Transcript Chapter 5 – Inside The Cell

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
Animation: Lysosome Formation
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• Some types of cell can engulf another cell by
phagocytosis; this forms a food vacuole
• A lysosome fuses with the food vacuole and
digests the molecules
• Lysosomes also use enzymes to recycle the
cell’s own organelles and macromolecules, a
process called autophagy
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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
Fig. 6-14a
Nucleus
1 µm
Lysosome
Lysosome
Digestive
enzymes
Plasma
membrane
Digestion
Food vacuole
(a) Phagocytosis
Fig. 6-14b
Vesicle containing
two damaged organelles
1 µm
Mitochondrion
fragment
Peroxisome
fragment
Lysosome
Peroxisome
Vesicle
(b) Autophagy
Mitochondrion
Digestion
The Endomembrane System: A
Review
• The endomembrane system is a complex and
dynamic player in the cell’s compartmental
organization
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Fig. 6-16-1
Nucleus
Rough ER
Smooth ER
Plasma
membrane
Fig. 6-16-2
Nucleus
Rough ER
Smooth ER
cis Golgi
trans Golgi
Plasma
membrane
Fig. 6-16-3
Nucleus
Rough ER
Smooth ER
cis Golgi
trans Golgi
Plasma
membrane
• Mitochondria and chloroplasts
–
–
–
–
Are not part of the endomembrane system
Have a double membrane
Have proteins made by free ribosomes
Contain their own DNA
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Mitochondria: Chemical Energy Conversion
• Mitochondria are in nearly all eukaryotic cells
• They have a smooth outer membrane and an
inner membrane folded into cristae
• The inner membrane creates two compartments:
intermembrane space and mitochondrial matrix
• Some metabolic steps of cellular respiration are
catalyzed in the mitochondrial matrix
• Cristae present a large surface area for enzymes
that synthesize ATP
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
Chloroplasts: Capture of Light Energy
• The chloroplast is a member of a family of
organelles called plastids
• Chloroplasts contain the green pigment
chlorophyll, as well as enzymes and other
molecules that function in photosynthesis
• Chloroplasts are found in leaves and other green
organs of plants and in algae
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• Chloroplast structure includes:
– Thylakoids, membranous sacs, stacked to form a
granum
– Stroma, the internal fluid
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 6-18
Ribosomes
Stroma
Inner and outer
membranes
Granum
Thylakoid
1 µm
Overview: Life at the Edge
• The plasma membrane is the boundary that
separates the living cell from its surroundings
• The plasma membrane exhibits selective
permeability, allowing some substances to cross
it more easily than others
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Cellular membranes are fluid
mosaics of lipids and proteins
• Phospholipids are the most abundant lipid in the
plasma membrane
• Phospholipids are amphipathic molecules,
containing hydrophobic and hydrophilic regions
• The fluid mosaic model states that a membrane
is a fluid structure with a “mosaic” of various
proteins embedded in it
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 7-2
WATER
Hydrophilic
head
Hydrophobic
tail
WATER
Fig. 7-3
Phospholipid
bilayer
Hydrophobic regions
of protein
Hydrophilic
regions of protein
Fig. 7-7
Fibers of
extracellular
matrix (ECM)
Glycoprotein
Carbohydrate
Glycolipid
EXTRACELLULAR
SIDE OF
MEMBRANE
Cholesterol
Microfilaments
of cytoskeleton
Peripheral
proteins
Integral
protein
CYTOPLASMIC SIDE
OF MEMBRANE
Discussion Questions
A Panoramic View of the Cell
• Distinguish between prokaryotic and
eukaryotic cells.
• Explain why there are both upper and lower
limits to cell size.
• Explain the advantages of
compartmentalization in eukaryotic cells.
Chapter Review
Inside of every cell there is some type of organization that allows cells to perform it’s life
functions. Some cells are more complicated that others. In this assignment you will
need to explain:
1. a. the process by which a cell takes mRNA (a code for an enzyme) from the nucleus .
b. converts it to an enzyme.
c. and transports it outside the cell.
2.
a. the process by which Starch is taken into the cell.
b. Broken down (digested).
c. What organelle is it taken to and Why?
3.
a. What is the difference between Eukaryotes and Prokaryotes.
b. In what type of cell would you find Plastids, Vacuoles and what’s their function.
c. In what type of cells would you find Cilia and Flagella and what’s their function.
Unicellular
Multicellular
Levels of Organization
Metabolisms
Organelles
Eukaryotes
Prokaryotes
Ribosomes
Endoplasmic Reticulum
Golgi Bodies
Mitochondria
Nucleus
Vacuoles
Centrioles
Plastids
Chloroplasts
Chlorophyll
Lysosomes
Cilia
Flagella
Symbiotic Theory
Vacuoles?
Fluid filled, membrane bound structures for storage.
Cytoskeleton?
Gives support and shape to the cell. 2 Parts
• 1. Microfilaments = protein strands (actin & myosin)
- Contractile proteins – support and help in cell movement.
• 2. Microtubules = long thick proteins that stretch form the cell
membrane to the nucleus. Help organelles move with in the
cell
Centrioles – Cilia / Flagella
Centrioles = used in cell division (made of microtubules)
Play
Cilia and Flagella – microtubules surrounded by the cell membrane
extending outside the cell used for locomotion
Evolution of Eukaryotes
Symbiotic Theory?
Symbiosis? 2 organisms living in close association.
Prokaryotic Characteristics? No Nucleus
DNA = single, double stranded, circular chromosomes
No membrane bound organelles, but do have ribosomes (smaller)
Mitochondria and Chloroplasts?
Contain their own DNA, RNA and ribosomes that are similar to
Prokaryotes.
Ribosomes? Smaller in Prokaryotes yet similar enzymes for making
proteins and Nucleic Acids
It’s Logical but incomplete. Why?
-Nuclear Membrane?
-Various Membrane bound structures?
-And other eukaryotic structures?
Symbiotic Theory