Biology - The Cell Flashcards
What are the main components of a virus?
Genetic material, protein coat (capsid), and sometimes a lipid-containing envelope
These components are essential for the structure and function of viruses.
What does it mean that viruses are obligate intracellular parasites?
They cannot survive and replicate outside of a host cell
This characteristic distinguishes viruses from other types of microorganisms.
What are individual virus particles called?
Virions
This term is used to describe a complete virus particle.
What are bacteriophages?
Viruses that target bacteria
Bacteriophages play a role in controlling bacterial populations.
What additional structures do bacteriophages contain?
Tail sheath and tail fibers
These structures help inject genetic material into bacteria and attach to host cells.
What types of nucleic acids can viral genomes be composed of?
DNA or RNA
This diversity affects how viruses replicate and interact with host cells.
What are the two types of single-stranded RNA viruses?
Positive sense and negative sense
Positive sense viruses can be translated directly, while negative sense viruses require a complementary strand for translation.
Fill in the blank: Individual virus particles are called _______.
Virions
This term is commonly used in virology.
True or False: Viruses can replicate on their own without a host cell.
False
Viruses rely on host cells for replication.
What type of genome do retroviruses contain?
Single-stranded RNA
Retroviruses use reverse transcriptase to create a complementary DNA strand.
What enzyme is used by retroviruses to make a complementary DNA strand?
Reverse transcriptase
This enzyme is crucial for converting RNA into DNA.
What happens to the DNA strand produced by retroviruses?
It can be integrated into the genome
This integration allows for the potential replication of the viral genome with the host’s DNA.
How do viruses infect cells?
By attaching to specific receptors
This attachment is essential for the virus to enter the host cell.
What are the three methods by which a virus can enter a cell?
Fusing with the plasma membrane, endocytosis, injecting their genome
These methods vary depending on the type of virus.
What cellular components do viruses utilize to reproduce?
Host cell’s ribosomes, tRNA, amino acids, enzymes
These components are necessary for the replication and translation of viral genetic material.
How are viral progeny released from the host cell?
Through cell death, lysis, or extrusion
Each method affects the host cell differently, with lysis typically causing immediate cell death.
What are the two specific life cycles of bacteriophages?
Lytic cycle and lysogenic cycle
The lytic cycle results in cell lysis, while the lysogenic cycle involves integration into the host genome.
What occurs during the lytic cycle of bacteriophages?
The bacteriophage produces massive numbers of new virions until the cell lyses
Bacteria in this phase are termed virulent.
What is a provirus or prophage in the context of the lysogenic cycle?
A virus integrated into the host genome
The provirus can reproduce with the host cell or may exit the genome under certain stimuli.
What are prions?
Infectious proteins that trigger misfolding of other proteins
They usually convert an a-helical structure to a B-pleated sheet.
How do prions affect protein structure?
They decrease protein solubility and increase resistance to degradation
This misfolding can lead to various diseases.
What are viroids?
Plant pathogens that are small circles of complementary RNA
They can turn off genes, leading to metabolic and structural changes in plants.
Fill in the blank: In the lytic phase, bacteria are termed _______.
virulent
True or False: The provirus in the lysogenic cycle can remain in the genome indefinitely.
True
What structural change do prions induce in proteins?
Conversion from a-helical structure to B-pleated sheet
Fill in the blank: Viroids can turn off _______ in plants.
genes
Pos sense RNA virus and type of polymerase
These viruses possess the genetic information for the synthesis of an RNA-dependent RNA polymerase. This enzyme transcribes the positive RNA strand as well as the complementary negative RNA strands, which arise as intermediate products of genome replication. In the course of this process, the new genomic RNA molecules are generated from the second transcription step
then generate negative-sense RNA to produce more positive-sense RNA.
Neg sense rna virus and type of polymerase
They have genomes that act as complementary strands from which messenger RNA (mRNA) is synthesized by the viral enzyme RNA-dependent RNA polymerase (RdRp). During replication of the viral genome, RdRp synthesizes a positive-sense antigenome that it uses as a template to create genomic negative-sense RN
In these types of viruses, RNA-dependent RNA polymerase is used to synthesize mRNA transcripts from the viral genome. The mRNA can then be translated to make viral proteins.
