Transcript CHAPTER 4 Functional Anatomy of Prokaryotic and

CHAPTER 4
Functional Anatomy of
Prokaryotic and Eukaryotic Cells
Stem Cells
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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
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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
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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 Structures
GLYCOCALYX (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)
Cyanobacterium
Capsule 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=ch03a02
file:///E:/Chapter_04/A_PowerPoint/a_Lecture_Outline/flagella_arrange.html
Fimbriae and Pili
Short, straight, thin hair-like
appendages
FIMBRIAE
 occur at poles or evenly
distributed
 Few to several hundred / cell
 Adhere to surfaces forming
biofilms
PILI
 Usually longer
 Only one or two /cell
 Involved in motility (twitching
and gliding motility) and DNA
transfer (conjugation)
Electron Micrograph of E. coli
Geobacter sulfurreducens
CELL WALL
FUNCTION
• Responsible for shape
• Prevents cell from rupturing from too much water
• Contributes to ability of some to cause disease
STRUCTURE
• Peptidoglycan: repeating disaccharide attached by
polypeptides forming a lattice
• Disaccharides: N-acetylglucosamine (NAG) and Nacetylmuramic acid (NAM)
Peptidoglycan in Gram-Positive
Bacteria
• Linked by polypeptides
Figure 4.13a
Gram-Positive Bacterial Cell Wall
Figure 4.13b
Gram-Negative Bacterial Cell
Wall
Figure 4.13c
Gram-positive
Cell Wall
Gram-positive
Cell Wall
 Thin peptidoglycan
 Outer membrane
• Thick peptidoglycan
 Periplasmic space
• Teichoic acids
Figure 4.13b–c
STRUCTURE:
Phospholipid bilayer
- Polar head: phosphate group
and glycerol that is hydrophilic
- Nonpolar tails: hydrophobic
fatty acids
Proteins
- Peripheral proteins: lie at
inner or outer surface
- Integral proteins: inside
membrane
- Glycoproteins: proteins
attached to carbohydrates
- Glycolipids: lipids attached to
carbohydrates
Help protect/lubricate cell
Internal Structures:
Plasma
(cytoplasmic)
Membrane
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 doublestranded 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 dyes
Polysaccharide Granules
• Glycogen (reddish brown) and
starch (blue)
• ID: iodine
Sulfur Granules
Lipid Inclusions
• ID: fat-soluable dyes
Carboxysomes
• Enzyme ribulose 1,5diphosphate carboxylase
• Use as sole source of
carbon
Gas Vacuoles
• Maintain buoyancy
Magnetosomes
• Iron oxide, act as magnets
• 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
Endospores
Core: DNA and protein
Cortex: peptidoglycan (rigid protective)
Spore Coat: protein
Exosporium: protective layer
Endospore formation in Bacillus subtilis.
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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