Lecture 4 Flashcards
What are the basic characteristics of prokaryotes?
- no nucleus
- no membrane-bound organelles
- unicellular
- reproduce by binary fission
What are the common shapes of bacteria?
bacillus: rod shaped
coccus: sphere
spirillum
star-shaped
rectangular
What are the different groupings of bacteria called?
pairs: diplo-
clusters: staphylo-
chains: strepto
groups of 4: tetrads
cubelike group of 8: sarcinae
What is glycocalyx? What is it made of?
cell coating on the cell wall
- viscous and gelatinous
- polysaccharide or polypeptide
What are the 2 types of glycocalyx?
capsule: organized and firmly attached
slime: unorganized
What is the function of glycocalyx?
prevents phagocytosis
- helps form biofilms
What is flagella and archaella?
help for movement of bacteria (external appendages)
- made of protein flagellin
What are the 3 parts of the flagella?
1) Filament
2) Hook
3) Basal body: anchors flagellum to cell wall
What are flagella proteins?
H antigens
What are axial filament? Where are they found? How does it move?
- endoflagella
- found in spirochetes
- moves by rotation, like a corkscrew
What are fimbriae?
hairlike appendages that allow for attachment
What is pili?
used for movement (gliding and twitching)
- conjugation helps with DNA transfer from one cell to another
What is the bacterial cell wall made of?
peptidoglycan
What is the purpose of the cell wall?
prevents osmotic lysis and protects cell membrane
What is peptidoglycan?
polymer of repeating disaccharide in rows
- NAG
- NAM
How does gram staining work?
Gram-positive: alcohol dehydrates peptidoglycan and crystal violet-iodine crystals form inside cell
Gram-negative: alcohol dissolves outer membrane and leaves holes in peptidoglycan and cells are colorless; safranin added to stain cells
What are the characteristics of gram-negative cell walls?
- thin peptidoglycan
- periplasmic space (periplasm between outer membrane and plasma membrane with peptidoglycan)
- outer membrane with polysaccharides, lipoproteins, and phospholipids
- protects from phagocytes, complement, and antibiotic
- made of lipopolysaccharides
- porins form channels through membrane
- 4 rings in basal body of flagella
- produces endotoxins and exotoxins
- low susceptibility to penicillin
What are the characteristics of gram-positive cell walls?
- thick peptidoglycan
- teichoic acids
- polysaccharides and teichoic acids provide antigenic specificity
- 2 rings in basal body of flagella
- produce exotoxins
- high susceptibility to penicillin
- disrupted by lysozyme
What are teichoic acids? What charge? What is their function?
- lipoteichoic acids link cell wall to plasma membrane
- wall teichoic acid links peptidoglycan
- carries negative charge
- regulates movement of cations
What are 3 examples of atypical cell walls?
- acid-fast cell walls
- mycoplasmas
- archaea
What are acid-fast cell walls?
- similar to gram-positive cell walls
- waxy lipid bound to peptidoglycan
- mycobacterium
- nocardia
- stain with carbolfuchsin
What are mycoplasmas?
- sterols in plasma membrane
- lack cell walls
What are archaea?
- no cell wall
OR - walls of pseudomurein (no NAM or D-amino acids)
When are endospores produced? By what? What are they resistant to?
- produced when nutrients are depleted by Bacillus and Clostridium
- resistant to desiccation, heat, chemicals, radiation
What is sporulation?
endospore formation
What is germination?
endospore returning to vegetative state
What causes damage to cell walls?
- lysozyme hydrolyzes bonds in peptidoglycan
- penicillin inhibits peptide bridges in peptidoglycan
What are examples of wall-less gram cells?
- protoplast: wall-less gram-positive cell
- spheroplast: wall-less gram-negative cell
- L forms: wall-less cells that swell into irregular shapes
What cells are susceptible to osmotic lysis?
protoplast and spheroplast
What are the functions of the plasma membrane?
- selective permeability
- contains enzymes for ATP production
- photosynthetic pigments on chromatophores
What is in the plasma membrane?
- peripheral proteins on the surface
- integral and transmembrane proteins in the membrane
- phospholipid bilayer that encloses cytoplasm
What is passive transport?
substances moving from high to low concentration
- no energy needed
What are examples of passive processes?
- simple diffusion
- facilitated diffusion
- osmosis
What is active transport?
substances needing energy to move from low to high concentration
What are examples of active processes?
- uniport
- antiport
- symport
What is simple diffusion?
small molecules passing through the phospholipid bilayer
What is facilitated diffusion?
solute combines with transporter protein
- transport ions and larger molecules with the concentration gradient
What is osmosis?
movement of water across a selectively permeable membrane through:
- lipid layer
- aquaporins
What is osmotic pressure?
pressure needed to stop the movement of water across the membrane
What is an isotonic solution?
solute concentrations are equal inside and outside the cell
What is hypotonic solution?
solute concentration is lower outside than inside
- water moves into the cell
What is hypertonic solution?
solute concentration is higher outside of the cell than inside
- water moves out of the cell
What does active transport require?
transporter protein and ATP
Which direction is the flow for uniport? Antiport? Symport?
Uniport: one way
Antiport: opposite ways
Symport: coupled
What is group translocation?
requires transporter protein and PEP
- substance changes as it crosses the membrane
What is the cytoplasm and its function?
substance inside plasma membrane with the proteins, carbohydrates, lipids, and ions
- cytoskeleton
What is the nucleoid and its function?
bacterial chromosome with circular thread of DNA
- contains cell’s genetic information
What are plasmids?
extrachromosomal genetic elements that carry nonimportant genes
What are ribosomes?
sites of protein synthesis
- made of protein and ribosomal RNA
What are some examples of inclusions and their functions?
- metachromatic granules: phosphate reserves
- polysaccharide granules: energy reserves
- lipid inclusions: energy reserves
- sulfur granules: energy reserves
- carboxysomes: Rubisco enzyme for CO2 fixation during photosynthesis
- gas vacuoles: protein-covered cylinders to maintain buoyancy
- magnetosomes: iron oxide inclusions, destroys H2O2
How did eukaryotes come to be?
endosymbiotic theory
- larger bacterial cells engulfed smaller bacterial cells
- ingested photosynthetic bacteria became chloroplasts
- ingested aerobic bacteria became mitochondria
What are cell walls made of in eukaryotes?
carbohydrates
- plants: cellulose
- fungi: chitin
- yeasts: glucan and mannan
How are eukaryote and prokaryote plasma membranes similar?
- phospholipid bilayer
- integral and peripheral proteins
- selective permeability
- passive and active transport
How are prokaryote and eukaryote plasma membranes different?
In eukaryotes:
- sterols: complex lipids
- carbohydrates: for attachment and cell-to-cell recognition
- phagocytosis: pseudopods extend and engulf particles
- pinocytosis: membrane folds inward to bring it fluid and dissolved substances
What is cytoplasm?
anything inside the plasma and outside the nucleus
What is cytosol?
fluid part of cytoplasm
What is cytoskeleton and its function?
made of microfilaments and intermediate filaments
- gives shape and support
What is cytoplasmic streaming?
movement of cytoplasm throughout a cell
What are organelles and their function?
specialized structures within eukaryotic cells that perform distinct functions necessary for cellular operations
- compartmentalize various biochemical processes, better for organization and efficiency
What is the difference between smooth and rough ER?
Smooth: no ribosomes, synthesizes cell membranes, fats, hormones
Rough: lots of ribosomes, synthesis of proteins
What is the golgi complex and its function?
transports organelles and modifies proteins from ER
- transports modified proteins by secretory vesicles to the plasma membrane
What are lysosomes and its function?
digestive enzymes
- trash disposal
What are vacuoles and its function?
cavities formed from golgi complex
- brings food into cells and provides storage
What is the mitochondria and its function?
contains inner folds (cristae) and fluid
- makes energy
What is chloroplast and its function?
contains thylakoids with chlorophyll
- photosynthesis
What are peroxisomes and their function?
free radical scavengers
- destroys H2O2 and oxidizes fatty acids
What are centrosomes?
networks of protein fibers and centrioles
- forms mitotic spindle (good for cell division)
What’s the main difference between flagella and cilia?
flagella: long tail, little amount
cilia: short, hair like, lots of them
What’s the purpose of flagella and cilia?
for movement along cell surface
How are microtubules organized?
9 pairs in a ring and 2 microtubules in the center
