Unit 4 objectives

Question 1

o Draw and explain GPCRs, including how they function and what they do

Answer 1

Steps:
1. Ligand binds to receptor, conformational change
2. G alpha subunit replaces GDP with GTP
3. G alpha moves from G beta/gamma to effector, activating it.
4. Activated effector makes cAMP
5. GTPase hydrolyzes GTP, deactivating G alpha
6. G Alpha associates with G beta gamma, deactivating effector.
7. Receptor phosphorylated with G protein
8. Receptor bound to arrestin, deactivates receptor and marks it to be destroyed

Question 2

o Draw and explain RTKs, including how they function and what they do

Answer 2

translate the presence of extracellular messenger molecules into changes inside the cell by receptor dimerization followed by activation of the receptor’s protein-kinase domain. phosphorylate specific tyrosine residues of cytoplasmic substrate proteins, turning them on/off

Question 3

o How does signal transmission happen in cells?

Answer 3

Cells use extracellular messaging molecules, which signal to nearby cells. Autocrine cells make molecules for themselves to respond to. Paracrine molecules travel short distances. Endocrine molecules travel through the bloodstream

Question 4

o What is the purpose of adenylate cyclase? What second messenger is made and why is
it significant?

Answer 4

Signal amplifier, cAMP. Interacts with the proteins adenylate cyclase tries to amplify and regulates their activity

Question 5

o What is the purpose of phospholipase C? What second messenger is made and why is it
significant?
* Link the previous material into signal transduction/mitosis.

Answer 5

Receptor and secretor- cAMP, regulates activity of phospholipase C. (ADD MORE DETAIL)

Question 6

o Apoptosis signaling? Extrinsic vs. intrinsic?

Answer 6

Programmed cell death. Extrinsic- tumor necrosis factor sends external signal
Intrinsic-Bax/Bak are released into cell, destroying it

Question 7

o Explain how piwi-RNAs differ from other RNAs

Answer 7

Move transposons

Question 8

o How does the proteasome fit into controlling the cell cycle?

Answer 8

Degrades proteins that control cell divisions

Question 9

o How does chromosome condensation happen?

Answer 9

Interphase chromatin turns into thread like structures as DNA wraps around histones. Condensins come in and promote supercoiling. H3 histone marks for condensation.

Question 10

▪ Draw out/Explain the structure of condensin, including their
functionalities

Answer 10

Condensin pulls DNA into loops, causing positive supercoiling and condensing it. Structure with smc4/2, 2 dimers wrapped around each other

Question 11

▪ Describe and explain the difference between glucagon and insulin pathways

Answer 11

Both + regulated. Insulin acts theough receptor protein tyrosine kinase. Ligand binding pocket for both receptors is different. **

Question 12

▪ Explain the Ras-MAP kinase cascade. What is the purpose of GEFs?

Answer 12

Controls cell proliferation and differentiation. Growth factor binds to EC domain of RTK. End path turns on GEF, which activates small GTPases

Question 13

• Explain the difference between first and second messengers in signaling pathways.

Answer 13

A substance that is formed in the cell as the result of the binding of a first messenger—a hormone or other ligand—to a receptor at the outer surface of the cell

Question 14

▪ Draw out/Explain the structure of cohesin, including their
functionalities

Answer 14

Hold sister chromatids together through G2. Cleavage causes separation of sister chromatids and starts anaphase. SMC 1/3 holdsit together, 2 dimers wrapped around each other

Question 15

S phase

Answer 15

DNA replication and chromosome duplication

Question 16

G1

Answer 16

Normal metabolism, organelle duplication

Question 17

G2

Answer 17

Cell grows and prepares for mitosis

Question 18

Prophase

Answer 18

the duplicated chromosomes are prepared for segregation and the mitotic machinery is assembled.

Question 19

Metaphase

Answer 19

chromosomes have become aligned at the spindle equator, with one chromatid of each chromosome connected to one pole and its sister chromatid connected to the opposite pole

Question 20

Anaphase

Answer 20

sister chromatids separate from one another

Question 21

Prometaphase

Answer 21

mitotic spindle is formed and the chromosomes are moved into position at the center of the cell

Question 22

Telophase

Answer 22

daughter cells return to the interphase condition: the mitotic spindle disassembles, the nuclear envelope reforms, and the chromosomes become more and more dispersed until they disappear from view under the microscope

Question 23

Cytokinesis

Answer 23

physical division of the cell into two daughter cells occurs

Question 24

o RB –

Answer 24

regulates cell cycle, G1 to S checkpoint

Question 24

o p53 –

Answer 24

transcription factor, can halt cell cycle and initiate apoptosis. Involved with many other proteins

Question 25

* Explain and describe the two main categories of genes that are commonly mutated in cancers: o Proto-oncogenes

Answer 25

Genes that could become cancerous- involve normal cell processes

Question 26

o Tumor-suppressor genes

Answer 26

Genes that regulate cell growth and division

Question 27

* Describe or draw the nuclear pore complex

Answer 27

Donut shaped structure with nucleoporins that allow stuff in and out. Central scaffold allows stuff in, FG domain in channel. Nuclear ring and basket allow stuff in nucloplasm

Question 28

o What determines which RNAs and proteins can move through the NPC?

Answer 28

Whether or not they have a nuclear localization sequence

Question 29

o What determines the directionality of movement?

Answer 29

Whether importins or exportins interact with them