BIOL UNIT 3 EXAM prt 2

viruses and bacteria/archaea

viruses are not alive therefore

they are not classified in a kingdom or domain

Viruses characteristics

acellular, no metabolism (can’t grow), host dependent, uncertain origin, can infect almost all forms of life, species: tissue

Which is the smallest: a period, eukaryotic cell, bacteria or virus

virus

Microorganisms

viruses, prokaryotes: bacteria and archaea, protists and fungi

Optional and Needed Characteristics of Virus

Required: genetic material, capsid

Optional: envelop, spikes

Bacteriophages

viruses that infect bacteria

Lytic Cycle

phage infects, replicates, and ruptures the host cell

Lysogenic Cycle

phage DNA is incorporated into the host genetic material; bacteria replicate viral genome. Phage enters lytic cycle sooner or later

Classification of viruses by shape

helical, polyhedral, spherical, complex

reminder to self to do slides 17-20

otie dotie

Acute Infection

symptoms get increasing worse for a short period of time followed by elimination of the virus or death (common cold, influenza, COVID 19, Ebola)

Chronic infection

long term infection, may be asymptomatic, hepatitis C infecting liver cells cause low levels of damage

Intermittent Infection

appear and disappear, herpes simplex, latent infection- hides and immune response wanes. Stress can reactivate the virus that causes outbreaks on the skin. Varicella-zoster (chicken pox) can cause shingles in old adults

Oncogenic viruses

viruses that can cause cancer - human papillomavirus, Hep. B. Introduce oncogenes that interfere with control cell growth/replication

Viral Immunizations: types of preparations

killed virus, live virus, molecular subunits, (all hardware vaccines)

genetic material (software vaccine)

Killed virus

killed virus acts as the antigen (salk polio)

Live Virus

attenuated (weakened) virus acts as the antigen- might revert to disease producing - back mutation (Sabin polio)

Molecular Subunits

a part of the virus (spike protein) is used as the antigen

Genetic material

viral DNA (J&J) or mRNA (Pfizer and Moderna) is delivered to the host and they make the antigen

Killed, attenuated and molecular subunits are

hardware vaccines

Genetic Material is

software vaccine

Sabin Polio Vaccine

attenuated virus used, immune barrier in circulating and gut, oral route, rarely reverts back to virulent strain

Prokaryotes

single cell/ unicellular organisms that lack organelles/internal membrane bound structures. No nucleus, have a single chromosome (circular double stranded DNA in the nucleoid)

Kingdoms, phylogeny of prokaryotes

based on mode of nutrition, mode of reproduction and body organization. Split organisms into 5 kingdoms

Domains, phylogeny of prokaryotes

based on rRNA structure- split prokaryotes into two domains

Bacteria are the oldest living inhabitants on Earth

3.5-3.8 billion years

Autotrophs: carbon from inorganic CO2

photoautotrophs: energy from Sun

chemolithoautotrophs: energy from oxidizing inorganic substances

Heterotrophs: carbon from organic moleculues

photoheterotrophs: light as energy source

chemoheterotroph: energy from organic molecules (humans)

Structure of a prokaryote

cell membrane, cell wall, capsule, flagellum, pilus, chromosomal DNA

Cell wall

peptidoglycan provides shape, protection

Capsule

lipopolysaccharide, found in gram. Protects from dehydration, attachment, resistance to immune function

Pilus

used for attachment and conjugation

Bacterial Shapes

Cocci, Bacilli, Spirillum

Gram Positive Cell Wall

does not have lipopolysaccharides, stains purple

Gram Negative Cell Wall

lipopolysaccharides layer, stains red

Gram Negative bacteria are harder to treat because

does not absorb drugs well, immune cells and antibody have a hard time binding to them

Bacteria are important to

cycling Carbon and Nitrogen

Prokaryotes reproduce by

binary fission which limits genetic diversity

3 types of horizontal gene transfer: enhances genetic diversity

Conjugation, Transduction, transformation

Conjugation

cell-cell contact: DNA transferred from one organism to another, REQUIRES A PILUS. This is how antibiotic resistance is transferred

Transduction

by bacteriophages carrying prokaryotic DNA from one cell to another. Bacteriophages are viruses that infect bacteria

Transformation

from the environment: genotype of cell altered by the uptake of DNA from environment. DNA usually comes from dead bacterial cells

Black Death/Plague comes from

Yersinia pestis, still infects people btw

Bacteria are important pathogens demonstrated by childhood diseases/deaths by organisms like

mycobacterium tuberculosis