Class Discussion exam 3 Flashcards
What is the 5’ end of the strand called?
free phosphate group
What is the 3’ end of the strand called?
Hydroxyl group (attachment site)
Do eukaryotes have operons?
NO. just prokaryotes
What is the lac repressor?
The PROTEIN that sits down and blocks RNA polymerase
Regulatory elements
DNA
What is the promotor?
Region of DNA that proceeds the coding sequence
What is the TATA box?
Signal that says “hey there’s a coding sequence coming up”
What are the steps of the hierarchy of eukaryotic compaction? (smallest to largest)
1) DNA double helix
2) Nucleosomes (“beads on strings”)
3) 30-nm fiber
4) Radial loop domains
5) Heterochromatin
6) Metaphase chromosome
Why is prokaryotic gene regulation important?
Responds to changes in the environment
What does lactose permease do?
transports lactose into the cell
What does B-galactosidase do?
breaks down lactose (product = allolactose)
What happens when lactose levels drop?
Proteins are no longer made
_____ genes are unregulated and have essentially constant levels of expression.
Constructive
All the cells contain the same genome but express different ______ due to ________.
Proteomes, gene regulation
What are repressors?
Inhibit (restrain) transcription
(SHUTS IT DOWN)
- negative control
What do activators do?
Increase the rate of transcription
- positive control
What is an allosteric site?
If there’s a ligand binding, it’s going to initiate a conf. change or a shift in 3D structure
What is a small effector molecule?
changes the shape and changes whether or not it can bind to DNA
What is an operon?
a CLUSTER of genes under transcriptional control of one promotor
- ONLY in bacteria
When the operon controls genes that function in CATABOLISM:
- Regulation is usually _____
- Gene product acts as an ________
inducible, inducer (TURN ON)
When the operon controls genes that function in anabolism:
- Regulation is usually by _____
- Gene product acts as a ______
repression, inhibitor (TURN OFF)
What does the lac operon do?
in E. coli genes for lactose metabolism
What does the lacP (lac promotor) do?
lac promotor
- regulatory DNA sequence that resides in the beginning of genes
- “flashing red light” for RNA synthesis
What does the lacZ (beta-galactosidase) do?
Breaks down galactose and produce allolactose
What does the lacY (lactose permease) do?
transmembrane protein that allows lactose to enter cell
- encodes lactose permease
What does the lacA (galactosidase transacetylase) do?
encodes galactoside transacetylase
