INTRODUCTION TO

MICROBIOLOGY

July 23, 2013 7th Grade

Objectives

Learn about the major categories of microbes

Bacteria

Viruses

Parasites

Fungi

Study further structural features of each

Give examples of clinically important microbes from

each category

Microbes

Oldest form of life on earth

Simple life forms, reproduce rapidly

Found everywhere!!

Some are pathogenic

Some are beneficial

Major categories of microbes

Bacteria

Viruses

Parasites

Fungi

Bacteria

Morphology

There are three basic shapes for bacteria

Cocci – round

Bacilli – rod shaped

Spirochetes – spiral

Bacteria

Metabolic needs of bacteria

3 different types

Obligate aerobes

Need oxygen to survive

Obligate anaerobes

Cannot survive in the presence of oxygen

Use fermentation

Facultative anaerobes

Can use both aerobic respiration and fermentation

Bacteria

Bacteria Cell Structure

Bacterial Genome

Circular

Not membrane-bound

Plasmids

Autonomous nucleotide-containing

structures

Often confer advantage to the

bacterium

Bacteria Cell Structure

Cell wall

Composed of peptidoglycan

Maintains overall shape of bacterial cell

Mycoplasma

Bacteria that have no cell wall, therefore no defined shape

Bacteria Cell Structure

Pili

Hollow, hair-like structures made of

protein

Allow bacteria to attach to other cells

Sex Pilus

A special kind of pilus

Allows the transfer of material from one

bacterial cell to another

Bacteria Cell Structure

Flagella

Long appendages that rotate by means of a “motor”

located just under the plasma membrane

For motility

Bacteria may have one or many flagella in different

positions on the cell

Bacteria Cell structure

Cytoplasm

Ribosomes

Plasma Membrane

Gram Staining

Staining technique used to visualize differences in

bacterial cell wall structure

Gram positive vs Gram negative

Virus

Submicroscopic particle that can infect the cells of a

biological organism

Are not plants, animals, or bacteria…but are

parasites of the living kingdoms

Not considered to be living organisms

Virus

The ultimate parasite

Rely on their host for survival

Have genetic material (DNA or RNA) but lack ribosomes

needed to translate it into proteins

Cannot generate or store energy in the form of ATP

Have to derive their energy and all other metabolic functions

from the host cell

They basically take control of the host cell and use it for its needs

They also rob the host cell for the basic building materials

Amino acids, nucleotides, lipids

https://www.youtube.com/watch?v=e7DkeQ0roAM

Viral Genetic Material

All viruses have DNA or RNA, but not both

It can be single or double stranded

This genetic material is then transcribed into proteins

using the host cell’s machinery

Virus Structure

Capsid

Is the protein shell that encloses the virus

All viruses have capsid

Has three functions

Protects the virus from digestion by enzymes

Contains special sites on its surface that allow the cell to

attach to a host cell

Provides proteins that enable the virus to penetrate the host

cell membrane

Virus Structure

Viral envelope

Many viruses have a glycoprotein envelope

surrounding the capsid

Is composed of a phospholipid bilayer, complete with

interspersed proteins

Not all viruses have envelope

Virus Structure

Major viruses and their diseases

West Nile- encephalitis

Retrovirus – HIV- AIDS

Influenza- the flu

Adenovirus – pink eye

Parasite

Is any organism the uses a host to live

in for food, shelter, protection,

reproduction

Major types

Protozoa

Single celled organisms

Helminths

Worms

Parasite

Protozoa

Single celled eukaryotes

Are motile

Belong to kingdom protista

Can be free- living or parasitic

Examples

Paramecium

Amoeba

Euglena

Parasite

Medically important protozoa:

Single celled

Plasmodium

Trypanosoma

Helminths (worms)

A worm or worm-like animal, that can be parasitic

Some are microbes, some are not

Include roundworm, tapeworm, flukes

Have intermediate hosts for larval development and

definitive host for adult form

Parasite Videos

Trypanosoma and Sleeping Sickness

https://www.youtube.com/watch?v=4aVUrGO97Z

g

Worms!

https://www.youtube.com/watch?v=LoDJuO1idvI

Parasite

Medically important

Helminths

Tapeworms

Hookworms

Pinworms

Roundworms

Chinese liver fluke

fungi

Microbiology

The best subject in the world!

Fungi

Single-celled (yeast)

Multi-cellular Networks of long hollow tubes called Hyphae

Hyphae can aggregate into dense network known as Mycelium

Mycelia cluster into complex structure, known as the Fruiting Body

Mushroom is often the name given to the fruit

Yes…mushrooms are fungi.

Fungus is used everyday in foods such as mushrooms, yeast for bread, beer, and drugs

Fungi

Hyphae

Mycelium

Fruiting body

A B C

Fungi

Medically important Fungi

Candida albicans

Aspergillus

Algae

Chiefly aquatic, eukaryotic plant like organisms without true

stems, roots, or leaves

Most are autotrophic, photosynthetic, and contain chlorophyll

Produce most of the oxygen in the world available to

humans (about 70%)

Today’s Lab

Objective: To observe the structure and morphology of various microorganisms under the microscope

No Hypothesis

Procedure:

Wet mounts were made and microscopes were used to observe different microorganisms

Results/Data: Draw, color and label what you see

Remember to treat your microscope with care

Clean objective lenses with lens paper/ lens wipes, but NEVER KIM WIPES

Slide Preparation

Wet mount

Drop of water on slide

Add cells

Cover with cover slip

View live cells

HOMEWORK

Review Today’s slides

Read and write up your lab procedures for the

simple staining lab and the Gram staining lab.