Bacteria And Viruses Flashcards
Sense RNA can…?
Be directly translated
What is a capsid?
Protein shell
Protects the inner nucleic acid and attaches to host cells
How are some viruses surrounded by an envelope?
Picks up the plasma memebrane in host cells on the way out
What is a virus?
Uses host cell’s machinery to replicate itself
Snaps of capsid so viruses?
Icosahedral - like a diamond or gem
Helical - like alpha helices
How do viruses bind to cells?
Ligand on capsid of naked virus or on envelope
What does the host cell contain, important got viral infection?
Cellular machinery
If the virus replicates successfully and causes an infection, it is…?
Productive
The host cell gets infected making it…?
Permissive for virus
What is the Baltimore Classification Scheme?
Relationship between viral genome and mRNA
Allows for targeting drugs and vaccines
And investigate evolution of viruses
What are the 4 effects viruses have?
Cytopathic
Cancer
Death of cells
Unable to see virus effects on cells
What are Cytopathic effects?
Visible effects on host cells due to viral replication
Inclusion bodies - active virus synthesis
Syncytia formation - giant multinucleated cell -
fusion of plasma membrane
Chromosomal DNA
Inhibition of host DNA, RNA or protein synthesis
How do viruses cause cancer?
Integrate with all or part of host DNA
Retroviruses cause cancer as turn on oncogenes which proliferate uncontrollably
Some viruses cause it in non-permissive cells by inactivating tumour-suppressor proteins hence cancer cells go through cell cycle
What occurs when host cells die?
Virus is released
What is an infection?
Establishment of an organism on or in a host associated to multiplication or damage
Causes of infection?
Pathogenic microbes:
Viruses, prions, bacteria, archea, fungi, Protozoa, helminths
Structures in bacteria?
Cell wall Peptidoglycan layer in gram positive Capsule in viruses and some bacteria Ribosomes Plasmids
Gram positive bacteria?
Staphylococcus aureus Streptococcus pyogenes Clostridium difficile and pertingens Group B Streptococci Streptococcus pneumoniae
Gram positive bacteria are what colour?
Blue
Gram negative bacteria are what colour?
Red
List of Gram negative bacteria?
E. coli Neissera Meningitidis and gonorrhoea Salmonella spp Shigella Ligionella spp Helicobacter pylori Chlamydia spp
What makes you more susceptible to infection?
Weakened immune system Poor nutrition Poor living circumstances No access to health Genetic disposition Lifestyle eg STIs
How does gram staining work?
Positively charged crystal violet bind to negative cell components
Iodine forms large complex with violet
Acetone or methanol extracts the complexes from gran negative walls as they have a thin peptidoglycan wall, whereas remains in gram positive bacterial walls.
A red dye is applied and stains the gram negative
Hence red for gram negative and blue for positive.
How are Acid Fast stains used?
Detect bacterial causes of tuberculosis and leprosy - mycobacteria - as can not be detected by gram staining
