PowerPoint #2 - Chapter 15 Genes and Proteins

What are genes?

Genes are linearly organized instructions for making RNA and protein molecules necessary for all life processes.

What are two examples of proteins encoded by genes?

Interleukin-2 protein and alpha-2u-globulin protein.

What are the components of an amino acid?

An amino group (NH3+), a carboxyl group (COO-), and a side chain.

What determines the variation in protein structure and function?

The variety of amino acid side chains.

What is the role of messenger RNA (mRNA) in protein synthesis?

mRNA carries the genetic information from DNA to ribosomes for protein synthesis.

How do ribosomes use mRNA?

Ribosomes read the genetic information on mRNA to string amino acids together into a protein.

What does the genetic code translate?

Each nucleotide triplet in mRNA into an amino acid or a termination signal in a protein.

What happens when two nucleotides are deleted from mRNA?

It shifts the reading frame and can create a nonfunctional protein or terminate protein synthesis.

What is the direction of RNA synthesis?

RNA is synthesized in the 5'-3' direction.

What enzyme is responsible for synthesizing RNA?

RNA polymerase.

What does the σ subunit of prokaryotic RNA polymerase do?

It recognizes consensus sequences in the promoter region upstream of the transcription start site.

What happens to the σ subunit after transcription initiation?

It dissociates from the RNA polymerase.

How can a specific protein rapidly reach a high concentration in a bacterial cell?

Multiple polymerases can transcribe a single gene while numerous ribosomes translate the mRNA transcripts concurrently.

What is the significance of the genetic code?

It provides the instructions for translating nucleotide sequences into functional proteins.

What is the role of transcription factors in gene expression?

Transcription factors recognize the promoter of a gene and facilitate the binding of RNA polymerase II.

What forms the transcription initiation complex?

RNA polymerase II binds to the promoter along with transcription factors to form the transcription initiation complex.

What is Trypanosoma brucei known for?

It is the causative agent of sleeping sickness in humans.

What modification must mRNAs of Trypanosoma brucei undergo before protein synthesis?

They must be modified by the addition of nucleotides.

What is the function of tRNA in protein synthesis?

tRNA adds specific amino acids to a growing polypeptide chain based on the codon sequence of mRNA.

How does the anticodon of tRNA interact with mRNA?

The anticodon of tRNA binds to the corresponding codon on the mRNA.

What is a peptide bond?

A peptide bond links the carboxyl end of one amino acid with the amino end of another, releasing one water molecule.

What are the components of a ribosome?

A ribosome consists of a large and small ribosomal subunit.

What initiates the process of translation?

Translation begins when an initiator tRNA anticodon recognizes a start codon on mRNA bound to a small ribosomal subunit.

What happens when a STOP codon enters the A-site of the ribosome?

The Release Factor protein enters, catalyzing the hydrolysis between the last amino acid and its tRNA, terminating translation.

What is the role of GTP hydrolysis in translation termination?

GTP hydrolysis provides energy for disassembling the large and small ribosomal subunits and mRNA after translation.

What is the significance of the promoter in gene transcription?

The promoter is a specific DNA sequence where RNA polymerase II and transcription factors bind to initiate transcription.

What is the structure of tRNA?

tRNA has an anticodon on one end and an amino acid attachment site on the other end.

What occurs during the elongation phase of translation?

As the mRNA moves through the ribosome, successive tRNAs bring amino acids that are added to the growing polypeptide chain.

What is the result of translation termination?

The newly synthesized protein is released, and the ribosomal components disassemble.

What is the function of the ribosome during protein synthesis?

The ribosome translates mRNA into a polypeptide chain by facilitating the binding of tRNA and catalyzing peptide bond formation.

What is the role of the large ribosomal subunit?

The large ribosomal subunit joins the small subunit and contains the enzymatic activity for peptide bond formation.

What is the significance of the A, P, and E sites in the ribosome?

These sites are where tRNA binds: A site for incoming tRNA, P site for the growing polypeptide chain, and E site for exiting tRNA.

What happens to the polypeptide chain during translation?

The polypeptide chain is formed as tRNAs sequentially add amino acids according to the mRNA codon sequence.

What is the function of the Release Factor?

The Release Factor recognizes STOP codons and facilitates the termination of translation.