DNA, Genes & Chromosome

Question 1

Sequence of DNA nucleotides that specifies the sequence of amino acids in a single polypeptide chain

Answer 1

Gene

Question 2

Chromosome

Answer 2

Contains a strand of DNA that is wrapped and tightly coiled around histone

Question 3

Genetic code

Answer 3

• Degenerate
• 61 out of 64 triplets used to specify amino acids
• Universial

Question 4

Transcription

Answer 4

1 - RNA polymerase binds to promoter region of gene and separates 2 strands of DNA
2 - Free ribonucleotide triphosphates base-pair with complementary deoxynucleotides
3 - Ribonucleotides are linked by RNA polymerase to form pre-mRNA
4 - RNA splicing removes introns in pre-mRNA and splices together exons, producing mRNA

Question 5

Translation

Answer 5

1 - mRNA binds to ribosome
2 - Free amino acids are linked to corresponding tRNA by aminoacyl-tRNA synthase
3 - Anticodon pairs with corresponding codon
4 - Amino acid linked by peptide bond to end of polypeptide chain
5 - Ribosome moves one codon along
6 - Repeated until stop codon, completed protein released
7 - Protein sometimes undergoes posttranslational processing in which chemical groups are added

Question 6

Transcription factors form a preinitiation complex at the promoter, need to carry out:

Answer 6

• Separating the DNA strands
• Removing any blocking nucleosomes
• Activating RNA polymerase
• Moving the complex along the template strand of DNA

Question 7

Rate of protein synthesis can be regulated at various proteins:

Answer 7

• Gene transcription into mRNA
• Initiation of protein assembly on a ribosome
• mRNA degradation in the cytoplasm