Viruses Flashcards
Viruses lead a kind of “——“ betweem life-forms and chemicals
Borrowed Life
Viruses cannot — or carry out — outside of a host cell
- reproduce
2. Metabolism
Viruses are ——, but rather a very small infectious particle consisting of —— enclosed in a —— and, in some cases, a membranous envelope
- Not cells
- Nucleic Acid
- Protein Coat
Viruses may also contain additional —, such as —, to support their — within a host
- Proteins
- Enzymes
- Replication
Viral genomes are comprised of one linear or circular nucleid acid molecule encoding — to ——
3 to 2000 gnees
Nucleic acid arranged as:
- Double- or single-stranded —
- Double- or single-stranded —
- DNA
2. RNA
—: protein shell that encloses the viral genome - built from protein subunits called —
- Capsid
2. Capsomeres
——: derived from membranes of host cells and surround the capsids of many viruses found in animals
Viral Envelopes
What are the 4 virus shapes?
- Filamentous
- Icosahedral
- Enveloped
- Head & Tail
Filamentous(Helical/Rod-Shaped):
- —&—
- Includes many ——, such as tobacco mosaic virus (TMV)
- Long & Cylindrical
2. Plant Viruses
Icosahedral:
- — with — triangular faces
- May contain —— that aid in infection
- Include viruses that cause ——,——,——
- Rarely cause serious — or —
- Polyhedron
- 20
- Protein Spikes
- Common cold, sore throat, pink eye
- Illness or death
Viral Envelope:
- Derived from the host ——
- Contain a combination of viral and host cell molecules, including —— that aid infection
- Include —— & ——
- Cell’s membrane
- Glycoprotein Spikes
- Influenza Viruses & Coronaviruses
Bacteriophages (Phages):
*Viruses that ——
*Have the most complex — found among viruses:
~Elongated icosahedral capsid head that — their DNA
~Rod-shaped tail piece — to the host and — the phage DNA inside
- Infect Bacteria
- Capsids
- Encloses
- Attaches
- Injects
Viruses are obligate ——
Intracellular Parasites
Each virus has a ——: limited number of host cells that it can infect
- Includes both species and cell types:
- E.g., ——— can infect mosquitoes, birds, horses and humans, but — only infects humans
- E.g., — only infects immune cells
- Host Range
- West Nile Virus
- Measles
- HIV
Infection begins when — binds to a — and the — enters the cells
- Depends on type of virus and host cell
- E.g., injection (bacteriophage) or endocytosis (influenza)
- Virus
- Host Cell
- Genome
Once a viral genome has entered, the cell begins to copy the —— and manufacture ——
* Virus makes use of host —,—,—,——,—, and other molecules
- Viral Genome
- Viral Proteins
- Enzymes
- Ribosomes
- tRNAs
- Amino Acids
- ATP
What are the 2 replication mechanisms of Phages?
- Lytic Cycle
2. Lysogenic Cycle
The lytic cycle produces —— & — the hosts cell wall, releasing the ——
* Culminates in the — of the host cell
- New phages
- Lyses (breaks open)
- Progeny Viruses
- Death
A phage that reproduces only by the lytic cycle is called a ——
Virulent Phage
The lysogenic cycle replicates the —— without — the host
- Phage genome
2. Destroying
In the lysogenic cycle the viral DNA molecule becomes incoporated into the host cell’s —
* Once integrated, the viral DNA is known as a —
- Chromosome
2. Prophage
In the lysogenic cycle every time the host divides, it copies the —— and passes the copies to the ——
- Phage DNA (prophage)
2. Daughter Cells
In the lysogenic cycle an environmental stressor can trigger the —— to exit the bacterial chromosomes and switch to the ——
- Virus Genome
2. Lytic Mode
Phages that ise both the lytic and lysogenic cycles are called ——
Temperate phages
Many viruses that infect animals have a ——
* —— on the envelope bind to a specific receptor molecules on the surface of a host cell
- Membranous envelope
2. Viral glycoproteins
After infection, new —— are made and transported to the plasma membrane for production of ——
* Viral envelope is formed from the host cell’s —— as the viral capsids exit
- Capsid glycoproteins
- New viruses
- Plasma membrane
3 types of single-stranded RNA genomes in animal viruses:
- RNA serves directly as —
- RNA serves as template for —— (requires viral enzyme)
- RNA serves as template for ——— that gets integrated into the host genomic DNA
- mRNA
- mRNA Synthesis
- Synthesis of DNA
RNA serves as template for synthesis of DNA that gets integrated into the host genomic DNA
- These are known as —
- Use the enzyme —— to copy their RNA into DNA
- HIV is the retrovirus that causes —
- Retroviruses
- Reverse Transcriptase
- AIDS
—: reverse-transcribed viral DNA that integrates into the host genome
*Unlike a prophage, a provirus remains a — resident of the host cell
- Provirus
2. Permanent
The host’s —— transcribes the proviral DNA back into RNA molecules
*Function both as — for synthesis of viral proteins and as genomes for new virus particles released from the cell
- RNA Polymerase
2. mRNA
—: harmless derivatives of pathogenic microbes that stimulate the immune system to mount defenses against the harmful pathogen
Vaccines
Viral infections — be treated by antibiotics
Cannot
Antiviral drugs can help to —, though not —, viral infections
- Treat
2. Cure
— and —— are caused by new strains of influenza or other viruses to which people have little immunity
- Epidemics
2. Global Pandemics
Emerging viruses can aris from 3 processes:
*— of existing virus – RNA viruses tend to have unusually high mutation rates
~E.g., seasonal flu epidemics
*— from small, isolated populations
~E.g., HIV
*Spread from —— (zoonotic)
~E.g., swine flu
~Accounts for ~75% of new human diseases
- Mutation
- Dissemination
- Other Animals
Normal seasonal flu viruses are not considered emerging viruses because — of these viruses have been circulating among humans for a — time
- Variants
2. Long
However, these viruses such as flu still undergo — and —
* Variations thought to be most likely to occur each year are selected to generate —
- Mutation
- Reassortment
- Vaccines
COVID-19 Single-strand enveloped RNA virus belonging to the family Coronaviridae
- Name derived from the Latin corona, meaning crown
- ‘CO’ short for —
- ‘VI’ for —
- ‘D’ for —
- ‘19’ for —
- Corona
- Virus
- Disease
- 2019
COVID-19 is the —
SARS-CoV-2 is the —
*SARS = ————
*Closely related to coronaviruses isolated from bat populations
- Disease
- Virus
- Severe Acute Respiratory Syndrome
Virus enters the body through binding of viral —— to ———— receptors on host cells
- Spike proteins
2. Angiotensin-converting enzyme 2 (ACE2)
COVID-19 is abundant in epitheliem of —, — & —, but also present in —,——,—, — & ——
* Infection ususally begins in —
- Nose, mouth, & lungs
- Heart, blood vessels, kidney, liver, & GI Tract
- Nose
COVID-19:
ACE2 modulates angiotensin II (ANG II) which acts to increase —
Inflammation
COVID_19:
Without ACE2, — proceeds without “breaks” to harmful levels
*In addition to respiratory distress, can lead to ——,——, & —
- Inflammation
- Vessel Damage
- Blood Clots
- Strokes
More than — types of viral diseases of plants are known and cause spots on leaves and fruits, stunted growth, and damaged flowers or roots
2,000
Most plant viruses have an ——
RNA genome
What are the 2 major routes plant viruses spread disease?
- Horizaontal Transmission
2. Vertical Transmission
——, from external source entering through damaged cell walls, e.g., from herbivores or pruning
Horizontal Transmission
——, inheriting the virus from a parent
Vertical Transmission
