Transcript Ch 6 ppt-1 - Bartlett High School

Chapter 6: A Tour of the Cell
10 m
Human height
1m
Length of some
nerve and
muscle cells
Unaided eye
0.1 m
Chicken egg
1 cm
Frog egg
1 mm
Most plant and
animal cells
10 µm
1 µm
100 nm
nucleus
Nucleus
Most bacteria
Most bacteria
Mitochondrion
Smallest bacteria
Viruses
Ribosomes
10 nm
Measurements
1 centimeter (cm) = 102 meter (m) = 0.4 inch 1 nm
1 millimeter (mm) = 10–3 m
1 micrometer (µm) = 10–3 mm = 106 m
1 nanometer (nm) = 10–3 µm = 10 9 m
0.1 nm
Proteins
Lipids
Small molecules
Atoms
Electron microscope
100 µm
Light microscope
1. What is a cell?
- Simplest collection of matter that can live
2. How can researchers study cells?
- Microscopes (Appendix C)
- Light microscope
- Electron microscope
- Scanning EM – surface details of cells
- Transmission EM – internal structures
Chapter 6: A Tour of the Cell
1. What is a cell?
- Simplest collection of matter that can live
2. How can researchers study cells?
- Microscopes (Appendix C)
- Cell fractionation
- Used to isolate cellular components
based on size & density
- Cells are homogenized
- Organelles separated by differential
centrifugation
Homogenization
Tissue
cells
1000 g
Homogenate
(1000 times the
force of gravity)
Differential centrifugation
10 min
Supernatant poured
into next tube
20,000 g
20 min
Pellet rich in
nuclei and
cellular debris
80,000 g
60 min
150,000 g
3 hr
Pellet rich in
mitochondria
(and chloroplasts if cells
are from a Pellet rich in
plant)
“microsomes”
(pieces of
plasma membranes and
Pellet rich in
cells’ internal ribosomes
membranes)
Chapter 6: A Tour of the Cell
1. What is a cell?
2. How can researchers study cells?
3. What is the difference between prokaryotic & eukaryotic cells?
- Prokaryotic
- No true nucleus or other membrane-bound organelles
- Bacteria & Archaebacteria
Pili: attachment structures on
the surface of some prokaryotes
Nucleoid: region where
the cell’s DNA is located (not
enclosed by a membrane)
Ribosomes: organelles that
synthesize proteins
Plasma membrane: membrane
enclosing the cytoplasm
Cell wall: rigid structure outside
the plasma membrane
Capsule: jelly-like outer coating
of many prokaryotes
0.5 µm
(a) A typical
rod-shaped bacterium
Flagella: locomotion
organelles of
some bacteria
(b) A thin section through the
bacterium Bacillus coagulans
(TEM)
Chapter 6: A Tour of the Cell
1. What is a cell?
2. How can researchers study cells?
3. What is the difference between prokaryotic & eukaryotic cells?
- Prokaryotic
- No true nucleus or other membrane-bound organelles
- Bacteria & Archaebacteria
- Eukaryotic
- Nucleus & other membrane-bound organelles are present
- Plants, animals, fungi, protists
Figure 6.9
Animal Cell
ENDOPLASMIC RETICULUM (ER)
Rough ER
Smooth ER
Nuclear envelope
Nucleolus
NUCLEUS
Chromatin
Flagellum
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)
Figure 6.9
Plant Cell
Nuclear envelope
Nucleolus
Chromatin
NUCLEUS
Centrosome
Rough
endoplasmic
reticulum Smooth
endoplasmic
reticulum
Ribosomes ( small brown dots )
Central vacuole
Tonoplast
Golgi apparatus
Microfilaments
Intermediate
filaments
CYTOSKELETON
Microtubules
Mitochondrion
Peroxisome
Plasma membrane
Chloroplast
Cell wall
Plasmodesmata
Wall of adjacent cell
In plant cells but not animal cells:
Chloroplasts
Central vacuole and tonoplast
Cell wall
Plasmodesmata
Chapter 6: A Tour of the Cell
1.
2.
3.
4.
What is a cell?
How can researchers study cells?
What is the difference between prokaryotic & eukaryotic cells?
What is the role of the nucleus?
- Houses most of the genes on chromosomes made of chromatin
- Chromatin = DNA wrapped around proteins
- Surrounded by nuclear envelope
- Double membrane lined with pores
- Pore complexes regulate movement of RNA & proteins into & out of nucleus
- Nuclear lamina – inner lining of nuclear envelope used for support
- Nucleolus
- Site of ribosome production
- rRNA + imported ribosomal proteins (through pore complexes)
Figure 6.10 The nucleus and its envelope
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
Ribosome
1 µm
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.
Chapter 6: A Tour of the Cell
1.
2.
3.
4.
5.
What is a cell?
How can researchers study cells?
What is the difference between prokaryotic & eukaryotic cells?
What is the role of the nucleus?
What is the role of the ribosome?
- Protein synthesis (aka…translation)
- Made in nucleolus
- Large & small subunit
- Free ribosomes in cytosol
- Bound ribosomes on rough ER or nucleus
Ribosomes
ER
Cytosol
Endoplasmic reticulum (ER)
Free ribosomes
Bound ribosomes
Large
subunit
0.5 µm
Small
subunit
TEM showing ER and ribosomes Diagram of a ribosome
Chapter 6: A Tour of the Cell
1.
2.
3.
4.
5.
6.
What is a cell?
How can researchers study cells?
What is the difference between prokaryotic & eukaryotic cells?
What is the role of the nucleus?
What is the role of the ribosome?
What is the endomembrane system & who are its members?
- Collection of membranes inside a eukaryotic cell related
through direct contact or by transfer vesicles
- Nuclear envelope, endoplasmic reticulum (ER),
Golgi apparatus, lysosomes,
Smooth ER
vacuoles, plasma membrane
Nuclear
Rough ER
7. What is the role of the smooth ER?
envelope
- Make lipids (oils, phospholipids, & steroids)
- Metabolism of carbs
- Detoxification of drugs & poisons
ER lumen
- Ca+2 ion storage
Cisternae
8. What is the role of the rough ER?
Ribosomes
Transitional ER
- Studded with ribosomes
Transport vesicle
- Makes secreted proteins, membranes &
Smooth ER
Rough ER 200 µm
glycoproteins
Chapter 6: A Tour of the Cell
1.
2.
3.
4.
5.
6.
7.
8.
9.
What is a cell?
How can researchers study cells?
What is the difference between prokaryotic & eukaryotic cells?
What is the role of the nucleus?
What is the role of the ribosome?
What is the endomembrane system & who are its members?
What is the role of the smooth ER?
What is the role of the rough ER?
What is the role of the Golgi apparatus?
- Center of manufacturing, warehousing, sorting & shipping
- ER products get modified & sent along
- Membrane phospholipids
- Sugars of glycoproteins
- Targets proteins for other organelles
- Sorts products for secretion
Figure 6.13 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
Chapter 6: A Tour of the Cell
1. What is a cell?
2. How can researchers study cells?
3. What is the difference between prokaryotic & eukaryotic cells?
4. What is the role of the nucleus?
5. What is the role of the ribosome?
6. What is the endomembrane system & who are its members?
7. What is the role of the smooth ER?
8. What is the role of the rough ER?
9. What is the role of the Golgi apparatus?
10. What do lysosomes do?
- Digestion & recycling at pH 5
- Hydrolytic enzymes break bonds of all macromolecules
Figure 6.14 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
Chapter 6: A Tour of the Cell
1. What is a cell?
2. How can researchers study cells?
3. What is the difference between prokaryotic & eukaryotic cells?
4. What is the role of the nucleus?
5. What is the role of the ribosome?
6. What is the endomembrane system & who are its members?
7. What is the role of the smooth ER?
8. What is the role of the rough ER?
9. What is the role of the Golgi apparatus?
10. What do lysosomes do?
11. What do vacuoles do?
- Food vacuoles – lysosomes
- Contractile vacuoles – FW protists use these to pump out excess water
- Central vacuole – reserve of many different substances or ions for plants
-
Let’s review the endomembrane system……
Figure 6.16 Review: relationships among organelles of the
endomembrane system
1 Nuclear envelope is
connected to rough ER,
which is also continuous
with smooth ER
Nucleus
Rough ER
Smooth ER
Nuclear envelope
3
Figure 6.16 Review: relationships among organelles of the
endomembrane system
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
Figure 6.16 Review: relationships among organelles of the
endomembrane system
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
Chapter 6: A Tour of the Cell
1. What is a cell?
2. How can researchers study cells?
3. What is the difference between prokaryotic & eukaryotic cells?
4. What is the role of the nucleus?
5. What is the role of the ribosome?
6. What is the endomembrane system & who are its members?
7. What is the role of the smooth ER?
8. What is the role of the rough ER?
9. What is the role of the Golgi apparatus?
10. What do lysosomes do?
11. What do vacuoles do?
12. What is the role of a mitochondria?
- Site of cellular respiration
- Double membrane (inner & outer) & mitochondrial matrix
- Has DNA & ribosomes & can reproduce on their own
Figure 6.17 The mitochondrion, site of cellular respiration
Mitochondrion
Intermembrane space
Outer
membrane
Free
ribosomes
in the
mitochondrial
matrix
Inner
membrane
Cristae
Matrix
Mitochondrial
DNA
100 µm
Chapter 6: A Tour of the Cell
1. What is a cell?
2. How can researchers study cells?
3. What is the difference between prokaryotic & eukaryotic cells?
4. What is the role of the nucleus?
5. What is the role of the ribosome?
6. What is the endomembrane system & who are its members?
7. What is the role of the smooth ER?
8. What is the role of the rough ER?
9. What is the role of the Golgi apparatus?
10. What do lysosomes do?
11. What do vacuoles do?
12. What is the role of a mitochondria?
13. What do chloroplasts do?
- Photosynthesis for plant energy transformations
- Double membrane (inner & outer) & stroma
- Has DNA & ribosomes & can reproduce on their own
- Thylakoids have chlorophyll & harness light energy
Figure 6.18 The chloroplast, site of photosynthesis
Chloroplast
Ribosomes
Stroma
Chloroplast
DNA
Inner and outer
membranes
Granum
1 µm
Thylakoid
Absent
Chapter 6: A Tour of the Cell
1. What is a cell?
2. How can researchers study cells?
3. What is the difference between prokaryotic & eukaryotic cells?
4. What is the role of the nucleus?
5. What is the role of the ribosome?
6. What is the endomembrane system & who are its members?
7. What is the role of the smooth ER?
8. What is the role of the rough ER?
9. What is the role of the Golgi apparatus?
10. What do lysosomes do?
11. What do vacuoles do?
12. What is the role of a mitochondria?
13. What do chloroplasts do?
14. What about peroxisomes?
- Enzymes that transfer hydrogen to oxygen forming peroxide
- Beta oxidation of fatty acids for energy
- Detoxifying alcohol in liver
15. How does the cell keep its shape?
- Cytoskeleton made of
- Microtubules
- Microfilaments
- Intermediate filaments
- Role – support, motility & regulation
Table 6.1 The Structure and Function of the Cytoskeleton
Chapter 6: A Tour of the Cell
1. What is a cell?
2. How can researchers study cells?
3. What is the difference between prokaryotic & eukaryotic cells?
4. What is the role of the nucleus?
5. What is the role of the ribosome?
6. What is the endomembrane system & who are its members?
7. What is the role of the smooth ER?
8. What is the role of the rough ER?
9. What is the role of the Golgi apparatus?
10. What do lysosomes do?
11. What do vacuoles do?
12. What is the role of a mitochondria?
13. What do chloroplasts do?
14. What about peroxisomes?
15. How does the cell keep its shape?
16. What important structures lie outside of the cell?
- Plants – primary cell wall (initially thin & flexible) & secondary
cell wall in mature cells
- Animals – Extra cellular matrix (ECM) – glycoproteins from cell
- Collagen embedded in proteoglycans
- Fibronectin & integrins
Figure 6.29 Extracellular matrix (ECM) of an animal cell
Collagen fibers
are embedded
in a web of
proteoglycan
complexes.
A proteoglycan
complex consists
of hundreds of
proteoglycan
molecules attached
noncovalently to a
single long polysaccharide molecule.
EXTRACELLULAR FLUID
Fibronectin
attaches the
ECM to
integrins
embedded in
the plasma
membrane.
Plasma
membrane
Integrin
Microfilaments
CYTOPLASM
Integrins are membrane
proteins that are bound
to the ECM on one side
and to associated
proteins attached to
microfilaments on the
other. This linkage can
transmit stimuli
between the cell’s
external environment
and its interior and can
result in changes in cell
behavior.
Polysaccharide
molecule
Carbohydrates
Core
protein
Proteoglycan
molecule
Chapter 6: A Tour of the Cell
1. What is a cell?
2. How can researchers study cells?
3. What is the difference between prokaryotic & eukaryotic cells?
4. What is the role of the nucleus?
5. What is the role of the ribosome?
6. What is the endomembrane system & who are its members?
7. What is the role of the smooth ER?
8. What is the role of the rough ER?
9. What is the role of the Golgi apparatus?
10. What do lysosomes do?
11. What do vacuoles do?
12. What is the role of a mitochondria?
13. What do chloroplasts do?
14. What about peroxisomes?
15. How does the cell keep its shape?
16. What important structures lie outside of the cell?
17. How are neighboring cells connected?
- Plants – plasmodesmata – openings in cell walls that cytosol can pass through
- Animals
- Tight junctions – membranes of neighboring cells bound by specific proteins
- Desmosomes – function like rivets fastening cells together into strong sheets
- Gap junctions – cytoplasmic channels between cells
Figure 6.31 Exploring Intercellular Junctions in Animal Tissues
TIGHT JUNCTIONS
At tight junctions, the membranes of
neighboring cells are very tightly pressed
against each other, bound together by
specific proteins (purple). Forming continuous seals around the cells, tight junctions
prevent leakage of extracellular fluid across
a layer of epithelial cells.
Tight junction
Tight junctions prevent
fluid from moving
across a layer of cells
0.5 µm
DESMOSOMES
Desmosomes (also called anchoring
junctions) function like rivets, fastening cells
together into strong sheets. Intermediate
filaments made of sturdy keratin proteins
anchor desmosomes in the cytoplasm.
Tight junctions
Intermediate
filaments
Desmosome
Gap
junctions
Space
between Plasma membranes
cells
of adjacent cells
1 µm
Extracellular
matrix
Gap junction
0.1 µm
GAP JUNCTIONS
Gap junctions (also called communicating
junctions) provide cytoplasmic channels from
one cell to an adjacent cell. Gap junctions
consist of special membrane proteins that
surround a pore through which ions, sugars,
amino acids, and other small molecules may
pass. Gap junctions are necessary for communication between cells in many types of tissues,
including heart muscle and animal embryos.