Gene Expression at the Molecular Level

These flashcards cover key concepts in gene expression, transcription, translation, and associated molecular biology processes.

What is gene expression?

The process by which the information of a gene is made into a functional product.

What does a mutation refer to?

A heritable change in the genetic material.

Who proposed the inborn error of metabolism concept?

Archibald Garrod.

What is alkaptonuria?

An inherited disease caused by an accumulation of homogentisic acid due to a missing or defective enzyme.

What did Beadle and Tatum study?

Amino acid synthesis in Neurospora crassa.

What is the one gene-one enzyme hypothesis?

The idea that a single gene controls the synthesis of a single enzyme.

What does mRNA stand for?

Messenger RNA.

What direction is RNA synthesized?

5' to 3' direction.

What is the role of sigma factor in prokaryotic transcription?

It binds to the promoter, allowing RNA polymerase to start transcription.

What is the function of the promoter in gene organization?

Signals the beginning of transcription.

What are exons?

The RNA sequences found in the mature mRNA.

What are introns?

Intervening untranslated sequences in RNA.

What does capping refer to in mRNA processing?

Covalent attachment of 7-methylguanosine to the 5' end of the mRNA transcript.

What is the function of the poly A tail?

It aids in export from the nucleus and increases mRNA stability.

What is alternative splicing?

A process that allows a single gene to produce different products by splicing the RNA in multiple ways.

What are codons?

Groups of three consecutive ribonucleotide bases in mRNA that specify amino acids.

What defines the reading frame of an mRNA?

The start codon.

What are the components of the translation machinery?

mRNA, tRNA, ribosomes, and translation factors.

What is the role of aminoacyl-tRNA synthetases?

They catalyze the attachment of amino acids to tRNA molecules.

What is the primary function of ribosomal RNA (rRNA)?

To help form the ribosomal structure and facilitate translation.

What occurs during the initiation stage of translation?

mRNA, tRNA, and ribosomal subunits form a complex.

What is the function of release factors in translation termination?

To recognize the stop codon and disassemble the translation machinery.

What is the central dogma of molecular biology?

DNA -> RNA -> Protein.

How many different aminoacyl-tRNA synthetases do cells contain?

20, one for each different amino acid.

What is the role of the ribosome during translation?

To provide a site for mRNA and tRNA interaction and catalyze peptide bond formation.

What is tRNA's acceptor stem responsible for?

Binding of the amino acid.

What happens when a stop codon is reached during translation?

The polypeptide is released, and the translation machinery dissociates.

What is the significance of the coding strand?

It has the same sequence as the mRNA, except for thymine being replaced by uracil.

In eukaryotes, how many RNA polymerases are there?

Three.

What is meant by 'translational frame'?

The specific way in which codons are read to produce a corresponding polypeptide.

What is a spliceosome?

A complex of RNA and proteins that removes introns from pre-mRNA.

What defines the structure of eukaryotic ribosomes?

They consist of 40S and 60S subunits, forming an 80S ribosome.

What is the function of the 5' cap in eukaryotic mRNA?

Protects mRNA and helps it bind to a ribosome for translation.

How many codons specify the 20 amino acids?

64 different codons.

What is one consequence of insertion or deletion of bases in mRNA?

Changes the amino acid sequence if not a multiple of three.

What does 'degenerate' mean regarding the genetic code?

More than one codon can specify the same amino acid.

What is the primary role of the small ribosomal subunit during initiation?

Binds to the mRNA's ribosomal-binding site.

What is the role of the initiator tRNA in translation initiation?

Binds to the start codon in mRNA.

What is the difference between prokaryotic and eukaryotic initiation of translation?

Eukaryotic initiation involves cap-binding proteins and position of the start codon is more variable.

What does RNA polymerase do during the elongation phase of transcription?

Slides along the DNA to synthesize RNA.

What is the function of the ribosomal-binding site in bacterial mRNA?

The site for ribosome binding.

What does translation involve?

The process of decoding mRNA into a polypeptide sequence.