Download Prokaryotes (bacteria) - Mrs. Ganske`s Science Classes

An overview
What to Expect:
• These notes focus on
–Cell theory
–Prokaryotes
Cell theory
1. All living things are made of cells
2. Cell can only come from other
cells
3. All functions of a living thing are
carried out in cells
•
Reminder: the functions of living things are:
respiration, metabolism, growth, adaptations to
the environment, reproduction, homeostasis
and interdependence
On your worksheet
1.State the 3 points of
cell theory.
1.List the 7
characteristics of life
There are two main groups of cells,
prokaryotic and eukaryotic cells.
Similarities: all are alive, all have a cell membrane, all
have DNA
Differences: appearance, structure, reproduction, and
metabolism.
–
.
biggest differences are between cells of different kingdoms
On your worksheet
• List the 2 types of cells
Where do we find Prokaryotes?
Prokaryotes are bacteria
• Prokaryotes are simple organisms
VS
Diagrams courtesy - http://www.cod.edu/people/faculty/fancher/ProkEuk.htm
According to current scientific thought;
Prokaryotes were formed 2 billion
years before eukaryotes (or about
3.5 billion years ago)
On your worksheet
• According to current
scientific thought, about
how old are prokaryotes?
Prokaryotes
from the Greek meaning “before nuclei”
Why “before nuclei?”
• Prokaryotic cells have no nucleus.
• Prokaryote’s DNA is circular (it has no
ends).
– Small circlets of DNA are called Plamids.
• Prokaryotic DNA is “naked” – it has no
histones associated with it and does NOT
form chromosomes
On your worksheet
• What does prokaryote mean?
• Why is the term prokaryote
used to describe the cells we
are talking about?
All Prokaryotes are in the
monera kingdom
domains Bacteria and Archaea
– bacteria
– Cyanobacteria
• also known as bluegreen algae
On your worksheet
• What kingdom to do all
prokaryotes belong to?
Prokaryote Characteristics
1. Very small size.
2. Lack membrane-bound organelles inside the
cell
3. have few internal structures that are
distinguishable under a microscope.
4. genetic information is in a circular loop called a
plasmid
5. Strong cell walls: resistant to environmental
changes
1. Size
• Bacterial cells are very small, roughly
the size of an animal mitochondrion
– about 1-2µm in diameter and 10 µm long
– µm = one millionth of a meter, or
equivalently one thousandth of a millimeter.
Video:
On your worksheet
•What is the size of an
average Prokaryote?
2. Lack membrane-bound
organelles inside the cell
3. have few internal structures
that are distinguishable under a
microscope.
http://www.umanitoba.ca/science/biological_sciences/lab3/biolab3_2.html#Examine
4. genetic information is in a
circular loop called a plasmid
• E. coli cell dividing.
• E. Coli Grows in
human intestine;
– Has a single, circular
chromosome
– contains DNA as
plasmids
• Plasmids are extrachromosomal DNA
http://www.bio.mtu.edu/campbell/prokaryo.htm
5. Strong cell walls: resistant to
environmental changes
On your worksheet
Describe the 5 items
used to classify a
prokaryote
Shapes
Spiral
Cocci - sphere
Bacilli - rods
Spirilla – spirals
Staph - in clusters
Strep - in chains
This spiral
shaped
bacteria is the
causitive
agent of
syphilis
Treponema
pallidum
Rod shaped
Spherical
Streptococcus sp.
Chains of nearlyspherical bacteria.
From The
Rockefeller
University.
Means Sphere-shaped
Streptococcus sp.
Chains of nearlyspherical bacteria.
From The Rockefeller
University.
Streptococcus pyogenes
Means Spiral-shaped
This spiral shaped bacteria is the causitive agent of syphilis Treponema
pallidum
Means Rod-shaped
• short rods - (coccobacilli).
• commas - (vibrii).
squares
stars
irregular
Cocci can divide to
form
• chains
(streptococci)
• groups of 4
(tetrads)
• irregular clusters
(staphylococci).
Real-life examples:
• Bacilli can divide to form
chains (streptobacilli)
• spiral bacteria normally
remain as separate
individuals.
To review:
Or, how bacteria move
• Some bacteria can be identified by how they move
– Stationary (don’t move at all)
– Flagella (whip like structure)
• Rotation and tumbling
• Number of flagella
– Monotrichous
– Lophotrichous
– Amphitrichous
– Peritrichous
•
Spiraling
– Slime and ooze
• Which means, some bacteria simply do
not move - - at all, ever.
• Some bacteria are
propelled (moved) by
a whip-like structure
called a FLAGELLA
– Flagella can be rotated
like tiny outboard
motors
– When flagella rotation
is reversed, bacteria
tumble about in one
place.
– Monotrichous- Having
one flagellum at only one
pole or end
– Lophotrichous- having
a tuft of flagella at one end
– Amphitrichous- having
flagella at both ends
– Peritrichous- Having
flagella uniformly distributed
over the body surface
Like a corkscrew
– Kinking different parts of
the bacteria body by
hardening one side and
then the other
• Other bacteria secrete a slime layer and
ooze over surfaces like slugs.
– slime layer is formed by decomposition of the
cell wall.
Replication
• Binary fission
– one cell splits into two cells,
• offspring are genetically identical to parent
• Bacterial
conjugation
– a form of sexual
reproduction where
bacteria exchange
genetic information
before dividing
• offspring have new
genes (and new
traits)
Figure 1. Schematic drawing of bacterial conjugation. 1Donor cell produces pilus; 2- Pilus attaches to recipient cell,
brings the two cells together; 3- The mobile plasmid is
nicked and a single strand of DNA is then transferred to the
recipent cell; 4- Both cells recircularize their plasmids,
synthesize second strands, and reproduce pili. Both cells
are now viable donors.
http://parts.mit.edu/igem07/index.php/Boston_University/Conjugation
• Transformation
– bacteria incorporate genes from dead
bacteria
• Transduction
– viruses insert new genes into bacterial cells.
– This method is used in biotechnology to
create bacteria that produce valuable products such as
insulin
Movement
Some can't move,
while others have
long threadlike
flagella.
E.Coli flagella
If bacteria doesn’t
move, how does it
get from person
to person?
How does a Bacteria get energy?
Or, how bacteria get energy
– 4 main ways bacteria get energy
•
•
•
•
Chemoheterotrophs
Photoheterotrophs
Photoautotroph
Chemoautotroph
– Energy is released through either cellular respiration
or fermentation
– Oxygen demands vary
• Obligate aerobe
• Obligate anaerobe
• Facultative anaerobe
• Heterotrophs get energy by eating other
organisms
– Chemoheterotrophs
• Eat other organisms for Energy
• Eat other organisms for carbon supply
– Photoheterotrophs
• Use sunlight for energy
• Eat other organisms for carbon supply
• At least 95% of life on
earth is heterotrophic
(including people)
staphylococcus aureus
• Chemoheterotroph
– “eat” same foods as
humans
– Release toxins that cause
food poisoning
– Antibiotic resistant strains
cause breakout pictured
here
Jannaschia
• marine bacteria found in
coastal and open ocean
surface waters.
• aerobic anoxygenic
phototroph (AAnP),
– Gets its energy from light,
not from eating other
organisms
• responsible for oceanic
photosynthesis in the ocean
and the ocean carbon cycle.
• Autotrophs make their own energy from
inorganic (not-living) molecules
– Photoautotroph
• Uses sunlight (light energy) to convert CO2 and
H2O into Carbon compound and oxygen
– Chemoautotroph
• Make organic carbon molecules from CO2 using
energy from chemical reactions involving
ammonia, hydrogen sulfide, nitrites or iron
Cyanobacteria
– Also called
bluegreen algae
– Found in fresh
water, salt water
and on land near
sources of light
– Photoautotroph
• Use sunlight to
make energy and
carbon compounds
• Chemoautotrophs get
energy and carbon
from chemical
reactions
• Some live near ocean
vents like the one
pictured
•
Once bacteria have “eaten” they need to break
down their “food” to make energy
•
The process of breaking down organic
compounds into ATP (energy cells can use) is
called cellular respiration
•
Same 1st step to begin with, but the lack or
presence of oxygen determines the 2nd step
– Step one – Glycolisis
– Step two – Fermentation or Kreb Cycle
• To oversimplify the first step
–called glycolysis
• Doesn’t require Oxygen (anaerobic)
• Takes place in the cytosol (fluid
surrounding organelles) of a cell
• Breaks glucose into pyruvate creating
ATP and H in the process
• If NO oxygen is present after glycolysis,
Fermentation begins
– 3 types
• Lactic acid Fermentation
– Occurs in muscles
» causes muscle cramps due to acidity
– Occurs in Bacteria
» used to make cheese and yogurt
• Acetic Acid Fermentation
– Occurs in Bacteria
» Forms vinegar
• Alcohol Fermentation
– Forms ethyl alcohol and CO2
» Used to make bread, wine and beer
• If Oxygen IS present after glycolysis,
Acetyl CoA is made and the Kreb cycle
begins
– we’ll save the chemical details of this process
for another class, but, basically it produces a
whole lot of ATP for the cell to use
• SOME BACTERIA REQUIRE OXYGEN,
SOME DON’T
– OBLIGATE AEROBES
– OBLIGATE ANAEROBES
– FACULTATIVE ANAEROBES
• Obligate aerobes NEED oxygen to live
– OBLIGATE means required to
– AEROBE means oxygen
• Release energy through cellular
respiration or fermentation
• Example: myobacterium tuberculosis
• Obligate anaerobes DO NOT need oxygen
to live
– OBLIGATE means required to
– ANAEROBE means without oxygen
• Release energy through cellular
respiration or fermentation
• Example: clostridium botulinum
• Facultative anaerobes can survive with or
without oxygen
– Facultative – means able to function in
different ways
• These bacteria can live just about
anywhere
• Example: E. coli
Functions
What does Bacteria do?
• decomposers, agents of fermentation,
and they play an important role in our own
digestive system.
• involved in many nutrient cycles such as
the nitrogen cycle, which restores nitrate
into the soil for plants.
What is Bacteria’s job?
What about “bad” Bacteria?
• Describe a benefit of having bacteria on
Earth
• Describe a “bad” bacteria and how it
affects people.
Images of Bacteria
• http://www.ulb.ac.be/sciences/biodic/ImBa
cterie2.html
• http://www.buckman.com/eng/micro101/ba
cteria.htm