chapter 4 functional anatomy of prokaryotic and eukaryotic cells stem cells
TRANSCRIPT
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