The Cell Flashcards
What is the main function(s) of the Nucleus?
Storage of genetic information.
Site of transcription.
What is the main function(s) of the Mitochondria?
Production of ATP via oxidative phosphorylation.
Programmed-cell death (apoptosis).
What is the main function(s) of the Lysosomes?
Catabolism of molecules and cellular waste products (e.g. excess or worn-out organelles) via hydrolytic enzymes.
Apoptosis/autolysis.
What is the main function(s) of the Rough Endoplasmic Reticulum [RER]?
Synthesis/ translation of proteins destined for secretion into lumen.
Ex. Glycoproteins
What is the main function(s) of the Smooth Endoplasmic Reticulum?
Synthesis of lipids
Metabolism of carbohydrates
Storage of calcium ions
Detoxification.
What is the main function(s) of the Golgi Apparatus?
Processing, packaging, and modification of cellular products (e.g. lipids and proteins).
What is the main function(s) of the Peroxisomes?
Catabolism of fatty acid chains via B-oxidation (hydrogen peroxide)
Synthesis of lipids
Enzyme contribution to the pentose phosphate pathway.
Describe the similarities and differences between apoptosis and autolysis.
Similarities:
- Result in cellular death
Differences:
- Apoptosis is controlled and intentional
- Autolysis is uncontrolled and unintentional
Define endocytosis.
The taking in of matter by a living cell via invagination of its membrane to form a vacuole.
Define exocytosis.
The process by which contents of a cell vacuole are released to the exterior of the cell membrane via fusion of both the vacuole and cell membrane.
What are the 3 components of the cytoskeleton?
- Microfilaments
- Microtubules
- Intermediate Filaments
Describe the structure and function(s) of microfilaments.
Solid polymerized rods of actin organized into bundles and networks for resistance to both compression and fracture, providing protection for the cell.
Describe the structure and function(s) of microtubules.
Hollow polymers of tubulin which radiate throughout the cell providing the primary pathways along which motor proteins (e.g. kinesin and dynein) carry vesicles.
Describe the structure and function(s) of intermediate filaments.
Diverse group of filamentous proteins (e.g. keratin and desmin) involved in cell-cell adhesion, maintenance of cytoskeleton integrity, and anchorage of organelles.
What are the 6 membrane-bound organelles belonging to eukaryotic cells?
- Nucleus
- Mitochondria
- Lysosomes
- Endoplasmic Reticulum
- Golgi Apparatus
- Peroxisomes
Name the 3 domains of classification for organisms.
- Archaea
- Bacteria
- Eukarya
What characteristic(s) do archaea and eukaryotes have in common?
Start translation with methionine, share similar RNA polymerases, associate their DNA with histones.
What characteristic(s) do archaea and bacteria have in common?
Both contain a single circular chromosome, divide by binary fission or budding, and share similar structure.
NOTE: Archaea and Bacteria contain all prokaryotic microorganisms
Name the 5 characteristics of prokaryotes that make them uniquely different from eukaryotes.
- DNA is not enclosed within a nuclear membrane and is in the form of a single circular chromosome
- DNA is not associated with histones
- Lack membrane-bound organelles
- Cell wall contains polysaccharide peptidoglycan
- Divide by binary fission
Name the 5 characteristics of eukaryotes that make them uniquely different from prokaryotes.
- DNA is enclosed within a nuclear membrane and is in the form of multiple linear chromosomes
- DNA is associated with histones
- Contain membrane-bound organelles
- Cell wall is chemically simple
- Divide by mitosis
Name the 6 classifications of microorganisms.
- Bacteria
- Archaea
- Fungi
- Protozoa
- Algae
- Viruses
Name 5 characteristics belonging to bacteria.
- Unicellular
- Lack nuclear membrane
- Contain cell membrane and cytoplasm
- Chemosynthetic or photosynthetic
- Move via flagella/fimbriae
Note: Bacteria are prokaryotes
What are the 3 classifications of bacteria by shape?
- Cocci = spherical-shaped
- Bacilli = rod-shaped
- Spirilli = spiral-shaped
Note: Vibria and spirochetes are additional types of spiral-shaped bacteria
Define photoautotroph.
Organism that uses light as its energy source and carbon dioxide as its carbon source.
Define photoheterotroph.
Organism that uses light as its energy source and an organic carbon source.
Define chemoautotroph.
Organism that uses an inorganic chemical as an energy source and carbon dioxide as a carbon source.
Define chemoheterotroph.
Organism that uses organic molecule as a source of carbon and energy.
Name 5 characteristics belonging to Archaea.
- Unicellular
- Lack peptidoglycan in cell walls
- Extremophiles (e.g. methanogens, halophiles, thermophiles).
- Chemosynthetic and photosynthetic
- Divide via binary fission or budding
Note: Archaea are prokaryotes
What are the two types of prokaryotes?
Bacteria and archaea
What are the three types of eukaryotes?
Fungi, Protozoa, and Algae
Define obligate aerobe.
Require oxygen for metabolism.
Define anaerobe.
Cannot survive in oxygen-containing environment.
Define facultative anaerobe.
Utilizes oxygen for aerobic respiration when present and switches to anaerobic metabolism when oxygen is not present.
Define aerotolerant anaerobes.
Tolerant of oxygen’s presence in environment but cannot utilize it for aerobic respiration.
Eukaryotic vs Prokaryotic Ribosomes
Eukaryotes: 80S ribosome (60S & 40S subunits)
Prokaryotes 70S ribosome (50S & 30S subunits)
What are the 2 types of cell walls in bacteria?
- Gram-positive (absorb crystal violet stain)
2. Gram-negative (absorb safranin stain)
Name the characteristic(s) of gram-positive bacterial cell walls.
Negatively charged lipoteichoic acid (LTA), thick peptidoglycan layer, highly cross-linked, smaller pores (able to retain crystal violet stain).
Name the characteristic(s) of gram-negative bacterial cell walls.
Negatively charged lipopolysaccharide (LPS), thin peptidoglycan layer, larger pores (able to retain safranin dye).
Note: Antibiotic breakdown of LPS can cause anaphylactic shock.
Define peptidoglycan.
Polymeric substance comprised of amino acids and sugars and is commonly found in cell wall of bacteria
How do the structures of flagella differ in eukaryotic and prokaryotic species?
Eukaryote flagella: Contain microtubules composed of tubulin in a 9 + 2 arrangement.
Prokaryote flagella: Made of flagellin and consist of a filament, basal body, and a hook.
What are the characteristic(s) of binary fission.
Type of asexual reproduction, occurs in prokaryotes, proceeds more rapidly than mitosis.
What is the name of extrachromosomal material found in bacteria?
Plasmids
How do bacterial cells benefit from plasmids?
Hint: Virulence factors
Increase pathogenicity via antibiotic resistance and toxin production, emit projections allowing ease of attachment to host cells, and evasion of host immune system.
How do bacterial cell benefit from genetic recombination?
Increases bacterial diversity by permitting the evolution of different bacterial species over time.
Name the 3 types of genetic recombination.
- Transformation
- Conjugation
- Transduction
Define transformation.
Integration of foreign exogenous genetic material into the host genome. Occurs, most frequently, when surrounding bacterial cells are lysed spilling their contents in the vicinity of a bacterium capable of transformation.
Note: type of genetic recombination
Define conjugation.
Transfer of genetic material from one bacterium to another across a conjugation bridge; a plasmid can be transferred from F+ cells to F- cells, or a portion of the genome can be transferred from an HFR cell to a recipient.
Note: type of genetic recombination
Define transduction.
Transfer of genetic material from one bacterium to another using a bacteriophage as a vector.
Note: type of genetic recombination
Define bacteriophage.
A virus that parasitizes a bacterium by infecting it and reproducing inside it.
Note: occurs in transduction
Define transposons.
Genetic elements capable of inserting and removing themselves from the genome.
Note: form of transposition (physical movement of genetic material)
What are the 4 phases of bacterial growth?
- Lag phase
- Log phase (exponential)
- Stationary phase
- Death phase
Define episomes.
Plasmids that are capable of integrating into the genome.
Define chemotaxis.
Movement of microorganism via flagella/fimbriae in response to chemical stimuli.
Define lag phase of bacterial growth.
Bacterial adaptation to local environment conditions.
Define log phase (exponential) of bacterial growth.
Bacterial growth increases rapidly through uptake of resources in surrounding environment.
Define stationary phase of bacterial growth.
Bacterial growth slows as resources are reduced causing growth to level off.
Define death phase of bacterial growth.
Bacterial growth ceases and bacterial cells begin to die as resources are depleted.
Describe the structure of viruses.
Composed of genetic material, a protein coat (capsid), and sometimes an envelope containing lipids.
Describe the genetic information of viruses.
May be circular or linear, single or double-stranded, and composed of either DNA or RNA.
Why are enveloped viruses easier to destroy?
Envelopes are sensitive to heat, detergents, and desiccation.
Viruses cannot reproduce independently and are therefore considered what?
Obligate intracellular parasites.
Note: viruses lack ribosomes which carry out protein synthesis
Define virion.
The complete, infective form of a virus outside the host cells, with a core of RNA or DNA and a capsid.
What purpose does the tail sheath of bacteriophages serve?
Acts like a syringe, injecting genetic material into a bacterium.
What purpose does the tail fibers of bacteriophages serve?
Assist bacteriophages to recognize and attach to the correct host cell.
What components of a host cell helps viruses to replicate and translate genetic material?
Hint: There are 4 components
Utilization of ribosomes, tRNA, amino acids, and enzymes.
What are the 3 ways viral progeny are released from the host cell?
- Apoptosis/ Autolysis (cell death)
- Lysis
- Extrusion
Define extrusion.
Process by which a cell exports large particles or organelles from within the cells membrane to the outside environment.
Name the 2 life cycles of bacteriophages.
- Lytic cycle
2. Lysogenic cycle
Describe the lytic cycle of a bacteriophage.
Bacteriophages produce massive numbers of new virions until the cell lyses. Bacteria in the lytic cycle are termed virulent.
Describe the lysogenic cycle of bacteriophages.
Virus integrates into the host genome as a pro-virus or prophage, which can then reproduce along with the cell. The provirus then leaves the genome in response to a stimulus at some later time and enters the lytic cycle.
Define provirus (prophage).
A form of a virus that is integrated into the genetic material of a host cell. By replicating with the hosts genetic material it can be transmitted from one generation to the next without causing the cell to lyse.
Define prions.
Infectious proteins capable of triggering the misfolding of other proteins. Typically converts a-helical protein structures to a B-pleated sheet thus decreasing solubility and degradability.
Define viroids.
Plant pathogens containing small circular complementary RNA capable of turning off genes thus resulting in metabolic and structural derangements of the cell and potentially cell death.
What are the characteristic(s) of mitochondrial DNA?
Circular and self-replicating
What is the main function of the the nucleolus?
Ribosomal RNA synthesis
