Nucleic Acids Flashcards
What does DNA do during cell division?
It replicates
What is the process of DNA replication?
1.DNA unwinds
2.Hydrogen bonds between complimentary base pairs break, and the 2 strands separate
3.Each DNA strand acts as a template
4.Free DNA nucleotides align opposite their complementary bases
5.DNA polymerase catalyses the reaction between 2 DNA nucleotides, from the 5 prime to the 3 prime
6.Each new DNA molecule is made from one original template strand and one newly replicated strand. This is known as semi-conservative replication
What experiment provided evidence for semi-conservative replication?
The Meselson-Stahl experiment
What does RNA stand for?
Ribonucleic acid
What is the pentose sugar in RNA?
Ribose
Which base is present in RNA but absent in DNA?
Uracil
Which base is absent in RNA but present in DNA?
Thymine
What is mRNA?
A single strand molecule that carries the genetic code for a specific protein from DNA in the nucleus to ribosomes in the cytoplasm
What does tRNA do?
Transfers specific amino acids to the ribosome. A single RNA strand forms a cloverleaf shape held together by hydrogen bonds between certain base pairs
What does rRNA do?
This, together with protein, forms a large complex molecule, a ribosome. Ribosomes translate the genetic code and join amino acids together to form polypeptides
What is the pentose sugar in DNA?
Deoxyribose
What does DNA stand for?
Deoxyribonucleic acid
What are the bases of DNA?
Purine-Adenine and guanine
Pyrimidine-Cytosine and thymine
What are the bases of RNA?
Purine-Adenine, guanine
Pyrimidine-Cytosine, uracil
What occurs during transcription?
It occurs in the nucleus. The genetic code for a certain protein is copied, and a complementary strand of mRNA is formed from one template strand of DNA. mRNA then leaves through the nuclear pore and travels to the ribosome.
What occurs during translation?
It occurs at the ribosome. The genetic code is translated on to a polypeptide. Amino acids that correspond to the codons on the mRNA are brought to the ribosome by tRNA. The amino acids are joined together at the ribosome to form the polypeptide chain.
What are the complementary bases to each DNA nucleotide?
Adenine-uracil
Thymine-adenine
Cytosine-guanine
Guanine-cytosine
Which enzyme catalyses the addition of RNA nucleotides?
RNA polymerase
How could multiple polypeptides be produced from one gene?
The exons could be spliced together in a different order
What is the enzyme that splices the exons together?
Ligase
What happens in between transcription and the mRNA leaving the cell?
The introns are removed from the Pre-mRNA using endonuclease enzymes, as the are non-coding. Then, the exons are spliced together using ligase enzymes
What is a ribosome made of?
Protein and rRNA
What happens during the initiation phase of translation?
1.Ribosome attaches to start codon on the mRNA
2.The first tRNA binds to the first attachment site, and the anti-codon on the tRNA binds to the complementary codon on the mRNA by hydrogen bonds, forming a codon-anticodon complex
3.A second tRNA forms a codon-anticodon complex at the second attachment site
What happens during the elongation phase of translation?
1.A ribosomal enzyme catalyses the formation of a peptide bond between adjacent amino acids
2.The first tRNA leaves site 1 and returns to the cytoplasm
3.The ribosome lives down the mRNA one codon so that the second tRNA moves from site 2 to site 1
4.A new tRNA bonds to site 1
