Chapter 3 Microbiology Cellular Structure and Function p

All living things can: 1)Grow- increase in size 2)Reproduce- increase in number 3)Respond- to environment 4)Metabolize- take in nutrients and use for energy *How are Viruses different? -unable to do 1, 2, 4 outside of a host cell, but respond to env. Schwann & Schleiden- all living things composed of cells (living) Review pg 60 – dif in cells

Prokaryotes- External Structures 1. Glycocalyces- gelatinous, sticky, surrounds outside of cell -protect from drying -capsule or slime layer -enable to survive and cause disease Ex: pneumonia

2. Flagella- whiplike, used for movement -composed of filament, hook, basal body Arrangement: a. Monotrichous-single b. Lophotrichous- tuft at one end c. Amphitrichous- both ends d. Peritrichous- covering Endoflagella- spirochetes, spiral tightly around cell to form axial filament instead of into environment, corkscrew rotation Taxis- move w/ series of runs and tumbles in response to stimulus Ex: Chemotaxis & Phototaxis

3. Fimbriae- sticky, bristlelike, adhere to one another and to substances in envir. -function in Biofilms-slimy masses of bact. -99% of bacteria in nature exist as 4. Pili- short hairs -move across a substrate or towards another bact - Used for conjugation (transfer of plasmid from one bacteria to another)

Bacterial Cell Walls -Composed of a complex polysaccharide called Peptidoglycan -Chains of sugars are connected by crossbridges of amino acids -Two types of cell walls: gram negative and gram positive

Gram Positive -Thick layer of peptidoglycan that also contains teichoic acids (negative charge) -Lipoteichoic acids anchor cell wall to cell membrane -Create exotoxins -Gram stain results in purple color -Ex. Mycobacterium species

Gram Negative -Thin layer of peptidoglycan but contains an outer membrane that covers layer (ex. E. coli) -Outer membrane contains lipopolysaccharides (LPS) -Hard to treat infections due to outer membrane -Lipid portion of LPS (Lipid A) released when outer membrane disintegrates, creates endotoxin -Killing lots of Gram – bacteria releases lots of lipid A -Porin proteins allow transport of molecules through outer membrane and into periplasmic space -Gram stain pink

Cytoplasmic Membranes (cell membrane) Structure -double-layered structure- phospholipids bilayer -hydrophilic phosphate heads (+water) -hydrophobic lipid tails (-water) -integral proteins *Fluid Mosaic Model *not in Archae- why they don’t melt

Function  separates contents of cell from outside  controls passage of substances  energy production & harvests light energy  Selectively Permeable-allows some substances in and not others  concentration gradient- conc of a chemical on both sides of memb  electrical gradient- charged chemicals

Passive Processes- no energy to move 1.Diffusion-net movement of a chemical down its conc. gradient -higher conc to lower conc 2.Facilitated Diffusion- proteins act as channels/carriers for certain molecules to flow 3.Osmosis- diffusion of water from higher conc of water to lower conc. of water Isotonic- same conc of solutes and water Hypertonic- solution w/ higher conc of solutes, less water Hypotonic- solution w/ lower conc of solutes, more water

Active Processes-require energy to move 1. Active transport- uses proteins but requires ATP uniport- 1 molecule symport- 2 molecules in same directions antiport- 2 molecules, in opposite directions 2. Group translocation- only in some prokaryotes -substance is chemically changed

Cytoplasm of Prokaryotes- pg 75 -semiliquid, gelatinous material inside a cell 1. Cytosol- liquid portion -contains DNA in nucleoid -site of chemical reactions-produce amino acids 2. Inclusions- reserve deposits of lipids, starch, or compounds store when nutrients are in abundance until needed Nonmembranous 3. Ribosomes- site of protein synthesis -composed of protein and rRNA -70S vs 80S 4. Cytoskeleton- internal network of fibers, basic shape

Eukaryotes External Structures 1.Glycocalyces- protection, adhesion, cell to cell recognition -absent in cells w/ cell walls (plants, fungi, algae) 2. Flagella- are within the cell membrane -"9+2" arrangement -9 pairs of microtubules around 2 in the center -basal body "9+0" but no hook -undulate rhythmically, push & pull, no runs and tumbles 3. Cilia- hairlike, only on Eukaryotes -same arrangement (9+2) -beat rhythmically for movement

Cell Walls- provides protection, shape & support Plants-composed of cellulose Algae- agar, algin, carrageenan Fungi-chitin *All have cytoplasmic membranes (fluid mosaic) also contain steroid lipids- controls movement in and out

Processes same as prokaryotes, but also: Active-uses ATP 1. Endocytosis- bringing in -membrane distends (pseudopodia-false feet) to surround food Phagocytosis- solid Pinocytosis- liquid 2. Exocytosis- exports substances

Organelles Nonmembranous 1. ribosomes- protein synthesis (80S) 2. Cytoskeleton-anchor and movement of organelles, shape 3. Centrioles in Centrosome- animal and some fungal -role in mitosis, cell division (cytokinesis)

Organelles Membranous 1. Nucleus- spherical to ovoid, largest organelle in cell -contains DNA- "control center of cell" -nucleoplasm-liquid matrix, contains nucleoli- RNA synthesis and chromatin(mass of DNA) -surrounded by nuclear envelope w/ nuclear pores 2. Endoplasmic Reticulum (ER) -smooth (no ribosomes) lipid synthesis, transport -rough (ribosomes)- protein production 3. Golgi Body- shipping department, receives, processes, packages in secretory vesicles (sacs) 4. SacsVacuole- (plants and algal) storage Vesicle- storage, digestion, transport Lysosomes- (animal) breakdown of nutrients, eat old/damaged cells Peroxisomes- neutralization of toxins 5. Mitochondria- "powerhouse of cell"produce ATP 2 membranes- inner folds into cristae 6. Chloroplasts- photosynthesis, light harvesters

Endosymbiotic Theory- pg 87 Lynn Margulis -to explain presence of circular DNA, 70S ribosomes, and 2 bi-lipid membranes in mitochondria and chloroplasts -Eukaryotes formed from the phagocytosis of small aerobic prokaryotes by larger anaerobic prokaryotes -became internal parasites -not universally accepted

Cell Biology Video 