Day5, Lecture 1: Biology of Cells: Cell Signaling

Question 1

Forms of Cell Signaling

Answer 1

Question 2

Example of intracrine signaling

Answer 2

DNA damage or reactive oxygen species inside the cell that lead to cell death

Question 3

What is a Ligand

Answer 3

It is the signaling molecule

Question 4

Examples of juxtacrine signaling

Answer 4

• Notch pathway
• Gap junctions
  
  • Direct connection between cytoplasm of two cells (electrical/chemical integration)
  • opening is regulated
  • Passable for molecules up to about 1,000 Dalton
  • Occurrence: everywhere, but especialy: heart muscle (signal to contract)
• Synaptic cleft

Question 5

Gap Junctions

Answer 5

• Form of juxtacrine signaling
• Direct connection between cytoplasm of two cells (electrical/chemical integration)
• opening is regulated
• Passable for molecules up to about 1,000 Dalton
• Occurrence: everywhere, but especialy: heart muscle (signal to contract)

Question 6

Auto-, para-, and endocrine signaling

Answer 6

Question 7

Signaling pathways modulate

Answer 7

everything, including growth, differentiation, mobility, immune responses.

Question 8

Signaling molecules

Answer 8

Range from small to large

Question 9

Most Signaling molecules are

Answer 9

• hydrophilic and thus require a extra-cellular receptor
  
  • in most cases binding of the hydrophilic ligand to the extra-cellular receptor leads to a conformational change and a signaling cascade in the cell

Question 10

Nuclear hormones

Answer 10

Question 11

Ligand concentrations are typically very small and thus

Answer 11

Receptor affinity is very large

Question 12

All nuclear hormone receptors must have what two domains

Answer 12

• DNA binding domain (DBD)
• Ligand binding domain (LDB)

Question 13

Estrogen Insensitivity Syndrome

Answer 13

Question 14

Two type of nuclear hormone receptors

Answer 14

Question 15

Agonists and Antagonists

Answer 15

Question 16

G Protein-coupled Receptors (GPCRs)

Answer 16

Question 17

Activation of G proteins

Answer 17

Question 18

The cAMP signaling pathway

Answer 18

Question 19

Question 20

cAMP-dependent processes

Answer 20

Question 21

Question 22

Second Messengers

Answer 22

Question 23

PIP₂ Pathway

Answer 23

• PIP₂ is a lipid and is membrane associated IP₃ hydrophilic and moves into the cytoplasm and moves to the ER to trigger the release of calcium

Question 24

PIP₂ dependent processes

Answer 24

Question 25

Answer 25

Question 26

Enzyme-linked Cell Surface receptors

Answer 26

Question 27

Receptor Tyrosine Kinases

Question 28

Receptor Tyrosine Kinase Activation

Answer 28

• Without a ligand bound the receptor is a monomer and can’t autophosphorylate
• Once a ligand is bound it leads to the dimerization of two receptors and thus the transphosphorylation of the tyrosines
• the phosphorylated tyrosines are recognized by other proteins that leads to cascades such as the ras pathway

Question 29

Receptor Tyrosine Kinase complex responses

Answer 29

Question 30

Why is Ras a protooncoprotein

Answer 30

because it is needed in development and it is not an oncogenic protein until something goes wrong

Question 31

Question 32

Why are GAP proteins functions

Answer 32

As their name states they are GTPase-activating proteins that will activate the GTP and lead to it cleaving the phosphate off the GTP and converting itself back to the inactive form of GDP bound GTPase

Question 33

Question 34

PIP₃: Phosphatidylinositol- (3,4,5)-triphosphate

Answer 34

Question 35

Question 36

Signaling pathways that regulate Proteolysis

Answer 36

• Notch pathway
• Wnt pathway

Question 37

Question 38

Question 39

Question 40

Question 41

Question 42

Question 43

What is Wnt

Answer 43

• a morphogen (glycoprotein)
• 19 members in humans

Question 44

Question 45

Question 46

Wnt Pathway

Answer 46

Question 47

Question 48