Embryology 101

Question 1

What are the purine and pyrimidine bases of DNA?

Answer 1

The purine are: A, G, and the pyrimidine are: C, T.

Question 2

What are the purine and pyrimidine bases of RNA?

Answer 2

The purine are: A, G, and the pyrimidine are: C, U.

Question 3

What is the transcription process?

Answer 3

It’s when the DNA is used as a guide to make a complementary base-pairing RNA.

Question 4

How does DNA turn into pre-mRNA?

Answer 4

The RNA polimerase separates the strands of DNA and follows the ribonucleoside triphosphate that indicate the correct strand for sequencing, the anti-sense strand (no gene strand = complementary to the one with the gene). From the start codon (AUG) to the end codon (UAA/UAG/UGA), the RNA polimerase makes a pre-mRNA strand copying the sequence of the sense strand by complimenting the bases of the anti-sense one.

Question 5

What is(are) the start codon(s)?

Answer 5

AUG

Question 6

What is(are) the end codon(s)?

Answer 6

UGA, UAA, UAG

Question 7

What is the splicing process?

Answer 7

A process that happens in transcription that takes off introns (extra codons), leaving the exons that are used to make the protein further on.

Question 8

What is the importance of introns?

Answer 8

They allow alternative splicing (one DNA can make multiple mRNA depending on the splicing), regulate gene expression, maximize silent mutations and other unknown functions.

Question 9

What is the translation process?

Answer 9

It’s when RNA is used as a “recipe” to make a protein.

Question 10

Define nucleosomes.

Answer 10

The chromatin basic structure, made with an octamer of histone proteins and more than 100 base DNA pairs.

Question 11

What is the DNA’s main composition?

Answer 11

The DNA is mainly composed of:
• Introns and exons
• Promoter region (binds RNA polimerase for transcription)
• Translation and transcription initiation sites
• Termination codon
• 3’ untranslated region (assists in mRNA stabilization, poly A addition site)