The Cell: Eukaryotes, Prokaryotes & Viruses Flashcards
Cytoskeleton
- Provides structure and maintains shape
- Provides conduit for transport of materials around the cell
- Made of microtubules, microfilaments and intermediate filaments
Microfilaments
- Solid polymerized rods of Actin; Provide protection for the cell
- Use ATP to generate force for movement by interacting with Myosin
- Plays a role in cytokinesis
Microtubules
- Hollow polymers of Tubulin
- Primary pathway for motor proteins (like kinesin / dynein) to carry vessicles
- Make up Cilia and Flagella
- 9 + 2 Structure = 9 microtubules in outer ring and 2 microtubules at center
Cillia
For movement of material along the surface of a cell
Flagella
For movement of the cell itself
Centrioles
Organizing center for microtubules
Nucleus
- Control center of the cell
- Contains all genetic information necessary for replication
Nuclear Pores
Allow for 2 way selective exchange between the cytoplasm and the nucleus
Nuclear Membrane / Envelope
Surrounds the nucleus to provide protection and selective exchange
DNA
- Contains coding regions called genes
Histones
- Charged organizing proteins that linear DNA (chromatin) is wrapped around
- Bunches of 8
Chromosome
Condensed DNA (during cell division)
Nucleolus
- Subsection of the Nucleus
- Ribosomal RNA (rRNA) is synthesized
Lysosome
- Contains hydrolitic enzymes capable of breaking down many substrates including those ingested by endocytosis and cellular waste products
Smooth Endoplasmic Reticulum (ER)
- Contains no ribosomes
- Series of interconnected membranes
- For lipid synthesis and detoxification
- Transports proteins
Ribosomes
- Permits the translation of proteins
- Eukaryotes have 40s and 60s
- Prokaryotes have 30s and 50s
Perioxisomes
- Contains hydrogen peroxide
- Breakdown long chain fatty acids via beta-oxidation
Mitochondria
- Powerhouse of the cell (ATP Production)
- Outer membrane is a barrier
- Inner membrane have Cristae (involved in ETC)
- Semi-Autonomous; replicate independently via binary fission
- Provide energy to keep the cell alive
- Capable of apoptosis
Location of the following processes: Pyruvate Dehydrogenase, Citric Acid Cycle, ETC, Oxidative Phosphorylation, Beta-Oxidation, Some of Gluconeogenesis, Urea Cycle)
Apoptosis
Killing of the cell with a release of enzymes
Cristae
Numerous folds containing molecules and enzymes for the Electron Transport Chain (ETC)
Golgi Apparatus
- Stacked membrane bound sacs
- Post-Translational modifaction of proteins through addition of carbohydrates, phosphates and sulfates to send them to specific cellular locations
Cytoplasm
Contains cytosol allowing for diffusion of molecules throughout the cell
Rough Endoplasmic Reticulum (ER)
- Studded with ribosomes
- Series of interconnected membranes
- Site of protein synthesis destined for insertion into a membrane or secretion
Intermediate Filament
- Cell to cell adhesion and maintenance of overall integrity of cytoskeleton
- Help anchor other organelles including the nucleus
Cell Theory
- All living things are composed of cells
- Cell is the basic functional unit of life
- Cells only arise from pre-existing cells
- Cell carry genetic information (DNA) which passes on to the daughter cells
Eukaryote Basics
- Multicellular
- Contain nucleus
- More than 1 chromosome
- Membrane bound organelles
- Animals and plants
Prokaryote Basics
- Unicellular
- No nucleus
- One “fake” chromosome, a plasmid
- No membrane bound organelles
- Single circular DNA in Nucleoid Region
- Bacteria and Archaea
Simple Epithelia
One layer of cells
Stratified Epithelia
Multiple layers of cells
Pseudostratified Epithelia
Appear to have multiple layers but is actually one large layer of cells
Cuboidal Cells
Cube shaped
Columnar Cells
Long and thin in shape
Squamous Cells
Flat and scale like cells
Archaea
- Single celled organisms (similar to bacteria)
- Contain genes and several metabolic pathways that are more similar to Eukaryotes
- Can use alternative sources of energy
- Single circular chromosome that divide by binary fission or budding
Bacteria
- Contain a cell membrane and cytoplasm
- Have flagella
Symbiotic
Both beneficial to host and themselves in the relationship
Pathogens
Provide no advantage / are not beneficial to the hose; cause disease
Cocci Bacteria
Spherical shaped
Bacilli Bacteria
Rod shaped
Spirilli Bacteria
Spiral shaped
Obligate Aerobes
Require oxygen
Anaerobes
No oxygen, but use fermentation or other cell metabolism for energy
Aerotolerant Anaerobe
Unable to use oxygen but not harmed by its presence
Obligate Anaerobes
Harmed by oxygen in the environment
Facultative Anaerobes
Can be anaerobic (no oxygen) or aerobic (use oxygen) - toggle between the two depending on the environment
Nucleoid Region
Prokaryotes:
possible plasmids; contain DNA
Plasma Membrane
Prokaryotes:
Composed of phospholipids
Cell Wall
The other barrier of the cell
Envelope
Prokaryotes:
Plasma membrane + Cell wall collectively
Filament
Prokaryotes:
Hollow helical structure composed of flagellin
Flagella
Prokaryotes:
whiplike structure used for propulsion composed of filaments
Hook
Prokaryote:
connects flagella and basal body
Basal Body
Prokaryotes:
Connects / anchors the flagellum to the cytoplasmic membrane
Chemotaxis
Ability of the cell to detect chemical stimuli and move away / toward them
Gram Positive Bacteria
- When stained with crystal violet stain - turn deep purple
- Thick layer of peptidoglycan (polymeric substance of amino acids and sugars)
- Contains Lipoteichoic acid
Gram Negative Bacteria
- When counterstained with Safranin stain - turns Red / pink
- Thin; contain small amounts of peptidoglycan
- Have outer membranes containing phospholipids and lipopolysaccharides
Binary Fission
How Prokaryotes Divide:
Form of asexual reproduction where the circular chromosome attaches to the wall and replicates
Binary Fission Steps
- Cell grows in size
- Replication of Circular chromosome
- Chromosomes attaches to cell walls
- Invagination where the plasma membrane moves inward and the cell wall begins to form along the midline
- Two identical daughter cells are produced
Plasmids
Extrachromosomal material that carry genes that impart some benefit to the bacterium
Virulence Factors
Traits which increase how pathogenic a bacterium is
Types of Genetic Recombination
- Transformation
- Conjugation
- Transduction
- Transposons
Transformation
Genetic Recombination:
Integration of foreign genetic material (generally from other bacteria) into the host genome
Conjugation
Genetic Recombination - Bacterial form of mating
- Two cells form a conjugation bridge allowing the transfer of genetic material unidirectionally
- Bridge is made from sex pilli and bacteria contain sex factor plasmids (female or male)
Transduction
Genetic Recombination:
- Requires a vector or virus that carries genetic material from one bacterium to another
Transposons
Genetic Recombination:
- Genetic elements capable of inserting and removing themselves from the genome
Bacterial Growth Semi-Log Plot
- Lag Phase - bacteria adapt to the new conditions
- Exponential Growth Phase
- Stationary Phase - reduction of resources slows reproduction
- Death Phase - Resources are depleted
Viruses
- Nonliving
- Composed of genetic material, protein coat and sometimes an envelope of phospholipids and proteins containing lipids
- Cannot reproduce independently - need a host cell
Obligate Intracellular Parasites
Expressing / Replicating genetic information within a host cell because of a lack of ribosomes
Bacteriophage
- Viruses that specifically target bacteria
- Composed of genetic material (nucleic acids), protein coat / caspid, tail sheath (syringe to inject genetic material), and sometimes an envelope of phospholipids and proteins containing lipids
- Cannot reproduce independently - Use Tail fibers to recognize and connect to correct host cell
Retroviruses
- Enveloped, single stranded RNA Viruses
- Carry a Reverse Transcriptase Enzyme which synthesizes DNA from single stranded RNA
- DNA is integrated into a host cell genome
Viral Life Cycle
- Infection
- Translation
- Progeny Release
Infection Step of Viral Life Cycle
- Virus must bind to specific receptors on the host cell
- Enveloped viruses fuse with the plasma membrane allowing entry
- Depending on virus; different portions of viron are inserted into host cell
Translation Step of Viral Life Cycle
Progeny Assembly:
- Translocation of genetic material to correct location in cell
- Using host cell machinery the viral RNA is translated into a protein
Progeny Release Steps of Viral Life Cycle
- Viral invasion- may initiate cell death which spills progeny
- Lytic Cycle
- Extrusion (Productive Cycle) - viruses leaves the cell by fusing with plasmid membrane allowing for survival / continual use of the host cell
- Lysogenic Cycle
Lytic Cycle
Viruses makes max use of cells machinery. Once the host cell is swollen it will lyse and other cells become infected
- Termed Virulent
Lysogenic Cycle
Viruses may integrate into the host genome or as a provirus or prophage (where the virus will replicate)
Prions
Infectious, non-living proteins that trigger misfolding of other proteins. Can drastically reduce solubility of a protein and cause protein aggregates to form
Viroids
Small plant pathogens that silence genes in the plant genome; preventing synthesis of necessary proteins causing metabolic and structural derangements
Fluid Mosaic Model of the Membrane
- Phospholipid bilayers fluid combination of phospholipids, cholesterol, and embedded proteins
- Exterior = Hydrophilic phosphate heads
- Interior = Hydrophobic fatty acids
