Micro - Chapter 3
Tonicity
how solute concentration affects shape of the cell - isotonic: equal inside to outside - hypotonic: outside solution has lower concentration than inside cell, water moves into cell, can cause osmotic lysis. - hypertonic: outside solution has higher concentration than inside cell, water moves out of cell
Membranous organelles
mitochondria nucleus endoplasmic reticulum golgi apparatus lysosomes peroxisomes
Telophase
nuclear membranes form around chromosomes, chromosomes decondense into chromatin, spindle disassembles, cytokinesis occurs
Passive Transports (Eukaryotes)
1. Simple diffusion 2. Facilitated diffusion 3. Osmosis All the same as described for prokaryotes
Golgi Complex
- 3 to 20 large cisterns, stacked, not interconnected - not attached to nuclear envelope or ER - modifies and sorts proteins 1. proteins made in RER are packed into transport vesicles with lipids from SER 2. transport vesicles to go ER and fuse with golgi 3. proteins and lipids modified by golgi and pass from cistern to next transport vesicles 4. mods include: add lipids or carbs to make lipoproteins, glycolipids, glycoproteins, and proteoglycans 5. proteins sorted to final destination and packed into lipid vesicles at the trans face
Functions of cell membrane (Prokaryotes)
- Enzymes on surface involved in ATP synthesis - Enzymes on surface for photosynthesis - damage to the membrane causes cell lysis = death - semi-permeable membrane: some things can pass and some cannot --- passive or active transport
Prokaryotes
- Size: 0.2 - 2.0 micrometers diameter - no nuclear membrane around genetic material - DNA = one circular chromosome - DNA organized with NAPs - Lack membrane enclosed organelles - chemically complex cell walls (peptidoglycan) - Simple flagella: two protein building blocks, no cilia - Capsule or slime layer glycocalyx (if present) outside of wall - No sterols in plasma membrane - Cytoplasm lacks cytoskeleton and cytoplasmic streaming - Small 70s ribosomes - Cell division by binary fission - genetic recombination involves DNA fragment exchange - Domains: Bacteria and Archaea
Eukaryotes
- Size: 5 - 100 micrometers diameter - Nucleus with double nuclear membrane houses genetic material separate from cytoplasm - DNA = multiple linear chromosomes - DNA wound around histone proteins into nucelosomes - Have membrane-enclosed organelles: Mitochondria, Endoplasmic Reticulum, Golgi complex, Lysosomes, Chloroplasts, etc. - Chemically simple cell walls (if present)ex. chitin, cellulose - Complex flagella or cilia composed of microtubules with membrane - Glycocalyx on membrane of cells that lack a wall - Plasma membrane contains sterols - Cytoskeleton and cytoplasmic streaming present in cytoplasm - Large 80s ribosomes - Genetic recombination involves meiosis - Domain: Eukarya (Algae, Protozoa, Fungi, Plants, Animals)
Axial Filaments (Prokaryotes)
- Used by spirochetes for taxis - flagella like structures wound around a spirochete under outer sheath - rotation of filaments produces cork-screw rotation of sheath and a whole spirochete moves - rotation allows penetration of secretions and tissues
DNA (Eukaryotes)
- chromsome # differ but all have more than one - can be haploid or diploid (two copies of each chromsome) - When DNA not used for RNA synthesis it is wound around histone proteins forming repeating nucleosomes Nucleosomes = 165 bp DNA wound around 8 histone proteins
Lysosomes (Eukaryotes)
- formed by golgi complex - single membrane bound sphere - contain digestive enzymes to break down large molecules organelles or bacteria - residual body waste is exocytosed
Chloroplasts (Eukaryotes)
- found only in algae and plants - used to carry out photosynthesis reactions , light dependent (sun to ATP) and light independent (CO2 fixation) - contain their own circular DNA chromosome and 70s ribosomes that replicate independent of cell via binary fission like process. - Smooth double membrane contains stroma in which the thylakoid membrane system floats - thylakoids in stacks called grana - thylakoid membranes contain chlorophyll (light trapping)
Gram Negative cell wall
- has outer membrane - 4nm thin - Periplasmic space between outer membrane and cell membrane houses peptidoglycan in periplasm - no teichoic acid - outer membrane: porins, phospholipids, lipoproteins, lipopolysaccharides, protection, evade phagocytosis and is chemical barrier
Nucleus (Eukaryotes)
- hereditary info in DNA chromosomes - double membrane bound: membrane = nuclear envelope, 2 phospholipid bilayers, nuclear pores control movement in and out of nucleus Nucleolus = visible dense region inside the nucleus, location where rRNA is synthesized and ribosomes begin to assemble Non-dividing cells: DNA appears as loose mass called chromatin Dividing cells: DNA tightly packed as separate and distinct DNA elements called chromosomes
Endomembrane System
- interconnected series of interior tubes and sacs of membrane - synthesize cellular components - moves materials around the cell - includes: endoplasmic reticulum, golgi, lysosomes, vesicles
Plasma membrane (Prokaryotes)
- located inside of cell wall - enclose cytoplasm - phospholipid bilayer --- phosphate + glycerol = hydrophillic --- fatty acid tails = hydrophobic - proteins: peripheral and integral - functions of membrane proteins: --- enzymes for metabolic reactions --- cell-to-cell comm, --- environ. changes --- virulence factors --- channels for transport
Cell wall (Prokaryotes)
- located outside plasma membrane - gives cell its shape - protection - resists osmotic lysis - anchorage for flagella in bacteria = peptidoglycan - lattice of polypeptides and carbs - NAG and NAM (carbs) - polypeptides tie NAG and NAM together
Nuclear area (nucleoid) (Prokaryotes)
- long loop DNA attached to plasma membrane - Nucleoid-associated proteins (NAPs): package and organize haploid chromosome - plasmid: small circular DNA element -- separate from chromosome -- no essential genes -- 5-100 bonus genes -- plasmids replicate independent of the host chromosome, can be passed to other cells -- found throughout cytoplasm and commonly found in bacteria
Vacuoles (Eukaryotes)
- membrane enclosed space in cytoplasm - derived from golgi - temporary storage - some have water to provide rigidity to cell
Centrosome (Eukaryotes)
- near the nucleus - important for nuclear division during mitosis Two parts of centrosome: 1. pericentriolar material: cytosol + protein fibers , organizes mitotic spindle for cell division 2. Pair of centrioles: composed of microtubules to form mitotic spindle to divide chromosomes
Mitochondria (Eukaryotes)
- rod shaped - enclosed in double membrane: outer=smooth, inner=cristae - open middle = matrix , contains enzymes, one chromosomes and 70s ribosomes. - provides most of cellular energy: vast majority of ATP is generated in oxidative phosphorylation reaction involving ETC which is on surface of cristae Contains own circle of DNA similar to chromosomes of bacteria - 70s ribosomes used to make proteins inside mitochondrion - each can replicate binary fission independent of mitosis or meiosis of cell
Fimbriae (Prokaryotes)
- short, hair-like appendages - made of pilin protein - at poles all over surface - up to a few hundred per cell - "fuzzy" coat used to stick to things
Ribosomes (Eukaryotes)
- site of protein synthesis - Eukaryotic ribosomes = 80s - consistently of two subunits: 60s and 40s - attached to the RER or in cytoplasm - free ribosomes: make proteins for cytoplasm use - membrane-bound or fixed: attached to RER, make proteins used in plasma membrane or exocytosis
Ribosomes (Prokaryotes)
- site of protein synthesis: create peptide bonds between AAs - composed of rRNA and proteins - consists of 2 subunits: 30s + 50s = 70s prokaryotic ribosome
Peroxisomes (Eukaryotes)
- spheres smaller than lysosomes - come from pre-existing peroxisomes - have enzymes made by free ribosomes contain: - enzymes for oxidation reactions - catalase to break down toxic peroxide
Cytoplasm (Prokaryotes)
- substance inside plasma membrane - 80% water with proteins (enzymes), carbs, lipids, and ions - Structures: nucleoid, ribosomes, inclusions
Gram Positive Cell wall
- thick walls of peptidoglycan, 30-100 nm thick, strong rigid - contain teichoic acids increase rigidity
Characteristics of Eukaryotic cell
- true nucleus - up to 100 micrometers - various shapes and sizes - algae, protozoa, fungi, plants, animals
Flagella and Cilia (Eukaryotes)
- used for cellular locomotion - contain cytoplasm, surrounded by plasma membrane (part of the cell not just outside the cell) - internal: microtubules composed of tubulin, move in beating or waving - flagella: long, wave motion (1 or few on cell) - cilia: short & beating motion, numerous
Pilus (Prokaryotes)
- usually one - made of piling protein - used to transfer DNA to neighboring cell rarely used for motility via piles retraction (twitchy, short or gliding)
Active Transport (Eukaryotes)
1. Active transport 2. Endocytosis 3. Exocytosis
What are the 3 possible fates after proteins come from Golgi complex?
1. Secretory vesicles: exocytosis proteins 2. Membrane renewal vesicles: carry new integral proteins, peripheral proteins, and lipids to be added to plasma membrane 3. Lysosomes: digestive enzymes housed in storage vesicle
Unusual wall structures (Prokaryotes)
1. Myobacterium species: gram+ structure with myocolic acids, resists dehydration 2. Mycoplasma species: smallest, no cell wall, have sterols in membrane (resist osmotic lysis) 3. Archaea: either no walls of walls having psuedopeptidoglycan (diff. carb)
Types of Endocytosis
1. Phagocytosis: "cell eating" cell reaches with pseudopods and engulfs large particles 2. Pinocytosis: "cell drinking" membrane folds inward taking extracellular fluid with it 3. Receptor-mediated endocytosis: ligands bind to specific cell surface receptors which are internalized in a piece of membrane.
Cell division (Eukaryotes)
1. mitosis: asexual reproduction 2. meiosis: produces sex cells for sexual reproduction
What is binary fission?
A form of asexual reproduction in which the parent divides into two approximately equal parts.
Cell wall (Eukaryotes)
Algae: wall composed of cellulose (polysaccharide) fungi: wall composed of chitin (polysaccharide) protozoa: no wall: flexible pellicle or no hard covering - when a eukaryote lacks a wall they usually have glycocalyx or extracellular matrix instead: - eukaryotes don't have peptidoglycan or pseudomurein in them
Prophase
Chromosomes become visable, nuclear envelop dissolves, spindle forms
Metaphase
Chromosomes line up in the middle of the cell
What are the 3 common shapes of Prokaryotic cells?
Coccus, bacillus, spiral
Cytoskeleton (Eukaryotes)
Composed of 3 kinds of filaments that form a scaffold: 1. microfilaments, actin protein 2. Intermediate filaments, protein varies 3. Microtubules, tubule proteins Functions: - support and shape - transporting substances inside cell - cell motility cytoplasmic streaming = movement of cytoplasm inside the cell along the cytoskeleton to mix cellular contents or change position of organelles
Facilitated diffusion
Diffusion that requires a transport protein: channel, transporter or permease - large, charged, polar molecules that can't pass through membrane
Movement of Flagella (Prokaryotes)
Flagella rotation causes taxis of bacteria: Run: rotate counterclockwise - move bacterium in straight line Tumble: rotate clockwise - change direction Bacteria display taxis in response to stimuli: Positive chemotaxis = move toward certain chemical Negative chemotaxis = move away from chemical Phototaxis = light Magnetotaxis = north pole
Structure of Flagella (Prokaryotes)
Filament: intertwined chains of flagellin protein, hollow core, sticks out beyond plasma membrane Hook: attaches filament to basal body, solid, made of hook protein Basal body: rod and disc structure, anchors flagellum to wall, functions as motor to rotate the hook
Cocci shapes
Single Coccus: daughter cells separate Diplococci: 2, flat on adjacent sides Streptococci: chain, all cells divides in the same plane Tetrad: 4, division occurs in 2 planes Staphylococci: group, cluster, cells divide in random planes
Glycocalyx (Prokaryotes)
Glycocalyx = external outermost surface layer of secreted carb-rich gelatinous material, usually sticky or slimy - capsule = organized glycoclayx, firmly attached - slime layer = unorganized glycocalyx, loosely attached to cell wall functions of glycocalyx - promote biofilm formation - allow cell adhesion to substrate or host tissues - protect from dehydration - protect cell from antibodies and disinfectants - protect from phagocytosis
What happens during osmosis in cells with cell walls?
Hypertonic: cell shrinks and cell membrane detaches from cell wall Hypotonic: cell wall counteracts osmotic pressure to prevent swelling and osmotic lysis
Flagella (Prokaryotes)
Long filamentous appendages used for motility A. Monotrichous: one on one end B. Lophotrichous: two or more on one end C. Amphitrichous: one or more on each end D. Petritrichous: all over cell
Simple diffusion
Molecules or ions move from high to low concentration across the lipid membrane until equilibrium is reached - gases, non polar molecules
Endoplasmic Reticulum
Network of membrane sacs called cisterns, continuous with nuclear envelope Rough ER: packaged and modified - flattened sacs of membrane - studded with ribosomes - proteins manufactured on fixed ribosomes are fed into lumen of cisterns to be modified - proteins to be used in membrane or outside of cell Smooth ER: toxin removal - more tubular, no ribosomes - biosynthesis of lipids, carbohydrate metabolism, and detoxification of harmful toxins
Spiral shapes
One or more twists Vibrio: curved rod Spirillum: rigid helical shape, move via flagella Spirochete: flexible helical shape, move via axial filaments Monomorphic: always one shape, always forms same way (most cells) Pleomorphic: varied shapes within the population of a single species, daughter cells vary in shapes (some)
Osmosis
Passive process the cell cannot control - through lipids or aquaporins - water moves from areas of high solute concentration when solutes cannot diffuse - water moves from water high to water low
How does penicillin work?
Penicillin: prevents cell wall from growing to divide, prevents formation of cells
Anaphase
Phase of mitosis in which the chromosomes separate and move to opposite ends of the cell
Gram positive vs negative
Positive: (glass of water advantage) - structurally simple - containing thick layer of peptidoglycan with embedded teichoic acid external to plasma membrane - Thick layer highly resistant to osmotic lysis Negative: (human host advantage) - structurally complex with two layers - thin layer of peptidoglycan and outer membrane containing lipopolysaccharides - outer membrane provides chemical protection
Cellular Evolution
Prokaryotes: appear 3.5 billion years ago Eukaryotes: appear 2.5 billion years ago Endosymbiotic Theory: eukaryotic cells evolved from a cooperation of prokaryotic cells - large pros lost their walls and engulfed smaller ones which became organelles. - evidence: both mitochondria and chloroplasts have features similar to bacteria - circular loop of DNA, 70s ribosomes, replicate independent of host cell via binary fission, double membrane (from being phagocytosed?)
Bacilli shapes
Rods of various length: oval to hot dog Rods divide only along short axis single bacillus: daughter cells seperate Diplobacillus: 2 Streptobacilli: Chain Coccobacillus: short oval, often confused with cocci (cocci are perfectly spherical)
Cell reproduction (Prokaryotes)
binary fission = cell division 1. DNA is replicated and cell elongates 2. cell wall and plasma membrane begin to divide 3. cross walls form between the divided DNA 4. Daughter cells separate
Active transport processes
Uses ATP to move substances with low concentration to high concentration (against gradient) - active transport - group translocation
Active transport
Uses transport proteins that require ATP energy to "pump" substances against the concentration gradient
Group translocation
active transport where substance is chemically altered during transport to make it membrane impermeable so it cannot diffuse back
Inclusions (Prokaryotes)
all tend to be storage deposits, reduce osmotic pressure caused by individual solutes - metachromatic/volutin granules - polysaccharide granules - lipid droplets - sulfur granules - carboxysomes - gas vacuoles - magnetosomes
Passive transport processes (Prokaryotes)
areas of high to low concentration - simple diffusion - facilitated diffusion
Cytoplasm (Eukaryotes)
contains: cytosol, cytoskeleton, cellular components - few enzymes, metabolic processes occur in organelles
Bacterial Endospore
formed by gram membrane + bacilli shape - dehydrated thick wall structure for survival: resistance to heat, toxins, radiation, etc. - occurs when environment becomes unfavorable
Mitosis (Eukaryotes)
one diploid/2n parent cell divides into two diploid/2n daughter cells 1. Interphase: cells not dividing, duplicate organelles and DNA for mitosis 2. Mitosis: Prophase, Metaphase, Anaphase, Telophase 3. Cytokinesis: division of cytoplasm
Meiosis
one diploid/2n parent cell divides to produce four haploid/1n daughter cells - all 4 cells are different from one another and haploid 1. Cells in interphase duplicate organelles and DNA to prep for meiosis 2. Meiosis I: 4 stages: Prophase I, Metaphase I, Anaphase I, Telophase I 3. Meiosis II: 4 stages: Prophase II, Metaphase II, Anaphase II, Telophase II Provides genetic diversity and greater survivability in population if environment changes.
Do membranes of prokaryotic cells or eukaryotic cells contain more enzymes?
prokaryotic. needs to carry out functions that eukaryotic cells do inside the organelles.
Sporulation process
replication of DNA and elongation of cell; forming of forespore; formation of plasma membrane around forespore and start of degardation of vegetative DNA; adding hardening substances and formation of "tough" spore coat; release
Non-membranous organelles
ribosomes centrosomes (centrioles)
Plasma Membrane (Eukaryotes)
similar to prok in structure and function main difference is with bacteria:. Phospholipids: form core bilayer structure, majority of membrane Sterols: interspersed between phospholipids, stiffen membrane to resist osmotic lysis Carbs: attachments of glycolipids, glycoproteins, proteoglycans, function as receptors, contribute to glycocalyx and extracellular matrix Proteins: intergral, peripheral, function in transport, metabolism, comm. and recognition
Osmolarity
solute concentration of solution - suck water towards it
Osmotic pressure
the amount of pressure you would have to apply to prevent the movement of pure water into a solution containing solutes.
Exocytosis
vesicles carry contents through cytoplasm to membrane to be exported outside of cell
