Gene Products Flashcards
What does the production of translatable mRNA from specific genes require?
- accessibility of gene to transcription factors (TFs)
- interactions with TFs with cis-regulatory elements
- initiation, elongation, and termination of RNA transcript
- processing (capping and splicing) of newly transcribed RNA
- transport of processed mRNA to cytoplasm
What are transcription factors?
proteins that can interact with regulatory elements of genes
What are trans-regulatory factors?
transcription factors, mostly DNA-binding proteins encoded by other genes
What are activators and what do they do?
DNA-binding proteins produced by other genes in the cell; activate transcription, leading to the gene body being described into a precursor RNA which will be translated
What is chromatin?
complex of chromosomes with protein inside cells
1/3 each of DNA, histones, and other types of protein
What are histones?
They form nucleosomes around which DNA is wound.
How many histones are there in each nucleosome?
8 units; 2x of four types; surrounded by an additional histone layer (but not part of the nucleosome itself)
What is euchromatin?
open chromatin that is more accessible to RNA polymerase and transcription factors, more likely to be transcriptionally active
What is heterochromatin?
closed chromatin that is tightly packed with nucleosomes, less accessible, and less likely to be transcriptionally active; often gene-poor and repeat-rich, dark staining and localized to periphery of nucleus
What determines chromatin state?
histone modification
What kind of post-translational modification can occur to histone tails?
acetylation, methylation, phosphorylation, and ubiquitination
How does acetylation happen?
via histone acetyl transferase (HAT); promotes transcription
What does histone deacetylase (HDAC) do?
represses transcription
What happens to acetylation of lysine?
Takes charged group and makes it uncharged.
Electrostatic interaction between negative DNA and positive histone lysines promotes transcription; reducing the positivity of the histone represses the transcription
What is methylation?
accomplished by protein arginine methyltransferase (PRMT) that adds methyl groups
