Lecture 19

Question 1

Protein coding genes

Answer 1

Different types. Compared to E.Coli, only small proportion of genome is dedicated to protein coding. Most proteins have 1 genetic cope. Gene families can arise from duplication of a single gene. Different cells have different proteomes which is function dependent.

Question 2

Introns and exons

Answer 2

Exons spliced together and that codes for proteins. Introns are removed.

Question 3

Repetitive sequence

Answer 3

Found in telomeres and centromeres. Include variable no. tandem repeats. Good for forensic and paternity tests.

Question 4

Chromatin

Answer 4

DNA/histone complex. DNA can be tightly packed (heterochromatin) or less tightly packed (euchromatin). Histones have 8 subunits and when DNA is wrapped, nucleosome forms.

Question 5

Packaging DNA

Answer 5

Not sequence-specific interaction and they are not fixed. DNA can wind and unwind. Histone tails have lots of arginine and lysine (positive at physiological pH) which electrostatically interacts with P backbone therefore, sequence independent. Positive shields from - charge allowing DNA to get closer together and repackage. Restricts transcription. They can be modified by removing + charge impacting packaging.

Question 6

Acetylation

Answer 6

Histone acetyltransferases (HATs) acetylates lysine, removing + charge. DNA wound less tightly making it more accessible to transcription factors. Histone deacetylates (HDACs) reverses this.

Question 7

Induced pluripotent SC

Answer 7

Induced pluripotent SC show differences in histone modifications and gene expression to differentiate cells.

Question 7

Methylation

Answer 7

Histone methyltransferase (HMTs) methylates lysine or arginine. Some proteins can bind to methylated residues. Some can be associated with activation or repression. Histone demethylates removes methyl when signal is not needed.