Lecture 3 Flashcards
How were the first genes formed?
- Collection of monomers (small molecules)
- Formation of shorter RNA polymers and simple genes
- Assembly of a complementary RNA chain
What was a crucial step in the formation of the first cells?
Formation of a membrane to separate the inside from the outside
What does the term “gene in a box” refer to?
Genetic material surrounded by a protein coat (capsid or membranous envelope)
What are 4 different types of genetic material?
ssDNA, dsRNA, dsDNA or ssRNA
Bacteriophages only infect…?
Bacteria
How do viruses enter a cell?
Viral surface proteins interact with specific molecules on host cell for entry
What does it mean when we say viruses are host specific?
They are restricted to their host kingdom meaning they can only infect cells in their specific kingdom
What is the Lytic cycle?
The cycle of how viruses infect a host cell
In the lytic cycle, viral DNA trigger what? When?
Viral duplication soon after infection
In the lytic cycle, what happens once one cell is infected? Why? What happens after?
New viruses are released to continue the infection. Then the host cell is destroyed
What is the lysogenic cycle? How is it different from the lytic cycle?
The host cell is not immediately destroyed, whereas in the lytic cycle, the host IS immediately destroyed
In the lysogenic cycle, how is viral DNA treated differently?
It is incorporated into the host chromosome
What is integrated viral DNA called?
Prophage
How does the lysogenic cycle work?
- Viral DNA is incorporated into host chromosome
2. Host divides and copies the phages DNA, the passes the copies onto daughter cells
What can change the lysogenic cycle into the lytic cycle?
Toxins, radiation, etc
How do the transmission of viruses occur in plants to animals and other plants?
Insect vectors, animals brushing against plants, offspring in seeds
How do viruses enter a plant?
They enter via damaged cell wall, spread to joining cells via plasmodesmata (intercellular junction)
What do viruses lack the cause them to not be able to make proteins?
Metabolic enzymes
Where can viruses only produce? What doe this mean?
Host cells, means they cannot sustain themselves on their own
When did viruses first appear?
After the first cells appreared
Are prokaryotes multicellular or unicellular? Some live in…?
Unicellular, some live in colonies
What are 3 kinds of bacteria shapes? What do they look like
- Cocci- sphere( can occur in chains)
- Bacilli- rod shaped (can occur in pairs or chains)
- Spiral- Can be short or long
What part of DNA physical makeup is missing in bacteria?
Histones
Is peptidoglycan found in both bacteria and archaea?
No only bacteria