Prokaryotic Cells

Prokaryotes VS. Eukaryotes No nucleus Not bound by a nuclear membrane Usually contains one circular chromosome composed of DNA with proteins Ex. bacteria Nucleus present Bound by a nuclear membrane Contains one or more paired linear chromosomes Ex. plants and animals

1. 2. 3.

Prokaryote Classification Once classified into Kingdom Monera Lack of nucleus & membrane- bound organelles Now divided into two domains: Domain Bacteria (most common/affect humans) Domain Archaea

a. Domain Bacteria Bacteria (Kingdom Eubacteria) Found everywhere except in extreme environments Have strong cell walls w/ peptidoglycan (sugars & amino acids)

Cocci (Spherical/Round) Shape Cocci (Spherical/Round) Bacilli (Rod-shaped) Spirilli (Spiral-shaped)

Arrangements of Cocci

Arrangements of Bacilli

Arrangements of Spirilli

Metabolism- How they obtain energy a. Heterotrophs “other feeder”- can’t synthesize own food; take in organic nutrients from the environment or other organisms Saprotrophs or saprobes- obtain energy by decomposing dead organisms Sapro- latin means rotten or putrid; troph means nutrition

Metabolism- How they obtain energy b. Photoautotroph “light self-feeder”-carry out photosynthesis ; uses inorganic molecules (CO2 and H2O) to create organic molecules for food Ie. Cyanobacteria

Metabolism- how they obtain energy c. Chemoautotrophs “Chemical self feeder”- break down/release inorganic compounds containing N or S in chemosynthesis Ie. Nitrogen Fixing Bacteria

Prokaryote Structure Microscopic Unicellular Organelles No Nucleus or nuclear membrane Contains circular DNA- nucleoid Has cytoplasm, cell membrane & cell wall Has ribosomes No mitochondria or chloroplasts Ribosomes make proteins from amino acids

Size 1-10 micrometers long, 0.7-1.5 micrometers wide Favorable surface area-to-volume ratio Nutrients & other substances can diffuse to all parts of the cell easily Small cells have a more favorable surface area to volume ratio than larger cells 1 micrometer= 1,000,000 of a meter

Chromosomes Genes are found on a large, circular chromosome in the area called the nucleoid Many prokaryotes also have a smaller piece of DNA called a plasmid Where are chromosome found in the cell of a eukaryotic cell? In the nucleus. What do chromosomes do? DNA containing structure that carries genetic material from one generation to another.

Capsule Complex sugar layer around cell wall Capsule Function: Prevents cell from drying out Helps cell attach to surfaces Shelters cell from White Blood cells (WBCs) & antibiotics Capsule Cell Wall Cell Membrane Polysaccharides are polymeric carbohydrate structures, formed of repeating units (either mono- or di-saccharides) joined together by glycosidic bonds

Movement Some are stationary Some have flagella Help bacteria move towards light, higher oxygen concentration, or chemicals to survive Tail like structure, some bacteria have more than one flagella Flagella

Pili Hair-like structures made of protein Function: Helps cells attach to surfaces Serves as a bridge between cells Copies of plasmids can be sent across this bridge giving bacteria new genetic characteristics Pili

b. Domain Archaea Live in extreme environments (called extremophiles) Thermoacidophiles Halophiles Methanogens Environment Hot (above 80C), acidic (pH of 1-2) Salty Anaerobes (can’t live in presence of oxygen) Environment Examples Sulfur hot springs, ocean floor thermal vents, volcanoes Great Salt Lake, Dead Sea Sewage treatment plants, swamps, bogs, GI tract

Bacteria & Archaea Differences Similarities Differences Different cell wall components Bacteria have peptidoglycan Archaea lack peptidoglycan Different lipids in cell membrane Different proteins & nucleic acid Size Prokaryotes Have cell walls

Reproduction Binary Fission- asexual reproduction Division of cell into two genetically identical cells Model with play dough

(Chromosome replicates) (Original chromosome and new copy separate) (New plasma membrane and cell wall form) (two identical cells)

Undergo Exponential Growth

Cell Walls Determines the bacteria’s shape All bacterial cells have cell walls Eubacteria- have peptidoglycan Archae- lack peptidoglycan; different lipids Dyes added to bacteria to identify two types: w/ outer layer of lipid w/o outer layer of lipid Sugars and amino acids Technique = Gram Stain

Gram Stain Gram Positive Gram Negative Large amount of peptidoglycan= dark purple Called gram positive W/ a lipid layer; less peptidoglycan= light pink Called gram negative Gram Positive Gram Negative Not used to classify archae bacteria; yields results quicker than growing bacteria in culture

Why does it matter? lipopolysaccharide Gram negative bacteria are protected against most antibiotics & chemicals by their outer cell wall. Only certain antibiotics can work against them.

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