BIOL 200 Lecture Notes - Lecture 3: Heterochromatin Protein 1, Chromodomain, Histone Code

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champagnemallard105

29 Nov 2017

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Lecture 3: chromatin dynamics and the histone code: chromatin dynamics. Nucleosome: middle part of histones interacts with other histones and forming the structure. For each histone there is a histone n- and c- terminal tail that sticks out. Amino-acids of that tail capable to interact with dna or proteins, very flexible. After a protein has been synthesized, there are enzyme that can modify amino acids of side chains (change chemical properties). Some amino acid side chains in histone tails are covalently modified post-translationally. Methylation of lysine or arginine amino group has 3 hydroxyl ions that can be replaced (mono, di- or trimethylation) Other modifications: small peptide (ubiquitin) can be added. Modifications can affect the charge on the histone and its electrostatic interactions with dna. Example: acetylation of lysine neutralizes its positive charge and reduces the interaction of histone with dna (cid:271)e(cid:272)o(cid:373)es the less (cid:862)(cid:271)eads o(cid:374) a st(cid:396)i(cid:374)g(cid:863) conformation conducive for transcription and replication.

Related Questions

QUESTION 3

What is the purpose of chromatin-remodeling enzymes in human cells?

The enzymes control the rate of translation of an mRNA transcript

The enzymes add phosphate or methyl groups to histone tails

The enzymes slide nucleosomes farther apart or closer to each other

The enzymes send damaged proteins to the proteasome for degradation

The enzymes cause DNA looping to occur

QUESTION 10

If you can drink milk as an adult, it means that you have inherited a mutation in the an enhancer for your lactase gene (the gene that encodes the enzyme you need to break down lactose). Predict the effect of this mutation:

The mutation changes the number of domains in the enzyme, which makes it work more efficiently

The mutation changes the amino acid sequence of the lactase protein

The mutation increases the number of copies of the lactase gene that will be found in your genome

The mutation changes whether the lactase sequence is found in an intron or exon

The mutation affects the expression of the lactase gene

QUESTION 12

What determines where in the genome a transcription regulator will bind?

Transcription regulators bind to the 5' UTR region of a gene

Regulators bind via complementary base-pairing to certain DNA molecules

Covalent bonds form between the transcription regulator and the atoms of the DNA backbone

Every eukaryotic gene has a different transcription regulator that will bind to the 5' end of the gene

Transcription regulators bind to specific DNA sequences via multiple weak non-covalent interactions

QUESTION 15

What is the histone code used for?

		Phosphorylation and acetylation of DNA affect its ability to be compacted
		Changes to the sequence of DNA change whether DNA will wrap around histone proteins
		Covalent modifications of histones affect the ability of the transcription initiation complex to form
		Histones provide the codon sequences needed for translation to occur
		The histone code affects which amino acids will get added to a polypeptide

BIOL 200 Lecture Notes - Lecture 3: Heterochromatin Protein 1, Chromodomain, Histone Code

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