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
Archaea and what evolved from a common ancestor?
Eukaryotes
What do phototrophs use as their source of energy?
Sunlight
What do chemotrophs use as their source of energy?
Organic molecules or chemicals
What do autotrophs use to get carbon?
CO2
What do heterotrophs use to get carbon?
Preformed organic compounds
What are two major resources needed to grow and survive for archaea?
Carbon and Energy
What increases surface area in archaea to make up for lack of membrane bound organelles
Infolding’s of plasma membrane
In cellular respiration, what makes up for the enzymes?
aerobic bacteria
In photosynthesis, what makes up for the enzymes?
cyanobacteria
What does cyanobacteria do?
Carry out oxygen, generating photosynthesis
What is a archaea called that lives in high salt content?
Extreme halophiles
What is an extreme thermopile?
A archaea that can survive in very hot water
What is a archaea called that can survive with very low oxygen?
Methanogens
What are the two things that contribute to prokaryote survival success?
- Modes of nutrition
2. Spore formation
What are 4 things that prokaryotes have in their anatomy that contribute to their success
- Cell wall
- Capsules
- Pili- for sticking to things
- Flagella- To move around
What does an endospore allow a prokaryote to do
Allows the prokaryote to survive harsh conditions or food scarcity
How is an endospore formed?
2 cells- Outer produces the endospore
The cell dehydrates and becomes dormant and can rehydrate when conditions become good again
What is a capsule?
Sticky layer of protein or polysaccharide on outside of prokaryote
What 2 things does a capsule allow a prokaryote to do?
- To adhere to substrate (where the prokaryote lives)
2. Shields it from host immune system
What 3 things does a cell wall do for a prokaryote?
- Maintains shape
- Protects cell
- Prevents dehydration
What are two types of cell walls?
Gram positive and Gram negative
In gram positive and gram negative, what does the cell wall look like?
\+ = thick layer of peptidoglycan - = thin layer of peptidoglycan in between outer membrane and plasma membrane
What do pili do?
Stick to each other and surfaces
What do sex pili do?
link 2 cells in conjunction to be able to transfer DNA between cells
What do flagella do?
Long appendages for movement, can move toward nutrients and move away from prey/toxins
For myxobacteria, what do flagellum allow it to do?
Allows them to charge at their prey and bore into them
How do prokaryotes reproduce?
By binary fission- a new generation every 1-3 hours
What two things prokaryote reproduction limited by?
- Lack of nutrients
2. Poisoning by own wastes
What is selected for quickly when it comes to prokaryote reproduction?
Beneficial mutations
Do prokaryotes need high levels of nutrients to reproduce?
No
What are the 3 ways in which genetic diversity occurs in a prokaryote?
- Transformation
- Transduction
- Conjunction
What is transformation regarding genetic diversity of a prokaryote
Obtain DNA from the bacterial cell directly
What is transduction?
Obtain DNA from other bacterial cell from phages
What is conjunction?
Merge with another cell, obtain DNA via mating bridge
Can reproductive isolation apply to prokaryotes?
NO
What can biologist sometimes look at to define a species?
The amount the DNA sequences differ
What does reproductive isolation not apply to?
Prokaryotes
What is a morphological species? What does it apply to?
Classified based on observable physical traits (flagella, shape, etc), prokaryotes
What is a phylogenetic species?
Smallest group that shares common ancestor(one branch of the phylogenetic tree)
What are plasmids?
Small circular DNA molecules, separate from the bacterial chromosome
What does plasmids genes allow to happen?
Allow conjunction to occur and for antibiotic resistance
How does antibiotic resistance and conjugation relate?
Inappropriate antibiotic, resistant bacerai survive, then transformation, conjugation and transduction spread the genes for resistance
What is a biofilm?
A complex community of prokaryotes that associate with each other
Where are biofilms found?
Rocker, water surfaces, ocean floor and medical devices
Within a biofilm what do cells do to eachother
Send signals to others
Within a biofilm how to nutrients move and waste leave?
Through channels that allow nutrients to get to the centre
How do prokaryotes make nutrients available for other organisms such as plants?
Decompose dead and organic material
What is a common soil bacteria that decomposes organic matter?
Actinomycetes
What do Rhizobium species do for plants?
Fix nitrogen to a form useable by the plant (N2 to NH3)
What is chemical warefare?
When bacteria and fungi compete for resources
What do prokaryotes do to outcompete competition?
Make antibiotics and antifungals
What kind of bacteria produces its own kind of antibiotic?
Streptomyces sp. produces streptomycin
What is a microbiome?
Normal residents in or on a host organism
What3 things do microbiome do?
- Decompose dead cells
- Aid in supply/ digestion of food
- Prevent the growth of pathogenetic organisms
If a community makeup is disrupted what can member of a biome do?
Multiply and become pathogenic
What can chemoautotrophic bacteria do to deep sea invertebrates
Supply organic compounds
Where are Chlamydias found and what do they cause?
Inside eukaryotic host organisms, causes STD and blindness
What shape of bacteria are spirochetes and what can they cause?
Helical, cause syphilis, lyme disease
What can streptococcus form?
Strep throat
Can some prokaryotes cause disease by producing a toxin?
Yes
What are exotoxins?
Toxic proteins secreted by cells
What can some exotoxins cause?
Necrotizing Fascitis
What are endotoxins?
Components of the outer membrane of gram negative bacteria which are released when cell dies
How can a prokaryote or bacteria destroy a host cells?
By living and reproducing in them
How does listeria work that it effects many areas of body?
Multiples within host immune and other cells and spreads from cell to cell
What can occur if there is an infection in a pregnant mothers blood?
The disease can spread to the fetus
How can anthrax bacteria be ‘weaponized’
Manufacturing of endospores
When endospores of anthrax bacteria are produced, how can it be very easy to spread?
- Easily dispersed in the air, they can be inhaled and begin to reproduce in the lungs
How can prokaryotes be positive in food production?
by injecting into sterilized milk with beneficial bacteria to produce milk and cheese
What does lactobacillus acidophilus do to milk
Secrete acid that coagulate milk (make it chunky) and makes it difficult for other bacteria to grow
What does biomediation mean?
Use of organisms to remove pollutants (oils spills, sewage treatment)
