7 Flashcards
What is the main role of RNA in cells?
RNA acts as the intermediate between DNA and protein synthesis, transferring genetic information from the nucleus to the ribosomes for translation
What are the main structural components of RNA?
RNA consists of a ribose sugar, phosphate group, and four nitrogenous bases (adenine, guanine, cytosine, and uracil).
How does RNA differ from DNA?
RNA contains the sugar ribose (instead of deoxyribose in DNA), is single-stranded, and uses uracil instead of thymine.
What are the three main types of RNA and their functions?
- mRNA
- tRNA
- rRNA
What is mRNA and its role?
messenger RNA
- Carries the genetic information from DNA to the ribosome
What is tRNA and its role?
transfer RNA
- Brings amino acids to the ribosome for protein synthesis
What is rRNA and its role?
ribosomal RNA
- Forms the core of ribosomes and catalyzes protein synthesis
What is transcription?
Transcription is the process by which RNA is synthesized from a DNA template
What enzyme is responsible for synthesizing RNA during transcription?
RNA polymerase
What are the three main stages of transcription?
- Initiation
- Elongation
- Termination
What happens during the initiation phase of transcription?
RNA polymerase binds to the promoter region of the DNA and begins unwinding the DNA to start RNA synthesis
How does RNA polymerase know where to start transcription?
RNA polymerase recognizes and binds to specific sequences called promoters in the DNA
What is the direction of RNA synthesis?
RNA is synthesized in the 5’ to 3’ direction
What does the diagram showing RNA polymerase moving along the DNA strand represent?
It represents the elongation phase of transcription, where RNA polymerase moves along the template strand and adds complementary RNA nucleotides
What are the two strands of DNA called in relation to transcription?
- The template strand
- The coding strand
Which of the 2 strands of DNA (of transcription) is transcribed
Template Strand
Which of the 2 strands of DNA (of transcription) is not transcribed
Coding Strand
How is transcription terminated?
Transcription is terminated when RNA polymerase reaches a terminator sequence in the DNA, signaling the end of RNA synthesis.
What is translation?
Translation is the process of synthesizing proteins from mRNA in the ribosome
What is the genetic code?
The genetic code is a set of rules by which the nucleotide sequence in mRNA is translated into the amino acid sequence of a protein
What are codons?
Codons are sequences of three nucleotides in mRNA that correspond to specific amino acids or stop signals during protein synthesis
What is the start codon and its role?
The start codon is AUG, which signals the beginning of translation and codes for the amino acid methionine
What is a stop codon, and how does it function?
Stop codons (UAA, UAG, UGA) signal the end of translation, causing the ribosome to release the completed polypeptide
What are the three main components involved in translation?
- mRNA
- tRNA
- Ribosomes
What is the role of tRNA in translation?
tRNA brings the correct amino acid to the ribosome by matching its anticodon to the mRNA codon
What are the two subunits of a ribosome?
The large subunit and the small subunit
How do the subunits of the ribosome function during translation?
The small subunit binds the mRNA, and the large subunit catalyzes the formation of peptide bonds between amino acids
What are the three main stages of translation?
- Initiation
- Elongation
- Termination
During which stage is the polypeptide chain extended?
Elongation
How is the correct amino acid added to the polypeptide chain?
The anticodon of the tRNA pairs with the complementary codon in the mRNA, ensuring the correct amino acid is added
How is translation terminated?
Translation is terminated when a stop codon is encountered, signaling the release of the newly formed polypeptide
How do the diagrams help explain the translation process?
The diagrams show the interaction between mRNA, tRNA, and the ribosome, visualizing how codons are translated into amino acids and how the growing polypeptide chain is formed
What is a promoter in the context of transcription?
A promoter is a specific DNA sequence where RNA polymerase binds to initiate transcription
What are the three main steps of RNA processing in eukaryotes?
- Capping
- Polyadenylation
- Splicing
What is the role of splicing in mRNA processing?
Splicing removes introns (non-coding regions) from pre-mRNA and joins exons (coding regions) together to form the mature mRNA
What does the “transcription bubble” in the diagram represent?
The transcription bubble is the region where the DNA double helix is unwound so RNA polymerase can synthesize RNA
What signals the termination of transcription in prokaryotes?
A terminator sequence in the DNA signals RNA polymerase to stop transcription
What is tRNA “charging”?
tRNA charging is the process of attaching an amino acid to its corresponding tRNA by an enzyme called aminoacyl-tRNA synthetase.
What is the importance of the codon-anticodon interaction?
The anticodon of tRNA pairs with the codon of mRNA, ensuring that the correct amino acid is incorporated into the growing polypeptide chain
What role does GTP play in the translation process?
GTP provides energy for various steps in translation, including ribosome assembly and translocation of tRNAs during elongation
What is a polyribosome?
A polyribosome (or polysome) is a complex of multiple ribosomes translating the same mRNA simultaneously
How does the diagram showing the ribosome moving along mRNA help explain translation?
It visualizes how ribosomes travel along mRNA, synthesizing proteins by adding amino acids as each codon is read
