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genetic
defective genes can lead to an inability of the body to produce proper proteins or structures in the body (E.g. Haemophilia)
Infectious
transmitted in four different ways:
direct
fomite
zoonotic
vectors
direct
people to people (E.g. conjunctivitis, Hepatitis A and B)
fomite
surface to people (E.g. cold sores, hand-foot-mouth disease)
zoonotic
animal to people (E.g. rabies, psittacosis)
vectors
using small organisms to transmit bacteria or viruses (E.g. Lyme disease, tick-borne encephalitis, west Nile virus)
virus structure
the simplest virus structure consist of two basic components: nucleic acid (single or double stranded RNA or DNA) and a protein coat, the capsid.
capsid
functions as a shell to protect the viral genome from nucleases and during infections attaches the vision to specific receptors exposed on the prospective host cell.
DNA
double-stranded molecules that has a long chain of nucleotides.
RNA
single-stranded molecule which has a shorter chain of nucleotides.
genetic material
any material of plant, animal, microbial or other origin that carries genetic information and that passes from one generation to the next.
not living virus particles
contains genetic information → DNA or RNA
replicate only with the help of living cells
does not have any metabolic processes
do not consume food or produce waste
do not grow
Intracellular Pathogen
organisms that are capable of growing and reproducing inside host cells.
Lytic Cycle
the virus invades a host cell and injects its DNA (or RNA) into the host
the host cell replicates the parts of the virus and other materials in viral DNA
New viral particles are assembled in the host cells
cell lysis (death) occurs releasing new viruses )E.g. common cold or flu)
Lysogenetic Cycle
upon infection the viral genome becomes integrated into that of the host
as the host cell undergoes cell cycle and cellular synthesis the viral DNA is copied and incorporated into all of the newly synthesised cell
after a prolonged period of time a trigger causes the switch to lytic cycle and a full blown infection occurs.
E.g. chicken poxes can manifest into shingles later in life.
Evolution of Viruses
RNA viruses have the capacity to mutate quickly
they can pick up genetic information from the host cell
there can be random errors that happen in the replication process of the RNA that own lead to change in the protein coat of the virus. This can make it easier for the virus to enter cells and/or make it harder for the immune system to detect the virus as a foreign particle.
significane → virus evolution impacts all life and viral emergence continues to threaten human health.
Aerobic
requires oxygen, releases more energy but slowly
Anaerobic
respiration access without oxygen and releases less energy but more quickly
Conjugation
process by which one bacterium transfers genetic material to another through direct contact.
Binary Fission
process of one cell simply dividing into two
Gram+
positive bacteria show blue or purple after straining in a laboratory test. They have thick cell walls.
Gram-
bacteria shows pink or red on staining and have a thin cell wall.
Cellular Structure of Bacteria
the cell wall forms a rigid structure of uniform thickness around the cell and is responsible for the characteristics shape of the cell.
Value/Important of Bacteria
helps you digest food → produces vitamins (E.g. vitamin K)
protects against infection → e.g. commensal bacteria
maintain your reproductive health → e.g. cervicovaginal lactobacillus
How bacteria cause illness or disease
Septicaemia → if bacteria spreads in a person may become septic and die from a bacterial infection
many bacteria produce specific surfaces proteins or toxins which may hurt the organism lives on or in.
How bacteria is cultured in the lab
Take a sample of something, for example ocean water and dilute it in water. Then spread a droplet of this dilation on a peak: dish full of nutrients. Each individual bacterium lands in a unique spot on the dish.
Independent Variable
the variable you manipulate, control, or vary in an experimental study to explore its effects.
Dependent Variable
what you measure in the experiment and what is affected during the experiment.
Controlled Variable
anything that is held constant or limited in a research study.
How bacteria evolves
amplified by bacteria’s ability to mutate and exchange genetic information from other bacteria
genetic combination can change through conjugation and gene transfer
a bacteria can cut out a gene, package it as a plasma and send it to another bacteria cell giving that bacteria antibiotic resistance as well.
principle of evolution of bacteria
bacterial diversity exists in a bacterial community
only the bacteria with certain characteristics survive the use of antibiotics. We would say that these bacteria are “fit”.
This results in a loss of genetic diversity. Only these bacteria that survive reproduce. The next generation of bacteria now are all antibiotic resistant.
Bacteria replicate
rapidly using a special form of mitosis called Binary Fission. (this can occur every 8 to 20 minutes)
HIV capsid
HIV’s core that contains HIV RNA
HIV envelope
outer surface of HIV
HIV enzymes
proteins that carry out steps in the HIV life cycle.
HIV RNA
HIV’s genetic material
cladistics
use shared characteristics to establish evolutionary relationships.
evolutionary events
the appearance of a new characteristics → These characteristics are assumed to be due to new forms of the genes that then get passed down to all successive generations.
In-group
share characteristics
Out-group
do not share characteristics
Nodes
represent an ancestral form of the species
Clades
are groups of species based on their evolutionary relationship.
Mutations
every time the viral DNA is replicated copying errors can occur
this leads to genetic mutation that will be prevalent in all future replications of the virus
by doing genome comparison between different viruses scientist can show the relatedness of viruses and generated phylogenetic trees mapping out the evolution of viruses
Significance of Antibiotic Resistance
medicines become ineffective and infection becomes difficult or impossible to treat.
increasing the risk of disease spread
Differences in the activity of bacteria and viruses and how they make you sick.
Bacteria:
multiply so rapidly, they crowd out host tissues and disrupt normal functions
kill cells and tissues
make toxins that can paralyze, or destroy cells.
Viruses:
cause infections by entering and multiplying inside the host’s healthy cells
cannot be detected by the immune system
E-coil (caused by bacteria)
food poison from contaminated food (e.g. raw meat)
Parkinson (caused by bacteria)
progressive disorder, which affects the nervous system and the parts of the body controlled by the nerves.
Flesh eating bacteria (caused by bacteria)
it destories skin, fat, and tissue covering the muscles within a very short time span
step throat (caused by bacteria)
spreads through droplets (e.g. a infected person coughs, sneezes, or you share food and drinks). It affect the throat and with antibiotic can heal pretty quickly.
mosquito-borne viruses (caused by a virus)
medium-size viruses like West Nile and transmitted to human by saliva in a mosquito’s bite and travel throughout the body in the bloodstream.
deadly adaptors
large viruses that infect humans, such as variula (which causes smallpox) and Ebola viruses, tend to have a high death rate. This is probably because many large viruses carry viral proteins, in addition to their genes, can overwhelm and shut down the host’s defences.