Midterm Flashcards
What are the key characteristics of a eukaryotic cell
Cytoplasm, cell membrane, mitochondria, nucleus, DNA, ER, Lysosome, ribosome, golgi apparatus
Features of a prokaryotic bacteria
Capsule, plasma membrane, pilli, plasma membrane, cytoplasmic INCLUSION, plasmid, ribosomes, cytoplasm, basial body, 70s ribosomes
Difference between a gram negative and gram positive cell wall
Gram positive: Purple- Lipid bilayer plasma membrane and cell wall w lipotechoic acids anchoring membrane (20-80 nm, peptidoglycan is digested by lysozyme)
Gram negative: lipid bilayer plasma membrane with lipid A in it. 3 layers and 1 compartment (periplasm)
Average size of a bacteria
average human cell= 25x10-6
average bacteria: 10^-6
average virus: 10^-8
Flagella structure and function
-Long helical protein filaments
-Allow movement through the environment
-Different between sperm cells and bacteria
Pilli/fimbrae structure and function
-Pili are used for attachment
-Attach bacteria to host cell
-E.coli use pili to attach to bladder for UTIs
-Can use gene recombination to avoid human immune system
Capsules structure and function
-Polysaccharides that form a silmy surface. Protect bacteria from phagocytosis. Increase virultance. Slimeiness evades immune system and desiccation
Cocci vs bacilli
Cocci= spheres, strep is chain and staph is clusters
Bacilli= rods
Which bacteria form endospores commonly
clostridum and bacillus (form to evade heat and chemicals). Multilayer coat around cell when they can’t grow in environment, help remain dormant.
Anaerobic vs aerobic final ATP
Anaerobic- O2 is final electron acceptor, 34 ATP are made.
Aerobic- use oxygen, 38 ATP made.
Obligate vs facultative vs aerobe vs anaerobe
Obligate = absolutely needs o2
Facultative = optional
Aerobe = O2
Anaerobe = no O2 (O2 is toxic)
Replication phases
Lag Phase/adjustment period = no cell division
Logarithmic Phase w/ abundant nutrients = rapid growth
Stationary Phase w/out nutrients = slow/no cell division
Death Phase w/ toxic waste accumulated = cells die
What is gene expression
transcribe a gene into RNA using RNA directly or translating RNA into a protein
What are operons
clusters of genes that are transcribed and translated together (form a pilli or toxin)
What is quorum sensing
gene transcription is activated in response to the concentration of bacteria (when a concentration gets high enough, starts to have an impact on the host)
Where does translation start
initiation complex
Where does translation end
stop codon
Ribosomes in prokaryotes vs eukaryotes
prokaryotes= 70s
eukaryotes=80s
Which antibiotics target bacterial ribosomes
Erythromycin and aminoglycosides, tetracyclines (TEA)
Which bacteria uses quorum sensing to be toxic
pseudomonas aerginosa
- Infects CF patients, activate biofilm production that hides bacteria from immune system and antibiotics
Describe transformation
donor cell lysis→ DNA fragments released→ DNA integrates into the recipient DNA
Describe transduction
(Generalized) donor cell infected with bacteriophage→ cell lysis and virus released→ virus infects new cell.
(Specialized) The lysogenic cell has prophage on chromosome→ inexact prophage induction → cell lysis→ virus infects a new cell and DNA incorporated into the recipient chromosome
Descrine conjugation
Conjugation: Plasmid transfer→ plasmids cross the cytoplasmic bridge and enter the recipient through sex pilus. Chromosomal transfer→ Plasmid can cause the transfer of DNA which integrates with the recipient’s DNA
Which type of gene transfer is most clinically important and doesn’t require recombination
conjugation
What are most antibiotic resistances in bacteria due to
plasmids (resistant plasmids, plasmids via horizontal gene transfer and conjugation, recombination)
Size range for viruses
Double digit nm
Small: Poliovirus (~30 nm)
Large: Poxvirus (~200-300 nm)
Basic structure in all viruses
Capsid, nucleic acid
Non-enveloped virus steps life cycle
Attachment: Virus binds to specific receptors on the host cell surface.
Entry: Nonenveloped viruses enter the cell by endocytosis.
Uncoating: The capsid breaks down, releasing viral nucleic acid into the host cell.
Replication: The viral genome is replicated using the host cell’s machinery.
Assembly: New viral particles are assembled inside the host cell.
Release: The virus is released from the cell via cell lysis, breaking the host cell open.
Enveloped virus steps
Attachment: Virus binds to host cell receptors via spikes on the envelope.
Entry: The virus enters the cell by fusion of its envelope with the host cell membrane or by endocytosis.
Uncoating: The viral capsid disassembles, releasing the genome into the host cell.
Replication: Viral genome replication occurs using the host’s machinery.
Assembly: New viral particles are assembled, incorporating the viral genome.
Release: The virus is released by budding/exocytosis, where it acquires its envelope from the host cell’s membrane.
What is the latest point in a virus where a CT cell can destroy a host cell without releasing virons
before viral assembly and release.
What usually determines the host specificity of a virus
The ability for the virus to attach to the host cell
What is the function of reverse transcriptase in retroviruses
Reverse transcriptase in retroviruses converts the viral RNA genome into DNA. This DNA is then integrated into the host cell’s genome, allowing the virus to hijack the host’s cellular machinery to replicate and produce more viral particles. It is a key enzyme that allows retroviruses, like HIV, to insert their genetic material into the host’s DNA.
What are the 3 general outcomes of a viral infection
Lytic Infection: The virus replicates and causes the host cell to burst (lysis), releasing new viral particles. (e.g., influenza)
Latent Infection: The virus remains dormant inside the host cell and can reactivate later (e.g., herpesviruses).
Chronic Infection: The virus continues to replicate at low levels, without destroying the host cell (e.g., hepatitis B).
What do all herpesviruses have
an envelope (establish latent infections)
HSV1 viruses cause
cold sores
HSV2 causes
genital herpes
Varicella-zoster (HSV3)virus causes
chickenpox and shingles
HSV 4 (Epstein-Barr virus) causes
mononucleosis (MS)
HSV 5 Cytomeglavoris causes
hepatitis, pnumonitis, most common cause of birth defects
HHV 6 and 7 causes
roseola in infants
HHV 8
Kaposki’s sarcoma herpes (HIV)
