From DNA to Protein: How Cells Read the Genome

These flashcards cover key concepts discussed in the lecture about the processes of transcription and translation, the structure and function of different types of RNA, and the significance of the genetic code.

What is the main difference between DNA and RNA regarding the type of sugar they contain?

DNA contains deoxyribose, while RNA contains ribose.

What substance is used by RNA instead of thymine?

RNA contains uracil (U) instead of thymine (T).

What are the functions of mRNA, rRNA, and tRNA?

mRNAs code for proteins, rRNAs form the core of ribosomes and catalyze protein synthesis, and tRNAs serve as adaptors between mRNA and amino acids.

In the transcription process, what does the DNA template provide?

The DNA template provides the sequence to be transcribed into RNA.

What is the role of the promoter in transcription?

The promoter is a sequence that indicates which DNA strand is the template and the direction of transcription, determining the start site.

What are the three steps of bacterial transcription?

Initiation, elongation, and termination.

What is the role of the RNA polymerase sigma factor in transcription?

The sigma factor controls the binding of RNA polymerase to the promoter to initiate transcription.

What causes RNA polymerase II to be released from transcription factors in eukaryotes?

The phosphorylation of RNA polymerase II by TFIIH allows it to be released to begin transcription.

How are mRNAs modified after transcription in eukaryotes?

mRNAs receive a 5' cap and a poly(A) tail, and undergo splicing to remove introns.

What is alternative splicing?

Alternative splicing is a process where a single pre-mRNA is processed in different ways to produce multiple types of mRNA.

What does the genetic code determine?

The genetic code determines how the nucleotide sequence specifies the amino acid sequence of a protein.

What are synonymous codons?

Synonymous codons are codons that specify the same amino acid.

What does the term 'wobble' refer to in the genetic code?

Wobble refers to the flexibility in base pairing between mRNA and tRNA, where some codons can pair with multiple tRNAs.

What are termination codons?

Termination codons (UAA, UAG, UGA) signal the end of protein synthesis; they do not have corresponding tRNA anticodons.

What is the function of aminoacyl-tRNA synthetases?

Aminoacyl-tRNA synthetases attach the appropriate amino acid to its corresponding tRNA.

What are the steps of translation initiation?

1. mRNA binds to the small ribosomal subunit. 2. Initiator tRNA binds to the mRNA. 3. The large ribosomal subunit joins to form the initiation complex.

What are the roles of the A, P, and E sites in the ribosome during elongation?

The A site holds the tRNA with the next amino acid, the P site holds the tRNA with the growing polypeptide chain, and the E site is where the empty tRNA exits.

What is the function of chaperones in post-translational modification?

Chaperones assist in the proper folding of proteins after translation.

How do proteasomes control protein concentration within a cell?

Proteasomes degrade short-lived and misfolded proteins, regulating protein levels.

What evidence supports the notion of an RNA world in early life evolution?

Thomas Cech discovered that RNA can perform catalytic functions, suggesting it may have been the first genetic material.

What is a ribozyme?

A ribozyme is an RNA molecule that possesses catalytic activity, capable of catalyzing chemical reactions.