biology chapter 20
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the three shapes of prokaryotes
- a rod shape (bacillus)
- a sphere shape (coccus)
- a spiral shape (spirillum)
two groups of prokaryotes
a single chromosome clustered in a mass called a nucleotide
small extra loop of dna
a protein-carb compound that makes up the bacterial cell wall.
this wall allows for the use of the gram stain
have a thick layer of peptidoglycan and no outer membrane. its stain is violet/purple
have a thin layer of peptidoglycan & have an outer membrane its stain is pink
organisms that get their energy from sunlight through photosynthesis
the only organisms that can get their energy from inorganic sources.
use molecules that contain sulfur or nitrogen & simple organic molecules
in the presence of hydrogen rich chemicals, chemoautotrophic bacteria can form all of their own amino acids and proteins.
most prokaryotes are this
get both energy & nutrition form other organisms
the means in which prokaryotes reproduce
forming new genetic combinations (prokaryotes)
conjugation~ when 2 bacteria exchange genetic material
transformation~ when bacteria take up dna fragments from their enviroment.
transduction~ when genetic material, such as a plasmid, is transferred by a virus. plasmids often convey antibiotic resistance
thick wall structures
help bacteria survive harsh conditions
they form inside the bacteria they surround the dna and a small bit of cytoplasm
show no signs of life & can be revived after hundreds of years.
pieces of nucleic acid contained in a protein coat
not considered to be living
two structures characteristic of all viruses
nucleic acid & a capsid
the protein coat of a virus encloses its genetic material.
viruses recognize their hosts by specific proteins on a host cell's surface. the proteins on the host cell have to match proteins on the capsid of the virus.
a membrane surrounding the capsid.
gives the membrane an overall spherical shape even if capsid is not.
its studded w/ receptors that help the virus enter cells. its made up of proteins, lipids, & glycoproteins
viruses that infect bacteria
have a complicated structure
lytic and lysogenic cycle.
lytic~ the cycle of viral infection, reproduction, & cell destruction
lysogenic~ host shares viral dna. host cell is not destroyed.
when viral dna becomes part of its host cell's dna
a virus whose reproduction includes the lysogenic cycle
nonliving particles that are able to reproduce & cause disease
viroids & prions
a single strand of rna that has no capsid.
rna of virus < rna o virus
disrupt host cell's regulation of growth
misshapen versions of proteins that are found in the brain.
bacteria and environment
vital role in all ecosystems
produce oxygen, makes nitrogen available, & helps decompose dead organisms. many form symbiotic relations
bacteria, viruses, & research
important in genetic reasearch
their genetic mataerial is easily studied
valuable info on dna replication, transcription, and translation
used in gene therapy
technique for diagnosing the cause of an infection
- 1) pathogen must be found in an animal w/ the disease & not in a healthy animal
- 2) pathogen must be isolated from the sick animal & grown in a laboratory culture
- 3) when injected into a healthy animal, the animal must contract the disease
- 4) pathogen from 2nd animal must be the same as the original pathogen
pathogenic bacteria ways to cause disease
by producing toxins
destroying body tissues( by producing enzymes that break down the host's tissues into nutrients that the bacteria can use)
the most common way that bacteria cause disease is by producing poisonous chemicals
chemicals that inhibit the growth of or kill micro-organisms
the spread of antibiotic resistance
spreads when sensitive populations of bacteria are killed by antibiotics. as a result resistant bacteria thrive
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