Transcript BACTERIA & VIRUSES - Bishop Shanahan High School

Prokaryotes & Viruses
PROKARYOTES
SINGLE CELLED; WITHOUT
NUCLEUS
1 – 5 MICROMETERS IN SIZE
ARCHAEBACTERIA
LACK PEPTIDOGLYCAN IN CELL
WALL
LIPIDS IN CELL MEMBRANE
DIFFERENT
DNA SEQUENCES HAVE
INTRONS – LIKE EUKARYOTES
EUBACTERIA (BACTERIA)
GREAT VARIETY; INCLUDES
MOST BACTERIA
LIVE ALMOST EVERYWHERE!
CELL WALL: PEPTIDOGLYCAN
SOME HAVE CAPSULE; PILI
SHAPES OF BACTERIA
BACILLUS – ROD SHAPED
COCCUS – SPHERICAL
SPIRRILLUM – SPIRAL
CHAINS: Strepto-; CLUSTERS:
STAPHO-
CELL WALL
GRAM STAIN: 2 dyes – violet
(main); red
Gram +: cell wall thicker; mostly
peptidoglycan; absorb violet stain
Gram -: second layer of lipid &
carbohydrate; absorbs red; more
resistant to antibiotics
CAPSULE
MANY HAVE ONE; SURROUNDS
CELL WALL
POLYSACCHARIDES; PROTECTS
CELL FROM DRYING OUT
IF FUZZY: glycocalyx – allows cell to
stick to host cell or substrate
PILI
SHORT EXTENSIONS ON SOME
ADHERENCE TO HOST; SOME
USED TO TRANSFER GENES
FROM ONE CELL TO ANOTHER
NUTRITION (GETTING
ENERGY)
AUTOTROPHIC
Photoautotrophs
Cyanobacteria (in jellylike
covering).
Heterocysts - N fixation
Phycocyanin & Chl a
AUTOTROPHS (CONTD)
Chemoautotrophs
– Use inorganic chemical energy to make organic
molecules
– Gram – bacteria
HETEROTROPHS
MOST
DECOMPOSERS/SAPROPHYTES
ENTERIC: Gram - inhabit animal
intestine. E. coli – Produces Vitamin
K
RELEASING ENERGY
AEROBIC
ANAEROBIC – Clostridium botulinum
FACULTATIVE ANAEROBE
GROWTH & REPRODUCTION
GROW AND REPRODUCE RAPIDLY
BINARY FISSION: no genetic
exchange or recombination; asexual
CONJUGATION: hollow bridge forms
between organisms; genetic
exchange
ENDOSPORE
DORMANT FORM
MAY FORM IN UNFAVORABLE
CONDITONS
THICK WALLED; ENCLOSES
CYTOPLASM & DNA
NOT FORM OF REPRODUCTION!
ROLE IN NATURE
DECOMPOSERS – MAJOR ROLE!
Recycle nutrients
Breakdown of dead matter
Important in sewage treatment plants:
organic matter broken down can be reused
as fertilizer
ROLE IN NATURE
NITROGEN FIXATION
Nitrogen need to make amino acids for
protein
Air: contains 79% nitrogen
Plants can’t use N2 directly
Bacteria “fix” Nitrogen into NH3 or NO3
Rhizobium – Nitrogen fixing bacteria in root
nodules of legumes
ROLE IN NATURE
DISEASE CAUSING: Pathogenic
Damage tissues directly or release
toxins (Streptococcus)
Antibiotics: Block growth and
reproduction of cell; breakdown or
weaken cell wall
POSITIVE USES
CHEESE; YOGURT; BUTTERMILK; SOUR
CREAM
CLEAN UP OIL SPILLS
MINE MINERALS
SYNTHESIZE DRUGS IN GENETIC
ENGINEERING
VIRUSES
Tobacco Mosaic Virus – first isolated
Subcellular; Obligate Intracellular
parasite
Can pass through a filter; can be
crystallized
STRUCTURE OF VIRUS
NUCLEIC ACID CORE
SURROUNDED BY A PROTEIN
COAT (CAPSID)
NUCLEIC ACID: EITHER DNA OR
RNA
SOME HAVE ENVELOPE: derived
from host cell membrane during
replication (flu; HIV; Chicken pox)
CLASSIFICATION OF VIRUSES
CLASSIFIED BY ORGANISM THEY
INFECT
VIRUSES ARE SPECIFIC TO WHAT
THEY INFECT
BACTERIOPHAGE: infect bacteria;
DNA
VIRAL REPLICATION
LYTIC CYCLE – Virus enters the cell;
makes viral copies; cell bursts and is
destroyed
LYSOGENIC CYCLE- Viral DNA
becomes embedded into DNA of host
and replicates with host DNA. Cell is
not destroyed
LYTIC CYCLE: VIRULENT VIRUS
5 STAGES:
ATTACHMENT
ENTRY OF NUCLEIC ACID
REPLICATION OF VIRAL PARTICLES
ASSEMBLY
RELEASE: Lysis of cell
LYSOGENIC CYCLE:
TEMPERATE VIRUS
ATTACHMENT
INJECTION OF NUCLEIC ACID
INTEGRATION INTO BACTERIAL
CHROMOSOME (prophage)
CELL MULTIPLICATION
VIRAL DISEASES
POLIO; MEASLES; AIDS; MUMPS;
FLU; YELLOW FEVER; COLD
SOME VIRUSES ARE ASSOCIATED
WITH CANCER
VACCINE: preparation of weakened
or killed virus
RETROVIRUS
RNA CONTAINING VIRUS
RNA  DNA uses enzyme: reverse
transcriptase
DNA produced from RNA is inserted into
host cell DNA: PROVIRUS
HIV
PRIONS
PROTEIN PARTICLE CAPABLE OF
CAUSING DISEASE
ABNORMAL FORM OF PROTEIN THAT
CLUMPS INSIDE A CELL; CLUMPING
KILLS CELL
MAD COW DISEASE; SCRAPIE IN
SHEEP (nervous system degeneration)
VIROIDS
SMALLEST PARTICLES ABLE TO
REPLICATE
SHORT, SINGLE STRAND OF RNA
WITHOUT CAPSID
HARMFUL TO PLANTS
ORIGIN OF VIRUSES?
Many believe viruses evolved from
early cells
First viruses may have been naked
nucleic acid that could move from cell
to cell
Derived from degenerated form of
evolution