Molecular Basis of Inheritance

Question 1

What do nucleic acids consist of?

Answer 1

Deoxyribose with H at 2’ position
phosphate
nitrogenous bases

Question 2

What are the 5 nitrogenous bases?

Answer 2

Thymine, adenine, guanine, cytosine and uracil

Question 3

The sugars in DNA and RNA?

Answer 3

DNA = Deoxyribose
RNA = RIbose

Question 4

Where do nucleotides attach?

Answer 4

3’ to 5’ phosphodiester bond formed by DNA polymerase
To the 3’ OH groups of the other nucleotides
5’ end is phosphate (charged) and 3 end is hydroxyl (charged) making the bond polar

Question 5

Features of DNA?

Answer 5

Has two strands held together by A-T and C-G
The coiled strands are antiparallel
base pairs are stabilised by hydrogen bonds

Question 6

What does the prokaryotic genome contain?

Answer 6

A promotor region, a coding sequence and a transcription terminator

Question 7

Pre-mRNA to mRNA?

Answer 7

Eukaryotes have exons and introns. Pre-mRNA is spliced to form mRNA. this removes introns

Question 8

X-inactivation?

Answer 8

X inactivation centre contains the Xist gene. transcribed to long, non-coding RNA leading to heterochromatin formation which spreads from the inactivation centre.
X inactivation happens in embryogenesis where an X is chosen at random and all cells from that initial cell will exhibit inactivation of the same chromosome

Question 9

Synthesis of miRNA?

Answer 9

Transcription from miRNA gene gives precursor miRNA
Exported into the cytoplasm and processed by nuclease
This leaves a single strand of RNA that base pairs with coding mRNA

Question 10

The mitochondrial genome?

Answer 10

Contains circular genome, highly compact, no introns and no repetitive DNA
it is matrilineal