Bio 1 Chapter 19
restriction enzymes
Foreign DNA can be identifies as such and cut up (destroyed) by cellular enzymes called _____
bacteria, viruses
Go back and forth between ____ having the upper hand and ___ having the upper hand
infections
Have to have vaccine before _____
lysogenic cycle steps
1. Phage DNA becomes integrated into bacterial chromosome = prophage 2. Prophage is copied with bacterial chromosome and splits making a daughtercell (many cell divisions create many infected bacteria 3. Daughter cell with prophage is made
virulent phage
A phage that reproduces only by the lytic cycle is called a _____
Lytic cycle steps
1. Attachment 2. Entry of phage DNA and degradation of host DNA (injected) 3. Synthesis of viral genomes and proteins (following directions of phage DNA) 4. Self-assembly 5. Release -Cell bursts, releasing the newly formed viruses that may now go out and effect other cells
Viral replicative cycle
1. Entry and uncoating (infection) 2. Replication 3. Transcription and manufacture of capsid proteins 4. Self-assembly of new virus particles and their exit from cell
CRISPR-Cas system steps
1. Infection by a phage triggers transcription of the CRISPR region of the bacterial DNA 2. THE RNA transcript is processed into short RNA strands 3. Each short RNA strand binds to a Cas protein, forming a complex 4. Complementary RNA binds to DNA. The Cas protein cuts the phage DNA 5. Phage DNA can no longer replicate
vaccine
A _____ is a harmless derivative of pathogenic microbes that stimulate the immune system to mount defenses against the harmful pathogen -Elicites an immune response in our bodies so when we are infected by the virus, out immune system already recognizes it and deals with it appropriately
Nucleic acid, capsid, genes
A virus is a very small infectious particle consisting of:
symptoms
Body response to the virus leaving the cell causes _____ of the viral infection
inhibiting synthesis, interfering with viral assembly
Drugs help treat an infection by _______ and _____ but will not kill it
prophage
During the lysogenic cycle ______ may fly under the radar
lytic cycle
During the lysogenic cycle, an environmental signal can trigger the virus genome to exit the bacterial chromosome and switch to the _____ , where the bacterial cell will ultimately die
host range
Each virus has a______, a limited number of host cells that it can infect -Types of cells that can infect EX. Messel virus can only affect humans while west nile virus can effect humans, birds, mosquitos and horses
mutate
Existing viruses can _____ (especially RNA viruses) this leads to different viral strains -Why influenza vaccine is different every year
bacterial mutants
Natural selection favors ______ that can withstand viral infection
double, single
Nucleic acid in a virus can be ______- or ______- stranded DNA or RNA (classifies virus as DNA or RNA virus)
viral proteins
Once the viral genome has entered a cell, the cell begins to manufacture _____ -Once the genome is inside the host cell, it hijacks the cellular machine of the host and the host starts to unwillingly follow the genetic instructions on the viral genome
the lytic cycle and the lysogenic cycle
Phages have two alternative reproductive mechanisms:
temperate phages
Phages that use both the lytic and lysogenic cycle are called _____
prophage, provirus
Prophage and provirus are similar but the difference is that a _____ can be removed from a bacterial chromosome where _____ remains a permenant fixture of the host cells genome
Cas
Resulting RNAs are cut into pieces and bound by ____ proteins
reverse transcriptase
Retroviruses use ______ to copy their RNA genome into DNA -reverse transcription (RNA to DNA instead of DNA to RNA) -EX. HIV
nucleic acid
Since viruses can replicate only within cells, they probably evolved as bits of cellular ____
accessory structures
Some viruses have ______ on the protein coat that help them infect hosts -glycoprotein spikes help to attach virus to host cells
genome
The Cas protein cuts the DNA destroying the ____ of the invading virus, protecting the bacteria from the virus
Phage related RNA
The Cas proteins use the _____ to target the invading phage DNA because this RNA is complimentary to the DNA of the invading phage it can bind to that DNA
lytic cycle
The _____ is a phage replicative cycle that culminates in the death of the host cell
lysogenic cycle
The ______ replicates the phage genome without destroying the host
CRISPR
The attempt of the phage to reinfect the cell triggers transcription of the ______ region (DNA turned to RNA during transcription)
animals
The broadest variety of RNA genomes is found in viruses that infect ____
regenerate
The damage a virus inflicts depends partly on the ability of the infected tissue to ______ by cell division -Some cells are regenerating themselves regularly while others are not. -EX. Easily coming back from a cold but nerve cells not easily replaced (polio)
death
The lytic cycle ends with the _____ of the host cell (virus bursts the cell)
provirus
The viral DNA that is integrated into the host genome is called _____
Injection, endocytosis, or fusion of the viral envelope to the hosts plasma membrane
The viral genome enters the host cell in a variety of ways:
before, after
There is controversy about whether viruses evolved _____ or _____ cells
obligate intracellular parasites
Viruses are ______, which means they can replicate only within a host cell -Also lack metabolic enzymes and equipment for making proteins
living, nonliving
Viruses are in the grey area between ____ and _____
cells
Viruses are not ____
reproduce, metabolism
Viruses cannot ____ or go through ____ outside of a host cell (properties of life)
living organisms
Viruses do not fit our definition of _____
damage, kill
Viruses may ____ or ____ cells
antibiotics
We take _____ for bacterial infections
both
Whereas few bacteriophages have an envelope (viral envelope) or an RNA genome, many animal viruses have _____
Phages
____ are the best understood of all viruses
Bacteria
____ have their own defenses against phages
Glycoproteins
____ help bind the virus to the host cell
Viral envelope
____ is usually derived from the host cells plasma membrane because as they leave the cell through exocytosis, it is packed up inside the hosts own plasma membrane
Viral nucleic acid, capsid proteins
_____ and _____ are going to self-assemble into new viruses that can then leave the cell (protein coats and genome)
Viral infections
_____ cannot be treated after the fact, and not treated by antibiotics
HIV (human immunodeficiency virus), AIDS (acquired immunodeficiency syndrome)
_____ is the retrovirus that causes ______
CRISPR-Cas system
_____: we can utilize this system to go in and change nucleotide sequences, changing the genetic code to help organisms have more disireable traits etc.
Animal viruses
______, typically have an RNA genome, about ¾ of new viral disease in humans spread from existing viruses in other animals -Ex. Bird flu, swine flu, covid-19
Bacteriophages
also called phages, are viruses that infect bacteria (infect prokaryotic bacteria) -Spider like form facilitates attaching to and infecting host cell
reinfected
bacteria who survives an infection cannot be _____ by the same kind of phage again
virus
is an infectious particle consisting of genes packaged in a protein coat -much simpler in structure than even prokaryotes
capsid
is the protein shell that encloses the viral genome
3-2,000
viruses have between ______ genes in their genome while bacteria contain about 200- a few thousand genes