DNA to Protein: Transcription and Translation Processes

How does information flow from DNA to proteins?

Information flows from DNA to mRNA through transcription and then to proteins through translation.

What are the basic components of RNA? How does it differ from DNA?

RNA is composed of a 5-carbon sugar (ribose), a phosphate, and bases (A, C, G, U)

Describe the process of transcription. What is the direction of transcription?

Transcription occurs in the 5' to 3' direction, copying from the template strand of DNA, and the mRNA produced resembles the non-template strand.

Define codon and describe the relationship between codons on mRNA and amino acids in a polypeptide.

A codon is a sequence of three nucleotides on mRNA that corresponds to a specific amino acid, determining the order of amino acids in a polypeptide chain.

Why is the genetic code said to be redundant? What are the signals for the start and stop of protein synthesis?

The genetic code is redundant because multiple codons can specify the same amino acid. AUG is the start signal, while UAG, UAA, and UGA are stop codons.

Describe the structure of tRNA and explain how its structure is related to function.

3-leaf clover structure, with three hairpin loops containing anticodons that recognize mRNA codons and decode them to their amino acid

What is the polarity of the interaction between tRNA and mRNA?

tRNA has a 3' to 5' polarity, while mRNA has a 5' to 3' polarity. The anticodon of tRNA pairs antiparallel to the codons of mRNA.

How is it possible to have only 45 types of tRNA recognize 64 codons?

The Wobble hypothesis explains that a single tRNA can pair with multiple codons due to flexibility in base pairing, particularly at the third base of the codon.

What is the role of amino-acyl tRNA synthetase?

pairs tRNAs with their corresponding amino acids for decoding mRNAs

Describe the structure of a ribosome and explain how structure is related to function.

Ribosomes are composed of rRNA and protein, responsible for protein synthesis by reading mRNA and translating it into a specific sequence of amino acids.

Whats translation initiation

Initiation involves mRNA binding to the ribosome

What are the different types of mutations?

1) Silent Mutation: No change in protein. 2) Frameshift Mutation: Alters the reading frame due to insertion/deletion. 3) Missense Mutation: Changes one amino acid. 4) Nonsense Mutation: Introduces a STOP codon.

What is the significance of the AUG codon?

AUG serves as the start codon for protein synthesis, signaling the beginning of translation.

What are the stop codons in protein synthesis?

The stop codons are UAG, UAA, and UGA, which signal the termination of translation.

What is the function of peptidyl-transferase during translation?

Peptidyl-transferase catalyzes the formation of peptide bonds between amino acids during elongation of the polypeptide chain.

What happens during the translocation step of translation?

During translocation, the ribosome moves three bases along the mRNA, shifting tRNAs into the E and P sites and ejecting the uncharged tRNA from the E site.

What triggers the termination of translation?

Termination is triggered when a release factor protein binds to the A site in place of a tRNA when a stop codon is reached.

How does the structure of tRNA facilitate its function in translation?

The unique cloverleaf structure of tRNA allows it to carry an amino acid and recognize the corresponding codon on mRNA, ensuring accurate translation.

What is the role of the ribosomal subunits in translation?

The small subunit binds to mRNA, while the large subunit catalyzes peptide bond formation and the overall process of translation.

What is the significance of the reading frame in protein synthesis?

determined how codons are grouped and read during translation, affecting the resulting polypeptide sequence

How do transcription factors influence gene expression?

Transcription factors bind to promoters and regulatory sequences to enhance or inhibit the transcription of specific genes.

What is the relationship between the template strand and the non-template strand during transcription?

The template strand is used to synthesize mRNA, while the non-template strand has the same sequence as the mRNA (except for uracil replacing thymine).

What is translation elongation?

Elongation adds amino acid

What is translation termination?

a stop codon enters the A site and binds with release factors to release the subunits and amino acid chain

What is the processes of translation and the 3 sites?

EPA, Translation of the RNA codon into polypeptide sequences occurs on ribosomes