Bacteria Flashcards
What are the three differences between Prokaryotes and Eukaryotes
Size: procaryotes are small, eukaryotes are much large. Nucleus: procaryotes have no membrane-bound nucleus, DNA exists as a single circle in the nucleotide. Eukaryotes have a membrane bound nucleus that is clearly visible. Organelles: Prokaryotes have no membrane bound organelles, eukaryotes do.
What type of cells are bacteria
prokaryotic
What are the 7 important structures of a bacteria cell
Capsule, Cytoplasm, Cell wall, cell membrane, Pilli, Flagella, Nucleoid.
what is a capsule in bacteria cell
a sticky layer that helps bacteria cling to surfaces
what is cytoplasm in a bacteria cell
jelly-like material that fills the cell
what is the cell wall in bacteria cell
made of unique chemical
what is the cell membrane in bacteria cell
regulates what comes in and out of the cell
what is the nucleoid in the bacteria cell
consists of a single strain of circular DNA
what are the flagella in the bacteria cell
used for movement
What are the three basic shapes of bacteria
Coccus (spheres), Bacillus (rods), Spirillum (spirals)
How does the amount of bacteria present affect the prefix of the name
if in doubles, prefix diplo- is used. if in chains, prefix strepto- is used. if in clusters, prefix staphylo- is used.
What are four ways to identify bacteria
By shape, by mode of nutrition, by motility, or by gram staining
Name the different identities for bacteria based on their mode of nutrition
Either heterotrophic (eat food to survive) or autotrophic (make their own food). Heterotrophics can either be parasitic (invade hosts) or saprophytic (live off dead organisms). Autotrophics can either be chemosynthetic (use chemical reactions) or photosynthetic (use sunlight)
Why do we do gram-staining
to help identity bacteria present in a sample and to determine which antibiotics to use. Purple means gram positive, pink means gram-negative. Pink is generally more harmful.
What are the steps of gram-staining
- Apply crystal violent for 30-45 seconds, rinse with distilled water 2. Apply iodine for 10 seconds, rinse with distilled water. 3. apply alcohol at a 45deg angle until run off becomes clear, immediately rinse with distilled water. 4. add safranin for 30 seconds. 5. dry bottom and observe in the microscope
why does gram staining work
all bacteria cell walls have a compound called peptidoglycan. If they become purple from gram staining, they have a thick layer of peptidoglycan and are considered gram positive. If they are pink from gram staining, they have a thin layer of peptidoglycan and are considered gram negative
How does staining gram-negative cells work
They have a thin layer of peptidoglycan, and they have an outer membrane composed of lipopolysaccharide. When we put alcohol on the bacteria, it dissolves the lipopolysaccharide and washes away the dye from the cell wall
What are the three ways bacteria cause disease?
- bacteria gets in body and starts to reproduce, crowding out helpful/harmless bacteria and creating an imbalance
- bacteria invade host cells through evolved mechanisms to allow them to get inside and evade destruction
- Bacteria emit toxins, and the toxins cause the disease symptoms
How do bacteria reproduce
asexually through binary fission
How does binary fission work?
- One cell replicates and copies its DNA, and then decides in half. The cell is then split into 2 cells as it pinches down in the middle.
What is one advantage of binary fission
reproduction can occur very quickly-the population doubles every 20 minutes
What is one disadvantage of binary fission
new cells are all clones, resulting in no genetic diversity. This means that if the environment suddenly becomes unfavourable, all bacteria will die.
How does bacteria get inside a host cell
bacteria will secrete “invasins” chemicals that ater the cytoskeleton of a human body cell, causing it to engulf the bacteria.
What are 2 advantages for the bacteria to get inside a human cell
- it provides the bacteria with a ready supply of nutrients
- it protects the bacteria from bodies immune defense mechanisms because the body will not attack it own cells
What are 2 ways bacteria evade destruction once inside a host cell
- block the lysosomes (release enzymes to breath down bad stuff) of the human cell.
- prevent cells from carrying out normal cell functions, and use cell actin fibers to move from one cells to another (it doesn’t have to leave a body cell so it avoids detection)
What are the two types of toxins
Exotoxins and Endotoxins
Compare 7 things about endotoxins and exotoxins
exotoxin: protein, highly antigenic, causes intense 3rd line defense, released from bacteria cell, very toxic and can be fatal, causes damage away from infection, typically gram positive. Endotoxins: lipids/carbs, poor antigen, very poor 3rd line defence, part of the bacteria cell wall, less toxic, localized effect, and typically gram-negative.
How do exotoxins work?
They are produced in the normal course of the life of a bacterium, the more prevalent type are A-B toxins. The B portion is for attachment to the host cell. The A portion does damage by altering cell functions like protein synthesis and can cause cell death.
How do endotoxins work
The cell wall is released in a local area, which causes fever, weakness, and shock
Explain the iron tug-of-war
Bacteria need iron to function normally and to reproduce. Human macrophage also need iron to fight infection. Therefore, as a second line of defence, our bodies withhold iron from pathogenic bacteria.
How is the immune reaction different for bacteria than for viruses.
The humoral system is the same, as it produces antibodies. The cell-mediated wing kills the bacteria directly instead of killing an infected cell.
What does the complement system make and what does it to
The complement system is a series of reactions that in the end, create a Membrane attack complex. This structure punctures the cell wall of a bacteria, causing it to swell and burst.
How does the complement system start?
The system is activated when it combines with antibodies that are attached to antigens after humoral immunity.
What is the alternative pathway of complement system?
The alternative pathway doesnt require humoral response to be activated. It can be triggered early on as the C3 complex already exists in low levels.
What is the difference between active immunity and innate immunity?
innate immunity means you are born with it (compliment system), while active immunity means it is constantly evolving
What are the 3 targets in breaking the chain of infection for bacteria
Suspectable host, resevoirs, and means of transmission
Give 2 examples of how the chain can be broken in susceptible host
personal hygiene and vaccinations
Give 2 examples of how the chain can be broken in means of transmission
canning/salting foods, sanitation
give 2 examples of how the chain can be broken in reservoir
isolation, surveillance
What is the role of plasmids in DNA Vaccines
Subsets of DNA exist in small circular units of a bacteria cell, called plasmids. These can be used in the production of DNA vaccines
What are the 5 steps to creating a DNA vaccine
- plasmids are created in a lab and then cut open using enzymes 2. DNA from the pathogen is insrted into the plasmid with an on/off switch 3. plasmid is added to a bacteria 4. the bacteria grow and replicate the plasmid 5. the plasmid is then purified and used as vaccine
what are 3 advantages of DNA vaccines over mRNA vaccines
- easier to produce, more stable 2. administered into skin without injection 3. wider immune response (stimulate both cell-mediated response and humoral) while mRNA only trigger antibody resistance
What is an endospore
An endospore is a thick protective wall around DNA that bacteria form under harsh conditions. They are resistant to high temps, toxins, etc. The rest of the cell may die, but the endospore will continue to live and can emerge as new cells when conditions are favourable
What is canning
a method of preserving food in which the foods are heated and then sealed to kill off any bacteria
what is freezing and how dow it work
inhibits microorganism growth by slowing reactions needed for bacterial growth
what are 5 ways to prevent contamination of food
canning, freezing, salting, drying, and pickling
how does salting and drying work
it draws out water that contain microorganisms
what are 2 ways pickling works
- lowers pH so bacteria cant survive 2. encourages growth of good bacteria
describe 3 issues that link gender with water fetching and/or sanitation
- women are the ones that fetch water, giving them no time for education 2. women have to relief themselves at private in the night, leading to increased cases of harassment 3. women use unsanitary water to cook/clean, giving them the most exposure to bacteria
what are antibiotics
naturally or syntehtically produced substances that kill or inhibit growth of microbes
what are 3 ways antibiotics work
- disrupt the synthesis of microbe DNA so the microbes cannot reproduce. 2. disrupt protein synthesis so that the microbes cannot produce what they need. 3, disrupt cell wall or its formation, killing the microbe
why do antibiotics not work on viruses
need host cell to work, viruses are non-living
binary fission disadvantages
no genetic diversity
How does bacterial conjugation work
a plasmid within a donor cell copies itself and passes through the pilli into recipient cell through a bridge. this causes different plasmids and combinations of plasmids, resulting in genetic diversity
What is 1 advantage and disadvanage to conjucation
advantage: results in genetic variation, no two bacterial strains will have the same DNA present in main DNA and plasmid. disadvantage: requires more time, and doesn’t create new cells, doesn’t increase population size.
what are 3 ways antibiotic resistance develops
- the full course of antibiotics is not completed, the slightly resistant bacteria will survive 2. leftover antibiotics are being flushed and getting into water supply 3. unnecessary prescriptions are given
What is quorum sensing
when bacteria are in large numbers, they develop a biofilm, which allows for cell-to-cell communication. They can communicate how/when to attack
what are two potential ways of disruption for quorum sensing
- blocking receptors of communication 2. preventing biofilm from forming
what is phage therapy
using viruses to kill bacteria
What is iChip
a new technique that lets researchers identity antibiotics treatments from bacteria that are hard to cultivate in a lab
what are the 3 steps to an ichip
- the chambers of a tiny well-plate are each filled with a cell from a different bacterium that is hard to grow in a lab, and are placed in the soil to grow 2. the bacteria are then placed in a petridish and covered by a gel containing the target bacteria 3. if there’s no growth over a particular bacteria colony, it means that the bacteria is releasing a potential antibiotic
what is maggot therapy and how will it help with antibiotic resistance
placing maggots on wounds to clean up rotting flesh instead of using antibiotics. less antibiotic usage = less antibiotic resistance
how does CRISPR work for a new type of antibiotics
Crispr was originally discovered in bacteria, where it helps keep track of past viral infections. When a virus attacks, the bacterium stores small chunks of the viral DNA within its own DNA. This helps the bacterium recognize viral infections when they occur again. Then, using Crispr-associated enzymes, it can chop up the viral DNA/RNA and prevent the infection from spreading.
