Download cell structure

Cells
Wassily Kandinsky
(1866-1944)
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Cell Theory:
- all organisms are composed of cells
- all cells come from other cells
Figure 4.1x
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• Scanning
electron
microscope
(SEM)
TEM
Figure 4.1B
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• Cell size and
shape relate
to function
• Minimum
• Maximum
Figure 4.2
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• A small cell has a greater ratio of surface area
to volume than a large cell of the same shape
30 µm
Figure 4.3
Surface area
of one large cube
= 5,400 µm2
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10 µm
Total surface area
of 27 small cubes
= 16,200 µm2
2 kinds of cells: prokaryotic and eukaryotic
• Prokaryotic cells - “before nucleus”
- small, relatively simple cells
– Single-celled organisms
– May not require oxygen
– No organelles (with membranes)
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• A prokaryotic cell has:
- plasma membrane
- rigid cell wall
– sticky capsule
– Nucleoid
region with
DNA
Capsule
Cell wall
Plasma
membrane
– Some w/
flagella
Pili
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Prokaryotic
flagella
Ribosomes
Nucleoid region
(DNA)
Figure 4.4
• Prokaryotic cells, Bacillus polymyxa
Figure 4.4x1
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Eukaryotic cells - functional compartments
- true nucleus
- larger: 10-100 microns
- often multicellular
- organelles surrounded by membranes
- usually need O2
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Endomembrane System
• a group of organelles that manufactures and
distributes cell products
• nucleus
• endoplasmic reticulum (ER), ribosomes
• Golgi complex, vesicles
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ENDOMEMBRANE SYSTEM
nucleus is the control center
• largest organelle
• nuclear envelope
• contains DNA that directs cell’s activities
• DNA copy goes into every progeny cell
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NUCLEUS
Chromatin
Nucleolus
Two membranes
of nuclear
envelope
Pore
ROUGH
ENDOPLASMIC
RETICULUM
Ribosomes
Figure 4.6
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nucleus
nuclear
pores
Rough endoplasmic reticulum
• Makes proteins, membranes
Transport vesicle
buds off
4
osome
Sugar
chain
1
Polypeptide
3
Secretory
(glyco-) protein
inside transport
vesicle
Glycoprotein
2
ROUGH ER
Figure 4.8
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SMOOTH ER
ROUGH
ER
Nuclear
envelope
Ribosomes
SMOOTH ER
Figure 4.9
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ROUGH ER
• The Golgi complex finishes, sorts, and ships
cell products
Golgi apparatus
Golgi
apparatus
“Receiving” side of
Golgi apparatus
Transport
vesicle
from ER
New
vesicle
forming
“Shipping”
side of Golgi
apparatus
Transport vesicle
from the Golgi
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Figure 4.10
Lysosomes
• sacs of digestive
enzymes budded
off the Golgi
• Fuse with
membrane
around debris
LYSOSOME
Nucleus
Figure 4.11A
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• Lysosomal enzymes
– digest food
– destroy bacteria
– recycle damaged organelles
– function in embryonic development in animals
– Storage of undigestable waste
Pombe’s disease - glycogen
Tay-Sachs disease - lipids
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Rough ER
Transport vesicle
(containing inactive
hydrolytic enzymes)
Plasma
membrane
Golgi
apparatus
Engulfment
of particle
Lysosome
engulfing
damaged
organelle
“Food”
LYSOSOMES
Food
vacuole
Figure 4.11B
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Digestion
Smooth endoplasmic reticulum
• synthesizes lipids
• regulates carbohydrate metabolism (liver)
• breaks down toxins and drugs (liver)
• Stores Ca++ in muscle cells
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Endomembrane system
• Nucleus, ribosomes, RER ,SER, Golgi, vesicles
Rough
ER
Transport
vesicle
from Golgi
Transport
vesicle
from ER
Plasma
membrane
Vacuole
Nucleus
Lysosome
Smooth
ER
Nuclear
envelope
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Golgi
apparatus
Figure 4.14
• Vacuole in plants
– Lysosomal
– storage of
pigments,
poisons
Central
vacuole
– Water relations
Nucleus
Figure 4.13A
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• plant cells
– large central vacuole
– rigid cell wall
– chloroplasts
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Chloroplasts
• in plants and some protists
• convert solar energy to chemical energy in
sugars
Chloroplast
Stroma
Inner and outer
membranes
Granum
Figure 4.15
Intermembrane
space
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• cellular
respiration
Mitochondrion
Outer
membrane
Intermembrane
space
Inner
membrane
Cristae
Figure 4.16
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Matrix
The CYTOSKELETON helps organize a cell’s
structure and activities
• network of protein fibers
Figure 4.17A
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microfilament
Intermediate
filament
microtubule
25 nm
10 nm
7 nm
Actin subunit
Cell shape,
movement
Fibrous subunits
reinforce cell,
anchor
organelles
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Tubulin
subunit
cell rigidity,
anchor & tracks
for organelles,
mitosis
• Nuclei (yellow) and actin (red)
Figure 4.6x
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Cilia and flagella
• locomotor appendages
• composed of a core of microtubules wrapped in
the plasma membrane
Basal body
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Cell surfaces protect, support, and join cells
Surfaces allow exchange of signals and molecules.
• Plant cells connect by plasmodesmata
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Walls of two
adjacent
plant cells
Vacuole
PLASMODESMATA
Layers of one
plant cell wall
Cytoplasm
Plasma membrane
Figure 4.19A
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• Animal cells - surrounded by an
extracellular matrix
–sticky layer of glycoproteins
–binds cells together in tissues
–can also protect and support cells
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• Tight junctions can bind cells together into
leakproof sheets
• Anchoring
junctions link
animal cells
TIGHT
JUNCTION
ANCHORING
JUNCTION
• Gap junctions
allow substances
to flow from cell
to cell
COMMUNICATING
JUNCTION
Plasma
membranes of
adjacent cells
Figure 4.19B
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Extracellular
matrix
Eukaryotic organelles fall into 4 functional groups
• 1. Manufacture and transport –
dependent on network of membranes
- Nucleus
- Ribosomes
- Rough, smooth ER
- Golgi apparatus
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2. Breakdown – all single-membrane sacs
• Lysosomes (in animals, some protists)
• Peroxisomes
• Vacuoles (plants)
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3. Energy Processing – involves extensive
membranes embedded with enzymes
• Chloroplasts
• Mitochondria
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4. Support, Movement, Communication
• Cytoskeleton – includes cilia, flagella,
filaments, microtubules
• Cell walls
• Extracellular matrix
• Cell junctions
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings