Chapter 3 Flashcards
What are transcription factors?
Proteins that regulate gene expression
What are secreted signaling molecules?
Usually proteins involved in cell-cell communication via signal transduction cascades
What are cell surface receptor proteins?
Proteins on a cell’s surface that receive signals and propagate them intracellularly.
What are the components of the central dogma of biology?
Transcription from DNA, processing of mRNA (splicing out of introns), transport out of the nucleus, translation of the mRNA into protein, protein folding and modification, protein fucntion.
What is the basic structure of a nucleosome?
An octomer formed by two groups of four histones: H2A, H2B, H3, H4 with DNA wrapped around them. They are linked to other nucleosomes by H1 and linker DNA.
What is the difference between condensed and uncondensed nucleosomes and what does this mean for transcription?
Condensed: H3, H4 methylated, transcription will not occur
Uncondensed: H2, H3, H4 acetylated, transcription can occur
Epigenetic regulation.
How are histones acetylated?
through HATs and HDs.
What is the role of HP1?
Silent heterochromatin: Binds to trimethylated H3 tail, represses transcription
What is an enhancer?
A noncoding DNA sequence that binds transcription factors and activates transcription of a specific gene in cis.
How is expression of a developmental gene in different tissues controlled?
Often by separate discrete enhancers specific to that tissue.
What are the two important DNA methyltransferases?
Dnmt3 (de novo methyltransferase): Places a methyl group on unmethylated cytosines
Dnmt1 (perpetuating methyltransferase): recognizes methylated Cs on one strand, methylates C on CG pair of opposite strand.
This works because many promoters are CG rich and contrain CpG islands.
How can multiple proteins be produced from a single gene?
Alternative RNA splicing.
