Download Prokaryotic cells

Pre-Quiz: True or False?
• T or F: Larger organisms do not generally have larger cells
than smaller organisms; instead they have more cells.
– True
• T or F: Plants obtain ATP from aerobic respiration only in
the dark.
– False
• T or F: The endomembrane system includes the nuclear
envelope, endoplasmic reticulum, Golgi apparatus,
lysosomes, vacuoles, and the plasma membrane.
–
True
Pre-Quiz: Correct or Incorrect?
•
The volume of an average eukaryotic cell is ten times the volume of an
average prokaryotic cell
–
•
Plant cells produce ATP during photosynthesis, whereas animal cells
produce ATP during aerobic respiration
–
•
INCORRECT: the length of an average eukaryotic cell is ten times
the length of an average prokaryotic cell; the volume of an
average eukaryotic cell is 1,000 times the volume of an average
prokaryotic cell
INCORRECT: plant and animal cells both carry out aerobic
respiration, producing ATP
The nucleus, chloroplasts, and mitochondria within a eukaryotic cells
are bounded by double membranes
–
CORRECT
Comparing Prokaryotic and Eukaryotic Cells
• Basic features of all cells:
– Plasma membrane
– Semifluid substance called cytosol
– Chromosomes (carry genes)
– Ribosomes (make proteins)
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
• Prokaryotic cells are characterized by having
– No nucleus
– DNA in an unbound region called the nucleoid
– No membrane-bound organelles
– Cytoplasm bound by the plasma membrane
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 6-6
Fimbriae
Nucleoid
Ribosomes
Plasma membrane
Bacterial
chromosome
Cell wall
Capsule
0.5 µm
(a) A typical
rod-shaped
bacterium
Flagella
(b) A thin section
through the
bacterium
Bacillus
coagulans (TEM)
• Eukaryotic cells are characterized by having
– DNA in a nucleus that is bounded by a
membranous nuclear envelope
– Membrane-bound organelles
– Cytoplasm in the region between the plasma
membrane and nucleus
• Eukaryotic cells are generally much larger than
prokaryotic cells
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 6-9a
Nuclear
envelope
ENDOPLASMIC RETICULUM (ER)
Flagellum
Rough ER
NUCLEUS
Nucleolus
Smooth ER
Chromatin
Centrosome
Plasma
membrane
CYTOSKELETON:
Microfilaments
Intermediate
filaments
Microtubules
Ribosomes
Microvilli
Golgi
apparatus
Peroxisome
Mitochondrion
Lysosome
Fig. 6-9b
NUCLEUS
Nuclear envelope
Nucleolus
Chromatin
Rough endoplasmic
reticulum
Smooth endoplasmic
reticulum
Ribosomes
Central vacuole
Golgi
apparatus
Microfilaments
Intermediate
filaments
Microtubules
Mitochondrion
Peroxisome
Chloroplast
Plasma
membrane
Cell wall
Plasmodesmata
Wall of adjacent cell
CYTOSKELETON
Fig. 6-10
Nucleus
1 µm
Nucleolus
Chromatin
Nuclear envelope:
Inner membrane
Outer membrane
Nuclear pore
Pore
complex
Surface of
nuclear envelope
Rough ER
Ribosome
1 µm
0.25 µm
Close-up of nuclear
envelope
Pore complexes (TEM)
Nuclear lamina (TEM)
Fig. 6-11
Cytosol
Endoplasmic reticulum (ER)
Free ribosomes
Bound ribosomes
Large
subunit
0.5 µm
TEM showing ER and ribosomes
Small
subunit
Diagram of a ribosome
Concept 6.4: The endomembrane system regulates
protein traffic and performs metabolic functions in
the cell
• Components of the endomembrane system:
– Nuclear envelope
– Endoplasmic reticulum
– Golgi apparatus
– Lysosomes
– Vacuoles
– Plasma membrane
• These components are either continuous or
connected via transfer by vesicles
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 6-12
Smooth ER
Rough ER
ER lumen
Cisternae
Ribosomes
Transport vesicle
Smooth ER
Nuclear
envelope
Transitional ER
Rough ER
200 nm
Functions of Smooth ER
• The smooth ER
– Synthesizes lipids
– Metabolizes carbohydrates
– Detoxifies poison
– Stores calcium
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Functions of Rough ER
• The rough ER
– Has bound ribosomes, which secrete
glycoproteins (proteins covalently bonded to
carbohydrates)
– Distributes transport vesicles, proteins
surrounded by membranes
– Is a membrane factory for the cell
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
The Golgi Apparatus: Shipping and
Receiving Center
• The Golgi apparatus consists of flattened
membranous sacs called cisternae
• Functions of the Golgi apparatus:
– Modifies products of the ER
– Manufactures certain macromolecules
– Sorts and packages materials into transport
vesicles
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 6-13
cis face
(“receiving” side of
Golgi apparatus)
0.1 µm
Cisternae
trans face
(“shipping” side of
Golgi apparatus)
TEM of Golgi apparatus
Lysosomes: Digestive Compartments
• A lysosome is a membranous sac of hydrolytic
enzymes that can digest macromolecules
• Lysosomal enzymes can hydrolyze proteins,
fats, polysaccharides, and nucleic acids
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 6-14
Nucleus
1 µm
Vesicle containing
two damaged organelles
1 µm
Mitochondrion
fragment
Peroxisome
fragment
Lysosome
Lysosome
Digestive
enzymes
Plasma
membrane
Lysosome
Peroxisome
Digestion
Food vacuole
Vesicle
(a) Phagocytosis
(b) Autophagy
Mitochondrion
Digestion
Vacuoles: Diverse Maintenance Compartments
• A plant cell or fungal cell may have one or
several vacuoles
– Food vacuoles are formed by phagocytosis
– Contractile vacuoles, found in many
freshwater protists, pump excess water out of
cells
– Central vacuoles, found in many mature plant
cells, hold organic compounds and water
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 6-15
Central vacuole
Cytosol
Nucleus
Central
vacuole
Cell wall
Chloroplast
5 µm
Concept 6.5: Mitochondria and chloroplasts
change energy from one form to another
• Mitochondria are the sites of cellular
respiration, a metabolic process that generates
ATP
• Chloroplasts, found in plants and algae, are
the sites of photosynthesis
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
• Mitochondria and chloroplasts
– Are not part of the endomembrane system
– Have a double membrane
– Have proteins made by free ribosomes
– Contain their own DNA
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 6-17
Intermembrane space
Outer
membrane
Free
ribosomes
in the
mitochondrial
matrix
Inner
membrane
Cristae
Matrix
0.1 µm
Fig. 6-18
Ribosomes
Stroma
Inner and outer
membranes
Granum
Thylakoid
1 µm
Cell Structure Review
•
Which two domains consist of prokaryotic cells?
–
•
•
Bacteria and Archaea
A major difference between prokaryotic and eukaryotic cells is the
location of the DNA. Describe this difference.
–
Eukaryotic DNA – within a membrane bound nucleus
–
Prokaryotic DNA – concentrated in the nucleoid region
What are microvilli and how do these structures relate to the function of
intestinal cells?
–
Mircovilli are long thin projections from the cell surface, which increase
surface area without increasing volume. Intestinal cells require a large
surface area to volume ratio to allow for absorption of nutrients.
Cell Structure Review
•
•
Chromosomes are made of chromatin. What is chromatin composed
of? When does chromatin condense to form chromosomes?
–
DNA and Histone Proteins
–
Condense for cell division
When are nucleoli visible and what is assembled there?
–
nucleoli are visible when cells are not dividing
–
protein and rRNA are assembled into ribosomal subunits (large
and small)
• Differentiate between proteins produced by free and attached
ribosomes
–
Free – proteins that function within the cell
–
Attached – proteins for insertion into membranes
Cell Structure Review
•
List the 3 major functions of the smooth ER
– Synthesis of lipids; detoxification of drugs and poisons;
and storage of calcium ions
• What do lysosomes contain and what is the pH range
inside a lysosome?
– Contain hydrolytic enzymes for digestion; pH range is
acidic
• What is autophagy?
– Damaged organelle becomes surrounded by a double
membrane and lysosome fuses with the outer
membrane of this vesicle - the organelles are
dismantled to their monomers for reuse
Cell Structure Review
•
•
Differentiate between food vacuoles, contractile vacuoles, central
vacuoles.
–
Food: formed by phagocytosis
–
Contractile: pump out excess water out of the cell
–
Central: contain solution called cell sap, is the plant cell’s main
storage area for inorganic ions; plays a major role in growth
What is an endosymbiont?
–
•
A cell living within another cell
Why do you think the inner membrane of the mitochondria are highly
folded? Same with the function of the many individual thylakoids…
–
Increase the surface area increasing productivity