Lecture #2
Cellular Anatomy
The Eukaryotic Cell
ENDOPLASMIC RETICULUM (ER)
Rough ER
Smooth ER
Nuclear envelope
Nucleolus
NUCLEUS
Chromatin
Flagelium
Plasma membrane
Centrosome
CYTOSKELETON
Microfilaments
Intermediate filaments
Ribosomes
Microtubules
Microvilli
Golgi apparatus
Peroxisome
Mitochondrion
Lysosome
In animal cells but not plant cells:
Lysosomes
Centrioles
Flagella (in some plant sperm)
The Nucleus
Nucleus
Nucleus
1 µm
Nucleolus
Chromatin
Nuclear envelope:
Inner membrane
Outer membrane
Nuclear pore
Pore
complex
Rough ER
Surface of nuclear envelope.
TEM of a specimen prepared by
a special technique known as
freeze-fracture.
0.25 µm
1 µm
Ribosome
Close-up of nuclear
envelope
Pore complexes (TEM). Each pore is ringed
by protein particles.
Nuclear lamina (TEM). The netlike lamina
lines the inner surface of the nuclear envelope.
The Nuclear Envelope
Ribosomes
Ribosomes
ER
Cytosol
Endoplasmic reticulum (ER)
Free ribosomes
Bound ribosomes
Large
subunit
0.5 µm
TEM showing ER and ribosomes
Small
subunit
Diagram of a ribosome
The Endoplasmic Reticulum (ER)
Smooth ER
Rough ER
Nuclear
envelope
ER lumen
Cisternae
Ribosomes
Transport vesicle
Smooth ER
Transitional ER
Rough ER
200 µm
The Golgi apparatus
Golgi
apparatus
cis face
(“receiving” side of
Golgi apparatus)
1 Vesicles move 2 Vesicles coalesce to
6 Vesicles also
from ER to Golgi form new cis Golgi cisternae
transport certain
Cisternae
proteins back to ER
3 Cisternal
maturation:
Golgi cisternae
move in a cisto-trans
direction
5 Vesicles transport specific
proteins backward to newer
Golgi cisternae
0.1 0 µm
4 Vesicles form and
leave Golgi, carrying
specific proteins to
other locations or to
the plasma membrane for secretion
trans face
(“shipping” side of
Golgi apparatus)
TEM of Golgi apparatus
Lysosomes
Nucleus
1 µm
Lysosome containing
two damaged organelles
1µm
Mitochondrion
fragment
Peroxisome
fragment
Lysosome
Lysosome contains Food vacuole fuses Hydrolytic
active hydrolytic
enzymes digest
with lysosome
enzymes
food particles
Digestive
enzymes
Lysosome fuses with
vesicle containing
damaged organelle
Lysosome
Plasma membrane
Lysosome
Lysosome
Hydrolytic enzymes
digest organelle
components
Digestion
Food vacuole
(a) Phagocytosis: lysosome digesting food
Digestion
Vesicle containing
damaged mitochondrion
(b) Autophagy: lysosome breaking down damaged organelle
Peroxisomes
Chloroplast
Peroxisome
Mitochondrion
1 µm
Summary
1 Nuclear envelope is
connected to rough ER,
which is also continuous
with smooth ER
Nucleus
Rough ER
Smooth ER
Nuclear envelope
3
Summary
1 Nuclear envelope is
connected to rough ER,
which is also continuous
with smooth ER
Nucleus
Rough ER
2 Membranes and proteins
produced by the ER flow in
the form of transport vesicles
to the Golgi
Smooth ER
cis Golgi
Nuclear envelope
Transport
vesicle
3 Golgi pinches off transport
vesicles and other vesicles that
give rise to lysosomes and
vacuoles
trans Golgi
4 Lysosome available 5 Transport vesicle carries
for fusion with another proteins to plasma
vesicle for digestion
membrane for secretion
Summary
1 Nuclear envelope is
connected to rough ER,
which is also continuous
with smooth ER
Nucleus
Rough ER
2 Membranes and proteins
produced by the ER flow in
the form of transport vesicles
to the Golgi
Smooth ER
cis Golgi
Nuclear envelope
Transport
vesicle
3 Golgi pinches off transport
vesicles and other vesicles that
give rise to lysosomes and
vacuoles
trans Golgi
Plasma
membrane
4 Lysosome available 5 Transport vesicle carries 6 Plasma membrane expands
for fusion with another proteins to plasma
by fusion of vesicles; proteins
vesicle for digestion
membrane for secretion
are secreted from cell
Mitochondria
Mitochondrion
Intermembrane space
Outer
membrane
Free
ribosomes
in the
mitochondrial
matrix
Inner
membrane
Cristae
Matrix
Mitochondrial
DNA
100 µm
Plant Cells
Nuclear envelope
Nucleolus
Chromatin
NUCLEUS
Centrosome
Rough
endoplasmic
reticulum Smooth
endoplasmic
reticulum
Ribosomes ( small brown dots )
Central vacuole
Tonoplast
Golgi apparatus
Microfilaments
Intermediate
filaments
Microtubules
Mitochondrion
Peroxisome
Plasma membrane
Cell wall
Wall of adjacent cell
Chloroplast
Plasmodesmata
CYTOSKELETON
The Central Vacuole
Central vacuole
Cytosol
Tonoplast
Nucleus
Central
vacuole
Cell wall
Chloroplast
5 µm
Chloroplasts
Chloroplast
Ribosomes
Stroma
Chloroplast
DNA
Inner and outer
membranes
Granum
1 µm
Thylakoid