasts and a rigid cell wall
Nucleus
Rough
endoplasmic
reticulum
Ribosomes
Golgi
apparatus
Not in
animal
cells
Central
vacuole
Chloroplast
Cell wall
Mitochondrion
Peroxisome
Plasma membrane
Figure 4.4B
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
Smooth
endoplasmic
reticulum
Microtubule
Intermediate
filament
Microfilament
Cytoskeleton
ORGANELLES OF THE ENDOMEMBRANE SYSTEM
The nucleus is the cell’s genetic control center
• The largest organelle is usually the nucleus
– separated from the cytoplasm by the
nuclear envelope
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
• The nucleus is the cellular control center
– Containing the cell’s DNA, directs cellular
activities
Chromatin
Nucleolus
Nucleus
Two membranes
of nuclear
envelope
Pore
Rough
endoplasmic
reticulum
Figure 4.5
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
Ribosomes
Overview: Many cell organelles are connected
through the endomembrane system
• The endomembrane system is a collection of
membranous organelles
– That manufactures and distributes cell
products
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
Smooth endoplasmic reticulum has a variety of functions
• 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
Figure 4.7
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
Ribosomes
Rough ER
TEM 45,000
Smooth ER
Rough endoplasmic reticulum makes membrane
and proteins
• The rough ER
– Manufactures membranes
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
• Ribosomes on the surface of the rough ER
– Produce proteins that are secreted,
inserted into membranes, or transported in
vesicles to other organelles
Transport vesicle
buds off
4
Ribosome
3
Secretory
(glyco-) protein
inside transport vesicle
Sugar chain
1
2
Glycoprotein
Polypeptide
Rough ER
Figure 4.8
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
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
Golgi apparatus
Golgi
apparatus
Transport
vesicle
from ER
New vesicle
forming
Figure 4.9
“Shipping” side
of Golgi apparatus
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
Transport
vesicle from
the Golgi
TEM 130,000
“Receiving” side of
Golgi apparatus
Lysosomes are digestive compartments within a
cell
• Lysosomes are sacs of enzymes
– That function in digestion within a cell
Rough ER
1
Transport vesicle
(containing inactive
hydrolytic enzymes)
Golgi
apparatus
Plasma
membrane
Engulfment
of particle
Lysosome
engulfing
damaged
organelle
2
“Food”
Lysosomes
3
5
Food
vacuole
Figure 4.10A
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
4
Digestion
• Lysosomes in white blood cells
– Destroy bacteria that have been ingested
Lysosome
Figure 4.10B
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
TEM 8,500
Nucleus
• Lysosomes also recycle damaged organelles
Lysosome containing
two damaged organelles
Peroxisome fragment
Figure 4.10C
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
TEM 42,500
Mitochondrion fragment
Vacuoles function in the general maintenance of
the cell
• Plant cells contain a large central vacuole,
– Which has lysosomal and storage functions
Nucleus
Chloroplast
Figure 4.12A
Colorized TEM 8,700
Central
vacuole
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
• Some protists have contractile vacuoles
– That pump out excess water
Contractile
vacuoles
Figure 4.12B
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
LM 650
Nucleus
A review of the endomembrane system
• The various organelles of the endomembrane system
– Are interconnected structurally and functionally
Rough ER
Transport vesicle
from ER to Golgi
Transport vesicle from
Golgi to plasma membrane
Plasma
membrane
Nucleus
Vacuole
Lysosome
Figure 4.13
Smooth ER
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
Nuclear envelope
Golgi apparatus
ENERGY-CONVERTING ORGANELLES
Chloroplasts convert solar energy to chemical
energy
• Chloroplasts, found in plants and some protists
– Convert solar energy to chemical energy in
sugars
Chloroplast
Inner and outer
membranes
Granum
Intermembrane
space
Figure 4.14
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
TEM 9,750
Stroma
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
Inner
membrane
Cristae
Figure 4.15
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
Matrix
TEM 44,880
Intermembrane
space
THE CYTOSKELETON AND RELATED STRUCTURES
4.16 The cell’s internal skeleton helps organize
its structure and activities
• A network of protein fibers
– Make up the cytoskeleton.
Tubulin subunit
Actin subunit
Fibrous subunits
7 nm
Microfilament
Figure 4.16
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
25 nm
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
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
4.17 Cilia and flagella move when microtubules bend
• Eukaryotic cilia and flagella
Figure 4.17A
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
LM 600
Colorized SEM 4,100
– Are locomotor appendages that protrude from
certain cells
Figure 4.17B
• Clusters of microtubules
– Drive the whipping action of these organelles
Flagellum
Electron micrographs
of cross sections:
Outer microtubule
doublet
TEM 206,500
Central
microtubules
Radial spoke
Dynein arms
Flagellum
Figure 4.17C
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
Basal body
(structurally identical to
centriole)
TEM 206,500
Plasma
membrane
Basal body
CELL SURFACES AND JUNCTIONS
Cell surfaces protect, support, and join cells
• Cells interact with their environments and each
other via their surfaces.
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
• Plant cells
– Are supported by rigid cell walls made largely
of cellulose
– Connect by plasmodesmata, which are
connecting channels
Walls of two
adjacent plant
cells
Vacuole
Plasmodesmata
Layers of one
plant cell wall
Cytoplasm
Plasma membrane
Figure 4.18A
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
• Animal cells are embedded in an extracellular
matrix
– Which binds cells together in tissues
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
• 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
Anchoring junction
Gap junctions
Figure 4.18B
Extracellular matrix
Space between cells
Plasma membranes of adjacent cells
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
FUNCTIONAL CATEGORIES OF ORGANELLES
4.19 Eukaryotic organelles comprise four
functional categories
• Eukaryotic organelles fall into four functional
groups
– Manufacturing
– Breakdown
– Energy processing
– Support, movement, and communication
between cells
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
• Eukaryotic organelles and their functions
Table 4.19
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings