Prokaryotes

1
(No Transcript)
2
Prokaryotes
3
The Current Kingdoms

• Kingdom Monera - Eubacteria - new bacteria
• Prokarya - Archaebacteria old bacteria
• Kingdom Protista- 1 celled organisms- Eukaryotes
• Kingdom Fungi- multicellular fungi/yeast-
  Eukaryotes
• Kingdom Plantae- photosynthetic plants-
  Eukaryotes
• Kingdom Animalia- animals from zygote-
  Eukaryotes

4
History of the Prokaryotes

• 1735 Plant and Animal Kingdoms
• 1857 Bacteria and fungi put in the Plant
  Kingdom
• 1866 Kingdom Protista proposed for bacteria,
• protozoa,
  algae, and fungi
• 1937 Prokaryote introduced for cells "without
  a
• nucleus"
• 1961 Prokaryote defined as cells in which
• nucleoplasm is
  not surrounded by a
• nuclear
  membrane
• 1959 Kingdom Fungi
• 1968 Kingdom Prokaryotae proposed
• 1978 Two types of prokaryotic cells found

5
History of the Prokaryotes

• Prokaryotes date back 3.5 billion years.
• They were probably the first living organisms.
• In comparison, animals date back to 700 million
  years ago.
• Plants date back 470 million years ago.

6
Species Definition

• Eukaryotic species A group of closely related
  organisms that breed among themselves
• Prokaryotic species A population of cells with
  similar characteristics
• Clone Population of cells derived from a single
  cell
• Strain Genetically different cells within a
  clone
• Viral species Population of viruses with similar
  characteristics that occupies a particular
  ecological niche

7
Dichotomous Key- to Identify Bacteria
8
Identification Methods

• Morphological characteristics Useful for
  identifying eukaryotes
• Differential staining Gram staining, acid-fast
  staining
• Biochemical tests Determines presence of
  bacterial enzymes

Figure 10.8
9
(No Transcript)
10
SSvedberg Unit
Table 10.2
11
The Three-Domain System
Figure 10.1
12
Endosymbiotic Theory
Figures 10.2, 10.3
13
Kingdom Prokaryota

• 1. All unicellular microscopic prokaryotes
• 2. Two subkingdoms,
• a. Archaea
• b. Bacteria
• 3. Viruses- sometimes included but usually are not

14
Bacteria Organelles

• Fimbriae or pilliThread-like structures present
  on some bacteria.
• Pili are shorter than flagella and are used to
  adhere bacteria to one another during mating and
  to adhere to animal cells.
• NucleoidIn contrast to eukaryotes with a
  nucleus, prokaryotes have a nucleoid where the
  chromosomes with the genetic material can be
  found.
• In the nucleoid the genetic material is not
  enclosed in a membrane to separate it from the
  cytoplasm.
• PlasmidsIn addition to one chromosome,
  prokaryotes usually contain one or more smaller
  circular DNA molecules called plasmids.

15
Bacteria Chromosome

• Prokaryotes have one main chromosome which is
  made of a continuous, circular molecule of double
  stranded DNA

16
Physical Traits

• Prokaryotes are extremely small.
• A spoonful of garden soil may contain 10 billion
  of them.
• The total number of prokaryotes in your mouth is
  greater than the number of humans who ever lived
  on Earth.
• Prokaryotes cover the skin, line the nose and
  mouth, and live in our intestines.

17
Bacteria Shapes

• Bacteria come in a wide variety of shapesA.
  Rod-shapeB. Round or sphericalC. Round in
  clustersD. Round in twosE. SpiralF.
  Comma-shape

18
Bacterial Shapes

• 
  
• Coccus Bacillus Spirillum
• Diplo- Strepto-
  Staphylo-

19
Distinguishing Features

• Members of the kingdom Prokaryota have cells
  that
• Lack a true nucleus
• This means that the nucleus does not have a
  nuclear membrane (envelope) and the DNA is not
  organized into chromosomes.
• Do not have membrane bound organelles
• Lack many of the organelles found in eukaryotes
• Reproduce mostly by binary fission but can
  reproduce sexually through conjugation.

20
Cell Walls

• Eubacteria cells have a cell wall.
• Some Archaean bacteria have a cell wall, but some
  do not.
• Plants, bacteria, fungi and algae all have cell
  walls around their cells.
• Animal and protozoan cells do not have cell
  walls.
• In plants, the cell wall is made from the sugar
  cellulose.
• In fungi the the cell wall is composed of chitin
  which is the same complex sugar that composes the
  exoskeleton of arthropods.

21
Peptidoglycan

• Many true bacteria (eubacteria) have a cell wall
  made of a huge molecule called peptidoglycan
  which is a combination of sugars and amino acids.
• One method for identifying bacteria is to use a
  blue stain called a Gram stain.
• In gram-positive bacteria the peptidoglycan forms
  a thick meshlike layer that retains the blue dye
  of the Gram stain by trapping it in the cell.
• In contrast, in gram-negative bacteria the
  peptidoglycan layer is very thin so the blue does
  not show.
• Archaeobacteria lack peptidoglycan but some have
  glycan cell walls.

22
Photosynthesis

• Many bacteria are capable of photosynthesis.
• Photosynthetic halophiles use rhodopsin instead
  of chlorophyll.
• Cyanobacteria use chlorophyll.
• However, unlike plants, cyanobacteria do
  photosynthesis in their cytoplasm.
• Chloroplasts in plants probably evolved from
  cyanobacteria.

23
Prokaryotic Environments

• Prokaryotes can survive in almost any
  environment.
• Some species live in freezing temperatures and
  others live in boiling hot springs and hot acids.
• Some species can survive the high pressure at the
  depths of the ocean and the low pressure of the
  upper atmosphere.
• When volcanoes damage environments, bacteria are
  among the first organisms to move in. They make
  it the environments liveable for other organisms.

24
Prokaryotic Digestion

• As a group, prokaryotes can digest almost
  anything, even cellulose and petroleum.
• Prokaryotes are the major decomposers in most
  ecosystems.
• They can break down complex organic compounds
  into simple inorganic materials used by
  autotrophs, prokaryotes are essential to all food
  webs.

• In addition to being able to break complex
  organic molecules down, prokaryotes can also
  build simple inorganic molecules into complex
  organic molecules like some antibiotics.

25
Bacteria Nutrition
26
Prokaryote Respiration

• 1. Aerobic respiration
• 2. Anaerobic respiration
• 3. Fermentation

27
Aerobic Respiration

• 1. Complete oxidation of organic compounds to CO2
  using oxygen
• 2. Mitochondria oxidize glucose to CO2
• C6H12O6 6O2 g 6CO2 6H2O

28
Anaerobic Respiration

• 1. Complete oxidation of organic compounds to CO2
  using oxidizers other than oxygen
• 2. Instead of breaking down glucose and oxygen
  into carbon dioxide and water, these bacteria
  break down acetic acid, sulfuric acid and water
  into carbon dioxide, hydrogen sulfide and water.
• C2H4O2 H2SO4 H2O g2CO2 H2S 3H2O

29
Fermentation

• 1. Incomplete anaerobic breakdown of an organic
  molecule
• 2. Saccharomyces cerevisiae ferment glucose to
  CO2 ethanol
• C6H12O6 g 2CO2 2C2H5OH

30
(No Transcript)
31
Archaea or Extremophiles

• Ancient bacteria
• Differ from all other forms of life
• Live in extreme conditions
• Probably the oldest organisms on Earth
• Some are motile
• Break down chemicals for food
• In some ways more advanced than the eubacteria
  because they have had longer to evolve.
• Example Archaea have DNA binding proteins
  eubacteria do not

32
Types of Archaebacteria

• Three main types
• a. Methanogens- methane producing live in
• anaerobic conditions. As a bi-product
  they
• produce methane (CH4).
• Methanogens live in the digestive tract
  of
• animals.
• b. Halophiles- Extreme saline loving
• c. Thermoacidophiles- Extreme heat or acid
  loving

33
Archaebacteria Unique Traits

• Cell walls lack peptidoglycan

34
(No Transcript)
35
Eubacteria Metabolism

• Eubacteria may be aerobic, anaerobic,
  photosynthetic, chemosynthetic, thermophilic or
  cryophilic.
• The three major groups of eubacteria are
• No cell wallsMycoplasmas
• Thin cell wallsGram negative
• Thick cell wallsGram positive

36
Mycoplasmas

• No cell walls
• Simple cell structure
• Resistant to penicillin because penicillin
  attacks the cell wall
• Smallest known organisms capable of independent
  growth
• Some mycoplasmas cause diseases pnuemonia
• Most mycoplasmas are harmless

37
Gram Positive Antibiotics

• 1. Gram stain is absorbed by peptidoglycans, only
  found in bacteria
• 2. Bacteria with thick cell walls have lots of
  peptidoglycan and absorb lots of stain so appear
  purple, Gram
• Streptococcus Lactobacillus
• thermophilus acidophilus

38
(No Transcript)
39
Uses of Gram Positive Bacteria

• Some Gram Positive bacteria produce lactic acid.
• These are used to prepare sauerkraut, buttermilk
  and yogurt.

40
Antibiotics

• Gram positive bacteria are used to make
  antibiotics such as streptomycin, tetracyclin,
  and erythromycin.

41
Gram Negative Photosynthesis

• 3. Bacteria with thin cell walls have little of
  peptidoglycan and absorb small amounts of Gram
  stain so appear pink, Gram -
• Escherichia coli

42
Gram- Sulfur Using Bacteria

• Green and blue eubactaria are photosynthetic,
  gram negative forms that are anaerobic do not
  use water in photosynthesis and do not produce
  oxygen gas.
• C2H4O2 H2SO4 H2O g2CO2 H2S 3H2O

43
Gram- Cyanobacteria

• Cyanobacteria or blue-green eubacteria are the
  best known of the gram- bacteria because they use
  true photosynthesis.
• However, instead of needing chloroplasts,
  cyanobacteria are able to photosynthesize from
  chlorophyll located in the cell membranes.
• One theory is that the chloroplasts in plants
  evolved from a symbiotic relationship between
  cyanobacteria and algae.
• Cyanobacteria can grow in colonies thick enough
  to be mistaken for algae.

44
Cyanobacteria, Oxygen and Eukaryotes

• One theory is that 2 billion years ago,
  photosynthetic cyanobacteria started a metabolic
  revolution that led to the increase of oxygen in
  the atmosphere to 1.
• This allowed plants to evolve.
• Plants then took the oxygen from 1 to the 21 in
  the atmosphere today.
• Almost all eukaryotic life depends on this oxygen
  today.

45
Harmful Gram Negative Bacteria

• Spirochetes
• Chlamydias
• Proteobacteria

46
Nitrogen Cycle

• Chemoautotrophs are eubacteria that obtain energy
  from inorganic molecules in the environment.
• Among the most important chemoautotrophs is the
  nitrifying and denitrifying bacteria.
• These are the bacteria that control the nitrogen
  cycle.

47
Bacterial Reproduction

• 1. Asexual binary fission is the primary form
• 2. Single parent cell splits into two genetically
  identical sibling cells
• 3. Each new cell has an exact copy of the parent
  cells DNA
• 4. Conjugation, transformation, transduction
  also occur

48
Conjugation- Transfer of DNA between two
temporarily joined cells

• 1. The cell donating DNA extends an external
  appendage, sex pili
• 2. Pili attaches to the cell receiving DNA
• 3. A cytoplasmic bridge forms the DNA is
  transferred
• 4. Pili is withdrawn
• 5. Not an equal sharing of genetic material.

49
Bacterial Transformation

• Bacterial transformation is when the bacteria
  cell takes in the DNA of another organism.
• If the foreign DNA is able to trick the bacteria
  DNA into recognizing it as its own DNA by
  imitating the protein recognition pattern of the
  cell, the bacteria will replicate the foreign DNA
  along with its own.
• This is how viruses work.
• It is also how antibiotics work

50
Plasmids and Transformation

• Bacteria have evolved to take in other DNA in
  addition to their own through plasmids.
• Plasmids are in addition to the single chromosome
  in bacteria.
• They provide additional sources of DNA in a
  bacteria.
• Bacteria have plasmids, but they can also take
  them up from other organisms or infect other
  organisms with them.
• Think of a plasmid as a computer code used to
  change an organism like a virus attacks your
  computer.
• Plasmids are the key to genetic engineering!

51
Germ Warfare

• This is how bacteriophages work the virus
  infects the bacteria by injecting its own DNA as
  a plasmid vector.
• Then the bacteria infects us.
• The bacteria then acts as a vector for the virus,
  reproducing its DNA.
• Some organisms are able to kill bacteria by using
  bacteria killing DNA to infect the bacteria and
  kill it.
• Antibiotics work based on this principle.
• It is this ability of bacteria to take up the DNA
  of foreign organisms that could be the key to
  unlocking the secrets of evolution.

52

• http//uk.encarta.msn.com/media_461521734/members_
  of_the_kingdom_prokaryota.html
• hawaii.hawaii.edu/brashear/Micro130ch9a.ppt
• http//biologypro0.tripod.com/id2.html