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Chapter 3
Structure and Function of Plant
Cells
Scales of Microscopic
Observation
Sizes either metric or as magnifications
mag = nx
The human eye is 1x
Lenses increase magnification, series even
more (ex. Compound light microscope)
Total mag is achieved by multiplying the
powers: 5x X 10x = 50x
The light microscope: 100-1000x mag.
The electron microscope: >100,000x mag.
Resolving Power
(most cells cannot be seen unaided)
Cytology = the study of cell structure and
function
Tools used:light microscope
electron microscope
stains
special scopes
Electron microscopy: TEM and SEM
Cell freeze fractionation and organelles
Biochemical cytology
Cell Organization
Prokaryote vs. Eukaryote
Cell defined: (bag of sugary water?)
Cell size: surface area to volume ratio; limits
on distance and transport
The Plant Cell
Eukaryotic cells and compartmentalization!
Parts of a typical plant cell:
 Plasma (cell) membrane
 Cytoplasm
 Nucleus
 Ribosomes
 Cytoskeleton
 Organelles
 Cell wall
Membranes and Cell
Compartments
Plasma membrane
 Surrounds cell, partially fluid
 Semi(selectively)permeable
 Barrier that protects cell, gives cell support
and some shape
 Allows passage of gases and nutrients into
and out of cell only at surface
 Metabolic activities occur in or on
membranes
Organelles = “tiny organs”
 Small internal spaces or compartments
inside a cell surrounded by additional
membrane
 Compensate plasma membrane
 Increases surface area
 Compartments maintain different
environments for different types of reactions
 Perform own special functions
Internal Membrane Systems
The endomembrane system
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network of membranes that interconnect
organelles for the synthesis, packaging and
transport of substances
Consists of:
• Plasma membrane
• Endoplasmic reticulum (ER) – two types
• Rough ER
• Smooth ER
•
Dictyosomes (Golgi bodies)
• Flattened membrane sacs
• Primarily for secretion
• Major shipment center
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•
Vesicles
Vacuoles
• Large central vacuole and turgor pressure
•
Microbodies
• Ex. Peroxisomes and glyoxysomes
Connections between cells
Plasmodesmata (plasmodesma)
- open channel for movement of material from
one cell to the next
- show picture
The Nucleus
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Is an organelle
Very very large
Genetic control center
DNA and chromosomes
Nuclear envelope
Nuclear pores
Nucleolus and ribosomes
Cytosol and nucleoplasm
Ribosomes
Not an organelle
Site of protein synthesis
Made up of protein and RNA