Download Cell Structures

A TOUR OF THE CELL
CELLS
• All organisms are
made of cells
The cell is the
simplest collection
of matter
that can be alive
Cell structure is
correlated to
cellular function
All cells are related
by their descent
from earlier cells
EUKARYOTIC CELLS –
MEMBRANES TO
SEPARATE FUNCTION
WHAT IS A CELL?
Basic features of all cells
Plasma membrane
Semifluid substance
called cytosol
Chromosomes (carry
genes)
Ribosomes (make
proteins)
Prokaryotes
EUKARYOTIC VS PROKARYOTIC
Prokaryotic
Eukaryotic
No nucleus
Nucleoid
Membrane-less organelles
Nucleus
Nuclear envelope
Organelles with membranes
FIGURE 6.5
Fimbriae
Nucleoid
Ribosomes
Plasma
membrane
Bacterial
chromosome
Cell wall
Capsule
0.5 m
(a) A typical
rod-shaped
bacterium
Flagella
(b) A thin section
through the
bacterium Bacillus
coagulans (TEM)
EUKARYOTIC
CELLS
Outside of cell
 Have
Inside of cell
plasma
0.1 m
membranes
 selective
barrier
 double
layer of
phospholipi
ds
TEM of a plasma
membrane
Carbohydrate side chains
Hydrophilic
region
Hydrophobic
region
Hydrophilic
region
Phospholipid
Proteins
(b) Structure of the plasma mem
Surface area increases while
total volume remains constant
5
1
1
Total surface area
[sum of the surface areas
(height  width) of all box
sides  number of boxes]
6
150
750
Total volume
[height  width  length
 number of boxes]
1
125
125
Surface-to-volume
(S-to-V) ratio
[surface area  volume]
6
1.2
6
FIGURE 6.8A
Animal
Cell
ENDOPLASMIC RETICULUM (ER)
Flagellum
Nuclear
envelope
Nucleolus
Rough Smooth
ER
ER
NUCLEUS
Chromatin
Centrosome
Plasma
membrane
CYTOSKELETON:
Microfilaments
Intermediate filaments
Microtubules
Ribosomes
Microvilli
Golgi apparatus
Peroxisome
Mitochondrion
Lysosome
FIGURE 6.8B
Animal Cells
Fungal Cells
10 m
Parent
cell
Cell wall
Vacuole
Buds
5 m
Cell
Nucleus
Nucleolus
Human cells from lining
of uterus (colorized TEM)
1 m
Nucleus
Mitochondrion
Yeast cells budding
(colorized SEM)
A single yeast cell
(colorized TEM)
FIGURE 6.8C
Nuclear
envelope
NUCLEUS
Nucleolus
Chromatin
Rough
endoplasmic
reticulum
Smooth
endoplasmic
reticulum
Plant
Cell
Ribosomes
Central vacuole
Golgi
apparatus
Microfilaments
Intermediate
filaments
Microtubules
Mitochondrion
Peroxisome
Chloroplast
Plasma membrane
Cell wall
Wall of adjacent cell
Plasmodesmata
CYTOSKELETON
FIGURE 6.8D
Cell wall
8 m
5 m
Cell
Flagella
1 m
Protistan Cells
Plant Cells
Nucleus
Chloroplast
Nucleolus
Mitochondrion
Vacuole
Nucleus
Nucleolus
Cells from duckweed
(colorized TEM)
Chloroplast
Chlamydomonas
(colorized SEM)
Cell wall
Chlamydomonas
(colorized TEM)
THE NUCLEUS
THE NUCLEUS:
HOME OF GENETIC INSTRUCTIONS
 The nucleus
contains most
of the DNA in
a eukaryotic
cell
 Ribosomes
use the
information
from the DNA
to make
proteins
NUCLEAR ENVELOPE:
SEPARATION OF NUCLEUS AND CY TOPLASM
Double
membrane of
lipid bilayer
Surrounds
nucleus
Tightly controlled
FIGURE 6.9A
Nucleus
Nucleolus
Chromatin
Nuclear envelope:
Inner membrane
Outer membrane
Nuclear pore
Rough ER
Pore
complex
Ribosome
Close-up
of nuclear
envelope
Chromatin
FIGURE 6.9B
1 m
Nuclear envelope:
Inner membrane
Outer membrane
Nuclear pore
Surface of nuclear
envelope
0.25 m
Pore complexes regulate
entry and exit of nucleus
Pore complexes (TEM)
1 m
Nuclear lamina are a
matrix of proteins that
line the interior of the
nuclear membrane
Nuclear lamina (TEM)
Provide support to the
envelope
CHROMATIN TO CHROMOSOMES
DNA is organized into discrete
units called chromosomes
Each chromosome composed of
a single DNA molecule
associated with proteins
The DNA and proteins of
chromosomes together called
chromatin
The nucleolus located within
the nucleus and is the site of
ribosomal RNA (rRNA) synthesis
RIBOSOMES
Made of
ribosomal RNA
and protein
Carry out protein
synthesis in two
locations
ENDOMEMBRANE
SYSTEM
ENDOMEMBRANE
regulates protein
traffic and performs
metabolic functions
in the cell
continuous or
connected via
transfer by vesicles
Nuclear envelope
Endoplasmic
reticulum
Golgi apparatus
Lysosomes
Vacuoles
Plasma
membrane
Smooth ER
Nuclear
envelope
Rough ER
ER lumen
Transitional ER
Cisternae
Ribosomes
Transport vesicle
ER
Collectively account for more than ½ the
membrane in a cell
 Membranous
cisternae
 Lumen =
internal space
 Nuclear
Envelope
continuous with
lumen
Smooth ER
Rough ER
200 nm
SMOOTH VS ROUGH ER
Smooth ER
Synthesizes lipids
Metabolizes
carbohydrates
Detoxifies drugs
and poisons
Stores calcium
ions
Rough ER
Has bound
ribosomes, which
secrete
glycoproteins
Distributes
transport
vesicles
Is a membrane
factory for the cell
Ribosome
Protein
Lumen
Endoplasmic
Reticulum
GOLGI APPARATUS
 Made of flattened
stacks = cisternae
 2 distinct “sides” cis
and trans
 Modify molecules as
they move through
 Synthesizes
macromolecules
GOLGI APPARATUS
cis face
(“receiving” side of
Golgi apparatus)
0.1 m
Cisternae
trans face
(“shipping” side of
Golgi apparatus)
TEM of Golgi apparatus
LYSOSOMES
 Membranous sac of enzymes
 Used to digest
macromolecules
 Contents and membranes of
lysozymes synthesized in ER
 ER protected by 3D structure
INTRACELLULAR DIGESTION
Phagocytosis –
engulf “food”
Lysosomes fuse with
food vacuole
Create nutrients for
cell
Autophagy – recycling
cell’s own materials
Damage organelle
tagged
Surrounded by
membrane
Lysosome fuses
Nucleus
Vesicle containing
two damaged
organelles
1 m
1 m
Mitochondrion
fragment
Peroxisome
fragment
Lysosome
Digestive
enzymes
Lysosome
Lysosome
Plasma membrane
Peroxisome
Digestion
Food vacuole
Vesicle
(a) Phagocytosis
(b) Autophagy
Mitochondrion
Digestion
Animation: Lysosome Formation
Right-click slide / select “Play”
© 2011 Pearson Education, Inc.
VACUOLE
DIVERSE MAINTENANCE CHAMBERS
Central vacuole
 Membranous
vesicle from
ER
 Many
functions:
food,
contractile,
storage
 Function varies
based on cell
structure
Cytosol
Nucleus
Central
vacuole
Cell wall
Chloroplast
5 m
FIGURE 6.15-1
Nucleus
Rough ER
Smooth ER
Plasma
membrane
FIGURE 6.15-2
Nucleus
Rough ER
Smooth ER
cis Golgi
trans Golgi
Plasma
membrane
FIGURE 6.15-3
Nucleus
Rough ER
Smooth ER
cis Golgi
trans Golgi
Plasma
membrane
MITOCHONDRIA AND
CHROLOPLASTS
MITOCHONDRIA
Mitochondria are
the sites of cellular
respiration
Turn O 2 into ATP
Have own DNA
Double membrane
Contain free
ribosomes
Grow independently
of rest of cell
FIGURE 6.17A
Intermembrane space
Outer
membrane
DNA
Free
ribosomes
in the
mitochondrial
matrix
Inner
membrane
Cristae
(a) Diagram and TEM of mitochondrion
Matrix
0.1 m
FIGURE 6.17AA
Outer
membrane
Inner
membrane
Cristae
Matrix
0.1 m
FIGURE 6.17B
10 m
Mitochondria
Mitochondrial
DNA
Nuclear DNA
(b) Network of mitochondria in a protist
cell (LM)
CHLOROPLASTS
Chloroplasts are
the sites of
photosynthesis
 Thylakoids are
membranous sacs
stacked into granum
 Contain chlorophyll
and other enzymes
necessary for
photosynthesis
FIGURE 6.18A
Ribosomes
Stroma
Inner and outer
membranes
Granum
DNA
Intermembrane space
Thylakoid
(a) Diagram and TEM of chloroplast
1 m
FIGURE 6.18AA
Stroma
Inner and outer
membranes
Granum
1 m
FIGURE 6.18B
50 m
Chloroplasts
(red)
(b) Chloroplasts in an algal cell
Endoplasmic
reticulum
Engulfing of oxygenusing nonphotosynthetic
prokaryote, which
becomes a mitochondrion
Nucleus
ENDOSYMBIONT
THEORY
Nuclear
envelope
Ancestor of
eukaryotic cells
(host cell)
Mitochondrion
Nonphotosynthetic
eukaryote
At least
one cell
Engulfing of
photosynthetic
prokaryote
Chloroplast
Mitochondrion
Photosynthetic eukaryote
PEROXISOME
 Peroxisomes are
specialized metabolic
compartments
bounded by a single
membrane
 Peroxisomes produce
hydrogen peroxide and
convert it to water
 How peroxisomes are
related to other
organelles is still
unknown
FIGURE 6.19
1 m
Chloroplast
Peroxisome
Mitochondrion
CELL SEPARATION
FIGURE 6.4
TECHNIQUE
Homogenization
Tissue
cells
Homogenate
Centrifuged at
1,000 g
(1,000 times the
force of gravity)
for 10 min Supernatant
poured into
next tube
20,000 g
20 min
Pellet rich in
nuclei and
cellular debris
Centrifugation
Differential
centrifugation
80,000 g
60 min
150,000 g
3 hr
Pellet rich in
mitochondria
(and chloroplasts if cells
are from a plant)
Pellet rich in
“microsomes”
(pieces of plasma
membranes and
cells’ internal
Pellet rich in
membranes)
ribosomes
FIGURE 6.4A
TECHNIQUE
Homogenization
Tissue
cells
Homogenate
Centrifugation
FIGURE 6.4B
TECHNIQUE (cont.)
Centrifuged at
1,000 g
(1,000 times the
force of gravity)
for 10 min Supernatant
poured into
next tube
20,000 g
20 min
Pellet rich in
nuclei and
cellular debris
Differential
centrifugation
80,000 g
60 min
150,000 g
3 hr
Pellet rich in
mitochondria
(and chloroplasts if cells
are from a plant)
Pellet rich in
“microsomes”
Pellet rich in
ribosomes