Transcript Classification, Bacteria, and Viruses notes

CLASSIFICATION,
BACTERIA, AND VIRUSES
Biology 
Classification

Taxonomy is:
 the

science of naming and classifying organisms
Linnaeus developed a two-word naming systems
called binomial nomenclature.
 Each
species is assigned a two-part scientific name.
 Written in italic, with just the first word capitalized
 First
word: Genus
 Second word: species
 For examples, humans are Homo sapiens
Classification

Overtime, Linnaeus’s classification/taxonomy system
expanded to organize living things further. This
includes:
 Kingdom
 Phlyum
 Class
 Order
 Family
 Genus
 Species
Classification
Classification

Cladograma
model used by evolutionary biologists to represent
evolutionary history among species
 Clade- a group of species that includes a single
common ancestor and all descendants of that ancestor.
 Derived character- a trait that arose in the most recent
common ancestor of a particular lineage and was
passed along to its descendants.
Classification
Classification

Classification has broaden beyond kingdoms to
domains:
 Bacteria
 Archaea
 Eukarya
Domain Bacteria

Characteristics:
 Unicellular
prokaryotes
 Peptidoglycan cell wall, cell membrane, ribosomes
 No membrane-bound organelles
 Naked DNA, single circular chromosome
 Asexual reproduction= binary fission
 Heterotrophs, photoautotrophs, chemoautotrophs
 Rods, spheres, spirals: Gram positive and gram
negative
Domain Bacteria

Domain Bacteria
 Examples
include: Bacillus, E. Coli, Streptococcus
Domain Archaea

Characteristics
 Unicellular
prokaryotes
 Cell wall (no peptidoglycans), cell membrane,
ribosomes, no membrane-bound organelles
 DNA + histone proteins, single circular chromosome
 Asexual reproduction = binary fission
 Extremophiles: halophiles, thermophiles, methanogens
Domain Archaea

Examples:
 Methancoccus,
Halobacterium, Thermoproteus
Domain Eukarya

Examples:
 Animals,
 *We
Plants, Fungi, Protists
will explore each Kingdom in more detail
throughout the remainder of the year 
Prokaryotes

All bacteria are prokaryotes unicellular
organism that lack a nucleus.
 small cells (about 1-10 µm) that do not have
membrane-bound organelles
 Found in bacteria and archaebacteria
Prokaryotes

Bacteria
 Surrounded

by cell wall which contains peptidoglycan
Archaebacteria
 Look
similar to bacteria
 Lack peptidoglycan in cell walls
 Live in harsh environments
Bacteria

Prokaryotic Cell Structures:
 Nucleoid region –


Cell membrane –


innermost covering of the cell
Cell wall –


part of the prokaryotic cell where the DNA is found
outside of cell membrane
Capsule –

outside of the cell wall, protective covering (not all
bacteria have it)
Bacteria
Prokaryotic Cell Structures (continued):
 Flagella (sing. Flagellum) –


Endospore


short, hair-like projection used to stick to other surfaces and for
conjugation (exchange of genetic materials between bacteria)
Cytoplasm –


A thick wall that encloses DNA; resistance structure enabling
bacteria to survive harsh conditions
Pili –


long, whiplike structure that moves bacteria
jelly-like fluid that dissolves substances and holds organelles
Ribosomes –

organelles that make proteins in the cytoplasm
Bacteria
Bacterial cell walls

In bacteria, the cell wall consists of a
protein/carbohydrate complex called carbohydrate
called peptidoglycan. They are classified based on
their cell walls:
 Gram
positive bacteria
 More
peptidoglycan in cell walls
 Appear purple under the microscope after gram stain
 Gram
negative bacteria
 Have
less peptidoglycan in cell walls
 Have outer membrane
 Apper pink under the microscope after gram stain
Bacteria- shapes

Bacilli
 Rod-shaped

Cocci
 Spherical-shaped
 Staph-
clusters
 Strep-chains

Spirilla
 Spiral-shaped
as either:
Bacteria-shapes
Bacteria- modes of nutrition

Heterotroph


Photoheterotroph


Consume other organisms and can use light energy:
Rhodobacter
Photoautotroph


Consume other organisms: Clostridium
Use light energy to make carbon compounds;
Cyanobacteria
Chemoautotroph

Use chemicals, like ammonia and hydrogen sulfide, to obtain
energy; Nitrogen-fixing bacteria
Bacteria- Aerobic, Anaerobic, and
Facultative Anaerobes

Aerobic
 Need

oxygen to live
Anaerobic
 Cannot

live with oxygen
Facultative anaerobes
 Can
live with or without oxygen
Bacteria- Binary Fission

Binary fission
 Process
by prokaryotes reproduce by cell division.
 Steps:
 Duplication
of chromosomes and separation of copies.
 Cell elongates
 Divides into two daughter cells
Bacteria- Binary Fission
Bacteria and Disease

Pathology- the study of disease caused by
pathogens (microorganism—viruses or prokaryotes–
that cause disease)
Bacteria and disease

Bacteria cause disease by destroying living cells or
by releasing chemicals that upset homeostasis.
 Damaging
host tissue
 Releasing toxins
Bacteria and Disease

Bacteria can be controlled via:
 Physical
removal
 Disinfectants
 Food storage
 Food processing
 Sterilization by heat
Bacteria and Disease

Bacterial diseases can be treated via Antibiotics
 Blocks
the growth and reproduction of bacteria
 Examples: penicillin, streptomycin, and tetracycline
Bacteria and Disease

Prevention of a bacterial disease via:
 vaccineA
preparation of weakened or killed pathogens or
inactivated toxins that prompt the body to produce immunity
to a specific disease upon injection.
Virus

Virus
A
nonliving particle made of proteins and nucleic acids.
 Can reproduce only by infecting living cells.
 Have no cytoplasm or organelles
 Cannot carryout metabolism or homeostasis
 Can’t grow like cells.
Virus

Viruses consist of…
 Capsid-
protein coat surrounding a virus
 Some viruses have an envelop that surrounds the
capsid (Influenza)
 Nucleic acids (either DNA or RNA)
Virus

Shapes
 Helical-
Tobacco Mosaic Virus (contains RNA)
 Polyhedral- Herpes (contains DNA) , Chicken Pox (contains
DNA), Polio (contains RNA)
 Spherical (enveloped)- Influenza (contains RNA)
 Bacteriophage- T4 (contains DNA)
Helical
Spherical
Bacteriophage
Virus

Viral Infections In
order to infect a cell, a virus must be able to
recognize it.
 Viruses must bind the proteins on their capsid
specifically to the proteins on their specific host.
 Viruses then “trick” the cell to take in its genetic
material.
 Viruses will then make multiple copies of themselves
inside the cell, ultimately destroying the cell.
Virus

Viral Infections can take place in two ways Lytic
infection
 Lysogenic infection
Virus

Lytic Infection
 The
virus infects a cell, it replicates, and the new viruses
burst or “lyse” from the cell.
Virus

Lysogenic Infection
 host
cell is not immediately taken over
 The virus infects a cell, the viral DNA integrates with
host DNA where it may stay for a long period of time.
 The viral DNA multiplies as the host cells multiply.
 Eventually, it will become lytic, and the viruses will burst
from the cell.
Viruses and Disease

Viruses cause disease by directly destroying living
cells or by affecting cellular processes in ways that
upset homeostasis. Diseases include:
 Common
cold
 Influenza
 AIDS
 Chicken
pox
 Hepatitis
 Wes Nile Virus
 HPV (Human papillomavirus)
Viruses and Disease

Ways to fight viruses Hygiene Washing
hands, avoiding contact with sick individuals, coughing
or sneezing into a tissue or your sleeve
 Vaccinations
 Exposure
to inactive forms of the virus that prompt the body to
produce immunity to a specific disease upon injection.
 Vector
control
 West
Nile Virus is carried by mosquitoes (the vector). Controlling
the population mosquitoes could eliminate the spread of the
virus.
 Antiviral
 Attack
drug therapy
virual enzymes that in turn slow down or stop the infection
cycle of the virus.