PROKARYOTES, BACTERIA, & VIRUSES · Eukaryotes v. Prokaryotes Eukaryotes Larger (up to 100 times!)...
Transcript of PROKARYOTES, BACTERIA, & VIRUSES · Eukaryotes v. Prokaryotes Eukaryotes Larger (up to 100 times!)...
PROKARYOTES, BACTERIA, &
VIRUSES
Eukaryotes v. Prokaryotes
Prokaryote Characteristics
Single cell
No true nucleus
Few organelles
Archaebacteria – extreme environments
Eubacteria –
“normal” bacteria
Eukaryotes v. Prokaryotes
Eukaryotes
Larger (up to 100 times!)
More complex
Nucleus
Have chromosomes
Membrane bound organelles
Ex: Animals, plants, protists
Prokaryotes
Smaller
Not as complex
No nucleus
Have single strand of DNA and plasmid
No membrane bound organelles
Ex: Bacteria
CHARACTERISTICS of Bacteria
Prokaryotes – meaning “before a nucleus”
Divided into 2 domains
Bacteria
Archaea
Archaebacteria
Dominate in extreme environments
3 types
Thermoacidophiles
Hot, acidic areas (ex: sulfur hot springs, thermal vents on ocean floor)
Halophiles
Very salty areas, usually aerobic (ex: Great Salt Lake, Dead Sea)
Methanogens
No oxygen (anaerobic) areas, take in oxygen and give off methane (ex: sewege treatment, swamps, bogs)
EUBACTERIA
Most studied organism
Found everywhere, except extreme environments
Very strong cell walls (has peptidoglycan)
Some have a second cell wall
PROKARYOTE STRUCTURE
Genetic material (DNA)
Flagella
Pili
Ribosomes
Capsule
FUNCTION of the Structure
DNA – found in nucleoid (Remember: prokaryotes DO NOT have a nucleus)
Capsule – polysaccharide layer (aka sugar), prevents dry-out, helps attach cell to surfaces, prevents WBC’s from “eating” them
Pili – made of protein, hair-like, also helps attachment, can act as a bridge between cells
Flagella – helps with locomotion (aka movement)
Ribosomes – make proteins for the chromosomes
HOW DO WE IDENTIFY BACTERIA??
Shape
Cell Walls
Movement
SHAPE of Bacteria
Cocci – spherical, round shape
Bacilli – rod-shaped
Spirilli – spiral - shaped
Strepto – long chains
Staphylo – clumps
Diplo - pairs
Let’s Practice… DRAW THE FOLLOWING BACTERIA:
1.Staphylococcus
2.Streptococcus
Now, write the types from the pictures below…
1. 2. 3.
CELL WALLS
Have peptiodglycan
(made of dissacharides & peptide fragments)
Why is it important for
bacteria to have strong cell walls?
MOVEMENT
Some are stationary
Some use flagella to move
Bacteria REPRODUCTION Sexual Reproduction – called
Conjugation
Cells attach and exchange info
Asexual Reproduction – called Binary Fission
Chromosome replicates, then separates
Can happen every 20 min.
Becomes 1 BIL. IN 10 HRS!
METABOLISM of Bacteria Photoautotrophs
Do photosynthesis need light to live
Called cyanobacteria
Release Oxygen into the environment
Chemoautotrophs
Do not require light
Break down & release inorganic compounds (Nitrogen or Sulfur) and keeps them cycling
Aerobes
Require oxygen to grow
Anaerobes
Do not require oxygen, use fermentation instead
SURVIVAL
Endospores
Dormant cell
Resistant to harsh conditions
Forms around chromosome and small part of cytoplasm
Ex: anthrax, botulism, tetanus
Mutations
Quick reproduction, so genetic mutations help survival
Leads to “antibiotic - resistant bacteria”
ECOLOGY of Bacteria
Bacteria are decomposers and return vital nutrients to the soil/environment
NORMAL FLORA – harmless bacteria in & out of your body
E.Coli in your intestines makes Vitamin K (for blood-clotting)
DIFFERENT from the food poisoning kind
FOOD & MEDICINE
Cheese, yogurt, pickles – made w/the help of bacteria
Used to make CHOCOLATE (bacteria breaks down the cocoa bean covering)
MEDICINE – some anti-biotics (ex: tetracycline) originally made by bacteria
DISEASE –CAUSING Bacteria
Only a small % of bacteria ACTUALLY cause disease
They harm in two ways…
Bacteria multiply quickly @ the infection site
Bacteria secrete a toxin that can cause harm
(ex: Botulism – paralyzes nervous system cells)
DISEASE –CAUSING Bacteria
PATHOGENS – disease-causing bacteria
ANTIBIOTICS – block the growth & reproduction of bacteria (they break down the cell wall)
How to Control “BAD” Bacteria
STERILIZATION – heat or chemically treat bacteria to kill it
Disinfect – chemical solution kills bacteria
Refrigerate – bacteria grows slower in the cold
Heat/Boil – high temps kill bacteria
VIRUSES
Why are viruses NOT ALIVE???
No organelles to take in nutrients or energy
Cannot make proteins
Cannot reproduce on their own
VIRUS STRUCTURE
Viruses contain a nucleic acid & a protein coat
Two regions: head & tail
HEAD:
Capsid – protein coat
Nucleic acid core (DNA)
TAIL:
Tail:To attach to host
Tail fibers
VIRAL INFECTION
To infect, a virus must find a host cell
The virus attaches to a specific site
Most viruses cannot transfer between species
BASIC STEPS OF
VIRAL INFECTION
1.Attachment to the host cell
2.Release of the viral genes
3.Replication
4.Assembly of viral components
5.Release of viral particles for further infection
Lytic vs. Lysogenic Cycles
Lytic Cycle
The host cell immediately makes many copies of the viral DNA or RNA
Viral genes instruct host cell to make more viral capsids before the viruses leave the cell
Lysis of host cell (or bursting when virus exits)
Common diseases: common cold, influenza
Lysogenic Cycle
Viral DNA inserts (or integrates) into a host cell and becomes part of the nucleus
This virus can be dormant for a long time in the cell’s nucleus
Infected cell will have the viral genes permanently
Common diseases: AIDS, herpes
RETROVIRUSES
Viruses that have RNA instead of DNA for their genetic material
Contains the enzyme reverse transcriptase
Retroviruses have a protein capsid
Example: HIV
PRIONS
A protein that can cause an infection
Normally exist in cells, although their function is not well know
Normal prions = coil-shaped
When mutations occur they become accordian-shaped, which can then cause disease because of their shape
Disease caused by prions – Mad Cow Disease
Types of Viruses - Bacteriophage
Bacteriophage – a virus that infects bacteria
KNOW THIS STRUCTURE! (Capsid, tail, tail fibers, DNA (or genetic material))
PATHOGENIC VIRUSES (something that causes a disease or disorder)
Ebola zaire
AIDS
Rhinovirus
Influenza
Measles, mumps, chicken pox
Polio
Rabies
Smallpox