Transcript Ch 6: Cells
Ch 6: Cells
History of Cytology
1665 – Robert Hooke
1673 – Anton van Leeuwenhoek
Viewed cork
Named “cells”
Unicellular pond organisms – named
“animalcules”
First to see bacteria and yeast
1833 – Robert Brown discovered nucleus
Cell Theory
1838 – Matthias Schleiden
1839 – THeodor Schwann
All plant parts are composed of cells
All animal tissues are composed of cells
1858 – Rudolph Virchow
All cells come from other cells
Cell Theory:
1) All living things are composed of 1 or more cells
2) Cells are the basic unit of structure and function
3) All cells are produced from existing cells
Cells
All cells have:
Plasma membrane (cell
membrane)
regulates materials in/out of cell
Composed of phospholipid
bilayer
Contains different proteins
Cytoplasm
everything inside the cell
membrane
Medium for chemical rxns
Cytosol – fluid portion
Chromosomes (Genes) - DNA
Ribosomes –site of protein
synthesis
Cell Size – must be small
To efficiently exchange materials in/out of
cell membrane
Cell surface is the only area of interaction w/
environment
To transport materials inside of cell
Efficiency depends on surface area to
volume ratio
Small cells function more efficiently than
larger cells!
Surface Area to Volume Ratio
Prokaryotic Cells
DNA is located in nucloid region (NO
NUCLEUS)
Does not contain membrane bound
organelles
Only Eubacteria and Archeabacteria
Kingdoms
Prokaryotic Cell
Evolution of Eukaryotic Cells
Theory of Endosymbiosis – one
prokaryotic cell engulfed another and did not
digest it, :. Forming a double membrane…
successful relationship
Evidence: Chloroplasts and mitochondria
each have their own separate DNA and can
reproduce on their own, and are similar to
prokaryotic cells
Endosymbiosis
Eukaryotic Organelles
Nucleus – contains chromosomes
Nucleolus
contain materials for RNA
Makes ribosomes
Nuclear Membrane w/ nuclear pores
Nucleoplasm – jelly like material w/in nucleus
Mitochondria
Powerhouse of the cell
Releases E stored in food
Produces ATP
Eukaryotic Transport System
Ribosomes – site of protein synthesis
Free floating in cytoplasm (free)
Attached to ER (bound)
Endoplasmic Reticulum (ER)
An internal channel system
Rough ER – has ribosomes on surface, aids in
transporting proteins
Smooth ER – involved in making lipids and breaking
down toxic substances
Eukaryotic Transport System
Vesicles – membrane buds off ER w/
proteins or lipids enclosed
Lysosome – contains digestive enzymes to
break down macromolecules and worn out cell
parts
Peroxisome - contains enzymes that converts
fat to carbohydrates (from smooth ER)
Golgi body (complex/apparatus) –
packaging and distribution center of the cell
Cis golgi – arrival side
Trans golgi – departure side
Cytoskeleton
Cytoskeleton – internal framework
Mesh-like network of protein fibers
Supports cell shape and anchors organelles
Microtubules – hollow tubes move chromosomes
during cell division by forming centrioles (animal cells
only)
Actin – long intertwined microfilaments that contract or
expand to determine shape
Intermediate fibers – fibrous protein cables that
anchor ribosomes and enzymes
Cytoskeleton
Cellular Movement
Flagella – long threadlike microtubules
(whip-like tail)
Cilia – numerous short and tightly
packed microtubules
Intercellular Junctions
Plants
Plasmodesmata – perforated channels in plant
cell wall allowing cytosol, water and small
solutes to pass freely
Animals
Tight junctions – forms tight seal between cells
Desmosomes – anchor cells together in strong
sheets
Gap junctions – cytoplasmic channels between
adjacent cells allowing communication
Animal Cells only
Extracellular Matrix (ECM)
Collagen – strong glycoprotein fibers
Proteoglycans – network of glycoproteins
Fibronectin – attaches ECM to Integrins
Integrins – membrane proteins bound to
ECM and interior microfilaments
Centrioles
composed of microtubules
Aid in moving chromosomes during cell division
Centrosome – 2 centrioles
Plant Cells Only
Cell Wall
Central Vacuole
Extra protective layer
Cellulose - maintains structure
Stores water, ions, nutrients, and waste materials
Controls pressure w/in cell
Tonoplast – membrane surrounding vacoule
Chloroplast
Contains chlorophyll – photosynthetic pigment
Uses water, carbon dioxide and sunlight to make food in
the form of glucose