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Cytology. Cytology. The Study of Cells. Transmission EM Internal features. Scanning EM Surface features. Electron Microscopes. EM Drawbacks Expense B&W Images Dead specimens. Why are cells so small?. Volume - PowerPoint PPT Presentation
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The Study of Cells
Electron Microscopes Transmission EM
Internal features Scanning EM
Surface features
EM Drawbacks Expense B&W Images Dead specimens
VolumeThe need to exchange materials is the same with one large or many small cells.
Surface AreaThe ability to exchange materials is greater w/ small cells.
Why are cells so small?
Increasing exchange Cells alter shape to increase surface area
(ability to exchange materials).
SA = 6SA = 7
(same V) SA = LARGE(same V)
½ 12111
Cell Membrane Phospholipid Bi-Layer
Selectively permeable Small, nonpolar molecules pass easiest
Cell Membrane Membrane Proteins
Assist passage of materials Bind cells together Enable cell recognition
Cell types Eukaryotes
Animals, plants, fungi, protists DNA enclosed in nuclear envelope Membrane-bound organelles
Prokaryotes Bacteria and Archaea DNA not in nuclear envelope No membrane-bound organelles
Nucleus Nuclear Envelope
Membrane protects DNA Pores allow passage of RNA
Nucleolus Ribosome synthesis
Chromosomes DNA + Proteins
Visible during cell division Otherwise, indistinguishable
(chromatin)
Nucleus
Organelles Ribosome
Protein synthesis No membrane
Endoplasmic Reticulum Transport Alterations
Organelles Golgi Apparatus
Packaging and export of materials
Lysosome Digestive sacs Break down
food, invaders, dead organelles
Organelles Cytoskeleton
Protein cell framework Provides cell shape Cell movement Cell division
cilia flagellum
Plant Organelles Cell Wall
Support/protection Plants Cellulose Fungi Chitin Bacteria Peptidoglycan
Chloroplast Convert Light E Glucose
Vacuole Storage space
Contains water, waste, starch
Review QuestionsComplete these analogies1. Volume : surface area :: cytoplasm : _______________2. Sundae : sprinkles :: rough endoplasmic reticulum : __
Which structure is dysfunctional?4. Desirable materials are not able to enter the cell.5. Engulfed food is building up in the cell.6. The cell is unable to power any functions despite an
ample food supply.
Review QuestionsWhich structure?1. Protein synthesis2. Made of microtubules3. Selectively permeable4. Only found in plant cells5. Makes ribosomes6. Coiled up DNA