Prokaryote Basics
What is a prokaryote?
A single-celled organism lacking a nucleus.
What is the outer layer of a bacterial cell called (outside of the cell wall and plasma membrane)?
Capsule
What is the difference between an obligate anaerobe and an obligate aerobe?
Anaerobes cannot tolerate oxygen
Aerobes must have oxygen
How does the size of a virus compare to the size of single-celled organisms?
It is smaller!
Give one example of a viral infection.
Answers will vary.
What are the two domains of prokaryotes?
Bacteria and archaea
What are pili?
A pilus is a submicroscopic hairlike structures made of protein.
Pili help cells attach to surfaces, serve as bridges between cells to send plasmids to each other.
What is the process by which bacterial cells divide into two identical cells?
Binary fission
What are 2 reasons viruses not considered living?
No organelles to take in nutrients or use energy
Cannot make proteins
Cannot move
Cannot replicate on their own
What is a prion?
An infectious particle made entirely of protein.
What is the key difference between eubacteria and archaebacteria?
Archaebacteria live in extreme environments.
They have different organelles (ribosomal proteins, RNA, lipids, cell wall proteins).
What structure do bacteria use for movement?
Flagella
What happens when bacterial cells are exposed to harsh conditions?
An endospore forms. Once conditions are favorable again, the spore germinates and grows into a new bacterial cell.
What are 2 structures that compose viruses?
DNA/RNA
Envelope
Protein Spikes
Which part of the body is typically affected by a prion infection?
Brain
What type of chromosome is found in prokaryotes?
They have a long, circular chromosome found in the nucleoid.
Usually have at least one smaller piece of DNA called a plasmid, which is also circular.
What are the 3 possible shapes of bacteria?
Cocci (spherical or round)
Bacilli (rod-shaped)
Spirilli (spiral-shaped)
What is conjugation? What does it result in? How is this beneficial for bacteria?
In conjugation, two prokaryotes attach to each other and exchange genetic information.
This results in genetic diversity, which is beneficial as it increases chances of survival.
Explain how a virus invades a host cell.
The virus attaches itself to a cell and uses specific receptors on the plasma membrane. It injects genetic material into the cytoplasm of the host cell, and the material replicates itself inside the cell.
What is the difference between a virus and a retrovirus?
A virus has DNA
A retrovirus has RNA
What are two types of archaea and what are their defining characteristics?
halophiles (salt-loving)
methanogens (use CO2 and give off methane)
thermoacidophiles (high temperature, low pH)
What protein in bacterial cell walls does a Gram stain target? Why is this test important?
Peptidoglycan
Gram stains tell us if the bacteria is Gram-positive or Gram-negative, which is important for antibiotic treatment.
What are normal flora and what are 2 functions of it?
Normal flora are bacteria that have a symbiotic relationship with humans – prevent disease, aid with digestion, make vitamins.
What are the two types of viral life cycles? Explain each in detail.
Lytic: the host cell makes many copies of the viral RNA or DNA. The viral genes instruct the host cells to make more viral protein capsids and enzymes. Viruses leave the cell by exocytosis or by causing the cell to burst.
Lysogenic: viral DNA integrates into a chromosome in a host cell. Viral genes may remain dormant for some time. Activated viral genes result in the lytic cycle.
What is the enzyme that retroviruses use to synthesize DNA from RNA?
Reverse Transcriptase