Nucleic Acids
What are the three components of a nucleotide?
A phosphate group, a five-carbon sugar, and a nitrogenous base
RNA polymerase
Where does transcription take place in eukaryotic and prokaryotic cells?
Prokaryotic: nucleoid region
Eukaryotic: Nucleus
Which molecule carries anticodons to the ribosome?
tRNA (transfer RNA)
What is the flow of infomration in the central dogma?
DNA to RNA (through transcription)
RNA to polypeptide (through translation
Polypeptide to protein (through folding)
Which bases are purines/ which bases are pyrimidines?
Purines: Adenine and Guanine
Pyrimidines: Cytosine, Thymine, Uracil
Why are nucleic acid strands described as having a 5' and a 3' end?
The ends are named based on the carbon numbers on the sugar. The 5' end has a phosphate group attached to the 5' carbon, while the 3' end has a hydroxyl group on the 3' carbon.
What are the three major steps of transcription?
Initiation, elongation, and termination
What is a three base sequence on mRNA called?
A codon
Which molecule carries genetic information from DNA to the ribosome
mRNA
Explain Chargaff's rules for double stranded DNA
The amount of Adenine equals the amount of Thymine (A=T), and the amount of Guanine equals the amount of Cytosine (C=G)
What is the purpose of the 5' cap?/ What is the purpose of the 3' poly A tail?
5' capping: helps prevent degradation of the mRNA and helps with ribosomal binding
3' poly A tail: protects the mRNA strand and helps with ribosomal recognition
During elongation, which direction does the RNA polymerase move along the DNA template?
RNA polymerase moves along the DNA template 3' to 5' while synthesizing RNA 5' to 3'.
What is the three-base sequence on tRNA called?
An anticodon
If the DNA template is 3' TAC 5', what mRNA sequence is produced
5' AUG 3'
A DNA sample has 35% Adenine. What percentages are T, G, and C?
A= 35%
T= 35%
G= 15%
C=15%
Explain how nucleotides are linked to form a strand of nucleic acids
Nucleotides are bound through a phosphodiester bond between the phosphate group of one nucleotide and the 3' hydroxyl group of another. This creates the sugar-phosphate backbone
What happens during transcription initiation?
RNA polymerase binds to the promoter region of a gene and begins separating the DNA strands so transcription can begin
What is the role of the ribosome during translation.
The ribosome reads the mRNA codon and helps link the amino acids together to form a polypeptide
If mRNA is 5' AUG GCU UAA 3', what hapens during trnalsation?
The ribosome reads AUG as the start codon, adds the amino acids specified by AUG and GCU, and reaches UAA, a stop codon causing translation to terminate.
What is the differnece between ribose and deoxyribose?
Ribose has an OH group on the 2' carbon, while deoxyribose only has an H. Ribose is found in RNA; Deoxyribose is found in DNA.
Explain why RNA processing/modifications are necessary before mature mRNA can leave the nucleus
Pre-mRNA must be modified to become mature mRNA. This includes removing introns through splicing, 5' capping, and adding a 3' poly A tail. These modifications help protect the mRNA, allow it to leave the nucleus, and prep it for translation
What happens when RNA polymerase reaches the terminator region?
Transcription stops, the newly made RNA molecule is released from the DNA
Explain the process of initiation, elongation, and termination in translation.
Initiation: the small subunit attaches to the ribosomal site, tRNA anticodon binds with the start codon, and the large subunit attaches to the ribosomal site
Elongation: tRNA binds to the A site, a peptide bond forms, and translocation occurs
Termination: ribosome reaches the stop codon, release factors trigger the release of the polypeptide, tRNA, and both subunits
Exaplin how information flows form DNA to RNA to protein and why eahc step is necessary
DNA stores genetic information. In transcription, the information in a gene is copied into mRNA. The mRNA travels to a ribosome, where translation uses its codons to determine the corresponding amino acid sequence of a polypeptide. Folding takes place and results in a functional protein with a specified function.