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KimberlynHernandez Chpt:19&27 - Coggle Diagram
KimberlynHernandez Chpt:19&27
Virus
Virus is an infectious particle consisting of genes packaged in a protein coat
They have a membrane
Discovery viruses
In the late 1800's researchers hypothesized that unusually small bacteria might be responsible
Structure Of Viruses
Non - Living
Membrane like envelope
Viruses are not cells
Viral Genomes
Double or Single stranded DNA
Double or Single stranded RNA
Viral genomes may consist of either
The genome is either a single linear or circular molecule of the nucleic acid
Viruses have between 3 and 2,000 genes in their genome
Virus enters cell
More severe symptoms
Result in the death of the host cell
Shorter Duration
Capsids and Envelopes
Capsis, is the protein shell that encloses the viral genome
Viral Envelopes, (Derived from membranes of host cells) surrounded the capsids of influenza viruses and many other viruses found in animals
Bacteriophages / Phages, are viruses that infect bacteria
Viruses replicate only in host cells
Each virus has a host range a limited number of host species that it can infect
Measles virus only infects humans
Viral replicative Cycles
The virus makes use of host enzymes, ribosomes, tRNA's, amino acids, ATP, and other molecules
Lytic cycle
Phage replicative cycle, culminates in the death of the host cell
Phage produced by the lytic cycle called virulent phage
Produces new phages lyses (breaks open) the host cell wall, releasing progeny viruses
Lysogenic Cycle
Use both lytic and lysogenic cycles are called temperate phages
Viral DNA molecules is incorporated into the host cells chromosoems
Replicates that phage genome without destroying the host
Retrovirus
Retroviruses use reverse transcriptase to copy their RNA genome into DNA
Reverse transcriptase
Has RNA to start vs. DNA
Viral gene material
Viral DNA is integrated into the host genome is called provirus
Provirus permanet incorporation viral genome into host genome
Viruses and Prions
Prions are infectious proteins
Happens in the brain
Emerging viral diseases
AIDS Virus
Zika
HIV
Epidemic (within the region) Pandemic (world wide)
Plant viruses
Horizontal transmission, entering through damaged cell walls
Vertical transmission, inheriting the virus from a parent
Prions
Prions are infectious proteins that appear to cause degenerative brain diseases in animals
Incorrectly folded proteins, can be transmitted in food
Prokaryotes
Single, celled organisms that make up domains bacteria & Archaea
Cell - Surface structures
Archaeal walls contain a variety of polysaccharides and proteins
Gram stain - bacteria by cell wall composition
Peptidoglycan - network of sugar polymers cross linked by polypeptides
Gram Positive - bacteria have simpler walls with large amount of peptidoglycan
Gram Negative - bacteria have less peptidoglycan
Internal Organization DNA
Prokaryotes have one circular chromosomes
Eukaryotes have multiple linear chromosomes
Prokaryotes have less DNA & produce fewer proteins that eukaryotes
Reproduction
They reproduce by binary fission
They have short generation time
They are small
Rapid Reproduction Mutation
Genetic diversity in prokaryotic population enables rapid adaptation
Transformation
Prokaryotic cells incorporate foreign DNA taken up from their surroundings
Transduction
Phages from bacteriophages viruses that infect bacteria carry prokaryotic genes from one host cell to another
Conjugation
Process through which DNA is transferred between twi prokaryotic cells
E.coli conjugation
DNA is transferred through a temporary structure called the "mating bridge"
Pilus rettracts, pulling two cells together
Pilus donor cell attached to the recipient
TACK - Related to Archaea
Thaumarchaeota
Aigarchaeota
Crenarchaeota - Included most extreme thermophiles
Korarchaeota
Prokaryotes Obtain energy & carbon
Autotrophs require CO2 or related compounds as a carbon source
Heterotrophs require and organic nutrient to make other organic compounds
Chemotrophs obtain energy from chemicals
Phototrophs obtain energy from light
Archaea
Share certain traits with bacteria and other traits with eukaryotes
Methanogens
Are obligate anaerobes that produce methane as by - product of their metabolism
F Factor as a Plasmid
F+ cell can convert an F- cell to an F+ cell if it transfers an entire F plasmid to the F-cell
F plasmids DNA is transferred the recipient cell will be recombinant
Cells lacking the F Factor (F- cells_ are recipients
Cells containing F Plasmid(F+ cells) function as DNA donors
R Plasmids
R plasmids carry genes for resistance to multiple antibiotics
Antibiotics kill most bacteria, but not those with R Plasmids that carry resistance genes
Exotoxins
Proteins secreted by bacteria that can cause disease even if the bacteria are no longer present
Endotoxins
Are lipopolysaccharide components of the outer membrane of gram - negative bacteria
CRISPR - Cas 9 System
Helps prokaryotes defend against viral attacks