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84 Cards in this Set

  • Front
  • Back
2 major compartments of cell
function of compartmentalization wi the cell
makes metabolisms possible by the exchange of small molecules and their use in different functions
where are proteins made?
in the cytosol
purpose of receptors
allows specific recognition of proteins and other molecules to target cell. The hi degree of specificity of protein transport is crucial to the survival of thecell and the organism
what is wi the nucleus?
nuclear env
nuclear pores
nuclear lamina
site of DNA/RNA syntheisis
site of protein synthisis and int. metabolism
ribosome bound to membrane surface for synthesis of integral protins and soluble proteins destined for secretion
golgi apparatus
modifies and transports lipids and proteins received from ER
generates ATP used to drive cellualar rxns
has enzymes to degrade endocytosed macromolecules and particles
has enzymes used in oxidative rxns
major membrane bound organelles in animal cell
signal peptide
aa sequence that direct the delivery of protein out of cytosol. If protein does NOT have signal peptide then it will remain in the cytosol

the signal peptides are recognized by receptors on specific organelles
mechanism to move proteins between compartments
gated transport
transmembrane transport
vesicular transport
gated transport
used to get proteins out of cytoplasm through pores in membrane

used to get NA out of nucleus through nuclear pores

(only between cytosol and nucleus)
transmembrane transport
gets proteins from cytosol directly across membranes into mitochondria,ER, peroxisome. (membrane bound organelle)
vesicular transport
transports vesicles proteins from one compartment to another

transports from Golgi, vescilces get pinched off and move along microtubles to their target organelles where they fuse w/the surface
describe protein synthesis
mRNA made from DNA in nucleus

mRNA goes into cytoplasm

ribosomes travel along mRNA and protein extends using tRNA to carry new AA to extend the AA

when stop codon reached complex disacciates and protein is released
clusters of ribosomes on mRNA

appear in cell involved in lots of proteins synthesis
site of RNA transcription and RNA splicing
describe nucleur envelope
2 membranes continuous w/the ER

inner and outer membrane sperated by perinuclear space

where the 2 membrane fuse they form nuclear pores
chromosomes and histone proteins
what are chromosomes composed of?

when are chromosomes highly dispersed in the cell?
made of DNA

highly dispersed during interphase(nondividing stage)
small conserved proteins complexed w/DNA

positively charged proteins that bind to negatively charged DNA in the nucleus
2 types of chromatin
highly condensed chromatin

darkly stained

DNA is inactive bc wound tightly around histone
less condensed chromatin

stains lighter

active chromatin bc open

contains gens that are transcribed into RNA

allows things to pass and merge w/nuclear pores
difference between nuclear env inner and outer nuclear mem
inner n. membrane has proteins that bind to nuclear lamina

outer membrane have ribosomes bound
describe the breakdown of the nuclear env during cell divison and the reassembly
nuclear lamins are phosphorylated and fragment into smaller groups for cell divison

after chromosomes move apart, the lamins are dephosphorylated and reaggregate forming envelopes around each chromosome

these envelopes fuse so that all the chromosomes are in a common env. to make a nucleus
dark staining region where ribosome synthesis occcurs by rRNA assembly

contains large loops of DNA that encode rRNA genes
in what cells is nucleolus prominent
motor neurons
how are ribosomes made?
proteins in cytosol get in nucleolus through pores and assemble with rRNA and form subunits which leave through pores

the subunits aggregate outside in cytosol to form ribosomes
nuclear pores
perforation in n.env
nuclear pore complex
comprised of proteins that form channel through which small mol. can pass

passage of large proteins requires specific receptor proteins located in the pore complex. they are actively transported across the n. env. and require nuclear localization signal to pass through n.pores
how to proteins get through n. pores into the nucleus?
n. import receptors bind to the prospective n. proteins. the complex binds and the pore opens and the n.protein and receptor get actively transported into the nucleus. the receptor is then exported back into the cytolplasm to be reused
how does mitochondria change shape and move around cytoplasm?
by associating w/microtubules
purpose of matrix granules in mitochondrial matrix
sequester calcium
2 compartment of mitochondria
matrix space- contains enzymes that metabolize pyruvate and fa to acetyl CoA and citric acid cycle enzymes that oxidize acetyl CoA

intermembrane space chemically equivalent to cytosol
differing proteins in outer and inner mitochondrial membranes
outer membrane contains transport proteins that are permeable to small molecules

inner membrane is highly covoluted foming infoldings called cristae
inner is impermeable to
inner contains respiratory
chain enz(ETC)
summary of mitochondrial energy metabolism
pyruvate and fa enter the mitochondrion and are broken down to acetyl Co A and then metabolized by citric acid cycle.

in the process of ox phos hi nrg e- from NADH are passed to O2 by respiratory chain in inner membrane making ATP by chemiosmotic mech.
mitochondrial DNA
encodes for 37 genes
all mitochondrial DNA is from maternal side

damage by free radicals contribute to aging

mutations cause serious illness

oxidative rxn can cause mutations in the DNA which can damage the cell
what encodes mitochondrial proteins?
mitochondrial proteins ae encoded by nuclear DNA and are transported into mitochondria by transmembrane transport using molecular chaperones to guide the proteins through channels and then refold them into their active configuration
membrane bound organelle that carries out oxidative rxn using molecular O2.
enzymes in peroxisomes
catalase and urate oxidase used to detox cmpds
peroxisome core
crystalloid core compose of urate oxidase (usually not in human)
purpose of Oxidase and Catlase in peroxisomes
oxidase uses molecular oxygen to remove hydrogen from organic substrates in oxidative rxn that produces hydrogen peroxide

Catalase uses the hydrogen peroxide generated to oxidize other substrates
what organs is the prescence of peroxisomes very important?
liver and kidney bc they are involved in detoxing poision cmpds.
Zellweger syndrome
autosomal recessive disease associated w/ absence of peroxisomes

fatal by age 6mos
Rough ER
site of production of transmembrane proteins and lipids

membrane has ribosomes attached (rough)
Where are all proteins destined for secretion synthesized?
on rough ER
integration of proteins into rough ER membrane
1.mRNA binds to ribosomes in cytosol then translation starts
2.proteins w/signal peptide sequence bind to signal recognition particle (SRP) which causes a pause in translation
3.the ribosome is directed to ER by SRP
4.The ribosome binds to ER and translation continues
5.Newly synthesized transmembrane proteins are translocated across ER membrane but are not released into lumen. Soluble protiens (which are destined to be secreted from cell or go to lysomes) pass into ER lumen. Proteins made in ER are sent to Golgi apparatus for post translation modificaion and to be directed to final destination
smooth ER
series of interconnected tubules

prominent in steroidogenic cell and hepatocytes

can sequester Ca which is used in cell signaling pathway
what organelle is most abundant in cell that secretes steroid?
smooth ER
what structure/layer is present in thick skin and not in thin skin?
stratum lucidum
vesicular transport
transport vessicles bud off from one compartment and fuse with another

both intramembranous proteins and soluble proteins are transported from RER to golgi this way
how are proteins transported from RER to golgi?
by vesicular transport
receives and modifies newly synthesized lipids and proteins from RER by vesicular transport

distrubutes proteins to other cellular compartments
describe transport of proteins from RER to golgi
proteins destined for secretory vessicles, plasma membrane, or lysomsomes enter the Golgi at the cis face and move through the Golge then exit at trans golgi.
what mediates transfer of proteins from RER to golgi and between golgi compartments?
transport vessicles
membrane bound vesicles containing hydrolytic enzymes

controlled digestion of macromolecules

have acid hydrolases that require acidic env.
how does lumen of lysomsomes stay at acidic ph?
by proton pump in membrane
3 major pathways in cell that can lead to degradation of materials in lysosomes
endocytosis to form lysosomes
material is taken up into cell by endocytosis is delivered into intracellualr compartments called endosomes

endosomes fuse with transport vessicles from golgi containing acid hydrolases to form lysosome
degradation by phagocytosis
specialized cells like macrophages and neutrophils engulf particulates to form phagosomes

the phagomsome is converted into lysosome by fusion w/lysosome or late endosome
degradation by autophagy
disposal of obsolete organelles of cell. autophagy occurs by enclosure of organelle by membrane derived from the ER which creates an autophagosome

the autophagosome fuses w/a lysosome or late endosome
how to ID lysomsome
its hard so incubated tissue w/ phophatase and lead ions. the acid phosphatase in the lysomsome produces lead ppt which is e-dense
how are lysosomal proteins in golgi sorted?
1.M6P added to lysosomal hydrolases in cis golgi
2.M6P grps of lysosomal hydrolases bind to M6P receptors in trans golgi
3.Transport vesicles bud off trans golgi
4.transport vesicles fuse w/late endosome
5.dissociation of lysomal hydrolase and M6P receptor
6.M6P receptor is recycles back to trans golgi
lysomal storage diseases
genetic diseases which cause deficiency of one of the acid hydrolases cause accumulation of material in cell causing severe cellular malfunction or cell death.

ex:sphingolipid storage disease are associated w/defects in sphingolipid catabolism, the enzymes for this are in lysosomes.
Early Endosomes
just beneath plasma membrane

proton pums in membrane maintain pH 6

material is endocytosed from plasma mem and forms vesicle which is tranpsoted to early endosome. early endosome travels into cell to give its contents to late endosome
late endosome
close to golgi and nucleus

more acidic then early endsome bc it accumulates more vessicles to lower its pH

gets material from golgi and early endosome
what do golgi transport vessicles targeted to late endosmes contain?
either acid hydrolases or proton pumps

when golgi vesscicles fuse w/late endosome they become lysosome
material is enclosed by invagination of plasma mem
2 categories of endocytosis
1.pinocytosis-ingestion of fluid (continuous)

2.phagocytosis-ingestion of large particles (require rec must be activate)
receptor mediated endocytosis
macromolecules in ECF bind to cell surface receptors

Clathrin binds to cytosolic side of receptors

Clathrin coated vesicles contain receptor macromolecue complexes bud off membrane and enter the cytolsol as coated vessicles. the vessicles shed their coats and fuse w/early endosomes

contents of the vesicles travel trhough endosomal comparments by vesicular transport

specific receptor proteins on vicle membrane determine the selectivity of transport visicle docking to other cellular compartments
secretory pathway

vesicular transport of material from trans golgi to cell surface.
2 pathways that exocytosed material can take
constitutive secretory pathway

regulated secretory pathway
constiutive secretory pathwy
default pathway

vesicle directly targeted to cell surface

occurs in all cells

continuous secretion of soluble proteins in ECF
regulated secretory pathway
protein storage in secretory vesicles

present in cells specialized for secreting products in response to specific extracellualr signals

stored in apical part of cell

if become large, vesicles are called storage vesicles

hormonal/neuronal signal stimulates cell to release vesicle contents to EXF by exocytosis
cytoplasmic inclusions
secretory granules

pigment granules



secretory granules containing mucus
goblet cells lining ep tissue

secret mucus by exoctosis to keep surface of ep protected
pigment granules (melanosomes)
membrane bound
contain melanin
protect DNA from UV iradation
residual bodies in old cells: debris filled vacuoles in long lived cells (undegraded lysomal material)
non membranous granles of glucose polymer

often around skeletal m.