Protein Synthesis and Gene Expression Quiz

Questions and Answers

What does mRNA stand for?

Messenger RNA (correct)

Transfer RNA

Ribosomal RNA

DNA Polymerase

What is the role of tRNA?

Helps assemble the protein by reading the mRNA

What is transcription?

The process of copying a segment of DNA into RNA by RNA polymerase.

RNA has ___ instead of thymine.

Uracil Signup and view all the answers

___ are the removed segments from RNA.

Introns Signup and view all the answers

MRNA leaves the nucleus to find a ____.

Ribosome Signup and view all the answers

Transcription from DNA to mRNA occurs in the ___ of eukaryotes.

Nucleus Signup and view all the answers

What is translation?

The process of synthesizing proteins from mRNA. Signup and view all the answers

Each tRNA binds to a specific sequence of 3 bases called a ___.

Codon Signup and view all the answers

Translation from mRNA to proteins occurs on ribosomes in the ___ of the cell.

Cytoplasm Signup and view all the answers

What is a codon?

A three nucleotide/base code for an amino acid on mRNA. Signup and view all the answers

What is an anticodon?

A three nucleotide/base code for an amino acid on tRNA. Signup and view all the answers

A single amino acid is coded for by multiple codons, but any given codon codes for only ___.

One Signup and view all the answers

What is the function of RNA polymerase?

Unzips DNA at the gene during transcription and synthesizes RNA. Signup and view all the answers

What is the initiation promoter region?

A region of DNA that initiates transcription of a gene. Signup and view all the answers

What is elongation in protein synthesis?

The stepwise addition of amino acids to the growing protein chain. Signup and view all the answers

What is the purpose of the 5' cap and Poly-A tail?

They help initiate translation and stabilize mRNA. Signup and view all the answers

What are introns?

Segments of DNA or RNA that do not code for proteins. Signup and view all the answers

What are exons?

Segments of DNA or RNA that contain information coding for a protein. Signup and view all the answers

What does charged tRNA refer to?

tRNA with an amino acid attached. Signup and view all the answers

What does uncharged tRNA refer to?

tRNA with no amino acid attached. Signup and view all the answers

What is a silent mutation?

A DNA mutation that does not significantly alter the phenotype. Signup and view all the answers

What is a missense mutation?

A mutation that causes one amino acid in the protein to be incorrect. Signup and view all the answers

What is a nonsense mutation?

A mutation that causes the protein chain to stop prematurely. Signup and view all the answers

What is a reading frame shift?

A gene mutation that alters the reading frame of codons in mRNA. Signup and view all the answers

What are mutagens?

Agents that cause genetic mutation. Signup and view all the answers

Is mRNA synthesized during translation or transcription?

Transcription Signup and view all the answers

Study Notes

Protein Synthesis Terms

mRNA (messenger RNA): Acts as a copy of a gene from DNA; crucial for protein synthesis during translation.
tRNA (transfer RNA): Assembles proteins by decoding the sequence of mRNA codons.

Processes of Protein Synthesis

Transcription: RNA polymerase copies a specific segment of DNA into RNA, producing mRNA.
Translation: Converts the mRNA sequence into a polypeptide or protein, occurring on ribosomes in the cytoplasm.

Key Components of RNA

Uracil: Replaces thymine in RNA nucleotides.
Introns: Non-coding segments of RNA that are removed during processing.
Exons: Coding sequences in RNA that remain after splicing and are translated into proteins.

Translation Mechanics

Codon: A three-nucleotide sequence on mRNA that specifies a particular amino acid.
Anticodon: A three-nucleotide sequence on tRNA that pairs with a codon on mRNA during translation.
Charged tRNA: tRNA with an attached amino acid, ready to contribute to the growing protein chain.
Uncharged tRNA: tRNA without an amino acid; if mischarged, it can lead to protein misfolding.

Genetic Code and Mutations

The genetic code is redundant but not ambiguous; multiple codons can code for one amino acid, but each codon codes for only one amino acid.
Silent mutations: Do not significantly alter the phenotype; can occur in coding or non-coding regions.
Missense mutations: Substitutes one amino acid in a protein, resulting from a single nucleotide change.
Nonsense mutations: Prematurely stop protein synthesis due to an erroneous stop codon.
Reading frame shifts: Cause shifts in the codon sequence when nucleotides are added or deleted, potentially altering the resulting protein sequence.
Mutagens: Agents like radiation or chemicals that can induce genetic mutations.

Additional Notes on RNA Processing

5' Cap and Poly-A Tail: Modifications essential for mRNA stability and export from the nucleus; protect against degradation and assist in translation initiation.
Nucleus: Location of transcription in eukaryotic cells; mRNA processing occurs here before mRNA's exit to the cytoplasm.

Transcription Initiation

Promoter regions: DNA sequences that signal RNA polymerase to start transcription; located near the start site of the gene.

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Description

Test your knowledge on protein synthesis and gene expression with these flashcards. Explore key terms like mRNA, tRNA, and transcription to understand the molecular processes behind genetic expression. Perfect for students studying biology or molecular genetics.