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55 Cards in this Set

  • Front
  • Back
Virus
- Obligate intracellular parasite
- Can only reproduce in other host's cells
- NOT LIVING
- Can't synthesize ATP on its own, have to hijack the host's cell
Virus Genome
- Either DNA or RNA (not both)
- Single or double stranded
- Linear or circular
- Contained in a protein capsid shell
Bacteriophage
Virus that infects bacteria
Bacteriophage Genome
- Rigid and economical in size
- Carries only really necessary genes and relies on host for transcription/translation proteins
- Can overlap reading frames to code for two proteins
Bacteriophage Structures (4)
- Head
- Tail Fiber
- Sheath
- Capsid
Head
Genome located here
Tail Fiber and Base Plate
What attaches to the cell's surface
Sheath
- Injects Genome into host by contracting
- Uses stored ATP as energy
- Need to puncture cell walls
Capsid
Protein coat surrounding viral genome structure used to classify viruses
Animal Viruses
Envelope
- Surrounds capsid
- Derived from the membrane of its host
Animal Viruses
Budding
- How a virus gets the envelope covering
Animal Viruses
"Naked" Virus
- Don't have envelopes, don't need them
- Associated with cell walls, plant viruses, phages...
Lytic Cycle
- Rapid increase in numbers
- Destroys host cell in the process
- Phage genome made from dNTP of degraded host genome
Hydrolase
- Lytic Cycle
- "Early Gene" which is transcribed first, degrades host genome
- Expressed immediately after infection
Lysozyme
- Typical "Late Gene"
- Destroys bacterial cell wall (which protects against osmotic pressure)
- Cell bursts, releases viruses
Lysogenic
- Clever girls...
- Virus genome incorporates itself into host genome
- When host replicates genome it replicates prophage
Prophage
- Virus phage genome
- "Silent". Genes not expressed, progeny not made directly
- Prevented from replicating itself by host proteins that bind to to operator
- The trick is that the virus doesn't care. It sits there..waiting..until it removes itself and enters lytic.
Animal Virus Replication
Protein Receptors
- Animal virus likes to hijack receptors on a cel that have a normal function, virus uses these to recognize its target cell (smart)
- Host can't change this process because they have normal physiological functions too
Endocytosis
- Animal Virus Replication
- How the virus gets in, host cell engulfs it and internalizes it (recall membrane coat)
Provirus
Same thing as a prophage (virus DNA inserted into DNA of host)
Life Cycles of Animal Virus
- Lytic
- Lysogenic
- Productive
(+) RNA Virus
- MUST encode RNA dependent RNA polymerase
- Don't have to carry this
- Simplest kind of viral genome
- Makes (-) strand before generating new (+) genomes
- Host can't distinguish between virus mRNA and its own, so it's replicated
(-) RNA Virus
- Must carry RNA dependent RNA polymerase and encode it
- Makes a (+) strand when it infects host, and uses this (+) strand to make (-) strands.
Retroviruses
- Must encode reverse transcriptase
- They are basically (+) RNA viruses that incorporate themselves into host genome as proviruses
- Lysogenic viruses
- Enter as RNA, use enzyme to turn to DNA
What's special about Prokaryotes?
- No membrane bound organelles (nucleus, mitochondria, lysosome)
- Can still do cellular respiration and photosynthesis!
Shapes (3)
Cocci - Round
Bacilli - Rod
Spiralla - Spiral
Prokaryotic Cytoplasm
- No nucleus, so the genome is here (circular)
- Plasmid is here
- Transcription and translation occur in the same place, at the same time
Plasmid
- Circular piece of ds-DNA smaller than the actual genome
- Has genes that are advantageous, help with exchange of info in conjugation
Prokaryotic Cell Wall
- Has a lipid bilayer, outside of which is a cell wall (prevent lysis from osmotic pressure)
Peptidoglycan
- Unique construction of cross-linking sugars
- What's actually in the cell wall of prokaryotes
Gram (+) Stains
- Cell wall with peptidoglycan
- Lipid Bilayer
- Cytoplasm

- Stain DARK!
Gram (-) Stains
- Outer Membrane
- Periplasmic space with peptidoglycan
- Inner Membrane

- Stain LIGHT
Prokaryotic Flagella
- Whiplike filaments used for moving
- Can have one, at both ends, or many
- Different from eukaryotic!
What affects Bacterial Growth?
- Temperature
- Nutrition
Chemoautotroph
Build stuff from carbon dioxide using chemical energy
Chemoheterotroph
Rely on organic cmpounds for carbon and use energy from chemicals (this is us)
Photoautotroph
Use carbon dioxide as carbon source and light for energy (plants)
Obligate Aerobes
Love oxygen, need it to live
Facultative Anaerobes
Don't need oxygen, but will use it if it's there
Tolerant Anaerobes
Grow with oxygen or without it, won't use it
Obligate Anaerobes
Hate oxygen, it's a poison to them because they lack the enzyme that gets rid of oxygen free radicals
Binary Fission
- Bacteria don't have mitosis or meiosis
- They grow in size until they've got enough genome for two of them, and then split in half
- Genetically identical cells
Lag Phase
- Cell division doesn't happen here even in good times
- Need time to get division materials ready (genome)
Log Phase
- Major Groph
- If time to double is 20 minutes, and we start with 1 bacteria, after 4 hours we get 4096 bacteria
Stationary
- No dividing, because nutrients are getting limited
Carrying Capacity
- Maximum number the population that can withstand in an environment
- Limited by nutrients
Endospores
- Gram (+) Bacteria
- Form in unfavorable conditions
- Thick shells made of peptidoglycan, inside is everything needed to be metabolically active
- Sleep through bad times
Sex in Bacteria (3)
- Tranduction
- Transformation
- Conjugation
Transduction
Transfer of one genome to another
Transformation
Eat DNA, get new genes
Conjugation
- Physical contact, bridges mae from F+ (males) to F- (females)
- Transfer "factor" to females, which then become males
- Only occurs in the presence of females
F Plasmid
Has genes to produce sex pillus
Fungi Composition
- Multicellular eukaryotes
- Cell walls are rigid and made of chitin
- Chemoheterotrophs that feed primary through absorption (digestion outside cells)
Fungi Reproduction (Asexual - 3)
- Budding
- Fragmentation
- Spore Formation
Fungi Reproduction (Sexual)
- Adults are haploid (n)
- Fuse to form diploid (2n), which produce by meiosis to get more haploids.
- Do this through having opposite hyphae (+ and -)