Transcript Viruses, Bacteria & Protists

Viruses, Bacteria & Protists
Quarter 4 Week 2
Viruses: Structure and
Reproduction
• Structure
• --biological particles composed of DNA
or RNA and a protein coat
• --Protein coat can be all different types
of shapes
• --Some contain a membrane-like
envelope to help it reproduce (chicken
pox, influenza, HIV)
Reproduction
• —cannot reproduce on their own
• inserts virual DNA into a cell, which then takes
over the cell’s reproduction and quickly produces
• new viruses until the cell dies and breaks open
(called the lytic cycle).
• some virus DNA will incorporate into the cell’s
DNA and will wait to make more viruses until there is
some external stimuli (fever, stress, etc.). All of the
cell’s offspring will include this viral DNA (called the
lysogenic cycle)
Reproduction
Viruses
• viruses gain new genetic material through
mutations
•
This ability to inject DNA into a cell is
used now as a treatment method. Ex: A
person cannot make insulin and has
diabetes. Put the gene within a disabled
virus and it injects it into the DNA of the sick
person.
• **Because they do not meet all of the
characteristics of lifethey are considered
non-living and do not have their own
kingdom!!
Bacteria Structure &
Reproduction
• Archaebacteria
• --prokaryotic, so basically DNA and
ribosomes within a membrane
• --oldest type of bacteria
• --live in extreme habitats (early Earth was
a toxic place!)
• --Reproduction through binary fission
(grow and then divide into two cells); this
is asexual reproduction.
Bacteria
• -Methanogens make methane gases
(intestines of humans and cows and
bottom of swamps)
•
-Extreme halophiles live in high salt
environments (Great Salt Lake)
• -Thermoacidophiles live in extremely hot
and acidic places (hot springs)
Eubacteria
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--prokaryotic
--have one of three basic shapes
-bacilli or rod-shaped
-spirrilla or spiral
-cocci or spherical (in chains or
clusters)
--uses cell membrane to produce ATP and go
through photosynthesis
Bacteria structure
Bacteria
• --DNA is a closed loop that floats in cytoplasm
with ribosomes
• --capsules or endospores form for protection if
conditions become to harsh for survival
• --pili are found in some bacteria that help it
attach to things and transfer some genetic
material
• --Reproduction is mostly asexual (binary
fission); new DNA can be gained through
mutations, pili, viral attacks, and taking in DNA
from environment
Protists
• --eukaryotic, so contain nucleus and other
membrane-bound organelles
• --can be divided into three groups:
•
-Animal-like (Protozoas)—heterotrophic,
move independently; unicellular
•
-Plant-like (Algae)—make food through
photosynthesis; some can be multicellular
• -Fungus-like (slime molds)
Protist
• --protists that are motile use many structures to move:
•
-flagella (one or two long hairs that have a whip
motion)
•
-cilia (many small hairs that beat back and forth
rhythmically)
•
-pseudopodia (extensions of cell; moves like the
“Blob”)
• --Reproduction is mostly binary fission (asexual)
•
some can go through can get new DNA through
conjugation
•
plant-like protists have sexual and asexual
reproductive stages
Protists
Fungi
• --most are microscopic molds or yeasts
• --molds and mushrooms produce filaments
to absorb their food
•
-hyphae-filaments
•
-mycellium—mat of hyphae you can
see
•
-cells of hyphae can be divided or
undivided
Fungi
• **Remember that fungi are
DECOMPOSERS. As the hyphae digest
the materials around them, the chemicals
that they do not absorb are returned to the
soil. They work at every trohpic level and
are the most important part of the nitrogen
cycle (working at every stage).**
Fungi
• --Reproduction--both sexual and asexual
•
asexually they produce genetically
identical spores, bud, or produce new
hyphae
• sexual reproduction through fusion of
hyphae which creates a genetically unique
individual.
Fungi