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Eukaryotic cellular biology 1 > Cell signaling > Flashcards

Cell signaling Flashcards

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1
Q

What sorts of activities can signalling trigger a cell to do?

A

Metabolism, protein production, physiological functions, survival, division, apoptosis, growth

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2
Q

What is signal transduction?

A

The process by which an extracellular signal is turned into an intracellular response

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3
Q

What is the general series of steps?

A
  1. A signal binds to a receptor
  2. The pathway gets activated and the effector proteins get activated
  3. Cellular response
  4. Deactivation of all the components of the pathway
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4
Q

What are 5 characteristics of signaling pathways?

A
  1. Has a programmed series of steps
  2. One signal can trigger many different responses depending on the cell type, what receptors are present, and the pathways in the cell
  3. Amplification occurs, each step can activate many copies of the next one
  4. signals and pathways integrate and converge
  5. Fast on and fast off process
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5
Q

What is signal integration?

A

Cross talk between pathways. One signal can activate many pathways, two separate receptors can activate a pathway, messengers within a pathway can affect another pathway

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6
Q

What are the 4 common components of pathways?

A
  1. A ligand interacting with a receptor
  2. GTP binding proteins (G proteins)
  3. Kinases and phosphatases
  4. Secondary messenger molecules
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7
Q

What is a ligand?

A

The signalling molecule that binds to a receptor to change its shape and turn on the pathway

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8
Q

How is ligand binding reversible?

A

Weak, non-covalent interactions hold the ligand to the receptor

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9
Q

What changes a G protein between its off conformation and its on conformation?

A

If it is binding to GTP, it’s on. If its binding to GDP, it’s off

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10
Q

What proteins switch a G protein between its on and off conformation?

A

GEF: guanine exchange factor removes the GDP and replaces it with a GTP
GAP: GTPase accelerating protein speeds up GTP hydrolysis

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11
Q

How do G proteins automatically turn themselves off?

A

They have an intrinsic GTPase activity and will eventually break down the GTP to GDP and turn off the protein

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12
Q

What is the difference between monomeric and heteromeric G proteins?

A

Monomeric is one protein chain and is used in other activities besides signalling. Heteromeric is made of 3 different protein chains in alpha, beta, and gamma subunits that are only involved in signalling

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13
Q

What are kinases?

A

Enzymes that phosphorylate stuff

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14
Q

What are phosphatases?

A

Enzymes that dephosphorylate stuff

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15
Q

What are intracellular secondary messengers? How are they different from all other common components of pathways?

A

Amplified molecules that bring messages and activate other stuff. They are created every time the pathway is turned on, which is different from everything else that is already expressed when the pathway is turned on

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16
Q

What are long term responses to cellular signalling? How does the cell respond to these signals?

A

They don’t occur very frequently, and take longer to do (such as cell division). Long term responses are related to gene expression

17
Q

What are the 3 components of the Ras/MAPK pathway?

A
  1. formation of a receptor complex
  2. activation of kinases
  3. activation and movement of transcription factors
18
Q

What is the structure of tyrosine kinase receptors?

A

A single transmembrane domain, with a ligand binding domain on the extracellular side and a tyrosine kinase domain on the intracellular side

19
Q

What happens first in the Ras/MAPK pathway?

A

EGF binds to EGFR

20
Q

What happens after EGF binds in the Ras/MAPK pathway?

A

EGFR dimerizes with another EGFR and they cross phosphorylate each other

21
Q

What happens after EGFR is cross phosphorylated in the Ras/MAPK pathway?

A

It recruits GRB2 and it binds to EGFR with the SH2 domain

22
Q

What happens after GRB2 binds to EGFR in the Ras/MAPK pathway?

A

GRB2 recruits Sos

23
Q

What kind of protein is Sos?

A

GEF

24
Q

What happens after Sos is recruited in the Ras/MAPK pathway?

A

Sos exchanges the GDP on Ras, which is now right beside it, for a GTP and activates Ras

25
Q

What happens after Ras is activated in the Ras/MAPK pathway?

A

Ras dissociates from Sos and activates a kinase cascade, beginning with MAPKKK (Raf)

26
Q

What happens after MAPKKK/Raf is activated in the Ras/MAPK pathway?

A

It phosphorylates MAPKK/MEK and activates it

27
Q

What happens after MAPKK/MEK is activated in the Ras/MAPK pathway?

A

It phosphorylates MAPK/Erk and activates it

28
Q

What happens after MAPK/Erk is activated in the Ras/MAPK pathway?

A

It translocates to the nucleus and activates transcription factors that turn on genes for DNA replication enzymes

Eukaryotic cellular biology 1 (14 decks)

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