Transcription an Translation

Question 1

What is transcription

Answer 1

1. first stage of protein synthesis
2. the formation of pre-mRNA (in eukaryotes) and mRNA (in prokaryotes) from a section of the template strand of DNA

Question 2

What is the process of transcription?

Answer 2

1. it occurs in the nucleus
2. an enzyme breaks the hydrogen bonds between the complementary bases
3. the DNA ‘unzips’/uncoils which exposes only one the stand of DNA to be transcribed
4. free activated nucleotides aligns with the exposed bases (according to complementary base pairings)
5. they bind using temporary hydrogen bonds
6. the sugar-phosphate backbone of the mRNA/pre-mRNA is then formed between the RNA nucleotides (ATP required)
7. if it’s in a Eukaryote then splicing occurs to change the pre-mRNA to mRNA

Question 3

what is the DNA strand in transcription called?

Answer 3

the template stand or transcribed stand

Question 4

what bonds the free bases and exposed DNA bases together?

Answer 4

temporary hydrogen bonds

Question 5

what creates the sugar-phosphate backbone of the mRNA?

Answer 5

RNA polymerase

Question 6

what bond is formed between the pentose sugar and the phosphate molecules to make the backbone of the mRNA?

Answer 6

phosphodiester bonds

Question 7

what happens after mRNA is formed

Answer 7

1. the temporary hydrogen bonds break and it leaves the nucleus via the nuclear pores
2. it then attaches to a ribosome in the cytoplasm for translation

Question 8

what is the direction of transcription

Answer 8

5’ - 3’

Question 9

what is translation?

Answer 9

1. The second phase of protein synthesis that takes place in the ribosomes
2. a process where mRNA and tRNA are used to form a chain of amino acids

Question 10

what is the process of translation?

Answer 10

1. mRNA attaches to the ribosome
2. tRNA then brings specific amino acid to the ribosome
3. ribosome allows complementary anticodon of tRNA and codon of mRNA to bind (2 at a time as it can only fit two tRNAs)
4. the amino acids on the 2 tRNAs bind through condensation using ATP
5. they form peptide bonds
6. tRNA then detaches leaving the amino acids on the polypeptide chain
7. the ribosome then moves down the mRNA to repeat the process
8. until stop codon is reached

Question 11

what is spicing?

Answer 11

the process of turning pre-mRNA into mRNA by removing introns and joining extrons together

Question 12

why does splicing occur?

Answer 12

DNA is made of extrons and introns and the introns prevent the synthesis of polypeptides. So by removing them polypeptide synthesis can occur.

Question 13

why do prokaryotes not require splicing?

Answer 13

they don’t usually have introns