Lecture7

Question 1

Mitochondrial DNA in mammals is…. in length. However, we see it as discrete foci, termed nucleoids, which have a diameter of around… nm. Hence, there must be factors that package mtDNA.

Answer 1

5 µm, 100nm

Question 2

Is there any histone protein in mt? explain!

Answer 2

There are packaging proteins
Abf2 (S. cerevisiae) and TFAM (mammals)
• Identified as DNA binding proteins
• Contain HMG-boxes (required for DNA binding)
How do you show that these proteins package DNA?

Question 3

Intensity along DNA strand divided by intensity of a single TFAM molecule
= 10 bp footprint
right?

Answer 3

No, Intensity along DNA strand divided by intensity of a single TFAM molecule
= 30 bp footprint

Question 4

~1000 molecules of TFAM cover a single copy of mtDNA

-> One TFAM molecule per…?

Answer 4

~16 bp

Question 5

is this true: All amino acids in mt only have one specific tRNA.

Answer 5

No, expect leucine and serine
Only two amino acids (Leu and Ser) have two tRNAs they can be linked to (Isoacceptors)
All other amino acids only have one specific tRNA they can be linked to

Question 6

What is the feature of D-Loop?

Answer 6

A triple stranded DNA region in the non-coding area
• Known for >45 years
• Function remains unknown
• Site of initiation of transcription and replication

Question 7

What are the requirement of transcription factors for mtDNA?

Answer 7

• Mitochondrial polymerase POLRMT (T7 like)
• TFAM
• Mitochondrial transcription factor B2

Question 8

If there will be no TFAM but the other two requirements for transcription, will we have transcription?

Answer 8

No, TFAM is required

Question 9

What does Terminates transcription of LSP transcript?

Answer 9

MTERF1