Glossary of Cell Bio 2

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_______ form the spindle, bind chromosomes, and move them to daughter cells during mitosis.
Microtubules (MTs)
How do MTs generate bending movements in cilia?
using dynein molecules
Assembly and organization of microfilaments are controlled by _____________.
microfilament (actin or MT) associated proteins
What are lysosomes?
acidic; hydroytic enzymes degrade
What process can be exploited by viruses and bacteria to enter a cell?
Microtubules radiate from the cell center with their ___ ends projecting outward.
______________ are sphingomyelins with hydrophilic sugar groups on extracellular surface.
How would you get multiple pass loops in a membrane protein?
more start-stop signals (Beta adrenergic receptor has 7)
Name 3 components of the plasma membrane.
1) hydrophobic lipid bilayer
2) integral & peripheral proteins
3) carbohydrates (oligosaccharides) only on outside
_________ filaments are structural and non-motile.
Improperly folded proteins are returned to __________ for degradation in __________.
cytoplasm, proteosomes
Name 2 types of aerobic metabolism that mitochondria does.
1) TCA cycle
2) OxPhos
What mediates separation of receptor and ligand in endosomal compartments?
lowered pH
What are lipid rafts?
Cholesterol and sphingomyelin. Less fluid. Protein aggregate sites.
Which type of chromatin is inactive?
dark heterochromatin
_________ seal apical borders b/t epithelial cells. Do they have associated filaments?
tight junctions
Can phospholipids flip-flop?
Name 2 types of glycolipids and their distinguishing features.
1) cerebrosides - small uncharged sugar groups
2) gangliosides - large negatively charged sialic acid groups
What are endosomes?
Vesicles from cell surface that internalize extracellar material
The extracellular, but not intracellular, domains of most integral proteins are _____________.
Which type of chromatin is active?
light euchromatin
Mitochondria may have evolved from ______ ______ ________. (3 words)
ancient symbiotic bacteria
Most proteins are made in the _____ on ________.
cytoplasm on free ribosomes
What is the process by which a vesicle is formed at one cell surface and re-released at another surface?
Actin subunits and filaments are in ____________________: filaments continually form, breakdown, and reorganize.
Actin filament organized into __________ or _________.
meshworks or bundles
________ hold nucleus in position.
IMFs (just structural)
mediate direct cell-cell communication by allowing exchange of small molecules
gap junctions
How does mitochondria get energy?
Proton Motive Force (PMF)
IMFs are relatively stable in organization, but do break down and reform during ________.
What kind of tail does sphingomyelin have?
ceramide tails
What are rigid, hollow, polarized tubules providing structural support and movement?
What are 2 diseases associated with peroxisomes?
1) ALD - cannot oxidize long-chain fatty acids. (lethal).
2) Zellweger - peroxisomes empty. (lethal).
Where is protein packaging done?
Phospholipids are ___________, meaning they contain both hydrophobic and hydrophilic moities.
actin subunits add at the _____ end and get removed at _____ end. This treadmilling means they're in ______________.
add at +, remove at -
What are the pathways of vesicles?
What do mitochondria do in the liver?
Beta oxidation of fatty acids
Organization and behavior of microfilaments are controlled by _______________.
actin-associated proteins.
Can cholesterol flip flop? Why/why not?
yes, adds membrane fluidity
What's the IMF in nerve axons?
Can integral proteins flip flop?
no, they're stuck in the membrane, duh.
Oligosaccharides only appear on the __________ surface of the plasma membrane.
What attaches cell to matrix?
Name 3 filamentous structures of the cytoskeleton.
1) actin filaments
2) microtubules
3) intermediate filaments
In non-polarized cell, MTs anchored by their ____ ends at the _______.
anchored by - ends at MTOC.
Adhesion belt: 3 things
T/F: actin filaments are inserted into the membrane.
FALSE. Integrins connect actin filaments to matrix at focal contact
What's the IMF in epithelial cells?
How do MTs support uni-directional vesicle movement?
using motor proteins kinesin and dynein
Gangliosides are a type of ________________ that have ________________.
negatively charged sialic acid groups
desmosome: 3 things
Cell migration: __________ extends edge, ____________ retracts tail.
actin extends, actin and myosin retract tail
99.99% of mitDNA comes from ________?
the mother
What's an autophagosome?
When part of the ER wraps around an organelle and degrades it.
What's the word for mitDNA variation?
What are contractile bundles?
stress fibers at apex of epithelial cells, also constricts during cytokinesis
The polar head group of glycerophospholipids is either ________ or ____________, which is a _______.
INOSITOL, which is a SUGAR.
What attaches cell to cell?
How are proteins inserted into membrane of ER?
co-translationally inserted from ribosomes into ER membrane
What are proteosomes?
degrade ubiquinated proteins w/ protease activity in central cavity.
Plasma membrane gets its structure by _____________ and ______________.
phospholipids and cholesterol
What do perioxisomes do?
beta oxidation of fatty acids
Extends the leading edge and retracts the tail of crawling cells.
Where does N-linked glycosylation occur? How?
ER - high mannose oligosaccharides are attached to asparagine residues on peptides containing appropriate aa sequence
MTs have ________ subunits that grow and shrink at __________ ends.
Name 3 basic functions of the plasma membrane.
1) transport of material in/out of cell
2) anchoring internal cytoskeleton, cell to extracellular matrix, cell to cell
3) receptors relay signals into the cell from external environment
What's the IMF in nuclear envelope?
nuclear lamins
Where is ribosomal RNA synthesized?
___________ junctions inhibit cell division;
____________ junctions promote cell division.
cell-cell junctions inhibit division;
cell-matrix junctions promote cell division.
IMFs are anchored to plasma membrane at ____________.
Explain the OxPhos hypothesis.
b/c mitDNA has no introns, everything codes. It's particularly susceptible to ROS damage.
Mutations accumulate more with age.
Mitochondria segregate randomly to daughter cells, so the mtDNA genotype can fluctuate. So you have mutant and normal mtDNA = HETEROPLASMY.
Form contractile ring that separates mitotic daughter cells.
MFs (microfilaments)
What's ONLY on the outside (extracellular side) of plasma membrane? 2 things...

Tell what property this gives the membrane:
1) oligosaccharides
2) cross-linked sulfhydryl groups (S-S)

_____________ underlie and strengthen plasma membrane.
MF (microfilament) MESHWORKS
Name 5 metabolic activities of the cytoplasm.
1) glycolysis - anaerobic break down of glucose into 2 ATP
2) fatty acid synthesis - long chains for lipids
3) protein synthesis - mRNA, tRNA, ribosomes
4) proteolysis - protein degradation
5) maintain reducing env't - via glutathione
hemidesmosome: 3 things
cell-basal lamina
What provides motive force for bending of cilia and flagella?
dyneins and MTs
Name the 2 types of phospholipids.
1) glycerophospholipids (most) [KINK]
2) sphingomyelin [CERAMIDE TAILS]
Which phospholipid group adds to membrane fluidity and why?
glycerophospholipids b/c cis-double bond kink
Microfilament assembly is ___________ and under the influence of _____________.
actin-associated proteins
What's the IMF in muscle cells?
How are microtubules anchored in cell?
by their minus (-) ends in an organizing center (MTOC)
What forms a gap junction?
2 connexons
Microvilli have __________, cilia have _________.
actin, MTs
What happens with accumulated mitDNA mutations?
reduced ATP production
focal adhesion: 3 things
actin filaments
How do mitochondria produce ATP? (2 ways) What else do they do in liver?
1) Krebs cycle
2) OxPhos
break down fatty acids
Name 3 peripheral membrane proteins and their functions.
1) cytoskeletal - anchored to inner surface
2) signal transduction complexes - relay signals to interior
3) extracellular matrix - (laminin, collagen, fibronectin) anchor cells to surroundings
Name 5 IMFs and where they're found.
1) KERATIN- epithelial
2) VIMENTIN- mesenchymal (connective tissue)
3) DESMIN- muscle
4) NEUROFILAMENTS- nerve axons
5) NUCLEAR LAMINS- nuclear envelope
What are start transfer sequences?
ER: bound by signal receptor protein (SRP), which stops translation until ribosome binds to SRP receptor on ER. Now translation is unblocked and peptide can go in ER.
Hydrolytic enzymes destined for degradation in lysosomes are tagged with ________ that is recognized by receptors in _____________.
mannose 6 phosphate (M6P)
trans Golgi
High _________ component of oligosaccharide is transported to Golgi, removed in ____ Golgi, then __________ is added in _____ Golgi.
-chg. sialic acid
Proteins destined for the mitochondria are targeted by _______________.
amino-terminal sequence
Name 6 functions of cytoskeleton filaments
1) maintain cell shape
2) support projections (cilia & microvilli)
3) position organelles
4) mvmt of organelles
5) contract microfilament bundles
6) cell migration
What is at the polar head of sphingomyelin?
Which protein is most abundant in cells?
______________ separates daughter cells after mitosis by "purse string" contraction of ____________.
MFs (microfilaments)
kinesin moves along MTs toward _____ ends.
dynein moves toward _____ ends.
Kinesin toward +
Dynein toward -
Name 2 types of secretory vesicles.
transport from Golgi to cell surface
1) regulated
2) constitutive (always on)
Where is location of translational material for mRNA?
nucleus in spaces b/t chromosomal domains
____________________ anchored to plasma membrane stabilize cell shape.
Contractile bundles (stress fibers) of microfilaments
Name 2 ER cisternae and their functions.
1) rough - docking ribosomes,
secretory protein synthesis
2) smooth - membrane lipid synthesis,
drug detox,
Ca2+ storage,
glycogen synthesis
Cerebrosides are under the category of ____________, and cerebrosides have _______________.
uncharged sugar residues
Name 4 adhesions junctions. Tell what they do.
1) adhesion belt: cell-cell, cadherin, actin.
2) desmosome: cell-cell, cadherin, IMF.
3) hemidesmosome: cell-basal lamina, integrin, IMF.
4) focal adhesion: cell-matrix, integrins, actin.
How does N-linked glycosylation occur?
co-translationally via transfer from dolichol carrier
Proteins made in cytoplasm that lack a targeting signal go where?
remain in the cytoplasm
The presence of ___________ in nascent peptides determines that they will be integral proteins in ER membrane, not lumen.
stop-transfer sequences
What's the IMF in mesenchymal cells (connective tissue)?
How is mitochondrial DNA different from other DNA?
no introns. it all codes.
Where are ATP synthase particles bound?
inner membrane of mitochondria
Which adds more membrane fluidity to the membrane, glycerophospholipids or sphingomyelin, and why?
glycerophospholipid b/c cis-double bond kink
Can receptors be recycled?
yes - to cell surface except growth factor receptors
Where does Golgi get proteins from? What does it do with them?
POLARIZED cis-trans processing, sorting, packaging, export.
Which tissues are particularly susceptible to OxPhos damage?
muscle and nerve
The nuclear envelope is continuous with _____.
The inner membrane of mitochondria folds to form __________.
What is transcytosis? Give example.
Uptake at one cell surface, release at another.
maternal to placental; liver; skin
Glycerophosphoipids have __________ tails with ______.
fatty acid tails with cis-double bond kink
Can phospholipids laterally diffuse?
The cytoplasm is a _________ environment. Therefore we only find __________________ on the cytoplasmic domains. But ___________ are an important structural determinant of extracellular domains.
free sulfhydryl groups,
interchain disulfide bonds
Why does 99.99% of mitDNA come from one parent? Which one?
mother b/c sperm contributes no cytoplasm
What defines the cytoplasmic compartment?
plasma membrane
How are the lipids in the plasma membrane organized?
hydrophobic bilayer
Which chaperones bind to protein destined for mitochondria?
Hsp70 - keep it unfolded so it can pass thru membrane
What keeps nascent, unfolded proteins from being hydrolyzed?
chaperones like Hsp70 (sm) and Hsp60 (lg)
Where do you find glycolipids? Why? Name the 2 types while you're at it...
on extracellular surface b/c sugar residues
1) cerebrosides (uncharged)
2) gangliosides (- chg. sialic acid)
What modulates membrane fluidity more than anything else?
Where does the TCA cycle happen?
matrix of mitochondria
What is N-linked glycosylation and where does it take place?
mannose-rich sugar is assembled onto a membrane lipid in the lumen of the ER and transferred to ASN.
What is O-linked glycosylation and where does it take place?
oligosaccharides attach to serine and threonine residues only in Golgi.
What happens to N-linked glycosylated stuff in the Golgi?
processed by removing mannose and adding - chg. sialic acid
From Golgi, stuff either goes to ____________ or _____________.
cell surface (secretory vesicles)
lysosomes (to get degraded)
How do lysosomes work?
Hydrolytic enzymes are recognized in the cis-Golgi, and their N-linked oligosaccharides from ER are phosphorylated to produce mannose-6-phosphate. The M6P receptor in the trans-Golgi recognizes it. Both the receptor and ligand are packaged and sent to a late endosome/multivesicular body forming an endolysosome. The low pH causes the receptor to be released and recycled. The pH slowly drops until pH 4.5 forming a lysosome that degrades its contents.
What is Tay-Sachs disease?
Absence of a lysosomal B-hexosaminidase leads to indigestible ganglioside in neurons leading to juvenile death
How do proteosomes work?
Proteins are tagged with ubiquitin and are recognized by barrel-shaped proteasomes (related to HSP 60) for degradation. The broken down protein fragments are imported to the ER and are attached to major histocompatibility (MHC) proteins on the ER membrane. These complexes routinely go from the ER to the Golgi and then to the cell surface. Foreign fragments are recognized by the immune system.
What is pinocytosis?
The formation of small vesicles from indentations from the cell
surface. The pits may be coated with CLATHRIN that helps to
round the pit and pinch it off.
Mitochondrial genes code only for proteins in what important metabolic process?
glucose metabolism (making ATP)
also does aerobic metabolism (TCA and OxPhos)
After an activated G-alpha subunit of a trimeric complex binds and activates its target, what's the effect of the target protein on the G-alpha subunit?
make cAMP, hydrolyze GTP-->GDP, dissociates and rebinds beta/gamma, thus inactivating enzyme.
2 pathways in cytoplasm activated by receptor tyrosine kinases:
1) ras (thru intermediate proteins)
2) kinase cascade
What does Cdk1/cyclin B do to promote onset of mitosis?
1) phosphoryl nuclear lamins and nuclear envelope breakdown
2) phosphoryl condensin to condense chromosomes
3) reorganize MTs for spindle formation
What is the role of cyclinE/cdk2 at G1 to S transition?
phosphorylate Rb and CDK4/6-cyclin D. Internal feedback. activate DNA synthesis.
*What is heteroplasmy in mitochondria?
co-existance of normal and mutant mtDNA in a cell
*Proteins that cannot fold properly are degraded within what structure?
*How are lysosomal hydrolases targeted for sorting to endosomes/lysosomes in the Golgi?
Hydrolytic enzymes are recognized in the cis-Golgi, and their N-linked oligosaccharides from ER are phosphorylated to produce mannose-6-phosphate. The M6P receptor in the trans-Golgi recognizes it. Both the receptor and ligand are packaged and sent to a late endosome/multivesicular body forming an endolysosome. The low pH causes the receptor to be released and recycled. The pH slowly drops until pH 4.5 forming a lysosome that degrades its contents
*Identify 2 different pathways that can be activated by G-protein linked stimulation.
1) increase cAMP
2) increase Calcium
*How does phosphoryl of Rb promote onset of DNA synthesis?
activated CDK4/6-cyclin D hyper-phosphorylates Rb. Rb releases E2F, which triggers last step of DNA synthesis
*What are the 4 types of signal receptors that ligands bind?
1) contact-dependent
2) paracrine
3) synaptic
4) endocrine
*What's enzyme-linked?
(receptor tyrosine kinase)
turned on when ligand dimerizes receptors (autoPO4). binds PLCgamma, cleaves PIP2 into IP3 & DAG. RTKs bind adaptor proteins (GEFs) that activate ras. Ras activates kinase cascade, nuclear transcription factors, gene expression. opposed by phosphotases
*What's G-protein linked?
(adenyl cyclase)
cAMP activates PKA, more glucose.

G-protein activates PLCbeta, cleaves PIP2 into IP3 & DAG. IP3 releases Ca+ from ER. Ca+ activates calmodulin. Calmodulin breaks down glycogen. DAG activates PKC (ser/thr kinase).
Cytokine receptor pathways
can overlap w/ RTK pthways through ras. Both activate nuclear transcription factors
Integrin pathway
cell-matrix jcn permissive for cell growth. activates ras and signals to nucleus
Cadherin receptors - permissive for cell division or not?
NOT b/c cell-cell jcns. Beta catenin links filaments to cell-cell jcns, but can also enter nucleus to promote cell division. APC inhibits cell division by keeping B-catenin out of the nucleus.
What's the "go to lysosome" signal?
What's the "go to proteasome" signal?
What's the "ER is the place to be" signal?
start-transfer sequence
recognized by SRP (signal recognition particle)
Where can you get disulfide bonds inside the cell? I thought the cytoplasm was a reducing environment?
it is. don't freak out. the lumen of the ER is not, however, so you can get disulfide bonds there.
What is a model G-protein-linked receptor? What does it do?
Beta-adrenergic. elevates glucose.
activated receptors -->
activate G-alpha -->
adenylate cyclase -->
cAMP -->
PKA -->
What does the phosphorylating?
What are they opposed by?
protein kinase
Another G-linked pathway...what if ligand activates trimeric G protein?
cleave PIP2 into IP3 (Ca+) & DAG-->
kinase cascade -->
transcription factors in nucleus
What are the 2 ways we can increase glucose in the cell?
increase cAMP or Ca+
Why are cell-cell jcns inhibitory for cell division?
beta catenin links cadherin receptors at cell-cell junctions; however, it can also enter the nucleus and promote cell division. APC inhibits cell division b/c it ties up B-catenin and keeps it out of the nucleus.
How do cell-matrix jcns promote cell division?
integrin binds focal adhesions or hemidesmosomes, activating ras, the kinase cascade, and transcription factors in the nucleus
Go thru the RTK pathway.
growth factor/ligand binds-->
activated RTKs dimerize, autophosphory-->
activate either PLC-gamma or ras (thru adaptor proteins) -->
kinase cascade --> nucleus.
*if PLC-gamma, cleaves PIP2 into IP3 (Ca+) & DAG (PKC, kinase cascade...)
What's the word for different # of chromosomes in a cell?
How can you look for appearance/quantity of DNA in stages of cell cycle?
thymidine labeling and time (b/c they only take up thy during S phase)
also, could do cell sorter flourescence
What happens if you fuse a mitotic cell with an S cell?
induce mitosis b/c there's a MPF (mitosis promoting factor)
What's the MPF?
mitosis promoting factor
has 2 proteins:
CDK1 (induces mitosis)
cyclin B (activates CDK1)

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