Transcript The Single Cell - Fulton County Schools

The Single Cell:
Viruses, Bacteria, & Protists
What do you
notice as the
levels go from
atom to
organism?
Once at the
organism level
how do we
organize?
Why are levels of
organization
important?
Structure:
Viruses, Bacteria, & Protists
What is a Virus?
½ to 1/100 the size of the smallest bacteria
DNA or RNA
Classification on basis of nucleic acid

DNA viruses: - Herpes simplex virus (HSV)

RNA viruses: - influenza virus
Structure of a Virus?
Envelope – additional layer
surrounding the capsid
Genetic material
Capsid
- a shell of protein
surrounding nucleic acid
Capsid
Envelope
Lipid bilayer
Proteins determine the viruses shape:
Polyhedral - papilloma virus
with projections - HIV
helical - tobacco mosaic virus
Polyhedral head w/cylindrical tail w/ leg fibers
What are Bacteria?
Kingdom Archebacteria
Prokaryote
Extreme environment
No free O2
High salt or sulfur concentration
Some produce methane
What are Bacteria?
Kingdom Eubacteria
Human pathogens
Decomposers
Symbiotic living
Prepare food
Make antibiotics
Structure of Bacteria
Prokaryotic cells lack a nucleus and membrane
bound organelles
Common shapes among prokaryotes
are spheres, rods, & spirals
What are Protists?
Kingdom Protista
All organisms that are neither animals, plants, bacteria
or fungi are called 'protists'
Unicellular, multicellular, colonial
Eukaryotic
Aquatic environments
What are Protists?
Plant like Protists - Algae
Live in fresh or salt water
Reproduction & metabolism similar to plants
Animal like Protists - Protozoa
Ciliate
Flagellate
Aquatic
All are single celled
Pseudopod
Metabolism similar to animals
Grouped according to how they move
Fungus like Protists –
plasmodium, slime mold, downy mildew
Behavior & metabolism similar to fungus
Sporazoan
Reproduction:
Viruses, Bacteria, & Protists
Viral Reproduction
Lytic Cycle
The viruses attaches to a host cell and deposits its
DNA
The viral DNA instructs the host cell to use its own
enzyme raw material & energy to only make new viruses
The new viruses burst from the host cell – killing it – &
are able to go infect other cells
•Attachment
•Entry
•Replication
•Assembly
•Release
Viral Reproduction
Lysogenic Cycle
The viral DNA is integrated into the host cells
chromosome - provirus
Every time the host cell replicates it also replicates the
viral DNA
Once activated, the provirus enters the lytic cycle
replicates and kills the host cell
•Attachment
•Entry
•Provirus formation
•Replication
•Assembly
•Release
Bacterial Reproduction
Most prokaryotes have a single,
circular, double-stranded DNA
chromosome condensed in the
nucleoid region of the cytoplasm
Many bacteria have an additional small ring of
DNA – The Plasmid – prokaryotes can survive
without the plasmid the genes for essential
functions are on the chromosome. Plasmids
sometimes contain genes for resistance and
other special issues
Bacterial Reproduction
ASEXUAL
No cell cycle like seen in
Eukaryotes
No mitosis or meiosis
Prokaryotes reproduce mostly
asexually via binary fission,
making DNA almost continuously
Translation and transcription
occur simultaneously
Allows for rapid response to Environment –
ADAPTATION
Bacterial Reproduction
SEXUAL
Conjugation, one cell directly transfers DNA to another
Resulting in a bacterium with a new genetic composition
Plant Like Protist Reproduction
Asexual & Sexual
Fragmentation occurs when a
filament breaks apart and each
piece develops into another
organism.
Spirogyra
Conjugation occurs when two filaments form
conjugation tubes. The contents of one cell passes
through the tube an fuses with a cell from the other
filament. Fertilization occurs and a zygote is formed.
(haploid)
Alternation of generations Sexual
(haploid)
(haploid)
and asexual reproduction occurs during
alternating periods in the life cycle of
the plant like protist.
(diploid)
(diploid)
(diploid)
Animal Like Protist Reproduction
Multiply asexually by
fission. The cell divides
into two individuals.
Paramecium undergoing fission.
Fungus Like Protist Reproduction
Plasmodium - Reproduces by
haploid spores
Slim molds are haploid their entire
life & reproduce by cell division
Metabolism:
Viruses, Bacteria, & Protists
Do viruses need energy?
Do viruses need to “eat”?
Do viruses produce waste?
Do viruses have a metabolism?
Heterotrophic Bacteria
Use organic molecules as a food source
Parasites –
Unable to produce organic molecules
Obtain nutrients from living organisms
Excretes waste thru cell wall
Saprophytes –
Feed on dead organisms or organic waste
Break down nutrients locked in body tissues
of dead organisms
Excretes waste thru cell wall
Autotrophic Bacteria
Use sunlight to make organic molecules
Photosynthetic
autotrophs –
Contain chlorophyll
Excretes waste thru
cell wall
Make organic molecules from inorganic ones
Chemosynthetic autotrophs –
Obtain energy needed to make food from
Chemicals like sulfur & nitrogen
Excretes waste thru cell wall
Protists
Plant like
Able to perform photosynthesis
contain chlorophyll
Not all are green. Diatoms &
dinoflagellates have yellow to
brown chloroplasts. There are
brown algae & red algae
Release waste thru cell wall
Animal like
Heterotrophic – feed on other
organisms or dead organic matter.
Some are parasitic
Have specialized organelles used
to release waste
Fungus like
Heterotrophic
Plasmodium Eats as it moves
Mildew Feed on dead organisms
Releases waste thru cell membrane
Gas Exchange:
Viruses, Bacteria, & Protists
Why is gas exchange
important?
Do viruses need oxygen
or carbon dioxide?
Bacteria Metabolism
Obligate aerobes –
require oxygen
Mycobacterium tuberculosis –
the organism that causes the lung
disease tuberculosis
Obligate anaerobes –
require NO oxygen
Treponema pallidum –
the bacterium that
causes syphilis
Bacteria Metabolism
Prokaryotes used infolded regions of the
plasma membrane to perform many
metabolic functions, including cellular
respiration and photosynthesis.
Respiratory
membranes
in aerobes
Heterotroph
Thykaloid
membranes in
photosynthetic
bacteria
Autotroph
Protists Metabolism
Protists are eukaryotic cells
Have many specialized organelles including
mitochondria or chloroplasts used in cellular
respiration
Protists are aerobic – they require oxygen
Paramecium
Homeostasis:
Viruses, Bacteria, & Protists
What is HOMEOSTASIS?
Why is it important?
How do VIRUSES
maintain homeostasis?
The Host Cell does it for them!!
Bacteria Homeostasis
The cell wall maintains the shape
of the cell, protects the cell, and
prevents the cell from bursting in
a hypotonic environment
When life gets rough some bacteria can
form resistant endospores
Endospores contain a bacterium’s DNA and a small
amount of cytoplasm
Endospores are encased in a tough outer covering
that resists drying out and extreme temperatures
Protist Homeostasis
Because the kingdom protista contains such a variety,
several homeostatic behaviors exist
If you would keep Euglenoids in the dark they start feeding on
organic matter and may loose their chloroplast. Sometimes classified
as animal like other times classified as plantlike
Amoebas can grow to very large sizes. Some species are 5
mm long! They can survive by having many nuclei within
their single cell.
Star-shaped contractile vacuoles are used to balance the
amount of water in the cell.
Two nuclei contain the genetic information.
Are viruses alive
What are the
characteristics of
life?
How do
characteristics of
viruses
compare to that of
living organisms?
Are viruses alive
How do
No cell
characteristics of
organization
viruses
compare to that of
living organisms?
Homeostasis?