Bio 123: PP6 Material Flashcards
What is bacteria?
The most basic and simple forms of life. They are also extremely diverse.
What are the 5 characteristics of prokaryotic cells?
1) They have no membrane bound nucleus
2)Typically have 1 chromosome (DNA molecule is circular) with no proteins. Many contain plasmids
3)Cell wall is present in most species
4)Reproduce through prokaryotic fission
5)Have great metabolic diversity
What are the components of a prokaryotic cell?
- Flagellum
- Pilus
- Capsule
- Cell Wall
- Cell Membrane
- Ribosomes
- Chromosomal DNA
Flagellum
A long, threadlike structure protruding from the surface of a cell and use in locomotion.
Pilus
-Helps with the movement of the cell
-Aids in adherence to surfaces
-Used during bacterial conjugation
Capsule
The 1st layer of the cell. Helps prokaryotes cling to each other, helps the cell from drying out, might act as some protection against pathogenic disease.
Cell Wall
The second layer of the cell. Is made up of cellulose, gives the bacterial organism its shape and structure, and helps maintain its shape and structure integrity.
Cell Membrane
Provides protection to the cell and is made out of fatty based lipids and proteins.
Ribosomes
Its main function is to make protein (protein synthesis).
Chromosomal DNA
chromosomal DNA replicates with the genome. The chromosomal DNA is vital for proper cell functioning and reproduction
Binary Fission
Also known as prokaryotic fission. How bacteria reproduce.
-First we must have chromosomes in a mother cell.
-The cell elongates and begins to replicate its DNA (the ORI is responsible for initiating the replication)
-The DNA molecules then separate and cross membrane starts to form
-Cross membranes completely form and splits into a daughter cell.
Bacterial Conjugation
How do bacteria exchange plasmids with each other.
1) The pilus of a donor cell ( F+ donor cell) which contains a chromosome and an F Plasmid, attaches to a recipient cell ( F- recipient cell) which only contains a chromosome.
2) One strand of F plasmid DNA transfers from the donor cell to the recipient cell.
3)Donor synthesizes complementary strand to restore plasmid. Recipient synthesizes complementary strand to become F+ cell with a pilus.
Pathogenic
Any bacteria that causes disease. (not all bacteria is pathogenic).
How does gram testing work?
The reagent crystal violet is used; if the test if gram negative the bacteria will appear pink under the microscope.
If the test is positive the bacteria will appear dark purple under the microscope.
The difference between gram positive and gram negative is that gram positive bacteria have a much thicker peptidoglycan layer and gram negative.
What is gram testing used for?
Helps in identifying which bacteria can be treated with antibiotics and which would be more resistant to medicine. Gram positive bacteria will show little to no resistance to antibiotics while gram negative bacteria will have resistance.
What is the cell wall in bacteria made out of?
Peptidoglycan
Gram-negative bacteria
They only contain a very thin layer of peptidoglycan and a thicker/larger layer of carbohydrate portion of lipopolysaccharide. During gram testing, crystal violet is easily rinsed away, revealing red dye.
Gram-positive bacteria
Has a thick layer to peptidoglycan. The layer of peptidoglycan traps crystal violet and appears dark purple. Gram-positive bacteria would be more easily destroyed by antibiotics.
Exotoxins
Are proteins produced inside pathogenic bacteria (commonly in gram positive bacteria). When the cell dies it basically crumbles and those exotoxins are released into the surrounding medium following lysis.
Endotoxins
Are the lipid portion of lipopolysaccharides (LPS) that are part of the outer membrane of the cell wall in gram-negative bacteria. The endotoxins break off the cell when the cell dies and falls apart.
How is bacteria classified?
- Cocci (spherical)
- Bacilli (rod shaped)
- Spiral (spirilla)
What are the arrangements of Cocci?
- Coccus
- Diplococci
- Tetrad
- Sarcina
- Staphylococci
- Streptococci
What are the arrangements of Bacilli?
- Bacillus
- Diplobacilli
- Streptobacilli
- Pallisades
- Coccobacilli
What are the arrangements of Spiral?
- Spirochetes
- Spirilla (helical-shaped/corkscrew form)
- Vibrio
What is a sex pilus?
It connects two bacterial cells but it does not exchange chromosomal info.
How does genetic diversity in bacteria occur?
Through bacterial conjugation.
Proteobacteria
an entire phylum of bacteria that included lots of pathogenic bacteria.
Obligate aerobes
must live in an oxygen rich environment
obligate anaerobes
Cannot exist in conditions that have high levels of oxygen
Facultative anaerobes
prefer to lives in environments that are hypoxic or anoxic
hypoxic
having low levels of oxygen
anoxic
having zero levels of oxygen
epidemiology
the study of disease in humans
Vector
an organism that is a direct spreader of a disease. A carrier that spreads a disease from one organism to the next. E.G a tick is a vector for lyme disease.
Bioremediation
Using bacteria to help with environmental cleanup.
Carl Woese
Methanogen Archaea
Live where they can produce methane
Extreme Halophiles
live in environments that have a high salt concentration
Extreme Thermophiles
archaea that can live in extremely high temperatures
Virology
The study of viruses
What is a virus?
- NOT a cell
-fails the cell theory
-Must have a host cell in order to be able to reproduce
-Must contain a nucleic acid and a protein
-May have additional structures such as spikes or envelopes
-Are RNA or DNA based
-Have horizontally or vertical transmission
Vertical transmission
When disease is passed down from parent to offspring in organisms that carry their offspring in utero or that lay eggs.
Horizontal transmission
Disease is spread from individual to individual.
Capsid
protein shell that encloses the viral genome
What are some characteristics of a viral particle?
- Has a nucleic acid
-Has a capsid
-Has a viral envelope
-Has spikes
Viral envelope
outer most layer of a virus that surrounds the capsid, derived from host cell membrane and protects the genetic material.
Spikes
used by the virus to help infect cells
What is the life cycle of a virus?
1) attaches to a host
2)Penetration of host cell
3)take over of host cell machinery
4)replication/assembly: use material to assemble and create new viral particles
5)release
The lytic cycle
1)Virus attaches to a host
2) Phage DNA is injected into host cell and leads to the degradation of the host DNA
3)Synthesis of the viral genomes and proteins occurs
4)Assembly of viral particle occurs
5)Host cell breaks and viral particles are released
*always leads to the death of the cell
The lysogenic cycle
1) phage injects its DNA into host cell
2) Phage dna integrates with the bacterial chromosome becoming a prophage
3) Bacterium reproduces as normal but with the prophage and copies are made with the viral genome in it.
4)Cell division produce a population of bacteria infected with the prophage
5)daughter cells with prophage are created
6) reproduction continues until something triggers it to enter the lytic cycle.
** this cycle does not lead to the death of the cell!
How do we treat or prevent viruses?
- They cannot be treated with antibiotics
- May be prevented with vaccines
- Antiviral drugs may be used to help treat viral infections
- Vaccines can aid in building immunity towards certain viruses
What is the co-evolutionary arms race?
We have to invent ways to enhance our immune system which puts a pressure on viruses to adapt. We try to predict and stay ahead of these possible adaptions in order to prevent major outbreak and deaths such as COVID outbreak!
