Chap 4+5 - Eukaryotic chromosomes Flashcards
Basic genetic mechanisms: DNA, chromosomes, genomes, DNA replication, repair and recombination
What is meant by the histone code?
Transcription of genetic info encoded in DNA is regulated by modifications to histone proteins.
Remodeling complexes can change the conformation of the histones
What is the role of histone H1?
Linker DNA
Makes eukaryotic chromosomes able to bind more tightly
Gives zig zag structure to chromosomes
What is the reader/writer complex?
A protein complex consisting of a writer enzyme and reader proteins that modifies nucleosomes by working in tandem. Over a number of cycles this complex can spread its modification along the chromosome until it is stopped by a barrier protein.
How is DNA associated with the histone core?
The negative charged backbone of the DNA is bound covalently with the positive charged lysine and arginine in the histone core.
How is transcription affected by DNA being packed in chromatin?
The condensation of DNA into chromatin makes it more difficult for transcription factors and other proteins to bind to the DNA in order to initiate transcription. Therefore it inhibits transcription.
How are chromosomes organized within the nucleus during the interphase?
Distributed loosely through the nucleus.
What is the difference between eu- and hetero-chromatin?
Heterochromatin: The DNA iismore tightly packed.
Euchromatin: more loose form like beads-on-a-string.