Download Bacteria: An Overview

Bacteria: An Overview
Eukaryotes
y Have cell membranes – Some have cell walls
y Structures in confined compartments
y Organelles (mitochondria, chloroplasts, vacuoles)
y Multiple strands of DNA and DNA is in nucleus
Prokaryotes
y Bacteria
y Cell membrane
y Some have an outer layer over membrane
y Cell Wall
y One strand of DNA y There is no nucleus
y No organelles
Prokaryote vs. Eukaryote
Eukaryote
Prokaryote
y Plants and Animals
y Bacteria
y Cell membrane
y Cell membrane
y Some have cell y Cell Wall
walls
y DNA is inside the nucleus
y Structures are in compartments (organelles)
y DNA floats around, no nucleus
y No organelles
Prokaryotes (aka. Bacteria)
Most successful organisms on Earth (~3.5 BILLION years old)
Two Types of Prokaryotes
Eubacteria
Archaebacteria
y Cell wall contains y Cell wall peptidoglycan
y Most common type
lacks peptidoglycan
y Can live in very harsh environments (heat, cold, salt ponds, acidic ponds, no oxygen)
y DNA is more similar to eukaryotes
Hydrothermal Vents
Pink, green, and brown‐colored archaebacteria occupy the thermal gradients in the flowing water (60‐100°C).
Salt Ponds
Arctic Ice
Acidic Environments
Structure of a Prokaryote
Peptidoglycan – Chemical outside Cell Wall
Structure of a Prokaryote
Three Shapes
y Spherical – “cocci” y Greek – berry y Spiral – “spirillum” y Latin – spiral
y Rod‐shaped – “bacilli” y Latin – little stick
Spherical – “cocci” Spiral – “spirillum” Rod‐shaped – “bacilli” Identify the Bacteria Based on the Name
y Staphylococcus (in clusters) –
y
y
y
y
y
causes lots of infections
Streptococcus (in chains) –
causes pneumonia, strep throat
Clostridium – causes tetanus,
lockjaw, food poisoning
Bordetella pertussis – causes
whooping cough
Samonella
Escherichia Coli (E.coli) –
causes stomach sickness
Identifying Types of Bacteria
y Gram‐staining
y Used to identify what type of bacteria
y Helps us determine if antibiotics will be effective
y Cells that have extra layer cannot be penetrated by antibiotics
Gram Staining - Steps
1) Stain it red
y
Red stain bonds to peptidoglycan in cell membrane
y
All bacteria cells have peptidoglycan in cell membrane
2) Stain it violet
y If bacteria stays violet – gram‐positive (violet stain sticks)
y If bacteria washes back to red – gram‐negative (violet stain washes off)
Gram Staining - Results
y Gram‐negative have extra layer of around cell wall
y Violet stain bonds to the chemicals in this layer
y Then gets washed off
y Gram‐positive do not have extra layer
y Violet stain bonds to cell wall and stays
Gram Staining - Implications
y Gram Negative – Have extra layer outside cell wall
y Cannot be penetrated by Antibiotics
y Gram Positive – No extra layer outside cell wall
y Can be penetrated by Antibiotics
Growth and Reproduction
Binary Fission
y Copy DNA
y Grow
y Split in Two
Conjugation
y Create bridge between two
bacteria cells
y Exchange genetic
information
Growth and Reproduction
Binary Fission
Conjugation
y Copy DNA
y Create bridge y Grow
between two bacteria cells
y Exchange genetic information
y Split in Two
Growth and Reproduction
y Spore formation
y Unfavorable conditions
y Create a cell wall around DNA
y Bacteria cell lays dormant
Colony Growth
y Cell division can be rapid
y Some can multiply once every 20 minutes
y 1Æ2Æ4Æ8Æ16 Æ32
y 64Æ128Æ256Æ512 Æ1024Æ2048
y 4096Æ8196Æ16382Æ32764Æ65528Æ131056
y 262112Æ524224Æ1048448
2 hour
4 hours
6 hours
7 hours
y The growth of a colony of bacteria is limited by the nutrients available and by the amount of waste products it produces
y http://www.tulane.edu/~dmsander/WWW/Video/pneu
mo.html
Nutrition
Autotroph
Hetertroph
y Makes its own y Gets food from food
another source
Autotroph
Photosynthetic Autotroph
Chemosynthetic Autotroph
y Makes food from y Makes food from other sunlight
y Cyanobacteria – usually first to recolonize wiped out area
y Blue‐green Algae
chemicals
y Chemical Vents, Soil, Swamps
Photosynthetic Autotroph
Chemosynthetic Autotroph
Heterotroph
Chemosynthetic Heterotroph
Photosynthetic Heterotroph
y Uses other cells for y Uses sun for energy
energy
y Decomposers
y Parasites
y Uses other cells for carbon
Spherical – “cocci” Spiral – “spirillum” Rod‐shaped – “bacilli” Chemosynthetic Heterotrophs
y Staphylococcus (in clusters) –
y
y
y
y
y
causes lots of infections
Streptococcus (in chains) –
causes pneumonia, strep throat
Clostridium – causes tetanus,
lockjaw, food poisoning
Bordetella pertussis – causes
whooping cough
Samonella
Escherichia Coli (E.coli) –
causes stomach sickness
Energy Release
y Obligate aerobes
y Need oxygen to survive
y Obligate anaerobes
y Destroyed by oxygen
y Facultative aerobes
y Do not need oxygen, but are not killed by it