nuclear hormone receptors; signaling, cell death, and cancer

Question 1

How do hormones get to their target tissue?

Answer 1

• endocrine system and the blood stream
• they are transported by serum binding proteins

Question 2

how do hormones get through the plasma membrane

Answer 2

• they diffuse through the membrane

Question 3

where can nuclear hormone receptors be found in a cell?

Answer 3

• they are found in the nucleus but also in the cytoplasm

Question 4

How do nuclear receptors that are bound to a ligand cause an effect on the cell?

Answer 4

• they form a dimer and change conformation when ligand (hormone) binds
• bind to hormone response elements in the DNA
• attracts coactivator or corepressor to help increase or decrease the rate of mRNA formation of that specific gene

Question 5

what are the three domains present in a nuclear hormone receptor?

Answer 5

1. hormone binding site
2. transcriptional activation domain
3. DNA binding domain

Question 6

what family of proteins are the final effectors leading to apoptosis? what posttranslational modification changes them from inactive to active?

Answer 6

• capsases
• after translation, they need to be activated by proteases

Question 7

what are 2 possible reasons a cell might undergo apoptosis

Answer 7

1. irreparable DNA
2. embryonic development

Question 8

what are 2 characteristics of apoptosis that you can look for experimentally

Answer 8

1. blebbing
2. annexin V assay - phosphatidylserine flips to outer membrane, which allows annexin to bind, which is a sign of apoptosis

Question 9

why is apoptosis preferable to necrotic cell death

Answer 9

• its more controlled - healthy parts reused in nearby cells
• allows the organism to eliminate a cell that is unneeded or potentially dangerous without wasting it’s components

Question 10

what is an oncogene

Answer 10

• encodes a mutant version of a protein with altered function or expression that helps turn a normal cell into a tumor cell
• genetically dominant

Question 11

what is a tumor repressor gene

Answer 11

• encode proteins that normally control cell division
• 1 good chromosomal copy is sufficient (must be double mutation to lose functionality)

Question 12

what is a stability gene

Answer 12

• encode proteins involved in DNA repair
• 1 good chromosomal copy is sufficient (must be double mutation to lose functionality)