Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MCS > Cell Bio > Flashcards

Cell Bio Flashcards

1
Q

Define zonula occludens and its functions

A

Tight junctions
maintains polarity and forms a paracellular barrier
Proteins Occludens, and Claudins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Define zoluna adherens and its functions

A

Transmembrane cadherin proteins that connect cells extracellularly and also to actin filaments within each cell
Mechanical connection between cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Define macula adherens and its functions

A

intracellular plaque-like proteins that connect cells extracellularly via complementary cadherin proteins
associates with intermediate keratin filaments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Define gap junctions and its functions

A

connexons that create channels between two cells for rapid transfer of ions and small molecules, as well as electrical and metabolic coupling
Connects two cells cytoplasm’s

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is a connexon and what is it composed of?

A

a gap junction protein, composed of a concentration of connexin proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the function of a hemidesmosome?

A

Anchors a cell to the basal lamina

similar to desmosomes but attach to integrin proteins as opposed to keratin filaments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are some functions of the cytoskeleton?

A 
Cell and organelle movement
Phagocytosis and cytokinesis
Cell-cell and cell-matrix connection
Cellular strength and support
Changes in cell shape
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Describe intermediate filaments and their functions

A

ropelike fibers

provide structural support and cell attachment sites (Desmosomes)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Describe microfilaments and their function

A

double-stranded, helical actin structures

provide structure and is involved in cellular movement (microvilli mvmt, Actin and myosin motor protein movement)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Describe microtubules and their function

A

Hollow cylinders of tubulin proteins

Polymerization and depolymerization control movement of vesicles and organelles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Describe the makeup and function of cilia

A

Motile processes on cell surface in respiratory and reproductive epithelium
Comprised of microtubules in a 9+2 arrangement
Connects to an intracellular basal body also comprised of microtubules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Describe the composition and function of microvilli

A

Increases absorptive surface area

Actin core that connects to intracellular actin network

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What process leads to the breakdown of the nuclear envelope?

A

Phosphorylation of nuclear lamina

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the nuclear lamina?

A

Network of intermediate filaments adjacent to the inner membrane of the nucleus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Describe the process of large molecules passing through nuclear pores

A

prospective nuclear protein binds to a nuclear protein importer
this complex is guided to a nuclear pore via fibrils which extend from the outer membrane adjacent to the nuc. pore
active transport is required to bring the complex into the nucleus

requires a nuclear localization signal (7 AA’s)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Describe the process of detoxification by peroxisomes

A

Oxidase removes H atoms via O2 molecules to form hydrogen peroxide (H202)
Catalase uses the free radical H2O2 to oxidize other substances

  • Zellweger Syndrome: Unable to recognize the 3AA sequence on peroxisome enzymes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are the four cell fates?

A
  • Survival (senescence) : Multiple distinct signals are required for cell to survive
  • Division : Need survival signals but also signals that drive activation of cell cycle machinery and cell division (Most cancers disrupt these signals)
  • Differentiation :Survival signals + new signals involving coordination of cell cycle exit and expression of distinct genes responsible for diff Phenotype
  • Apoptosis: Self propagated suicide (Why we lose webbed fingers)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Stem Cells

A

Undifferentiated cell, immortal, can replicate and divide indefinitely. Divide and send one cell down the path of differentiation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Describe motor protein movement across microtubules. What proteins are involved and in what direction do they move?

A

Microtube has minus end (centromere) and plus end
Plus end can grow, minus end can shrink
Dynein moves to the plus end
Kinesin moves to the minus end

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Nucleolus

A

Site of rRNA synthesis, contains multiple loops of DNA coding rRNA genes.
Ribosomal subunits are made in the nucleus but come together in the cytosol

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Describe the structure of cilia/flagella

A

Axoneme - inner core of cilia/flagella
Microtubules and dynenin arrange in 9 pair + 2 formation
Stabilized by nexin and radial spokes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are the three modes of transport of a cytosolic protein?

A

Gated-transport - transported through a gated membrane protein (nuclear pore)
Transmembrane transport - cytosolic protein moves across membrane via a specific transmembrane protein
Vesicular transport

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Heat Shock Proteins

A

Chaperones.

Nuclear mitochondria proteins use heat shock proteins to be transport into Mitochondria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Three pathways from the Golgie

A
  • Exocytosis (default): to plasma membrane
  • Secretory granules: vesicles accumulate secretory product and await stimulus
  • Lysosomes: Vesicle fusion with late Endosomes
25
Q

Lysosome Maturation

A
  1. Early Endosome - Found close to the membrane
  2. Late Endosome - found closer to Golgi and is lower in pH than the early endosome due to proton pumps accumulated from Golgi
  3. Lysosome: Late endosome that fuses with vesicles from Golgi containing acid hydrolase
  4. Residual (Inclusion) bodies - product after digestion, containing undigested material
26
Q

Two pathways of Exocytosis

A

Constitutive secretion: (Default) Continuous secretion
Regulated secretion: Molecule’s stored in storage granules, use clathrin coated vesicle and are released after specific stimuli

27
Q
  • Which cell fate is most surprising from an evo perspective?
  • Which cell fate(s) is suppressed for terminal differentiation?
  • Which cell fate(s) are generally not applicable to stem cells?
  • What is fate of liver cells upon ingestion of amatoxin?- A child is born with webbed fingers, which cell fate was disrupted?
A
  1. Apoptosis
  2. Proliferation and Apoptosis
  3. Stem cells don’t senesce or differentiate
  4. Apoptosis
  5. Apoptosis
28
Q

What are some functions of the smooth ER?

A

Synthesis of steroids
Sequesters calclium
detoxifies toxic, insoluble compounds

29
Q

Rheb

A
  • GTPase switch (Rheb hydrolyzes GTP>GDP and becomes inactive)
  • Causes cell proliferation so needs to be regulated to prevent cancer
  • GAP: GTPase Activating Protein (Causes the hydrolyzation of GTP and shuts off Rheb)
  • GEF : Guanine Exchange factor Exchanges GDP>GTP turns on GTPase
30
Q
  • Signaling specificity is achieve mainly at the level of ?
  • What is the major process driving cell cycle differentiation?
  • Gene expression changes are most directly mediated by?
  • The GAPs regulate Rheb by?
  • Leukemias can result in excess but nonfunctional blood cells. Which cell fate is affected?
A
  1. Ligand binding
  2. Gene expression
  3. Specific transcription factors
  4. GAPs activate GTPases turning them off
  5. Differentiation (???)
31
Q

Cell Cycle Stages

A
  • G1: Longest period of cell cycle in which cell grows and evaluates external signals to decide what to do
  • G0: Cell exiting cell cycle to adopt a new fate
  • R site: where decision of cell fate is made
  • S phase: Synthesis phases, DNA replicated completely and accurately as possible
  • G2: DNA replication is evaluated and preparations for M phase are made
    M phase: Mitosis
32
Q

Cyclin Dependent Kinases (CDKs)

A

Drive cell cycle transitions
CDKs activated by binding to different cyclins that are only expressed at random times of the cell cycle
Required order of cycle progression achieved by ordered expression and activation of specific cyclin-CDK complex

33
Q

CDK Cascade

A

Highly regulated by positive and negative events

  • CDK binds to Cyclin becoming partially active
  • Cyc-CDK gets phosphorylated by CAK -> Activated

Inhibition
INK4 Inhibits CDK and Cyc-CDK
CIP inhibits Cyc-CDK, Cyc-CDK +CAK, And Cyc-CDK-P

CDKs regulate transcription by removing Rb off of transcription factors (Rb is transcription inhibitor)

34
Q

Growth Factor

A
  • activating cell proliferation pathways
  • activate Ras/Raf/ERK pathways
  • Ras activate Cyclin D and inactive CDK inhibitors driving progression through G1
  • Ras is QUINTESSENTIAL GTPase switch (can lead to unstable proliferation
  • Controlled by GAPs and GEFs
35
Q
  • What is order of cell cycle phases?
  • CDKs catalyze what reaction?
  • Cyclin levels are mainly controlled by?
  • Ras is?
  • HPV can cause cervical cancer by infecting epithelial cells. What epithelial cell fate is affected?
A
  1. M, G1 (G0), S, G2
  2. Phosphorylation
  3. Transcription + Degradation
  4. Enzyme
  5. cancer effects proliferation
36
Q

When and how is p53 activated and what downstream cell fates can occur?

A

DNA damage signals at restriction check point result in kinase mediators phosphorylating and activating p53
p53 initiates cell cycle rest for DNA repair/apoptosis

37
Q

Restriction point

A

Where cell fates are made

Activate G1 CDKs to continue cycle to become mitogen independent or inhibit G1 CDKs to exit and adopt an alternate fate

38
Q

G1 progression

A

Switch to mitogen independence- Generate D-K4 that phosphorylate and inactivates Rb releasing E2F which transcriptionally activates Cyclin E
Cyclin E has a positive feedback loop making more Cyclin E and thus inhibiting Rb more and more

39
Q
  • Where is R point located
  • The R point is involved in?
  • What is substrate of Cyclin D-CD4?
  • Cyclin E-CDK2 is part of a positive feedback loop controlling what activity?
  • 100 mil bacteria must be injested to cause cholera. The # is lower for ppl taking antacids. What bacterial cell fate is being enhanced by antacids?
A
  1. After G1
  2. Fate decisions
  3. Rb
  4. Rb
  5. Survival
40
Q

Three Checkpoints monitoring cell cycle progression

A
  1. M phase: Spindle Assembly Checkpoint: check for chromosome attachment to spindle
  2. R point: Restriction checkpoint: Cell size, nutrients, GFs, DNA damage
  3. G2: check for cell size and DNA replication
41
Q

Intracrine signalling

A

signal produced within targeted cell

42
Q

Juxtacrine signalling

A

Direct contact signalling (cell-cell contact, synapses, gap junctions)
eg. notch pathway

43
Q

Autocrine signalling

A

signal is excreted and targets same cell

e.g. Hormones, Growth Factors

44
Q

Paracrine signalling

A

short distances (adjacent cells)

45
Q

Endocrine signalling

A

large distances (blood stream/lymph)

46
Q

Contrast transport of hydrophobic and hydrophillic signal molecules

A

Hydrophobic - require carrier protein for transport to target cell
diffuse through cell membrane
Require intracellular receptor

Hydrophillic - require extracellular receptor and transport across membrane

47
Q

What are defining characteristics of nuclear hormones?

A

Activity is in nucleus
Hydrophobic, require transport proteins
Persistent in blood stream (hours/days)
eg.steroids, vitamin A

48
Q

Describe nuclear hormone regulation of protein synthesis

A

Nuclear hormone enters the cell and binds to heat shock protein
Nuclear hormone receptor binds ligand on its ligand-binding domain, releasing HSP
receptor enters nucleus and binds to DNA via its DNA-binding domain
Down or up-regulates transcription

49
Q

Agonist

A

Binds a receptor to elicit a response

can be a synthetic hormone or naturally occurring hormone

50
Q

cAMP signalling

A

G-protein coupled receptor activates adenylate cyclase, which converts ATP to cAMP
cAMP can activate protein kinase A which is involved in many cellular pathways
cAMP is eliminated by phophodiesterase
G proteins can also inhibit cAMP signalling

51
Q

Antagonist

A

Binds to receptor to prevent function

Mifepristone/Ru-486 antagonist of progesterone used for medical abortions

52
Q

Receptor tyrosine kinase (RTK)

A

Enzyme-linked cell surface receptor
Activated when ligand binds to extracellular domain, inducing dimerization of two RTK’s
dimerized RTK’s phosphorylatte intracellular tyrosine residues on each other’s intracellular domains

53
Q

Activation of G-Protein

A
  • Ligands binds to GPCR, G proteins takes up GTP (activated)
  • alpha subunit will diffuse laterally to activate effectors
  • Alpha converts GTP-> GDP stopping activity
    - GAPs also help regulate
    G proteins activate adenylate cyclase which makes secondary messenger -> cAMP

Overall: G protein stimulates Adenylate cyclase (can also inhibit) which converts ATP->cAMP

54
Q

PIP2 Pathway (Phosphatidylinositol-4,5-bisphosphate)

A

Activated by G-protein

  • GProtein activates phospholipase C by phosphorylation
  • Phospholipase C cleaves PIP2 making IP3 and DAG
  • DAG and the Ca2+ activate protein kinase C which can activate other pathways
55
Q

What are characteristics of enzyme-linked cell surface receptors?

A

Have an extracellular ligand-binding domain
Transmembrane component
Intracellular domain w/ enzymatic activity or association with an enzyme

56
Q

Ras Pathway

A

GTPase indirectly activated by receptor tyrosine kinase (RTK)
three types: H-, K-, and N-
Activated mitogen activated protein kinases (MAPKs)
Activated by GEF, inactivated by GAP

57
Q

P13 kinase

A

P13K is activated via phosphorylation by RTK or Ras
P13K phosphorylates PIP2 to PIP3 which induces a growth and survival signal
PTEN dephosphorylates PIP3 back to PIP2

58
Q

WNT Signaling

A
  • WNT is a morphogen (governs tissue development) that binds to surface receptor
  • Leads to inhibition of Adenomatous polyposis coli(APC) which is an inhibitor of beta-catenin)
  • WNT –| APC –| B Catenin (WNT allows B-catenin to proliferate)
  • Very common in Colon cancer, APC is mutated and cant phosphorylate B-catenin

MCS (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions