The Cell Flashcards
4 Tenets of Cell Theory?
- All living things are composed of cell
- The cell is the basic functional unit of life
- Cells arise only from preexisting cells
- Cells carry genetic information in the form of DNA. This genetic material is passed on from parent to daughter cell.
Eukaryotes?
Membrane-bound organelles, a nucleus, and may form multicellular organisms
Nucleus
contains DNA organized into chromosomes, surrounded by nuclear membrane or envelope, a double membrane that contains nuclear pores for two-way exchange of materials between the nucleus and cytosol, DNA is organized into coding regions called genes
Nucleolus
subsection of the nucleus in which ribosomal RNA is synthesized
Mitochondira
Outer membrane forms a barrier with the cytosol, inner membrane is folded into cristae and contains enzymes for the electron transport chain, between the membranes is the inter membrane space, inner mitochondrial membrane is the mitochondrial matrix; can trigger apoptosis by releasing enzymes, can divide independently of the nucleus via binary fission
Lysosomes
contain hydrolytic enzymes that break down substances ingested by endocytosis, when these enzymes are released, autolysis can occur
Rough endoplasmic reticulum vs smooth endoplasmic reticulum
Rough ER–> studded with ribosomes, permit translation of proteins destined for secretion
Smooth ER–> used for lipid synthesis and detoxification
Golgi apparatus
stacked membrane-bound sacs in which cellular products can be modified, packaged and directed to specific locations
Peroxisomes
contain hydrogen peroxide and can break down very long chain fatty acids via B-oxidation, participate in phospholipid synthesis and the pentose phosphate pathway
microfilaments are composed of??
actin, they provide structural protection for the cell and cause muscle contraction thorough interactions with myosin, help form the cleavage furrow during cytokinesis in mitosis
Microtubules are composed off??
tubulin, they create pathways for motor proteins like kinesin and dynein to carry vesicles. They also contribute to the structure of cilia and flagella, where they are organized into 9 pairs of microtubules in a ring with two microtubules at the center; centrioles are found in centrosomes and are involved in microtubule organization in the mitotic spindle
intermediate filaments are involved in…
cell-cell adhesion and maintenance of the integrity of the cytoskeleton, help anchor organelles; ex. keratin and desmin
epithelial tissues for the….
parenchyma, the functional part of the organ, may be polarized, line its cavities
Types of epithelia (layers)
- simple epithelia (one layer)
- stratified epithelia (many layers)
- pseudo-stratified epithelia (appear to have multiple layers due to differences in cell heights, but actually have one layer)
Types of epithelia (by shape)
- cuboidal cells–> cube-shaped
- columnar cells–> long and narrow
- squamous cells–> flat and scale like
connective tissues
support the body and provide a framework for epithelial cells; form the stroma, or support structures, by secreting materials to form an extracellular matrix
bone, cartilage, tendons, ligaments, adipose tissues, and blood
prokaryotes
don’t contain membrane-bound organelles, contain their genetic material in a single, circular molecule of DNA located in the nucleoid region
ex. bacteria and archaea
shape of bacteria?
- cocci- spherical
- bacilli- rod-shaped
- spirilli- spiral-shaped
obligate aerobes
require oxygen for metabolism
obligate anaerobes
can’t survive in oxygen-containing environments and can only carry out anaerobic metabolism
facultative anaerobes
can survive in environments with or without oxygen and will toggle between metabolic processes based on environment
aerotolerant anaerobes
can’t use oxygen for metabolism, but can survive in an oxygen-containing environment
gram-positive bacteria
have a thick cell wall composed of peptidoglycan and lipoteichoic acid
turns purple with safranin/violet crystal stain
gram-negative bacteria
have a thin cell wall composed of peptidoglycan and an outer membrane containing phospholipids and lipopolysaccharides
turns pink-red with crystal violet stain
chemotaxis
moving in response to chemical stimuli, bacteria flagella contain a filament composed of flagellin, a basal body that anchors and rotates the flagellum, and a hook that connects the two
how do prokaryotes multiply?
binary fission
How can extrachromosomal material enter a prokaryote?
through plasmids, can contain antibiotic resistance genes or virulence factors
what are plasmids called that integrate with the genome?
episomes
4 ways bacteria go through genetic recombination?
transformation, conjugation, transduction, transposons
transformation
when genetic material from the surroundings is taken up by the cell, which can incorporate this material into its genome
conjugation
is the 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 Hfr cell to recipient
transduction
transfer of genetic material from one bacterium to another via a bacteriophage vector
transposons
genetic elements that can insert into or remove themselves from the genome
Bacterial growth pattern
- adapt to conditions–> lag phase
- exponential growth in –> exponential (log) phase
- growth levels off in the stationary phase
- resources are depleted, goes through death phase
What are bacteriophages?
viruses that target bacteria
viruses contain genetic material, a protein coat (capsid), sometimes a lipid-containing envelope
bacteriophages specifically have a tail sheath and tail fibers
Positive sense RNA viruses?
Can be translated by the host cell
Negative sense RNA viruses?
Requires a complementary strand to be synthesized by RNA replicase before translation
What are retroviruses?
Contain a single-stranded RNA genome, of which a complementary DNA strand is made using reverse transcriptase, the DNA can then be integrated into the genome
Lytic cycle?
The bacteriophage produces massive numbers of new virions until the cell lyses, bacteria in the lytic phase are termed virulent
Lysogenic cycle?
The virus integrates into the host genome as a pro-virus or prophage, which can then reproduce along with the cell, provirus can remain in the genome indefinitely, or may leave the genome in response to a stimulus and enter the lytic cycle
What are prions?
infectious proteins that trigger misfolding of other proteins, usually converting alpha-helical structure to beta-pleated sheet, decreases the solubility of the protein and increases its resistance to degradation
What are viroids?
plant pathogens that are small circles of complementary RNA that can turn off genes, resulting in metabolic and structural changes and potentially, cell death
