Transcription And Translation

Question 1

What is transcription?

Answer 1

The name of the process in which a copy of DNA is made in the nucleus

Question 2

Outline the process of transcription

Answer 2

1) Helicase enzymes unwind the DNA and hydrogen bonds between the complementary bases of the 2 strands of the gene
2) Free nucleotides join onto complementary bases against the template strand of DNA. (Uracil rather then Thymine)
3) RNA polymerase then moves along the DNA and joins the adjacent nucleotides to form mRNA. The length of mRNA is completely complementary to the template strand and is an exact copy of the coding strand of DNA (except U INSTEAD of T)
4) Completed mRNA moves out of the nucleus via a nuclear pore

Question 3

What is translation?

Answer 3

The process of translating the sequence of mRNA to a sequence of amino acids during protein synthesis.

Question 4

Outline the process of translation

Answer 4

1) mRNA from the nucleus binds to a ribosome, and is sectioned into its codons
2) tRNA carries 2 anticodons (which form amino acids) at a time to the mRNA into the ribosome.
3) After the process repeats, a polypeptide chain forms until a stop codon is reached

Question 5

Compare DNA, mRNA, and tRNA in terms of whether hydrogen bonds are present, how many polynucleotide strands the molecule has, its shape, size, sugar, and stability

Answer 5

DNA:

• Has hydrogen bonds
• 2 polypeptide strands
• Double helix
• Largest size
• Deoxyribose
• Very stable

mRNA:

• No hydrogen bonds
• 1 polypeptide strand
• Single helix
• Variable size
• Ribose
• Unstable

tRNA:

• Has hydrogen bonds
• 1 polypeptide strand
• Clover
• Smaller size
• Ribose
• More stable then mRNA, less then DNA