Eukaryotic Cells Flashcards
organelle
small structure within a cell that carries out a specific cellular function
nucleus
distinguishes eukaryotic cells from prokaryotic cells, contains genome surrounded by nuclear envelope
centromeres
located near middle of chromosome to ensure proper sorting of newly replicated chromosomes during cell division
heterochromatin vs euchromatin
densely packed inaccessible genes vs loosely packed activated genes
nucleolus
functions as a ribosome factory
nuclear envelope
surrounds the nucleus and separates It from the cytoplasm
ER lumen
interior of endoplasmic reticulum, shares space between inner and outer nuclear membrane
nuclear localization sequence
allows large proteins to pass through nuclear pores
mitochondria
site of oxidative phosphorylation, possess their own genome
endosymbiotic theory
theory that mitochondria originated as independent unicellular organisms living within larger cells
maternal inheritance
mitochondria are inherited only from the mother, since the cytoplasm of the egg becomes the cytoplasm of the zygote
rough vs smooth ER
rough - site of protein synthesis for proteins targeted to enter secretory pathway, proteins synthesized here end up secreted into extracellular environment, as integral plasma membrane proteins, or in the membrane or interior of the ER
smooth - contains enzymes involved in steroid hormone synthesis or in the degradation of environmental toxins, involved in glycogen breakdown in liver
signal sequence
present on some proteins, recognized by signal recognition particle, which binds to ribosome, determines whether protein will be translated on rough ER.
Integral membrane proteins
have sections of hydrophobic amino acid residues called transmembrane domains that pass through lipid bilayer membranes
targeting signals and localizations signals
targeting- needed if a protein going through secretory path to plasma membrane needs to go elsewhere
localization - for proteins that are made in cytoplasm but need to be sent to an organelle that is not part of the secretory path
Golgi apparatus functions
- modification of proteins made in rough ER
- sorting and sending proteins to their correct destinations
- also synthesizes certain macromolecules such as polysaccharides to be secreted
vesicles from ER fuse with cis part and exit the trans face in transport vesicles
constitutive vs regulated secretory pathway
proteins sent immediately from Golgi to cell surface vs proteins released at specific times in secretory vesicles
lysosome
responsible for degradation of biological macromolecules by hydrolysis, also degrade large particulate matter engulfed by cell by phagocytosis
peroxisomes
small organelles that perform a variety of metabolic tasks, metabolize lipids and toxins using H2O2
what are membranes of the cell composed of
lipid bilayer membranes, this is how phospholipids arrange themselves spontaneously, have hydrophilic head and hydrophobic tails
cell surface receptors
bind extracellular signaling molecules such as hormones
channel proteins
allow ions or molecules to cross the membrane
integral vs peripheral membrane proteins
embedded in membrane vs stuck to integral membrane proteins
fluid mosaic model
membrane is sen as a mosaic of lipids and proteins that are free to move back and forth fluidly but aren’t free to flip flop
passive vs active transport
doesn’t require cellular energy vs requiring cellular energy
molarity
concentration of solution in terms of moles of solute per volume
molality
expresses concentration in terms of moles of solute per mass of solvent
strong vs weak electrolytes
solutes that dissociate completely vs those that remain ion paired to some extent
van’t Hoff factor (i)
tells us how many ions one unit of a substance will produce in a solution
vapor pressure
pressure exerted by gaseous phase of a liquid that evaporated from the exposed surface of the liquid
easily vaporizable liquids are volatile
boiling point elevation formula
solvents boiling point elevation constant * i * molal concentration of solution
freezing point depression formula
-1 * solvent’s freezing point depression constant * i * molal concentration of solute
diffusion vs osmosis
diffusion - tendency for liquids and gases to fully occupy the available volume
osmosis - special type of diffusion in which solvent diffuses instead of solute, occurs when membrane is impermeable to solute, water goes from region of low solute concentration to region of higher solute concentration
hypertonic vs hypotonic
hypertonic - has more total dissolved solutes than cell
hypotonic - has less
simple vs facilitated diffusion
simple - diffusion of a solute through a membrane without help from a protein
facilitated - movement of a solute across a membrane when the membrane is impermeable to that solute
volage gated vs ligand gated ion channels
voltage gated channels are opened in response to a change in the electrical potential across the membrane and ligand gated channels open in response to binding of a specific molecule like a neurotransmitter
membrane pores
tube through membrane which is so large that it isn’t selective for any particular molecule
active transport
movement of molecules through plasma membrane against gradient, can be coupled to ATP hydrolysis (primary) or not coupled directly to ATP hydrolysis (secondary)
Na+/K+ ATPase
transmembrane protein in plasma membrane of all cells in the body, pumps 3 Na+ out of the cell and 2K+ into the cell
maintains osmotic balance between cellular interior and exterior
establishes resting membrane potential,
provides sodium concentration gradient used to drive secondary activity transport
resting membrane potential
net negative charge on interior of cell
three types of endocytosis
phagocytosis - cell eating
pinocytosis - nonspecific uptake of small molecules and extraceullar fluid
receptor mediated endocytosis - very specific, site of endocytosis is marked by pits coated with clathrin molecule and with receptors that bind to a specific molecule outside the cell
receptors
form an important class of integral membrane proteins that transmit signals form the extracellular space into the cytoplasm, binds lignand
signal transduction
response within cell triggered when a ligand binds to its receptor on the extracellular surface of the plasma membrane
G protein linked receptor
transmits signal into cell with second messenger, which is cyclic AMP, can be stimulatory or inhibitory
catalytic receptors
have an enzymatic active site on the cytoplasmic side of the membrane
cytoskeleton
provides structural support supplied by cell well in bacteria, plants, and fungi, composed of microtubules, intermediate filaments, and microfilaments
cilia
small hairs on cell surface that move fluids past cell surface
microtubules
hollow rod composed of alpha and beta tubular, contains microtubule organizing center, which is essential for mitosis
microfilaments
rods formed in cytoplasm from polymerization of globular protein actin, dynamic and responsible for gross movements of entire cell
intermediate filaments
provide strong cell structure
what are the cell junctions that link cells together
tight junctions, desmosomes, gap junctions
four phases of mitosis
prophase, Metaphase, anaphase, telophase
oncogenes
mutated genes that induce cancer, protoncogenes can become this
tumor suppressor genes
produce proteins that are then inherent defense system to prevent conversion of cells into cancer cells
caspases
required for carrying out apoptosis
van’t Hoff equation
osmotic pressure = MiRT
M= molarity of solution I = van't hoff factor R = universal gas constant (0.0821 L atm/K mol) T = temp in Kelvins
