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BIO 245 Final Exam 2024/2025 Questions And Answers $13.49   Add to cart

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BIO 245 Final Exam 2024/2025 Questions And Answers

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BIO 245 Final Exam 2024/2025 Questions And Answers BIO 245 Final Exam 2024/2025 Questions And Answers BIO 245 Final Exam 2024/2025 Questions And Answers

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  • November 19, 2024
  • 27
  • 2024/2025
  • Exam (elaborations)
  • Questions & answers
  • BIO 245
  • BIO 245
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lectjoseph
BIO 245 Final Exam
Virus Characteristics -Obligate intracellular parasites: require living host cells to multiply

-Contain either DNA OR RNA

-Protein coat (capsid) covering the nucleic acid (genome)

-NO ribosomes or ATP-generating mechanism



Virus Transmission

-Tissue Tropism

-Modes of transmission (3) -Hosts can be animals, plants or even bacteria (bacteriophages)

-Tissue Tropism: infect specific tissue and cell types within host

-Modes of viral transmission:

(1) Direct contact

(2) Indirect contact w/ fomite

(3) Vector: animal that transmits a pathogen from one host to another



Viral Size

-Range size -Needs an electron microscope to observe

-Range: 20 nm to 900 nm



Virion complete, fully developed viral particle (nucleic acid, capsid and envelope)



Nucleic acid DNA or RNA (never both)



Capsid protective protein coat; made of subunits called capsomeres

,Envelope

-Naked viruses

-spikes -coating seen outside the capsid in some viruses

-Naked Viruses: viruses whos capsid is not covered by an envelope

-Spikes: protein structures extending outward from the capsid; used for attachment and identification



Animal viruses occur...

RNA viruses replicate... inside the nucleus

in the cytoplasm



Virulent phages: typically lyse and KILL the bacterial cells



Lytic Cycle (5 steps) (1) Attachment -> interacts with bacterial surface receptors

(2) Penetration -> viral DNA enters cytoplasm

(3) Biosynthesis -> production of phage DNA

(4) Maturation -> assembly of phage

(5) Release -> cells are lysed and virus is released



Temperate phage temperate phage that becomes part of the host chromosome and are replicated in
the cell genome



Transduction (2) (1) Generalized transduction: during lytic cycle; random pieces of DNA are transferred

(2) Specialized transduction: during lysogenic cycle; specific pieces of DNA are transferred -> can be used
for antibiotic resistance

, Induction UV light or chemicals that separates the prophage from the bacterium and the lytic cycle is
initiated



Animal viruses have same five steps but with... an UNCOATING step



Retroviruses: +ssRNA viruses

-Carry a special enzyme called Reverse Transcriptase (RT)

(1) Converts +ssDNA to dsDNA

(2) Synthesizes a complementary ssDNA from +ssRNA

(3) Integrates into the host chromosomes as a provirus



Persistant Viral Infections (3) (1) Acute infections: an infection that only lasts for a set period of time and
then gets eradicated

(2) Latent infections: difficult to detect; remain hidden or dormant inside the cell

(3) Chronic infections: can be detected in tissues continuously; persistent symptoms over time and
generally fatal



Isolation within viruses virions in liquid medium can be separated from the host via centrifugation or
filtration



Cultivation

In vivo:

In vitro: how to grow viruses within the lab

-In vivo: within the living organism

-In vitro: within an artificial environment



Bacteriophages:

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