The Cell Flashcards
3 tenets of cell theory
- all living things are composed of cells
- the cell is the basic functional unit of life
- cells arise only from preexisting cells
nuclear pores
in the nuclear membrane
allow for selective two-way exchange of material into and out of the nucleus
where is rRNA synthesized?
nucleolus
extranuclear inheritance
transmission of genetic material independent of the nucleus
eg mitochondria - contain some of their own genes and replicate independently of the nucleus via binary fission
apopotosis
programmed cell death
mitochondria can kill the cell by release of enzymes from the electron transport chain
mitochondria
powerhouse of the cell
lysosomes
membrane-bound structures containing hydrolytic enzymes that are capable of breaking down many different substrates, including substances ingested by endocytosis and cellular waste products
rough vs. smooth ER
rough endoplasmic reticulum contains ribosomes for protein synthesis
smooth ER is for lipid synthesis and transport of proteins from rough ER to Golgi apparatus
Golgi apparatus
consists of stacked membrane-bound sacs
materials from the ER are transported to Golgi in vesicles
cellular products undergo modification
contents are released via exocytosis
peroxisomes
primary function: breakdown of fatty acid chains via beta-oxidation
microfilamnets
made up of solid polymerized rods of actin
organized into bundles and networks
resistant to compression and fracture (provide protection for the cell)
microtubules
hollow polymers of tubulin proteins
radiate throughout the cell
cilia and flagella
cilia primarily for movement along surface of the cell, whereas flagella primarily for movement of cell itself like sperm
9+2 structure = nine pairs of microtubules forming an outer ring with two microtubules in the center
intermediate filaments
diverse group of filamentous proteins
include keratin, desmin, vimentin, lamins
involved in cell-cell adhesion or maintenance of the overall integrity of the cytoskeleton
able to withstand a tremendous amount of tension, making the cell rigid
epithelial tissues
cover the body and line its cavities, providing a means for protection against pathogen invasion and desiccation
tightly joined to layer of connective tissue called basement membrane
simple/stratified/pseudostratified and squamous/cuboidal/columnar
parenchyma
functional parts of an organ
made up of epithelial cells
prokaryotic envelope
cell wall forms outer barrier (peptidoglycan)
plasma membrane forms inner layer
Gram positive vs. Gram negative bacteria
Gram stain applied to cell walls
gram positive - lipoteichoic acid in cell wall along with peptidoglycan, very thick
gram negative - additional outer membrane containing lipopolysaccharides and phospholipids, very thin
episomes
subset of plasmids capable of integrating into the genome of the bacterium
transformation
integration of foreign genetic material into the host genome
most frequently comes from neighboring bacteria upon lysing
conjugation
unidirectional transfer of genetic material from donor male (+) to recipient female (-)
conjugation bridge forms from sex pili on the donor male
requires sex factors such as F (fertility) factor
Hfr
high frequency of recombination
bacterium with sex factor (conjugative) plasmid integrated into its genome
transudction
requires a vector
viruses carry genetic material from one bacterium to another
phases of bacterial growth
lag phase - bacteria adapt to new environmental conditions
exponential phase - growth increases as bacteria adapt (aka log phase)
stationary phase - reduction of resources slows reproduction
death phase - after bacteria have exceeded environment’s ability to support them
bacteriophages
viruses that specifically target bacteria
inject genetic material into bacterial cell without actually entering it
composed of capsid (protein coat), genetic material, tail sheath, and tail fibers
single-stranded RNA viruses
positive sense RNA viruses: genome may be directly translated to functional proteins by ribosomes of the host cell, just like mRNA
negative sense RNA viruses: require synthesis of an RNA stand complementary to negative sense strand, which can then be used as a template for protein synthesis
retroviruses
enveloped, single-stranded RNA viruses
carry reverse transcriptase enzyme which can synthesize DNA from single-stranded RNA
DNA then integrates into host cell genome
eg HIV
lytic cycle
bacteriophage makes maximal use of the cell’s machinery with little regard for host cell survival
host swells with new virion –> host cell lyses –> other bacteria can be infected
lysogenic cycle
virus integrates into host genome as provirus/prophage and will be replicated as the bacterium reproduces
will typically revert to the lytic cycle at some point
prions
cause infections by triggering misfolding of other proteins
usually convert protein from alpha helix to B sheet structure
drastically reduces solubility of the protein and cell’s ability to degrade it
eg mad cow disease, Creutzfeldt-Jakob disease, familial fatal insomnia
viroids
short circular single-stranded RNA that infects plants
silences genes in the plant genome
