Cytology The Study of Cells

Electron Microscopes Transmission EM Transmission EM  Internal features Scanning EM Scanning EM  Surface features EM Drawbacks EM Drawbacks  Expense  B&W Images  Dead specimens

Volume Volume  The need to exchange materials is the same with one large or many small cells. Surface Area Surface Area  The 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). Cells alter shape to increase surface area (ability to exchange materials). SA = 6 SA = 7 (same V) SA = LARGE (same V) ½

Cell Membrane Phospholipid Bi-Layer Phospholipid Bi-Layer  Selectively permeable  Small, nonpolar molecules pass easiest

Cell Membrane Membrane Proteins Membrane Proteins  Assist passage of materials  Bind cells together  Enable cell recognition

Cell types Eukaryotes Eukaryotes  Animals, plants, fungi, protists  DNA enclosed in nuclear envelope  Membrane-bound organelles Prokaryotes Prokaryotes  Bacteria and Archaea  DNA not in nuclear envelope  No membrane-bound organelles

Nucleus Nuclear Envelope Nuclear Envelope  Membrane protects DNA  Pores allow passage of RNA Nucleolus Nucleolus  Ribosome synthesis Chromosomes Chromosomes  DNA + Proteins Visible during cell division Visible during cell division Otherwise, indistinguishable (chromatin) Otherwise, indistinguishable (chromatin)

Nucleus

Organelles Ribosome Ribosome  Protein synthesis  No membrane Endoplasmic Reticulum Endoplasmic Reticulum  Transport  Alterations

Organelles Golgi Apparatus Golgi Apparatus  Packaging and export of materials Lysosome Lysosome  Digestive sacs  Break down food, invaders, dead organelles

Organelles Cytoskeleton Cytoskeleton  Protein cell framework Provides cell shape Provides cell shape Cell movement Cell movement Cell division Cell division cilia flagellum

Plant Organelles Cell Wall Cell Wall  Support/protection Plants  Cellulose Plants  Cellulose Fungi  Chitin Fungi  Chitin Bacteria  Peptidoglycan Bacteria  Peptidoglycan Chloroplast Chloroplast  Convert Light E  Glucose Vacuole Vacuole  Storage space Contains water, waste, starch Contains water, waste, starch

Review Questions Complete these analogies 1. 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 Questions Which structure? 1. Protein synthesis 2. Made of microtubules 3. Selectively permeable 4. Only found in plant cells 5. Makes ribosomes 6. Coiled up DNA