CHAPTER 4Functional Anatomy of

Prokaryotic and Eukaryotic Cells

Stem Cells

PROKARYOTES

Greek “prenucleus”

• DNA not enclosed within a membrane

• DNA is usually a singular circularly chromosome

• DNA not associated with histones

• Lack membrane bound organelles

• Cell walls contain polysaccharide peptidoglycan

• Divide by binary fission

EUKARYOTES

“true nucleus”• DNA in a nucleus• DNA found in multiple

chromosomes• Histones with DNA• Membrane bound

organelles• Cell walls chemically

simple• mitosis

Prokaryote Characteristics• 0.2 to 2.0 μm in diameter and 2 to 8 μm in length• Shapes: coccus, bacillus, spiral

ARRANGEMENTS OF COCCI

Diplococci (remain in pairs)

Streptococci (remain in chain)

Tetra (divide in 2 planes, remain in groups of four)

Sarcinae (divide in 3 planes, remain in cube)

Staphylococci (divide in multiple planes, remain in grapelike clusters)

ARRANGEMENT OF BACILLI• Diplobacilli: appear in pairs

• Streptobacilli: appear in chains

• Coccobacilli: oval, look like cocci

• Palisades: picket fence

ARRANGEMENT OF SPIRILIUM

Vibrios: curved rods

Spirilla: helical shape, rigid bodies

Spirochetes: helical and fexible

External StructuresGLYCOCALYX (sugar coat): • sticky, gelatinous polymer outside the cell

wall• Composed of polysaccharide, polypeptide

or both• If attached to cell wall, considered a

capsule• If unorganized and loosely attached,

considered a slime layer• Contributes to bacterial virulence• Important component of biofims• Help attach to various surfaces, protects,

facilitates communication (Extracellular polymeric substance EPS)

CyanobacteriumCapsule in olive green

FLAGELLA Atichous: cell without flagella

Monotrichous: a single flagellum at one pole

Lophotrichous: tuft of flagella from one or both poles

Amphitrichous: single flagella at both boles

Peritrichous: distributed over the entire cell

FLAGELLA MOVEMENT

http://www.wwnorton.com/college/biology/mbio/animations/main.asp?chno=ch03a02file:///E:/Chapter_04/A_PowerPoint/a_Lecture_Outline/flagella_arrange.html

Fimbriae and PiliShort, straight, thin hair-like

appendagesFIMBRIAE occur at poles or evenly

distributed Few to several hundred / cell Adhere to surfaces forming

biofilmsPILI Usually longer Only one or two /cell Involved in motility (twitching

and gliding motility) and DNA transfer (conjugation)

Geobacter sulfurreducens

Electron Micrograph of E. coli

CELL WALL

FUNCTION• Responsible for shape• Prevents cell from rupturing from too much

water• Contributes to ability of some to cause diseaseSTRUCTURE• Peptidoglycan: repeating disaccharide attached

by polypeptides forming a lattice• Disaccharides: N-acetylglucosamine (NAG) and

N-acetylmuramic acid (NAM)

Figure 4.13a

Peptidoglycan in Gram-Positive Bacteria

• Linked by polypeptides

Gram-Positive Bacterial Cell Wall

Figure 4.13b

Gram-Negative Bacterial Cell Wall

Figure 4.13c

• Thick peptidoglycan

• Teichoic acids

Gram-positiveCell Wall

Figure 4.13b–c

Thin peptidoglycan Outer membrane Periplasmic space

Gram-positiveCell Wall

Internal Structures: Plasma

(cytoplasmic) Membrane

STRUCTURE: Phospholipid bilayer- Polar head: phosphate group

and glycerol that is hydrophilic- Nonpolar tails: hydrophobic

fatty acidsProteins- Peripheral proteins: lie at

inner or outer surface- Integral proteins: inside

membrane- Glycoproteins: proteins

attached to carbohydrates- Glycolipids: lipids attached to

carbohydratesHelp protect/lubricate cell

FUNCTION• Selective permeability• Breakdown of nutrients and production of energy• Some have pigments and enzymes involved in

photosynthesis in foldings– Chromatophores or thylakoids

file:///E:/Chapter_04/A_PowerPoint/a_Lecture_Outline/membrane_permeability.html

CYTOPLASM• 80% water, proteins,

carbos, lipids, inorganic ions

• Thick, aqueous, semitransparent, elastic

NUCLEOID• Single long, continuous circular

thread of double-stranded DNA• Attached to plasma membrane

PLASMID• Circular, double-stranded DNA• Replicate independently• 5 to 100 genes

RIBOSOMES• Site of protein synthesis

Inclusions (reserve deposits)Metachromatic granules• Volutin: reserve of inorganic

phosphate used in the synthesis of ATP

• Corynebacterium diphtheriae (agent of diphtheria)

• ID: stain red with blue dyesPolysaccharide Granules• Glycogen (reddish brown) and

starch (blue)• ID: iodine Sulfur Granules

Lipid Inclusions• ID: fat-soluable dyesCarboxysomes• Enzyme ribulose 1,5-

diphosphate carboxylase• Use as sole source of

carbonGas Vacuoles• Maintain buoyancyMagnetosomes• Iron oxide, act as magnets

Endospores• Cells formed when essential nutrients are depleted

• Very resistant to heat, chemicals, hard to kill

• Can be dormant for thousands of years

• Gram positive bacteria – Bacillus: anthrax,

food poisoning– Clostridium:

gangrene, tetanus, botulism

Core: DNA and proteinCortex: peptidoglycan (rigid protective)Spore Coat: proteinExosporium: protective layer

Endospore formation in Bacillus subtilis.

• http://student.ccbcmd.edu/courses/bio141/labmanua/lab1/images/u1coccus.gif

• http://www.slic2.wsu.edu:82/hurlbert/micro101/images/SpirochetesEx2.gif

• http://www.nslc.wustl.edu/courses/Bio2960/labs/04Microscopy/11299D.jpg

• http://images.iop.org/objects/nano/news/4/6/14/pili.jpg

• http://www.agen.ufl.edu/~chyn/age2062/OnLineBiology/OLBB/www.emc.maricopa.edu/faculty/farabee/BIOBK/14_1.jpg

• http://bioinfo.bact.wisc.edu/themicrobialworld/endospore.jpeg

• http://www.brighamandwomens.org/publicaffairs/Images/Cells.jpg