Classification, Bacteria, and Viruses

1
Classification, Bacteria, and Viruses

• Biology ?

2
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

3
Classification

• Overtime, Linnaeuss classification/taxonomy
  system expanded to organize living things
  further. This includes
• Kingdom
• Phlyum
• Class
• Order
• Family
• Genus
• Species

4
Classification
5
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.

6
Classification
7
Classification

• Classification has broaden beyond kingdoms to
  domains
• Bacteria
• Archaea
• Eukarya

8
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

9
Domain Bacteria

• Domain Bacteria
• Examples include Bacillus, E. Coli,
  Streptococcus

10
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

11
Domain Archaea

• Examples
• Methancoccus, Halobacterium, Thermoproteus

12
Domain Eukarya

• Examples
• Animals, Plants, Fungi, Protists
• We will explore each Kingdom in more detail
  throughout the remainder of the year ?

13
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

14
Prokaryotes

• Bacteria
• Surrounded by cell wall which contains
  peptidoglycan
• Archaebacteria
• Look similar to bacteria
• Lack peptidoglycan in cell walls
• Live in harsh environments

15
Bacteria

• Prokaryotic Cell Structures
• Nucleoid region
• part of the prokaryotic cell where the DNA is
  found
• Cell membrane
• innermost covering of the cell
• Cell wall
• outside of cell membrane
• Capsule
• outside of the cell wall, protective covering
  (not all bacteria have it)

16
Bacteria

• Prokaryotic Cell Structures (continued)
• Flagella (sing. Flagellum)
• long, whiplike structure that moves bacteria
• Endospore
• A thick wall that encloses DNA resistance
  structure enabling bacteria to survive harsh
  conditions
• Pili
• short, hair-like projection used to stick to
  other surfaces and for conjugation (exchange of
  genetic materials between bacteria)
• Cytoplasm
• jelly-like fluid that dissolves substances and
  holds organelles
• Ribosomes
• organelles that make proteins in the cytoplasm

17
Bacteria
18
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

19
Bacteria- shapes

• Bacilli
• Rod-shaped
• Cocci
• Spherical-shaped as either
• Staph- clusters
• Strep-chains
• Spirilla
• Spiral-shaped

20
Bacteria-shapes
21
Bacteria- modes of nutrition

• Heterotroph
• Consume other organisms Clostridium
• Photoheterotroph
• Consume other organisms and can use light energy
  Rhodobacter
• Photoautotroph
• Use light energy to make carbon compounds
  Cyanobacteria
• Chemoautotroph
• Use chemicals, like ammonia and hydrogen sulfide,
  to obtain energy Nitrogen-fixing bacteria

22
Bacteria- Aerobic, Anaerobic, and Facultative
Anaerobes

• Aerobic
• Need oxygen to live
• Anaerobic
• Cannot live with oxygen
• Facultative anaerobes
• Can live with or without oxygen

23
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

24
Bacteria- Binary Fission
25
Bacteria and Disease

• Pathology- the study of disease caused by
  pathogens (microorganismviruses or prokaryotes
  that cause disease)

26
Bacteria and disease

• Bacteria cause disease by destroying living cells
  or by releasing chemicals that upset homeostasis.
  
• Damaging host tissue
• Releasing toxins

27
Bacteria and Disease

• Bacteria can be controlled via
• Physical removal
• Disinfectants
• Food storage
• Food processing
• Sterilization by heat

28
Bacteria and Disease

• Bacterial diseases can be treated via-
• Antibiotics
• Blocks the growth and reproduction of bacteria
• Examples penicillin, streptomycin, and
  tetracycline

29
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.

30
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
• Cant grow like cells.

31
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)

32
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)

Bacteriophage
Spherical
Helical
33
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.

34
Virus

• Viral Infections can take place in two ways-
• Lytic infection
• Lysogenic infection

35
Virus

• Lytic Infection
• The virus infects a cell, it replicates, and the
  new viruses burst or lyse from the cell.

36
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.

37
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)

38
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 drug therapy
• Attack virual enzymes that in turn slow down or
  stop the infection cycle of the virus.