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