Protein synthesis

Question 1

Stages of protein synthesis are:

Answer 1

-transcription
-translation

Question 2

Transcription

Answer 2

-DNA doesn’t leave nucleus
-part of DNA acts as template for production of mRNA which carried info needed for p.s from nucleus to cytoplasm
-ribosomes in cytoplasm provide suitable surface for attachment of mRNA and assembly or protein

Question 3

Event 1 for transcription

Answer 3

-enzyme DNA helicase breaks hydrogen bonds between bases but in a specific region of DNA molecule, this causes two strands to separate and unwind, exposing the nucleotide bases

Question 4

Event 2 in transcription

Answer 4

-enzyme RNA polymerase binds to template strand of DNA at beginning of sequence to be copied

Question 5

Event 3 in transcription

Answer 5

-free RNA nucleotides (ribonucleotides) align opposite template strand, based on complementary relationship between bases in DNA and the free nucleotides:
-ribonucleotide containing cytosine aligns opposite guanine nucleotide in DNA(rest are same)

Question 6

Event 4 in transcription

Answer 6

-RNA polymerase moves along DNA forming bonds that add RNA nucleotides one at a time to growing RNA strand, results in synthesis of a molecule of mRNA alongside the unwound portion of DNA
-behind RNA polymerase, strands rewind to form the double helix

Question 7

Step 5 of transcription

Answer 7

-RNA polymerase separates from the template strand when it reaches a codon
-production of transcript is complete and newly formed RNA detaches from the DNA

Question 8

Transcription

Answer 8

-mRNA acts as a template to which complementary tRNA molecules attach, amino acids they carry are linked to form a polypeptide, this occurs on the ribosomes in the cytoplasm

Question 9

The sequence of codons on the mRNA is used to

Answer 9

-generate a specific sequence of amino acids, forming a polypeptide, takes places on a ribosome and involves tRNA

Question 10

Two subunits of a ribosome

Answer 10

-larger subunit - two sites for attachment of tRNA molecules so two tRNA molecules are associated with a ribosome at any time
-smaller subunit binds to the mRNA

Question 11

Ribosome acts as a

Answer 11

-framework, moving along the mRNA and holding the codon-anticodon complex together till two amino acids attached to adjacent tRNA molecules bind

Question 12

The ribosome moves along the mRNA, adding

Answer 12

-one amino acid at a time until the polypeptide chain is assembled, order of bases in DNA gas determined the order of amino acids in the polypeptide

Question 13

3 steps of translation

Answer 13

-Initiation
-Elongation
-Termination

Question 14

Initiation meaning

Answer 14

-ribosome attaches to a ‘start’ codon at one end of the mRNA molecule