In animal cells but not plant cells: Lysosomes Centrioles Flagella (in some plant sperm)
Lysosome
Mitochondrion
8
Ribosomes
Nucleus
Cytosol
Nucleus
1 µm
Nucleolus
Free Ribosomes
ER
Chromatin
Make Cytoplasmic Proteins
– Carry out protein synthesis
Nuclear envelope: Inner membrane Outer membrane
Membrane Bound Ribosomes
Pores
Make Proteins to be Exported
Pore complex Rough ER Surface of nuclear envelope.
1 µm
Ribosome
Large subunit
0.25 µm
Close-up of nuclear envelope
TEM showing ER and ribosomes
Figure 6.10 Nuclear lamina (TEM).
Pore complexes (TEM).
0.5 µm
Figure 6.11
Endomembrane System: NUCLEUS Endoplasmic Rough ER Smooth ER Synthesis and Transport Reticulum ENDOPLASMIC RETICULUM (ER)
RNA & Protein Complex
Cytosol
Rough ER Cisterna
CYTOSKELETON cis region
Microfilaments
10
Diagram of a ribosome
Figure 4.8 The Endomembrane System Nucleus
Plasma membrane
Centrosome
Small subunit
9
Lumen
Golgi
Intermediate filaments Ribosomes Ribosomes
Microtubules
trans region
Golgi apparatus Golgi apparatus
Proteins for use within the cell
Peroxisome Mitochondrion
Lysosome
In animal cells but not plant cells: Lysosomes Centrioles Flagella (in some plant sperm)
11
Cell membrane
Proteins for use outside the cell Outside the cell
2
Mitochondria
Energy Conversion NUCLEUS
Food à ATP Intermembrane space
Outer membrane
Inner membrane
Mitochondria (and chloroplasts)
Matrix Mitochondrial DNA
14
100 µm
13
Chloroplasts capture
ENDOPLASMIC RETICULUM (ER)
Breakdown and Recycling
energy from the sun
Rough ER
Smooth ER
Photosynthesis Stroma Chloroplast DNA
Peroxisome
1 µm
Sunlight à ATP, Sugar
Thylakoid
15
ENDOPLASMIC RETICULUM (ER)
Structure, Support, and Movement Rough ER
Smooth ER
NUCLEUS
Cytoskeleton CYTOSKELETON
Lysosome (animals only) Lysosome 16
Three types of fibers that make up the cytoskeleton Cell shape Chromosome separation Flagellar mvt Kinesin and Dynein
Microfilaments
Cell shape Cell cleavage Muscle contraction
Intermediate filaments Microtubules
Myosin
Cytosol
17
18
3
Movement of Vesicles along Microtubules Vesicle
ATP
Receptor for motor protein
Motor protein (ATP powered)
Microtubule of cytoskeleton
(a) Motor proteins that attach to receptors on organelles can walk the organelles along microtubules or, in some cases, microfilaments. Microtubule
Vesicles
0.25 µm
What evidence do we have that they actually move?
Figure 6.21 A, B
(b) Vesicles containing neurotransmitters migrate to the tips of nerve cell axons via the mechanism in (a). In this SEM of a squid giant axon, two vesicles can be seen moving along a microtubule. (A separate part of the experiment provided the evidence that they were in fact moving.)
19
20
Motor Proteins transport vesicles
Three kinds of Movement • Filament anchored: motor walks along filament (transport vesicles)
Dynein inbound
• Motor anchored: filament moves (muscles) • Both anchored: bending (cilia and flagella)
outbound kinesin
21
22
Ribosomes (small brown dots)
Fig. 6-24
Outer microtubule doublet
0.1 µm
Dynein proteins
Plasma membrane
Plants have 2 other support mechanisms
Rough endoplasmic reticulum
NUCLEUS
Central microtubules
Microtubules
Plasma membrane
Golgi apparatus
• Cell Wall • Vacuole or Tonoplast
(b) Cross section of cilium
Basal body
0.5 µm
(a) Longitudinal section of cilium
Smooth endoplasmic reticulum
Central vacuole/Tonoplast
Microfilaments Intermediate filaments
CYTOSKELETON
Microtubules
0.1 µm
Mitochondrion
Cilia and Flagella Triplet
Peroxisome
Have 9+2 arrangement of microtubules
Plasma membrane
and motor proteins.
Cell wall Wall of adjacent cell
(c) Cross section of basal body
23
Figure 6.9
Chloroplast Plasmodesmata 24
4
Extra Cellular Matrix
Central Vacuoles (Tonoplasts) – Only in plants
glycoproteins
Central vacuole Cytosol
Acts like a balloon in a box to hold plant cells rigid
