Functional Anatomy of Prokaryotic and Eukaryotic cElls Flashcards

Question

What are Axial Filaments and where are they located? Describe their function and where they are present.

Answer 1

Axial Filaments (aka Endoflagella) -Present in Spirochetes (ex; treponema pallidum (cause syphillis) and Borriella burgdorferi (cause Lyme disease) -Specialized flagella between cell wall and outer membrane called the "outer sheath" -anchored at one pole of the cell and wrap around -These filament bundles rotate to produce movement of outer sheath, propels in spiral motion (corkscrew) (flagella filament made of flagellin)

Answer 2

2 to > 100 endoflagella/cell, depending on the species Spirochetes is expected to stain similar to GRAM NEGATIVE bacteria

Answer 3

Fimbriae and Pili are Hair-like appendages that are both: 1) shorter, straighter and thinner than flagella 2) comprised of pillin arranged helically around a central core 3) present in most gram-negative bacteria (few gram-positive)

Answer 4

Fimbriae: -Occur at poles or evenly distributed -Number from a few to several hundred -Role: adhere to each other and to surfaces (liquids, glass, rocks, epithelial cells) Fimbriae are necessary for Neisseria gonoorrhea to colonize mucous membranes

Answer 5

Pili: Usually LONGER Than Fimbrae -Usally only one or two per cell Roles: Sex pili bring two cells together to allow DNA transfer from one cell to another in a process CONJUGATION Surface motility: -TWITCHING motility

Answer 6

Twitching motility -observed in Pseudomonas aeruginosa and Neisseria gonorrhoeae and some E.coli strains -Pilus extends by piling addition, attaches to a surface or another cell, retracts as pilin subnunits are disassembled (also called Grappling hook model ) -Results in short, jerky intermittent movements (pili tend to twitch forward and backward at both ends of cells)

Answer 7

Gliding motility- the ability of certain bacteria to smoothly glide on surfaces independent of flagella or pili -The gliding mechanism is unclear and might differ between speceis -Myxobacterial gliding motility is the most studied

Answer 8

The cell wall -Determines cell shape -Prevents Osmotic lysis -Anchors flagella -Made of PEPTIDOGLYCAN (in bacteria)

Answer 9

Peptidogylcan (aka murein) -Polymer of disaccharide: -N-acetylglucosamine (NAG) -N-acetylmuramic acid (NAM) (contains methyl and COOH)

Answer 10

Peptidogylcan structure: -Linear glycan chains (10-65) linked by polypeptides -although the cross-bridge length and composition varies with bacterial species, TETRAPEPTIDE side chains (attached to NAM) are always included connect the Lower layer to upper layer) The tetrapeptide side chain amino acids alternate between D and L amino acids. (2 NAG make up carb backbone and NAM in middle)

Answer 11

Mode of Action for Penicllin: -To prevent the final linking of tetra peptide side chains to peptide cross bridges (prevent new synthesis) Mode of Action for Lysozyme: -hydrolyze bonds between repeating disaccharide units (NAM and NAG) of peptidoglycan

Answer 12

LENGTH and COMPOSITION of cross link varies in different bacteria.

Answer 13

Gram Positive cell-walls: -MANY layers of Peptidoglycan -**Contain Teichoic acids (lipoteichoic and wall teichoic acids)**: -provide rigidity -gives the cell a net negative charge. Helps sequester cations (Calcium and Magnesium ; Mg2+) for eventual transport into the cell -Promote pathogen adherence to host tissues -Antigenic specificity used to identify gram positive bacteria

Answer 14

Gram- Negative Cell wall: -contains ONLY one or a few layers of peptidoglycan bonded to lipoproteins

Answer 15

Outer membrane of Gram-negative cells consist of: Periplasm, porin protein, LPS Forms the periplasm- rich in degradative enzymes -Strong negative charge is beneficial against phagocytes and complement -Provides a barrier against harmful substances (antibiotics, lysozymes, etc) but not small metabolites (due to porins) porins- are beta-barrel proteins that act as chemically selective passive fusion channels (allow passive transfer of specific molecules) - porins only found in outer membrane of gram-negative bacteria

Answer 16

BACTERIA, MITOCHONDRIA and CHLOROPLASTS

Answer 17

3 primary parts of the Lipopolysaccharide (LPS) 1) Lipid A- released from gram-negative bacteria when they die and is responsible for symptoms associated with their infection (fever, dilation of blood vessels, shock and blood clotting) (endotoxin- toxin released from cell's dye) 2) Core Polysaccharide- contains unusual sugars, structural role, provides stability 3) O polysaccharide, antigen useful for distinguishing gram-negative species (ex; E. coli O157:H7) (great variation in O-side chain composition; at least 20 different sugars known)

Answer 18

Acid-fast Cell walls are ATYPICAL Cell Walls Acid-fast cell walls: -Waxy lipid (MYCOLIC acid) bound to peptidoglycan -Found in Mycobacterium and Nocardia species -Prevents uptake of most dyes (ex: gram stain_ -During acid-fast staining, it RESISTS decolorization with acid-alcohol and retains the initial dye carbon fuchsin

Answer 19

They are IMPERVIOUS to gram staining (or stain weakly gram positive) -Each mycolic acid molecule contains between 60 to 90 carbon atoms

Answer 20

Mycobacterium tuberculosis: -Straight or slightly curved 3 x 0.3 um in size -Size depends on conditions of growth -Long filamentous, club-shaped, branching forms sometimes seen

Answer 21

organisms with Atypical cell walls: 1) Mycoplasma -Lack cell walls -Unique among bacteria due to STEROLS in plasma membrane 2) Archaea -Wall less Or walls of pseudomurein (N-acetyltalosaminuric acid instead of NAM and cross-links lack the D-amino aids)

Answer 22

they both appear gram NEGATIVE (they do Not retain peptidoglycan)

Answer 23

Cell Wall Removal Terminology: Protoplasts: cell wall ENTIRELY removed (ex: Lysozyme digestion of gram-positive cells) -Spheroplasts- cell wall only PARTIALLY removed (ex: lysozyme digestion of gram-Negative cells) Protoplasts and spheroplasts are BOTH susceptible to OSMOTIC lysis. If they remain intact, they are spherical and remain metabolically active

Answer 24

EDTA- a divalent cation chelator that binds divalent cations like Mg2+ from outer membrane and destabilizes the membrane (have access to peptidoglycan layer) EDTA is necessary because it will alter ionic interaction in the outer membrane allowing the lysozyme access to peptidoglycan layer. (EDTA chelator also used to prevent biofilms from forming, remove toxic metals from body)

Answer 25

Cell wall removal terminology: L forms (Lister Institute)- are "cell-wall- deficient" bacteria that can grow as spheroplasts or protoplasts. -They may form spontaneously or develop in response to penicillin or lysozyme. -They remain capable of cell growth and division and can return to walled state (can arise from numerous species ) ex: L forms seen in B. subtitles

Answer 26

No , mycoplasma are NOT considered L-forms, since they are NOT derived from bacteria that normally have cell walls.

Answer 27

The Plasma Membrane composition : 1) A phospholipid bilayer contains: - Peripheral proteins -integral proteins -**Transmembrane (most) -*some form pores 2) The Outer Leaflet also contains glycoproteins and glycolipids 3) Mycoplasma membrane also contain sterols

Answer 28

You can use salt to disrupt the peripheral interactions? COME BACK

Answer 29

The Fluid Mosaic Model: Describes the cell membrane as a Mosaic of molecules (phospholipids, proteins and carbohydrates) that are constantly moving within the phospholipid bilayer -Phopholipids rotate and move laterally -The membrane has a viscosity like olive oil -Unless ANCHORED, protein move in the membrane to perform their functions

Answer 30

Major functions of Plasma Membrane: 1) A selectively permeable (semipermeable) barrier: -Membrane: Ions penetrate membrane slowly while lipid soluble substances (O2, CO2, and non polar organic molecules ) transit more easily -Channels: transmembrane proteins that provide hydrophilic passage way for ions and small molecules (O2, CO2 an simple sugars) Fixed confirmation but can exclude all but most specific molecules. Channels are DISTINCT from porins -Transporters: transmembrane proteins that flip between two conformations while transporting specific molecules 2) May contain ATP production enzymes 3) May contain photosynthetic pigments -In some bacteria (green and purple bacteira), they are found in infoldings of the plasma membrane that extend into the cytoplasm (called CHROMATOPHORES) ex: rhodospirilum rubrum

Answer 31

Cyanobacteria have an internal thylakoid membrane system (separate from the plasma membrane) for photosynthesis Although Cyanobacteria are prokaryotes, lacking a nuclear membrane and membrane bound organelles, they have INTERNAL membranes Thylakoid membranes are also present in CHLORPOLASTS

Answer 32

1) Passive: cross from HIGH to LOW concentration (no energy required) -Simple diffusion -facilitated difffusion -osmosis 2) Active: cross from LOW to HIGH concentration (energy required) -active transport -group translocation

Answer 33

Simple diffusion: solute moves from high concentration to low concentration -Used for certain SMALL molecules (O2, CO2) -continues until equilibrium is reached. (simple diffusion occur through lipid bilayer)

Answer 34

Facilitated diffusion: solute combines with a channel or transporter protein in the membrane (from high concentration to low concentration) transporter can be specific or nonspecific Facilitated diffusion with NON-specific transporter common in prokaryotes; passage of SMALL inorganic ions -Diffusion through SPECIFIC transporter- common in eukaryotes: passage of LARGER compounds (ex: simple sugars, and vitamins)

Answer 35

Some molecules released by bacteria are too large to enter the cell by transporters, secreted enzymes can break down large molecules.

Answer 36

Osmosis; The movement of water across a selectively permeable membrane from an area of HIGH water to an area of LOWER water concentration (at beginning of osmotic pressure experiment, high concentration of water outside sac, which causes water to go into sac and expand it; then eventually water will fill sac and reach equillibrum)

Answer 37

Osmotic pressure: The pressure needed to stop the movement of water across the membrane

Answer 38

Through Simple diffusion -Facilitated diffusion through aquaporins (water channels)

Answer 39

3 osmotic solutions 1) Isotonic solution: No net movement of water (concentration of water inside = outside cell) 2) Hypotonic solution: Water moves into the cell. If the cell wall is strong, it contains the Swelling. if the cell wall is weak or damaged, the cell BURSTS (osmotic lysis) 3) Hypertonic solution: water moves OUT of the cell, causing the cytoplasm to SHRINK (plasmolysis) The terms, Isotonic, hypertonic, and hypotonic describe the concentration of solutes Outside the cell relative to inside of cell

Answer 40

Active Transport (move from low concentration to high concentration ) -requires a Transporter protein and ATP -Concentrates materials in the cell -Generally a different transporter for each substance or closely related substances -substances not altered by transport (minerals, sugars, and most amino acids, will move against [ ] gradient with input of energy)

Answer 41

Group Translocation (way of bacteria uptakes sugar from energy source PEP) -requires a transporter protein and an organic high energy phosphate compound (ex; PEP; substance in glycolysis) -Altered during import to make membrane impermeable (ex: Glucose-6-phosphate) -Exclusive to Prokaryotes -group transporter is a form of ACTIVE TRANSPORT

Answer 42

Some eukaryotic cells (without cell walls) can use pinocytosis, receptor-mediated endocytosis, macropinocytosis and phagocytosis

Answer 43

Prokaryotic cytoplasm, Nucleoid, Plasmids, Ribosomes Inclusions, and Endospores.

Answer 44

Prokaryotic Cytoplasm: The substance inside the plasma membrane -80% H2O + proteins, molecules, ions -Major structures: Nucleoid, ribosomes and inclusions

Answer 45

Nucleoid: irregularly-shaped region within the cell of prokaryotes which has nuclear material without a nuclear envelope Bacterial chromosome (usually 1 circular) : -attached to plasma membrane (can be spherical, elongated or dumbbell shaped) -No histones -how condensed? ; coils like rubber band -Replication and chromes segregation enzymes are plasma membrane bound

Answer 46

Plasmids: autonomously replicating, independent chromosomes (DNA) -contain 5 to 100 genes -NOT crucial for survival under normal environmental conditions -associated with plasma membrane proteins

Answer 47

Prokaryotic Ribosome: large and long ribosomal RNA with a lot of proteins bound -Protein synthesis -70 S (size of ribosome) -50S+ 30S subunits (cannot add them up, since it depends on the shape) -each subunit contains multiple polypeptides and rRNA -Common targets for antibiotics (small subunit is 30S; Large subunit is 50s (common target for antibiotics) to form a complete 70s ribosome)

Answer 48

Inclusions- (material heals inside a cell); some are widespread, others limited to few species -Metachromatic granules: phopshate reserves for ATP (membrane bound) The color they give off are different from the stain they apply (Ex: if use blue stain, they will appear red) -Polysaccharide granules- energy reserves (glycogen/starch) -Lipid inclusions: Energy reserves -Sulfur granules; Energy reserves -Carboxysomes: protein shells containing the enzyme Ribulose 1,5-diphosphate carboxylase for CO2 fixation -Gas vacuoles: protein-covered cylinders -Magnetosomes: Iron oxide (membrane bound; orient bacteria to geomagnetic fields) (may protect from H2O2)

Answer 49

Gas vacuoles; Is sulfur an energy source?

Answer 50

Endospores: Resting cell (don't carry out metabolic reactions) with thick walls and additional layers that are resistant to desiccation, radiation, heat and chemicals -contain only DNA, small amounts of RNA, ribosomes, enzymes a few important small molecules (ex; Dipicolinic acid) -can remain dormant for thousands of years -Prior to 1984, endospore bacteria were classified in either the Bacillus or Clostridium genera (anaerobic) (due to no access to RNA sequencing) -Although true endospores are only found in Gram-POSITIVE bacteria, an endospore-like body is found n gram-negative organism Coxiella brunette

Answer 51

Yes, endospores can survive pasteurization, and boiling , but NOT Autoclaving(heat will be above boiling point to kill the spores)

Answer 52

Sporulation; Endospore FORMATION Germination; RETURN to vegetative state Vegetative cells are triggered to sporulate when key nutrient (carbon or nitrogen source) becomes Scarce or unavailable -Endospore germination occurs when more favorable growth conditions are present and is triggered by high heat or small triggering molecules (two germinates known to date are alanine and inosine )

Answer 53

Endospores location is species-dependent, either terminal, subterminal or central (they are located in different areas in the cell)

Answer 54

Sporulation: The formation of spores and endospores Process: 1. Asymmetric Cell Division: A sporangium (spore cell ) divides asymmetrically to form Forespore and Mother cell 2. Engulfment - Then mother cells Engulfs the foreshore and forms a spore coat around foreshore (double membrane) 3. Late Sporulation - the peptiodgylcan cortex is formed in between the outer forespore membrane and inner forespore membrane 4. Mother Cell lysis - mother cell lyses to release the forespore into the environment 5. Germination - spores can quickly germinate and return back to vegetative growth in response to nutrients. 1 cell produces 1 endospore.

Answer 55

Spores formed by prokaryotic Actinomycetes and Eukaryotic algae and fungi detach from parent and develop into another organism. -They represent Reproduction!

Answer 56

Flagella and Cilia (Structure): -bundle of nine fused pairs of microtubule DOUBLETS surrounding two central Single microtubules "9+2 array" -Encased within the cell's plasma membrane -Anchored to the plasma membrane by a basal body Flagella: FEW and long Cilia: Numerous and SHORT

Answer 57

Eukaryotic flagellum moves in a WAVELIKE manner Prokaryotic flagellum ROTATES

Answer 58

Animal cells and Protozoans LACK cell walls (protozoans have a FLEXIBLE outer protein coat, called PELLICLE) -When the cell wall is present in organisms, the cell wall is quite simple: -NO Peptidoglycan -Algae and Plant cells: cell wall made usually of CELLULOSE (glucose polymer) -Fungi: cell wall usually made of CHITIN -Molds: Chitin (NAG polymer) and/or cellulose -Yeasts; Glucan, mannan, and small amount of chitin As with bacteria, cell wall structure contributes to the cell shape and helps resist osmotic lysis

Answer 59

A GLUCAN molecule is any polysaccharide of D-glucose monomers

Answer 60

Eukaryotic cells, including animal cells will often be surrounded by a GLYCOCALYX (gel-like layer) which can extend from either the cell wall or plasma membrane -In cells lacking a cell wall, the sticky carbohydrates are bonded to either.. strengthen cell surface, help cells attach to each other and help cell-cell recognition

Answer 61

The Plasma Membrane: -Similar in basic structure to bacteria -Phospholipid bilayer, -Peripheral, integral, transmembrane proteins -Glycocalyx carbohydrates. **Sterols (help resist osmotic lysis) (UNIQUE to eukaryotes, except for Mycoplasma (prokaryotes) who have them. Eukaryotic PM Similar in Function (to bacteria) : -membrane transfer by same mechanisms but.. Eukaroytic PM LACKS group translocation -have PINOCYTOSIS, Receptor mediated Endocytosis and Phagocytosis .

Answer 62

Cytoplasm: a substance that consists of all the contents inside plasma membrane and outside the nucleus Cytosol: the fluid portion of the cytoplasm NOT contained within membrane bound organelles. Cytoskeleton: Complex internal structure that provides support, shape and assists in transport through cell. Cytoskeleton has 3 fibers: -Microfilaments (red) -Intermediate filaments -microtubules (green) Cytoplasmic Screening: Movement of cytoplasm throughout the cell (helps distribute nutrients and move the cell over a surface)

Answer 63

Ribosomes: -Used for Protein Synthesis -80 S(60 S + 40S) -Membrane-bound: Attached to nuclear outer membrane and ER (endoplasmic reticulum) -Free ribosomes: in cytoplasm -two subunits assemble individually in nucleolus, exit the nucleus and then join for translation -70 S (50S + 30 S) in Chlorplasts and mitochondria -translate chloroplast/mitochondrial mRNAs

Answer 64

Membrane Bound Organelles (ALL Eukaryotes) -Nucleus: Contains chromosomes -ER(endoplasmic reticulum): Transport network, Smooth and Rough -Golgi Complex: Membrane formation and Secretion -Lysosome: Digestive enzymes -Vacuole: Diverse functions: storage (energy sources, toxins wastes), endocytosis role and plant rigidity.

Answer 65

Organelles that Some Eukaryotes have: -Most have Mitochondria: Cellular respiration -Chloroplast: Photosynthesis -Peroxisome: Oxidation of Fatty acids; destroys H2O2 -Centrosome: region consisting of a pericentriolar center (protein fibers) and a pair of centrioles; involved in the formation of the mitotic spindle

Answer 66

The Eukaryotic Nucleus: -contains most of the cellular DNA - Nuclear envelope (membrane that surrounds inner nucleus ) -Nuclear pores (protein complex with aqueous channel; used for transport)

Answer 67

Nucleolus: -NOT membrane bound -Formed around tandem repeats of rRNA genes (humans have 200 copies of rRNA genes on 5 chromomses ) -UNCONDENSED: -chromosome regions (no histones) -Site of assembly for small and large cytosolic ribosomes subunits

Answer 68

Endoplasmic Reticulum: Two forms of ER: Rough ER (contains ribosmes) and Smooth ER -The ER lumen is continuous with the perinuclear space (2 membranes between nuclear envelope) -Phospholipid synthesis occurs here -Processing and sorting center -entry point for the vesicular pathway (transporting vesicles from ER to Golgi) -carbohydrates and phospholipids may be attached to proteins

Answer 69

Golgi Complex; -receive transport vesicles from ER -proteins/lipids move from cistern-to-cistern via transfer vesicles -enzymatic reactions yield gylcolipids, glycoproteins and lipoproteins -Cargo containing vesicles leave for plasma membrane, lysosomes, etc.

Answer 70

Lysosomes -enclosed by a single membrane -contain digestive enzymes to break down cell components no longer needed as well as molecules or even bacteria that are ingested by the cell -The interior of a lysosome is moderately acidic (pH 5) -The Low pH is beneficial to the cell because it is used a safety mechanism. if NOT at a low temperature, you can lose the function of enzymes that degrade things (enzymes need an acidic environment to stay active and have proper functioning)

Answer 71

Vacuoles: -Enclosed by ER/golgi-derived membrane-bound sac (tonoplast) -generally small in animals cells but can occupy 90% of the cell volume in plants -has diverse functions depending on the cell. Some... act as storage organelles for proteins, sugars, organic acids and inorganic ions -acts a degradative compartments -store metabolic wastes and poisons -in plants, they can take up water to give rigidity to leaves and stems. (vacuole are located within cytoplasm in the cell wall, surrounded by plasma membrane next to a nucleus )

Answer 72

Nucleus: Contains chromosomes (that form through nuclear division), also contains nuclear envelope (double membrane that has nuclear pores and nucleoli) and nucleus contains almost all of cells Hereditary information (DNA)

Answer 73

Mitochondria: -Has two membranes (inner (respiratory chain) and outer membranes) -# of mitochondria varies greatly -Generates ATP -contains chromosome (DNA) -70S Ribosomes. (mitochondria also have cristae (increase SA to synthesize ATP) and matrix (where protons are pumped out)

Answer 74

Chloroplasts: -seen in Algae and Green plants -have THREE membranes (outer membrane, inter membrane space and inner membrane) Like Mitochondria, chloroplasts contain 70s ribosomes and Divide like bacteria

Answer 75

Chlorplasts contain: -THYLAKOIDS (sac-like photosynthetic membranes) -stroma (aqueous fluid) -Granum (stack of thylakoids) -lumen PHOTOSYNTHESIS occurs in the chloroplast (where sunlight is converted into food and energy for plants

Answer 76

Peroxisome: Spherical, single membrane, smaller than lysosomes -contain enzymes that oxidize organic compounds for normal metabolism (amino acids and fatty acids { Beta-oxidation}) or detoxification (alcohol) -Catalase converts H2O2 generated in the peroxisome to H2O and O2. (seen in Indian Mutjac Deer and Skin fibroblast cells) Peroxisomes in image: green, F-actin: red and Nuclei: blue

Answer 77

Centrosome: located near the nucleus 1) in Nondividing cells, they are the center for building and organizing center microtubule formation 2) During cell division, duplicates and migrates to opposite poles of the cell to form mitotic spindles (that separate chromosomes) Consists of two components: 1) pericentriolar area : a cytosolic region composed of a dense network of small protein fibers 2) centrioles

Answer 78

Centrioles: (made of microtubules like flagella, cilia) -A pair of centrioles within pericentriolar region (of centrosome) -Each centriole consists of 9 sets of triplet microtubules in a "9 + 0" array - the centrioles are at RIGHT ANGLES to each other

Answer 79

Endosymbiotic Theory: belief that progenitor cell came from Ancient archeon -The ancient arches had no cell wall and began with the invagination of Plasma Membrane, which derived nucleus. The nucleus then formed nuclear envelope and produced ER (endoplasmic reticulum) -Once nucleus and ER formed, the prokaryote engulfed the cellular mitochondria and photosynthetic prokaryote, which led to formation of plastid with mitochondria. (Endosymbiotic theory explains that some eukaryotic organelles like mitochondria and plastids evolved from free-living prokaryotes)

Answer 80

Supporting Evidence for Endosymbiotic Theory: -Like bacteria, ribosomes are similar (70s bacteria, mitochondria) -Size and shape of mitochondria are similar to bacterial size -Ribosomes in mitochondria target bacteria They divide COME BACK TO THIS

Functional Anatomy of Prokaryotic and Eukaryotic cElls Flashcards

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