2B: The Structure, growth, physiology and genetics of prokaryotes & viruses Flashcards
What are the 4 tenets of Cell Theory?
- All living things are composed of cells
- The cell is the basic functional unit of life
- All cells arise ONLY from preexisting cells
- Cells carry genetic information in the form of DNA
How do viruses violate cell theory?
They do not arise from preexisting cells and they do not carry genetic information the form of DNA
List the 7 organelles in eukaryotic cells:
N M R
L P S
G
Nucleus, Mitochondria, Lysosome, Rough E.R., Smooth E.R., Golgi Apparatus, Peroxisome
What surrounds the nucleus and what is that structures function?
Nuclear envelope, it has nuclear pores that allow selective 2 way exchange of material
What does the nucleus contain and what is that structures function?
Nucleolus, synthesizes ribosomal RNA
What is the function of the nucleus? What processes occur here?
To contain and protect DNA; DNA replication, transcription and partial RNA assembly
What is the function of mitochondria?
Produce ATP via Krebs Cycle & Oxidative Phosphorylation
List the structures of the mitochondria.
Outer Membrane
Intermembrane Space
Inner Membrane
Matrix
What is the function of cristae?
Increase surface area available for electron transport chain
What enzymes are contained in the mitochondrial matrix?
Pyruvate dehydrogenase complex
Citric Acid Cycle enzymes
What lines the inner mitochondrial membrane?
Electron Transport Chain & ATP Synthase
Describe the DNA in Mitochondria.
Single circular DNA molecule that encodes rRNA, tRNA and several mitochondrial proteins
What is the endosymbiotic theory?
That mitochondria originated as independent unicellular organisms living within larger cell
What is special about the DNA of Mitochondria?
It’s inherited only from the mother because the ovum supplies the organelles
How do mitochondria replicate?
Binary Fission
What process can mitochondria participate in?
Apoptosis
What is the function of the lysosome?
Degrades biomolecules through hydrolysis
What do lysosomes use to degrade molecules? When are they active?
Hydrolytic enzymes; active in only low pH environments
What is autophagy?
Lysosome degrades non-functional or damaged self-organelles
What is the Rough E.R.? What is it responsible for?
The part of the ER that contains ribosomes; it synthesizes proteins that are secreted extracellularly or plasma membrane proteins
What is the Smooth E.R.? What is it responsible for?
The part of the ER that lack ribosomes; responsible for lipid synthesis and detoxification of certain compounds
What is the function of the Golgi Apparatus?
It receives cellular products (proteins) and modifies them; sort and sends those proteins to their cellular destination; performs exocytosis
How does the golgi apparatus modify proteins?
Glycosylation, Phosphorylation, Sulfonation
What is the cis vs. trans face of the golgi?
Cis face is closer to the ER and Trans face is farthest from the ER
What is the function of peroxisomes?
They contain hydrogen peroxide which aid in metabolizing lipids and toxins (in the liver); phospholipid synthesis
What enzyme do peroxisomes contain? What does that enzyme do?
Catalase; converts H2O2 into H2O and O2
What is the function of the cytoskeleton? What is it composed of?
Provide structure to the cells and helps maintain cell shape; it’s composed of microfilaments, microtubules and intermediate filaments
What are microfilaments composed of? Are they thick or thin?
Polymerized rods of actin; thin
What is the function of microfilaments?
Use ATP to generate force for movement; forms the cleavage furrow in cytokinesis
What are the kinds of actin? Which is a monomer or polymer?
Filamentous Actin (F-Actin) [polymer] Globular Actin (G-Actin) [monomer]
What are microtubules composed of? Are they they thick or thin?
Hollow polymers of tubulin (alpha and beta), thick
What is the function of microtubules? Where are they organized?
They provide pathways for movement throughout the cell via kinesin and dynein; the centriole organizes them (9 w/ a hollow center)
What are some structures that are made of microtubules? What are their arrangements?
Cilia & Flagella; 9+ 2 arrangement w/ dynein arms
What are intermediate filaments composed of?
Filamentous proteins (such as keratin)
What is the function of intermediate filaments?
They are involved in cell-cell adhesion as well as maintenance of the cytoskeleton by resisting mechanical stress
What are the 4 tissue types?
Epithelial, Connective, Muscle and Nervous
Describe Epithelial Tissue
Cover the body, protect against invasion and desiccation, connected to the basement membrane
What is the parenchyma?
The functional part of an organ
What are the types of epithelial tissue? # of layers
Simple (1)
Stratified (multiple)
Pseudostratified (1 @ different heights)
What are the shapes of epithelial tissue?
Cuboidal (cube shaped)
Columnar (column shaped)
Squamous (flat and scalelike)
What is the function of connective tissue?
Supports the body and provides a framework for the epithelial cells to carry out their function
What is the stroma?
It is the part of a tissue or organ that has a connective and structural role
Describe the structure of a prokaryote.
It has no membrane bound organelles, single circular DNA in a nucleoid regions
What are the shapes of bacteria?
- Cocci (sphere)
- Bacilli (rod)
- Spirilli (spiral)
Obligate Aerobes
Require O2 for Metabolism
Anaerobes
Do not require O2 for metabolism
Obligate Anaerobes
Cannot survive in the presence of O2
Facultative Anaerobes
Use O2 if present; utilizes anaerobic metabolism if its not present
Aerotolerant Anaerobes
Unable to use O2 for metabolism but aren’t harmed by its presence
Describe prokaryotic cell structure; What are some of the structures?
They lack a nucleus and membrane bound organelles; cell wall & flagella
Cell Wall
Protects cell from outer environment; provides structure and controls movement in and out of the bacteria
Types of Cell Walls
Gram Negative
Gram Positive
Negative Gram Stain (Pink-Red)
Absorbs safranin counterstain but not crystal violet primary stain
Gram Negative Cell Wall
Thin wall of PTG (small amounts); outer membrane of phospholipids & lipopolysaccharide
Positive Gram Stain (Purple)
Absorbs crystal violet but not safranin counterstain
Gram Positive Cell Wall
Thick layer of PTG; contain lipoteichoic acid
Flagella
Used for taxis, composed of a filament, basal body and hook
Plasmids
Circular pieces of DNA that may confer particular characteristics such as antibiotic resistance
Bacterial Mitochondrial Subunits
30S and 50S
Binary Fission
Chromosome replicates while cell grows in size, the cell wall grows inward and eventually divides in two
Genetic Recombination Processes
Transformation, Conjugation & Transduction
Episomes
Plasmids that are capable of integrating into the host genome
Transformation
Integrates foreign genetic material into host genome
Conjugation
Two cells form a conjugation bridge between them allowing genetic material to transfer (unidirectional)
What does F+ indicate?
Donor (Male)
What does F- indicate?
Recipient (Female)
How does E. coli work?
F+ cells replicate their F factor and donate the copy to an F- cell which can donate it to other cells
Transduction
Requires a virus (bacteriophage); integrate genome from host cell to new cell
Transposons
Genetic elements capable of inserting themselves into the genome, if inserted into a coding region it can disrupt the gene
Stages of Bacterial Growth
Lag
Exponential
Stationary
Death
Lag Phase
Bacteria adapt to new environment, not much growth occurs
Exponential Phase
Growth increases exponentially on a linear path after they adapt to their environment
Stationary Phase
Reproduction slows down due to decreased resources
Death Phase
Number of bacteria exceed the ability of the environment to support them
Viruses
Obligate intracellular parasites
Characteristic of Viruses
Contains a head with nucleic acid inside; a tail that’s used for insertion
Virions
Viral progeny that can be released to infect additional cells
Viral Genome
They determine how infection by each virus proceeds
Positive Sense
Genome may be directly translated to functional proteins by the ribosomes of the host cell
Negative Sense
Requires synthesis of an RNA strand complementary to negative sense RNA that can be used as template for protein synthesis
[-] RNA Viruses
Carries & encodes RNA-Dependent RNA Pol; makes complimentary copy that acts as mRNA and are translated into viral proteins
[-] -replicase-> [+] -> proteins + [-]
[+] RNA Viruses
Encodes RNA-Dependent RNA Pol; synthesize [-] strand which can be used to make proteins for new viruses
[+] -replicase-> [-] -replicase-> [+] -> proteins + [-]
Retroviruses
Encode for reverse transcriptase; enveloped ssRNA;
[+] -RT-> dsDNA -integration/transcription-> [+]
Self Replication Process
Attachment -> Entry -> Uncoating -> Replication -> Post-Translational Modification -> Lysis
Attachment
Binding to receptors on host cell
Entry
Penetrates the host cell wall/membrane
Uncoating
Viral capsid is degraded by viral enzymes
Replication
mRNA, Proteins and other genomic material are produced
Lysis
Host cell lyses due to release of viral progeny
Lytic Cycle
Virus maximally uses cell machinery disregarding the survival of the host cell
Lytic Cycle Processes
Attachment -> Penetration -> Transcription/Translation -> Degradation of host genome -> Replication of phage genome -> Assembly of new capsid -> Lysosomes destroy bacterial cell wall
Lysogenic Cycle
Integration into the host genome as a provirus or prophage; virus is replicated as the bacterium reproduces since its a part of the host genome; does not lyse the host cell
Lysogenic Cycle Processes
Prophage integrates, reproduces with bacterium, are activated due to some excision event
Prions
infections proteins, trigger the misfolding of other proteins and affect their solubility causes aggregates
Viroids
Plant pathogens, circular ssRNA, bind to plant genome and silence it
