Cell Architecture
CELL THEORY
• Mathias Schleiden and Theodore Schwann
• Prokaryotic cell
• Eukaryotic cell – plant cell and animal cell
• Figure 9-1
Animal cell substructures
Single and Double Membrane
Substructures
• Single Membrane Structures
– Plasma Membrane
– Endoplasmic Reticulum
– Golgi Apparatus
– Lysosome
– Peroxisome
– Endosome
• Double membrane structures – Nucleus and
Mitochondria
Plant Cell Substructures
Single and Double Membrane
Substructures
• Single Membrane Structures
– Plasma Membrane
– Endoplasmic Reticulum
– Golgi Apparatus
– Lysosome
– Peroxisome
– Endosome
• Double membrane structures – Nucleus and
Chloroplast
Plasma Membrane Chapter10 Fig.10-1
EM OF A THIN
ERYTHROCYTE
MEMBRANE
How do endosomes work?
Lysosomes
• Internal compartment is very different form
the cytosol –more acidic pH
• Degrades substances that are obsolete
• Phagocytosis and Endocytosis
• All lysosmal enzymes are acid hydrolases
• Tays Sach’s disease – defect in enzyme
catalyzing a step in the lysosomal breakdown
of gangliosides.
Autophagy
Plant Vacuoles
• Similar to lysosomes – degradative enzymes
• Concentration of solutes is larger inside the
vacuole than outside
• Stores small molecules and is permeable to
water
• Elongation of the plant is related to water
uptake by the vacuole
EM OF A PLANT CELL
Peroxisomes
• 0.2-1.0 micrometer in diameter
• Oxidases
• Catalase
2H₂O₂ -----> 2H₂O + O₂
• Main site of fatty acid peroxidation
• Various toxic molecules that enter the body
are degraded here
Mitochondrial vs. Peroxisomal
Oxidation
Fig. 12-12
Endoplasmic Reticulum
• Smooth ER:
– Synthesis of Fatty Acids and Lipids
– Metabolism of Carbohydrates
– Detoxify Drugs and Poisons
• Rough ER:
– Synthesis of Secretory Proteins, Membrane and
Organelle Proteins
ROUGH ER IS MADE OF RIBOSOMES
RIBOSOMES
• Composed of rRNA and protein
• Site of protein synthesis
• Proteins are marked for different organelles or
for secretion
• Ribosomes are assembled in the nucleolus
• Free Ribosomes
PROTEIN MODIFICATION IN THE ER
SECRETED PROTIENS
– GLYCOSYLATION
– DISULFIDE BOND FORMATION
HORMONE
SECRETING
CELL FROM
RAT
PITUITARY
Golgi Apparatus
Golgi - Function
• Flattened membrane vesicles or sacs
• Cis, medial and trans -Golgi
• Proteins targeted for different points in the
cell are modified differently
• Secretory proteins
• Plasma membrane proteins
• Membrane or soluble proteins to other
organelles
HOW SECRETORY PROTEINS ARE TRANSPORTED?
ORGANELLES WITH DOUBLE MEMBRANES
• MITOCHONDRIA
– Power house of the cell
– Site of cellular respiration
– Organic molecules are used fro ATP synthesis
NUCLEUS
contains chromosomes, DNA and RNA
CHLOROPLAST
Site of Photosynthesis
EM OF A MITOCHONDRION
STRUCTURE OF A MITOCHONDRION
OUTER MEMBRANE AND INNER
MEMBRANE
• OUTER MEMBRANE
– 50% lipid and 50% protein
– Porin proteins (MW of 10,000)
INNER MEMBRANE
- CRISTAE
POWER HOUSE OF THE CELL
Nucleus
• Inner membrane and outer membrane
• Outer membrane is continuous with rough ER
• The intermembrane space is continuous with
the lumen of the ER
• Nuclear pores and nucleoporins
• Heterochromatin
• Ribosomal RNA assembly
HETEROCHROMATIN
CHLOROPLAST
•
•
•
•
•
•
Double membraned organelle
Length is 10µm and thickness of 0.5-2 µm
Sacs - Thylakoids
Stacks are grana
Matrix space called Stroma
Photosynthesis
MITOCHONDRIA
AND CHLOROPLAST
•
•
•
•
ATP production
Move around in the cell
Contain their own DNA
Some of their proteins are encoded in the
nucleus
EM OF A PLANT CHLOROPLAST