Introduction to Cells and
Microscopy
Introduction to cells A brief history leading to microscopy
Basic cell structure
Surface area (limitations to cell size)
Modes of Nutrition
Some History
The Renaissance (French for 'rebirth', or
Rinascimento in Italian),
The historical age spanning roughly the
14th through the 16th centuries.
The Renaissance
The principal features were the revival of
learning based on classical sources, a time of
significant advancements in science.
Brief History of Microscopy
Telescope introduced by Galileo Galilei to astronomy in 1609. Galileo's telescope was similar to a pair of opera glasses
First man to see the craters of the moon, sunspots, the four large moons of Jupiter, and the rings of Saturn.
Confirmed Copernican Heliocentric theory of solar system
In 1624, he developed an early example of the microscope
Early Microscopists:
1665
•Robert Hooke (1635-1703)
•Used simple microscope to view cork slices
•Observed tiny compartments or “cells”
1670
•Antoni von Leeuwenhoek (1632-1723)
•Exceptional lens maker
•First to observe microscopic organisms (protista, bacteria)
•He called them “animalcules”
Cell Theory (1838-1839)
1. All organisms
are composed
of one or more
cells
2. Cells are the
basic living unit
of organization
Schleiden (botanist) Schwann (zoologist)
Cell Theory (1839-1858)
3. All cells arise from
preexisting cells
Or
Omnis cellula e cellula
“every cell from a cell”
Rudolf Virchow (physician)
Cell Theory
1. Every organism is composed of one
or more cells
2. Cells are the basic living unit of
organization
3. All cells arise from preexisting cells
Smallest unit of life
Is highly organized for metabolism
Senses and responds to environment
Has potential to reproduce
Cell
Fig. 3-4, p.41
Most Cells Are Really Small
http://learn.genetics.utah.edu/content/cells/
scale/
http://learn.genetics.utah.edu/content/cells/
scale/
Create detailed images of something
that is too small to see
Light microscopes
Simple or compound
Electron microscopes
Transmission EM or Scanning EM
Microscopes
Ocular lens enlarges
primary image formed
by objective lenses.
Path of light rays
(bottom to top) to eyePrism
(directs rays to
ocular lens)
Objective lenses (closest
to specimen) form
primary image.
Stage (holds
microscope slide in
position)
Condenser lenses focus
light rays through specimen.
Illuminator
Fig. 3-2a, p.40
Compound Scope
• Has magnification limits
• Lower limit is ~0.25-0.5
µm
• Can barely discern
organelles
Electron Microscopy
Used since the 1950’s to
study finer call details
(ultrastructure)
Uses beams of electrons
rather than light
Electrons are focused by
magnets rather than
glass lenses
Can resolve structures
down to 0.5 nm
Fig. 3-10, p.48
Different Views
Structure of Cells
All start out life with:
Plasma membrane
Region where DNA
is stored
Cytoplasm
Two types:
Prokaryotic
Eukaryotic
Basic Cell Structures
1. Plasma
membrane
2. DNA
3. Cytoplasm
4. Ribosomes
DNA in
nucleoid
cytoplasm
plasma membrane
Bacterial cell
(prokaryotic)
Fig. 3-1a, p.39
Types of
Cells
DNA in nucleus
cytoplasm
plasma membrane
Plant cell
(eukaryotic)
Fig. 3-1b, p.39
Types of
Cells
DNA in
nucleus
cytoplasm
plasma
membrane
Animal cell
(eukaryotic)
Fig. 3-1c, p.39
Prokaryotic Cells
Pro - before karyote - nucleus
Smallest & simplest
Two Domains:BacteriaArchaea
Bacteria
Cyanobacteria
Plasma membrane
Cell Wall
Ribosomes
DNA
Nucleoid Region
Mesosome
Domain Bacteria
Bacteria and
circular DNA
Bacteria and flagella
Cyanobacteria
Domain ArchaeaMethanogens
Extreme Thermophiles
Extreme Halophiles
Eukaryotic Cells
Eu – true
Karyote - nucleus
All cells except
bacteria & archaea
Many membrane-
bound organelles
Domain Eukarya
Kingdom Animals
Kingdom Plants
Kingdom Fungi
Kingdom ProtistsPlants
Animals
Animal CellPlasma
membrane
Mitochondria
Nucleus
Cytoplasm
& ribosomes
Endoplasmic Reticulum
Golgi Bodies
Transport Vesicles
Lysosome
Animal Cell
Plant Cell
Cell Wall
Plasma
membrane
Chloroplast
Mitochondria
Cytoplasm &
ribosomes
Central vacuole
Nucleus
Endoplasmic Reticulum
Golgi Bodies
Plant Cell
Surface-to-Volume Ratio
Bigger cell, less surface area per unit
volume
Above a certain size, material cannot
move in or out of cell fast enough
1x1x1 10x10x10 100x100x100
SA = 6in2 SA = 600in2 SA = 60,000in2
V = 1 in3 V = 1000in3 V = 1,000,000in3
Ratio = 6/1 Ratio = 6/10 Ratio = 6/1000
Limits to Cell Size
Surface to Volume Ratio
As cells get larger volume increases by the cube (X3),
whereas the surface increases by the square (X2)
Surface-to-Volume Ratio
Bigger cell, less surface area per unit
volume
Above a certain size, material cannot
move in or out of cell fast enough
Surface / Volume Solutions
1. Increase surface area
flattened form
infolded edges
elongated cells
2. Benefits to Multicellularity
specialization of function
increased efficiency
Types of Nutrition
Nutrition – means by which organisms obtain
materials for growth, repair, and energy
Heterotrophic – organisms that obtain all
nutrients from the environment
animals
fungi
most bacteria
most protists
Types of Autotrophic Nutrition
Photosynthesis – use sunlight to make sugar
Plants
Some protists
Cyanobacteria
Photoautotrophic – organisms which can make
food by joining: energy + H2O + CO2 + some minerals
Types of Autotrophic Nutrition
Chemoautotrophic – utilize inorganic
compounds to synthesize sugar
Energy from the oxidation of:
Ammonia, Iron, Sulfur, Arsenic
Bacteria Only
Nutrients needed by plants:
1. Water (H2O)
2. Carbon dioxide (CO2)
3. Minerals+ + +
C6H12O6+O2
sugarSunlight + water + CO2 + minerals
Basic Organic Compounds of Life:
Compound Examples Composed of:
Carbohydrates Sugar, cellulose,
starch, glycogen,
chitin
CHO
Basic Organic Compounds of Life:
Compound Examples Composed of:
Carbohydrates Sugar, cellulose,
starch, glycogen,
chitin
CHO
Lipids Fats, oils, steroids,
waxes, phospholipids
CHO (P)
Basic Organic Compounds of Life:
Compound Examples Composed of:
Carbohydrates Sugar, cellulose,
starch, glycogen, chitinCHO
Lipids Fats, oils, steroids,
waxes, phospholipidsCHO (P)
Proteins Structural proteins,
enzymes
CHON (S)
Basic Organic Compounds of Life:
Compound Examples Composed of:
Carbohydrates Sugar, cellulose,
starch, glycogen, chitinCHO
Lipids Fats, oils, steroids,
waxes, phospholipidsCHO (P)
Proteins Structural proteins,
enzymesCHON (S)
Nucleic Acids RNA, DNA, ATP CHONP
Plants contain all the basic organic
compounds except glycogen & chitin