Viruses, prions and protists Flashcards
How does a virus make more viruses? explain
Viral genome enters Host cell
How does a virus make more viruses? explain
Viral genome enters Host cell, then replicated by host enzymes, copies of viral genomes are transcribed by host enzymes, transcribed viral mRNA are translated by host ribosomes, viral proteins are self assembled with viral genome to make new viruses. 398
What is the lysogenic cycle?
integration of the bacteriophage nucleic acid into the host bacterium’s genome or formations of a circular replicon in the bacterial cytoplasm.
What is a virus?
an infectious particle consisting of little more than genes packaged in a protein coat. 399
How does a viral infection affect the host?
Viruses may damage or kill cells by causing the release of hydrolytic enzymes from lysosomes. Some viruses cause infected cells to produce toxins that lead to disease symptoms, and some have molecular components that are toxic, such as envelope proteins. How much damage a virus causes depends partly on the ability of the infected tissue to regenerate by cell division. 408
what is a vaccine?
a harmless derivative of a pathogen that stimulates the immune system to mount defenses against the harmful pathogen.
Where do new strains of virus come from? (3 ways)
- One cause of rapidly emerging viral diseases in humans is mutation of existing viruses into new viruses that can spread more easily. RNA viruses have a high rate of mutation because viral RNA polymerases do not proofread and correct errors in replicating their RNA genomes
- A second cause of the emergence of viral diseases is the spread of a viral disease from a small, isolated human population.
- A third cause of new viral diseases in humans is the spread of existing viruses from other animals. 409
What is a Prion?
a type of protein that can cause disease in animals and humans by triggering normally healthy proteins in the brain to fold abnormally.
how do Prions propagate?
by folding normal proteins into other abnormal prions.
What gave rise to the great diversity of protists and how have their lineages diverged over time?
by endosymbiosis, prostists have evolved by ancestral cells and early eukaryotes ( heterotrophs) and early photosynthetic eukaryotes. This has given rise to 4 supergroups of eukaryotes….. SAR, excavata, archeaplastida, unikonta. 593
What is a Protist?
a single-celled organism of the kingdom Protista, such as a protozoan or simple alga 593
