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Robert Hooke Used early compound
microscope to look at slices of cork
Named the tiny chambers “cells” after rooms in monasteries ht
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Anton van LeeuwenhoekDutch janitor with
hobby of ocular grinding (making lenses)
Used single-lens microscope to look at raindrops
Found living organisms
https://mattwells.wikispaces.com/Biology+K
Schleiden concluded plants were made of cells (1838)
Schwann concluded animals were made of cells (1839)
Virchow concluded new cells could only be produced from existing cells (1855)
Principles of Cell Theory:1. All living things are
composed of cells.2. Cells are the basic
units of structure and function in living things.
3. New cells are produced from existing cells.
The light microscope enables us to see the overall shape and structure of a cell
Figure 4.1A
Image seen by viewer
Eyepiece
Ocularlens
Objective lens
Specimen
Condenser lens
Light source
Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings
Red blood cells
teaching.path.cam.ac.uk/partIB_pract/NHP1/
Invented in the 1950sThey use a beam of
electrons instead of light
The greater resolving power of electron microscopes • allows greater
magnification • reveals cellular details
websemserver.materials.ox.ac.uk/cybersem/getf...
Electron beam scans cell surfaceUsed to see detailed structure of cell surface
Figure 4.1B
Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings
Red blood cellshttp://commons.wikimedia.org/wiki/Image:SEM_blood_cells.jpg
Transmits electrons through specimenUsed to examine the internal structures of a cell
Figure 4.1CCopyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings
Red blood cell in capillary
commons.wikimedia.org/wiki/Image:A_red_blood_...
Cell size is limited by metabolic requirementsLower limits:
Enough DNA to program metabolism
Enough ribosomes, enzymes, & cellular components
Upper limits:Surface area and
plasma membrane large enough for cell volume to allow exchange of nutrients and wastes
ProkaryotesSmaller cellsSimpler structureCells do not have a nucleusCells do not have membrane
bound organellesSingle celled organisms
EukaryotesLarger cellsMore complex structureCells have a nucleusCells have membrane bound
organellesSingle celled organisms—ProtistsMulticellular organisms
All Cells:1. Are surrounded by a cell membrane2. At some time during their life contain DNA
Single cellEnclosed by a plasma
membrane Usually encased in a
rigid cell wall • The cell wall may be
covered by a sticky capsule
Inside the cell are its DNA and other parts
Ribosomes
Figure 4.4
Capsule
Cell wall
Plasmamembrane
Prokaryoticflagella
Nucleoid region(DNA)
Pili
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All other life forms are made up of one or more eukaryotic cells
These are larger and more complex than prokaryotic cells
Eukaryotes are distinguished by the presence of a true nucleus
Structure:Nuclear envelope: double
membrane perforated with pores
Contains most of cell’s DNA in form of chromatin (DNA and protein)
Houses nucleolusMakes ribosomal parts
Function:Control center of cellDirects protein synthesis
Structure:RNA and proteins
found throughout cytoplasm and attached to endoplasmic reticulum
Function:Site of protein synthesis
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• Cells that are active in making proteins have lots of ribosomes
Structure:Channels made of
membranesSmooth ER
Synthesizes lipids, phospholipids, and steroids
Carbohydrate metabolismDetoxifies drugs & poisons
Rough ERProtein synthesisMembrane production
Have lots of Smooth ERExtract many harmful
materials from the blood and excrete them in the bile or from the kidneys.
http://www.zoology.ubc.ca/~berger/B200sample/unit_8_protein_processing/images_unit8/0_300_er.jpg
Structure:Stack of membranes
Function:Modify, sort and
package proteins and other molecules for storage in cells or secretion out of cells
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http://cellbiology.med.unsw.edu.au/units/images/tem_golgi1.jpg
Structure:Small membrane sack
filled with enzymesFunction:
Digestion of lipids, carbohydrates, and proteins
Break down worn out organelles
http://publications.nigms.nih.gov/insidethecell/ch1_animalcell_big.html
http://publications.nigms.nih.gov/insidethecell/images/ch1_lysosome.jpg
Structure:Small membrane
sack filled with enzymes
Function:Contain enzymes for
specific metabolic pathways; all contain hydrogen peroxide
Contain catalase 2H2O2 catalase 2H2O + O2
Structure:Saclike structures of
membraneFunction:
Store materials like water, salts, proteins, and carbohydrates
Stores organic compounds
Stores inorganic ions
May contain pigments
May contain poisonsPlays role in plant
growth & elongation
Protists may have contractile vacuoles• These pump out
excess water
Figure 4.13B
Nucleus
Contractilevacuoles
Copyright © 2003 Pearson Education, Inc. publishing Benjamin CummingsCollapsing contractile vacuole of Protozoawww.microscopy-uk.org.uk/.../vidjuna.html
Structure:Enclosed by double
membraneContains ribosomes and
own DNA (maternal)Function:
Responsible for Cellular Respiration (converts chemical energy in glucose into chemical energy in ATP)
Grows and reproduces by itself
Structure:Enclosed by double
membraneContains ribosomes
and own DNA Function:
Site of photosynthesis in plants (converts solar energy into chemical energy in glucose)
http://www.s-cool.co.uk/assets/learn_its/alevel/biology/cells-and-organelles/organelles/chloroplast-b.gif
Structure:Network of protein
filamentsMicrofilaments-made of
actinMicrotubules-hollow
tubules made of tubulin
Function:Helps maintain cell
shape
MicrofilamentsTough, flexible framework
that supports cellCell movement-assembly
and disassembly for cytoplasmic movement
MicrotubulesForm mitotic spindle for
separating chromosomes
Form cilia and flagella for cell movement
Amoebahttp://plantphys.info/organismal/lechtml/images/amoeba.jpg