BIOL 3523 Study Guide - Fall 2018, Comprehensive Midterm Notes - Phagocytosis, Fever, Epithelium
BIOL 3523
MIDTERM EXAM
STUDY GUIDE
Fall 2018
What are the differences between prokaryotic and eukaryotic cells?
- Eukaryotic → has nucleus, tend to be larger and more complex
o Ex. Protozoa or algae or fungi
- Prokaryotic → No nucleus, smaller and less complex.
o Ex. Bacteria
- Bacteria and Archaea are similar in size but Archaea is more closely related to
Eukarya. Peptidoglycan is only found in cell walls of bacteria. No membrane bound
organelles or nucleus in bacteria.
Why are viruses and prions acellular?
- Viruses and prions don’t have a cell membrane and they can’t replicate on their
own. Viruses are composed of genetic material and proteins. Prions are made up of
just genetic material.
What are the steps of a gram stain?
- Heat fix bacteria to slide
- Add crystal violet, then iodine, then alcohol to remove color from gram-negative
cells. Then safranin will stain those cells pink.
Why is the acid-fast stain needed for mycobacteria?
- It is very high in mycolic acid so a harsher method is needed to stain the cells
What color do endospores stain?
- The stain used is malachite green so heat will be used to facilitate the uptake of the
primary dye by the endospore.
What are the different shapes of different bacteria?
- A circle is called a coccus, a rod is called a bacillus, if it’s a v shaped its vibrio,
spirilium are spirals and spirochetes are spirals as well.
- If they are generating chains, they are strep, if they form clusters they are staph
What are the differences in most bacterial cell walls?
- Gram-positive bacteria have a thick layer of peptidoglycan above its outer
membrane made of techoic acids
- Gram-negative bacteria have a thin layer of peptidoglycan and have LPS in their
outer membrane. The lipid A component of LPS is the endotoxin.
What makes up peptidoglycan?
- Glycan chains made up of NAM and NAG are linked together by a bridge.
How does penicillin work?
- It interferes with the peptidoglycan synthesis – it interferes with the synthesis of the
bridge between glycan chains
How are capsules virulence factors?
- It can help the microbe evade the host immune system by inhibiting phagocytosis
How are flagella virulence factors?
- Used for motility and can help microbes chemotax towards or away from something
How are pili a virulence factor?
- Important for attachment to different surfaces and for movement. Sex pilius is used
to join microbial DNA
What is the relevance of plasmids?
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- The plasmids are extra chromosomal pieces of DNA and are what may be copied and
move from one cell to another. Sometimes plasmids can contain DNA that codes for
a virulence factor.
Why would a bacterial cell become an endospore?
- Gram-positive bacteria can become endospores and they may become an endospore
when there is sign there is a decrease in nutrients available. They are not
metabolically active and they are resistant to heat, chemicals, desiccation.
Why are mitochondria and chloroplasts considered endosymbionts?
- They are considered to by symbionants because they are inside of eukaryotic cells
but they have features that are similar to bacterial cells. Both have their own
ribosomes and their own DNA. The ribosomes that are in mitochondria/chloroplasts
are similar in size to ribosomes you’d see in bacterial cells. They also have outer and
inner membranes. They are also similar in size to bacteria, which indicates that they
may at one point have been bacterial cells.
Why are biofilms beneficial for microbes?
- They are a way to encase microbes in a community. You have many different kinds
of bacteria in a community. They have ways to communicate with each other to
meet nutrient requirements. These biofilms are hard to get rid of.
What is happening in the stages of the growth curve?
- Lag phase → metabolically active, getting ready to divide
- Exponential phase → doubling in numbers
- Stationary phase → Number of cells dividing is equal to the number of cells dying
- Death phase→ The number of cells dying is greater than number of cells dividing
What else has an effect on microbial growth other than the starting number of cells?
- Temperature, pH, oxygen levels,
How do you figure out how many bacteria are in the tube?
- Take a culture, spread it out onto the plate and count the colonies that are on it.
Needs to be between 30 and 300 to count.
What is our first line of defense?
- The innate immune response. The skin is a physical barrier that is salty with fatty
acids. Things throughout the mucousa and cilia are also physical barriers.
- Lysozymes in tears and other secretions
- Defensins are antimicrobial peptides that poke holes in microbial membranes
What are some roles of normal microbiota?
- Compete with pathogens for nutrients
- Make toxin compounds that can kill other microbe
- A disruption in normal microbiota can lead to infection
What are the cells of the immune system? Where do they originate?
- Originate in the bone marrow – depending on different growth factors they become
different cells
- Lymphoid progenitor cells become lymphocytes and NKCs
- Myeloid progenitor cells give you APCs, granulocytes
- Granulocytes:
o Neutrophils – phagocytic and can release materials that can trap and destroy
microbes
o Eosinophils
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Document Summary
Eukaryotic has nucleus, tend to be larger and more complex: ex. Prokaryotic no nucleus, smaller and less complex: ex. Bacteria and archaea are similar in size but archaea is more closely related to. Peptidoglycan is only found in cell walls of bacteria. No membrane bound organelles or nucleus in bacteria. Viruses and prions don"t have a cell membrane and they can"t replicate on their own. Viruses are composed of genetic material and proteins. Prions are made up of just genetic material. Add crystal violet, then iodine, then alcohol to remove color from gram-negative cells. It is very high in mycolic acid so a harsher method is needed to stain the cells. The stain used is malachite green so heat will be used to facilitate the uptake of the. What are the different shapes of different bacteria? primary dye by the endospore.
