MicrobiologyIt’s a small world…

Chapters 7 and 19

LIFE IS CELLULAR•Cell Theory

–All living things are made up of cells.

–Cells are the basic units of both structure and function in living things.

–New cells are made only from existing cells.

BASIC CELL STRUCTURE

•All cells have:–Cell membrane – thin layer that surrounds cells

–Cytoplasm – gel like material inside cells (the “juice”)

–Genetic material (DNA and/or RNA)

–Ribosomes – make proteins

•Some cells have:–Cell wall – more rigid structure on outside of some cell membranes

–Nucleus – contains genetic material (brain of the cell)

–Mitochondria – make energy (powerhouse)

–Chloroplasts – make sugar (photosynthesis)

DIVERSITY OF LIFE• All cells fall into two categories of cells:

1.Prokaryotes• Includes bacteria

2.Eukaryotes• Includes animals, plants, fungi,

and protists (like amoebas and paramecium)

CHARACTERISTIC OF PROKARYOTES

•No membrane-bound organelles (“little organs” in cells)

•No nucleus, mitochondria, or chloroplasts

•Have DNA, ribosomes, cytoplasm, cell membrane, and cell wall

Bacterium

•Fossil evidence shows that bacteria have been on the earth for over 3.5 billion years

•Three major shapes–Cocci (round)–Bacilli (rod-like)–Spirilla (spiral)

HARMFUL BACTERIA• Some bacteria are pathogens (disease causing)• Some bacteria can make endospores, which

allow bacteria to survive long periods of time (even in bad conditions)

• Diseases caused by bacteria:

Botulism

Strep throat

Leprosy

HELPFUL BACTERIA• In your intestine, E. coli help to

digest food• Used to make yogurt• Can be used to degrade oil and

toxic waste spills• Used to make certain medicines• Used as “gene” factories• Help plants fix nitrogen• Major decomposers

Decomposition over 2 weeks

Legumes with nitrogen fixing bacteria in their

roots

KILLING BACTERIA• Antibiotics- drugs that kill bacteria by

blocking growth or reproduction– Antibiotics do NOT kill any viruses so

they do not cure the common cold or flu

– Some bacteria are now resistant to antibiotics (ex. MRSA)

– We must always take antibiotics as prescribed!

• Sterilization – destroying bacteria by heating or with chemicals

Archaea

• Extremophiles activity.• List seven different types of

extremophiles from the archaea domain and explain their habitat requirements.

CHARACTERISTICS OF EUKARYOTES

• Cell membrane• Cytoplasm• Cytoskeleton• Ribosomes• Organelles that are membrane bound

(ex. mitochondria and chloroplasts)• Fossil evidence shows that eukaryotic cells

have been on the earth for approximately 1 billion years.

Animal Cell

Plant Cell

VIRUSES• Viruses are particles made up of

nucleic acid (DNA and/or RNA), protein, and sometimes lipids.

• Viruses are NOT living because they cannot reproduce by themselves.

• All viruses enter (infect) living cells and once inside of a cell, they make more viruses.

• All viruses are pathogens.• Viruses are thought to have evolved

from pieces or fragments of cells.

VIRUS STRUCTURE

• Viruses have a core of genetic material surrounded by a capsid (protein coat)

• They are much smaller than bacteria and animal cells.

• They come in many shapes.

VIRAL INFECTIONS

• All cells can be infected by viruses including bacteria, animals, and plants.

• Bacteriophage – a virus that infects a bacterial cell

• There are two main methods of infection:1.Lysogenic2.Lytic

Bacteriophage (virus) infecting a bacterium

LYTIC CYCLE

• Viruses inject their genetic material (DNA or RNA) into the host cell.

• This genetic material gives instructions to make viruses.

• The viruses are released by causing the cell to burst (lyse), which kills the cell.

LYSOGENIC CYCLE • A virus injects its genetic material

(DNA or RNA) into the host cell.• The virus’s genetic material is

mixed in with the host DNA.• Viral DNA can stay embedded in the

host DNA for long periods of time.• Sometimes, the viral DNA will

instruct new viruses to be made and the lytic cycle begins.

VIRAL DISEASES• Polio• AIDS• Influenza (the flu)• Yellow fever• Rabies• Common cold• Some cancers like cervical cancer• Measles• Small pox

Small Pox

Measles

Polio

1918 Flu Pandemic

Herpes

VACCINES

• Vaccines – made from weakened or “killed” viruses

• Vaccines stimulate the immune system to fight a specific disease

• Vaccines help prevent viral and bacterial diseases from developing, but cannot help someone already infected

• Examples include: HPV, MMR, Hep A

PRIONS

• Prions - possibly infectious proteins that can change brain proteins causing brain damage

• Diseases caused by prions progress rapidly and are almost always fatal

• Diseases caused by prions include:– Mad Cow Disease– Creutzfeldt-Jakob Disease (CJD)

Creutzfeld-Jakob Disease

Spread the word, not the germs!1) WASH your hands when they are dirty and BEFORE

eating. 2) DO NOT cough into your hands. 3) DO NOT sneeze into your hands. 4) DO NOT put your fingers into your eyes, nose, or mouth.

• Regular soap and water are best. Antibacterial soaps are not necessary if you have spent enough time (at least 20 seconds) cleaning your hands with regular soap and water.

• (Source: www.henrythehand.com)