biol 101 chp 6: a tour of the cell
DESCRIPTION
This is a lecture presentation for my BIOL 101 General Biology I students on Chapter 6: A Tour of the Cell. (Campbell Biology, 10th Ed. by Reece et al). Rob Swatski, Associate Professor of Biology, Harrisburg Area Community College - York Campus, York, PA. Email: [email protected] Please visit my website for more anatomy and biology learning resources: http://robswatski.virb.com/TRANSCRIPT
A Tour of the Cell
BIOL 101: General Biology I
Chapter 6
Rob Swatski Associate Professor of Biology
HACC – York Campus 1
Cells
All organisms made of cells
Simplest level of life
Structure correlated
with function
Cells descend from
previous cells 2
3
4
Microscopy
Light microscopes
Magnification 1000x
Resolution
Contrast
Staining & labeling
10 m
1 m
0.1 m
1 cm
1 mm
100 m Human egg
Frog egg
Chicken egg
Length of some
nerve and
muscle cells
Human height
Un
aid
ed
eye
5
1 mm
100 m
10 m
1 m
100 nm
10 nm
1 nm
0.1 nm Atoms
Small molecules
Lipids
Proteins
Ribosomes
Viruses
Smallest bacteria
Mitochondrion
Most bacteria
Nucleus
Most plant and
animal cells
Human egg
Lig
ht
mic
rosco
py
Ele
ctr
on
mic
rosco
py
Super-
resolution
microscopy
1 cm
Frog egg
6
(a) Brightfield (unstained)
(b) Brightfield (stained)
TECHNIQUE RESULTS
50 µm
7
(c) Phase-contrast
(d) Differential-interference contrast (Nomarski)
TECHNIQUE RESULTS
8
9
Phase-Contrast
Water Bear with Differential-Interference 10
(e) Fluorescence
TECHNIQUE RESULTS
11
Fluorescence 12
(f) Confocal
TECHNIQUE RESULTS
standard fluorescence
13
14 Confocal
15
Electron Microscopes
Scanning Electron
Microscope (SEM)
Transmission Electron
Microscope (TEM)
Scanning electron microscopy (SEM)
TECHNIQUE RESULTS
Transmission electron microscopy (TEM)
16
17 SEM
18
19
TEM
20
Cell Fractionation
Separate organelles
Correlate cytology with biochemistry
Homogenization
Ultracentrifugation
Differential centrifugation
Homogenization
Homogenate
Differential Centrifugation
Tissue cells
TECHNIQUE
21
1,000 g 10 min
Supernatant
20,000 g 20 min
80,000 g 60 min
150,000 g 3 hr
Pellet rich in nuclei and
cellular debris
Pellet rich in mitochondria
(& chloroplasts in plants)
Pellet rich in “microsomes”
(membrane debris) Pellet rich in ribosomes
22
2 Main Types of Cells
Prokaryotic
(Domains Archaea & Bacteria)
Eukaryotic (Domain Eukarya)
23
24
Basic Features of All Cells
Plasma membrane
Cytosol: semifluid
DNA: Chromosomes
carry genes
Ribosomes
25
Features of Prokaryotic
Cells
No nucleus
DNA in nucleoid
No membrane-bound organelles
Cell wall, plasma membrane, &
cytoplasm
Fig. 6-6
(a) A typical rod-shaped bacterium
Ribosomes
Plasma membrane
Cell wall
Capsule
Flagellae
Bacterial chromosome
Fimbriae
Nucleoid
26
Prokaryotic Cell
27
Features of Eukaryotic Cells
DNA in nucleus
Nuclear envelope with pores
Membrane-bound organelles
Plasma membrane & cytoplasm
Larger size
28
29
30
Head
Polar
Hydrophilic
Glycerol & phosphate
Tails
Nonpolar
Hydrophobic
2 Fatty acids
Phospholipid Structure
Plasma Membrane (Phospholipid bilayer)
31
Structure of the Plasma Membrane
Outside of cell
Inside of cell
Hydrophilic region
Hydrophobic region
Hydrophilic region
Proteins
Carbohydrate side-chain
32
33
Permeable
34
Impermeable
35 Semipermeable (Selectively Permeable)
36
Surface Area-to-Volume
Ratio
SA divided by Volume
Membrane relationship
As SA doubles, volume triples
Small cells have more SA relative to
volume
Surface area increases while total volume remains constant
5
1
1
6 150 750
125 125 1
6 6 1.2
Total surface area [Sum of the surface areas
(height width) of all boxes
sides number of boxes]
Total volume [height width length
number of boxes]
Surface-to-volume
(S-to-V) ratio [surface area ÷ volume]
37
ENDOPLASMIC RETICULUM (ER)
Smooth ER Rough ER Flagellum
Centrosome
CYTOSKELETON:
Microfilaments
Intermediate filaments
Microtubules
Microvilli
Peroxisome
Mitochondrion Lysosome
Golgi apparatus
Ribosomes
Plasma membrane
Nuclear envelope
Nucleolus
Chromatin
NUCLEUS
38
39
NUCLEUS Nuclear envelope
Nucleolus
Chromatin
Rough endoplasmic reticulum
Smooth endoplasmic reticulum
Ribosomes
Central vacuole
Microfilaments
Intermediate filaments
Microtubules
CYTO- SKELETON
Chloroplast
Plasmodesmata
Wall of adjacent cell
Cell wall
Plasma membrane
Peroxisome
Mitochondrion
Golgi apparatus
40
41
Cytoplasm
Cytosol
Water Solutes Macro-
molecules
Cyto-skeleton
Protein filaments
Organelles
Membrane-bound
42
43
Nucleus
Nuclear envelope with
pores
Nuclear lamina: protein
Nuclear pores
Chromatin & chromosomes
Nuclear envelope:
Inner membrane
Outer membrane
Nuclear pore
Surface of nuclear envelope
1 m
44
45
DNA
Chromatin
Non-dividing cells
Unorganized, loose threads of DNA & protein
Chromosomes
Dividing cells Genes
46
47
Chromatin
Chromosomes
Chromosomes & loci 48
49
Nucleolus
Inside nucleus
Made of RNA & protein
Site of ribosomal RNA (rRNA)
synthesis
Makes small and large ribosomal
subunits
Ribosomes
Particles consisting of
rRNA & proteins
Made by nucleolus
Small & large subunits
Site of protein synthesis
50 Free Ribosomes
Free & Bound Ribosomes
51
52
Endomembrane System
Plasma membrane
Nuclear envelope
Endoplasmic Reticulum
(ER)
Golgi appara
tus Lysosomes
Vacuoles &
Vesicles
Performs metabolic functions
Regulates protein traffic
Endoplasmic Reticulum
Tube-like membrane
network
Biosynthetic factory
Rough ER
Smooth ER
53
Smooth ER
Rough ER
Cisternae Ribosomes
Transport vesicle
Transitional ER
Nuclear
envelope
ER lumen
54
55
56
Smooth ER Functions
Synthesizes lipids
Metabolizes carbohydrates
Detoxifies drugs & poisons
Stores calcium ions
57
Rough ER Functions
Contains bound ribosomes that
secrete glycoproteins
Makes membrane
proteins
Distributes transport vesicles
Sends vesicles to Golgi
apparatus
58
Golgi Apparatus
Cisternae: flattened
membrane sacs
Modifies products of the
ER
Makes macromolecules
Sorts & packages materials into
transport vesicles
59
60
cis face
trans face 61
Lysosomes
Membrane-bound vesicles
Cellular “stomachs”
Contain hydrolytic enzymes that break down
macromolecules 62
63
Phagocytosis
Phagosome
64
65
Phagocytosis
66
Autophagy
Peroxisome
67
Peroxisomes
Smaller membrane-bound
vesicles
Contain enzymes that oxidize
organic wastes
Convert hydrogen peroxide
water
Break down variety of
macromolecules
68
69
Peroxisome
70
Vacuoles
Larger membrane-bound organelle
derived from ER & Golgi
Food vacuole: from
phagocytosis
Contractile vacuole: protists
Central vacuole: plants
71 Contractile vacuole
72
Central vacuole
73
74
Mitochondria
Double membrane: outer & inner
Site of Aerobic cellular respiration
Makes ATP
In all Eukarya
75
76
Mitochondria Structure
Smooth outer membrane
Folded inner membrane = cristae
Intermembrane space
Matrix
Intermembrane space
Outer
DNA
Inner membrane
Cristae
Matrix
Free
ribosomes
in the
mitochondrial
matrix 0.1 m
membrane
Mitochondria Structure
77
78
Chloroplasts
In plants & protists
Type of plastid
Site of photosynthesis
Contain chlorophyll
79
80
81
Chloroplast Structure
Smooth outer membrane
Inner membranes =
thylakoids
Grana = stacks of thylakoids
Stroma
Ribosomes Stroma
Inner & outer
membranes
Granum
1 m Intermembrane
space
Thylakoid
DNA
Chloroplast Structure
82
83
Mitochondria &
Chloroplasts Similar to bacteria
Have a double membrane
Proteins are made by free
ribosomes
Have their own circular DNA
molecules
– An early ancestor of eukaryotic cells engulfed a nonphotosynthetic prokaryotic cell, which formed an endosymbiont relationship with its host
– The host cell and endosymbiont merged into a single organism, a eukaryotic cell with a mitochondrion
– At least one of these cells may have taken up a photosynthetic prokaryote, becoming the ancestor of cells that contain chloroplasts
The Endosymbiont Theory
84
Nucleus Endoplasmic
reticulum
Nuclear
envelope
Ancestor of
eukaryotic cells
(host cell)
Engulfing of oxygen-
using nonphotosynthetic
prokaryote, which
becomes a mitochondrion
Mitochondrion
Nonphotosynthetic
eukaryote
Mitochondrion
Photosynthetic eukaryote
Engulfing of
photosynthetic
prokaryote
Chloroplast
85
86
Cytoskeleton
Functions of the Cytoskeleton
Anchors organelles
& organizes cell
structure
Supports cell &
maintains cell shape
Regulates cell division
& biochemical
activities
Interacts with motor proteins to
move organelles
& cells
87
Cytoskeleton
Microfilaments
Intermediate filaments
Microtubules
88
Microtubules 89
Microtubules
Thick, hollow rods of tubulin
Maintain cell shape
Transport organelles & entire cell
Separate chromosomes during
cell division – form spindle
90
Centrosomes
91
Centrosomes
Contain centrioles
9 + 0 arrangement
of MT’s
MT-organizing
centers
Create mitotic spindle
92
Centrioles
93
Mitotic spindle
94
95
Cilia & Flagella
Both made of MT’s sheathed by plasma
membrane
9 + 2 MT arrangement
Anchored to cell by basal body
Motor protein (dynein) drives
bending movement
Cilia
Many
Short
Sweep materials across cell
Flagella
Fewer
Long
Move entire cell
96
97 Cilia
Flagellae 98
99
Basal body
Cilium or Flagellum
9+2
100
Power stroke Recovery stroke
Cilia
Flagellae
101
102
Dynein “Walking”
Dynein arms grab, move, & release
outer MT’s
Protein cross-links limit sliding
MT doublets curve, bending cilium or
flagellum
ATP
Effect of unrestrained dynein movement
103
ATP
Effect of cross-linking proteins
104
105
106
107
Microfilaments
108
Microfilaments
Thin, solid protein fibers
Twisted double-chain of actin
Bear tension & resist pulling forces
inside cell
Form 3-D network (cortex) under
plasma membrane
Functions of Microfilaments
Support & maintain
cell shape & allow
changes to shape
Cell motility:
amoeboid movement
& cytoplasmic streaming
Muscle contraction
Cell division
109
110
111 Microfilament Cortex
112
Microfilament core in microvilli
113
114 Actin (with myosin motors) in muscle
115
116 Myosin motor (head)
117
Cell motility using actin
100 m
Cortex (outer cytoplasm):
gel with actin network
Inner cytoplasm: sol
with actin subunits
Extending
pseudopodium
Amoeboid movement 118
119
120
Cytoplasmic streaming cortex
sol
Intermediate Filaments
Medium-diameter keratin cables
More permanent
Maintain cell shape
Anchor nucleus & other organelles
121
Intermediate Filaments
122
123
Extracellular Structures
Cell walls in plants
Extracellular matrix of animal
cells
Intercellular junctions
124
125
126
Cell Walls in Plants
Cellulose fibers embedded with
polysaccharides & proteins
Protect & maintain cell shape
Prevent excessive uptake of water
127
Structure of the Plant Cell
Wall
Primary cell wall
Middle lamella
Secondary cell wall
Plasmodesmata
Secondary
cell wall
Primary
cell wall
Middle
lamella
Central vacuole
Cytosol
Plasma membrane
Plant cell walls
Plasmodesmata
1 m
128
129
Extracellular Matrix (ECM)
of Animal Cells
Made of glycoproteins:
Collagen, proteoglycans,
fibronectin
ECM proteins bind to receptor proteins called integrins in plasma membrane
130
collagen proteo-glycan
Fibro-nectin
integrin
131
Functions of the ECM
Adhesion
Regulation
Movement
Support
132
Intercellular Junctions
Tight junctions
Desmosomes
Gap junctions
Plasmodesmata
133 Plasmodesmata
134
Plasmodesmata
Tight junctions prevent
fluid from moving
across a layer of cells
Tight junction
Tight junction
TEM 0.5 m
TEM 1 m
TE
M
0.1 m
Extracellular
matrix Plasma membranes
of adjacent cells
Space
between cells
Ions or small
molecules
Desmosome
Intermediate
filaments
Gap
junction
135
136
Tight Junctions
137 Desmosomes
138
Desmosomes
139
Gap Junctions