Lecture 17 study guide Flashcards
True or False: transcription factors can work by recruiting chromatin remodeling complexes and histone modifying enzymes?
true
What is the function of chromatin remodeling
increase access to transcriptional start sites
Define epigenetics
Changes in gene function without change in DNA sequence
Which of the following is true:
a. Epigenetic modifications propagate to daughter cells
b. Epigenetic modifications may not always propagate to offspring
Both are true
What are the two major mechanisms of epigenetic changes
DNA methylation
histone modification
Fill in the blanks: DNA methylation suppresse_____ gene expression by attracting transcription _____
- Suppresses, repressors
What enzyme is responsible for methylating cytosine?
methyltransferases
True or False: In humans, most histone modifications are erased in the gametes
true
- In higher eukaryotes, most of the genome encodes what special type of RNA?
Regulatory RNA
What is the function of miRNA?
Degrade mRNA or reduce their translational efficiency
What is the function of siRNA?
protect cells from foregin RNA
A certain miRNA has the following sequence: 5’ AUCAUCAUCCGUG 3’
a. If it encounters double stranded RNA with the following sequence what will happen? 3’ UAGUAGUAGGCAC 5’
b. What if it encounters dsRNA with this sequence? 3’ CGCGCUUAAGGCAC 5
KiFill in the blank: Gcn2 is a _____ that is activated by _____ tRNA and ______ the translation initiation factor eLF2.
Kinase
uncharged
phosphorylates
Phosphorylated eLF2 eventually blocks what major cell process?
translation
True or False: p53 is only degraded during the cell cycle stages.
false
What stops p53 degradation?
DNA damage detection
What is the main function of the p53/p21 pathway?
Arrest of DNA replication until the DNA damage can be repaired.
What happens if the cell takes too long to fix DNA damage in terms of p53 accumulation?
p53 accumulation works as a timer. If too much accumulates the cell undergoes apoptosis.
What are the three parts to cell signaling? (Think what is happening inside and outside of the cell)
a. Sensing of an extracellular signal
b. Transduction of that signal inside the cell
c. Resulting regulation of function
If a cytoskeletal protein is the target of a cell signal then what is the likely resulting regulation?
Altered cell shape or movement
Describe the phenomenon known as “community effect.”
positive feedback enhances and stabilizes signal and results in a “community effect”
What are the six types of cell communication? Give a brief description of each
a. 1. Contact dependent: Cell to cell contact. Actual contact between cells using a receptor and a ligand.
b. 2. Synaptic: close, directed release of a transmitter molecule from a neuron
c. 3. Paracrine: short distance release of a chemical messenger that is not necessarily directed to a specific cell.
d. 4. Endocrine: long distance release of a chemical messenger.
e. 5. Autocrine: self communication by releasing a chemical messenger that the cell itself takes up.
f. 6. Gap Junctions: sending chemical messengers from one cell to another via gap junctions.
Enzyme X requires activation by two different cell signals to be transduced before it activates. What is this an example of?
Signal integration
What is the benefits of signaling scaffolds?
increase speed, efficiency and specificity of signal transduction
Name two methods of signal adaptation or desensitization.
Cell surface receptors and Intracellular receptors.
What are the two types of receptors?
cell surface receptors
intracellular receptors
Which of the following are a possible signal for an intracellular nuclear receptor?
a. Insulin (large, polar)
b. Testosterone (A non-polar steroid)
c. Acetylcholine (smaller, polar)
- B- testosterone
What are the three amino acids that can be phosphorylated?
Ser
Thr
Try
Define second messenger
small molecules or ions that relay the signal from the plasma membrane to every part of the cytosol and nucleus
What are the three types of cell surface receptor families important for this class?
G protein coupled receptors, Receptor Tyrosine Kinases, Notch Receptors
