Nuclei Acids And Nucleotide Flashcards
What does mRNA do
Carries genetic information out of the nucleus to the Ribosome
Enzymes involved in dna replication
Helicase:splits strands by breaking hydrogen bonds
Polymerase:aligns complementary base pairs between nucleotides
Ligase:joins sugar phosphate backbone
Explain the uses of the remaining 44 combinations
Several codons differ in their triplet sequence but code for the same amino acid
Some are used as start and stop codons
Describe how a nucleotide base sequence in a gene is used to synthesize a polypeptide
By transcription the gene sequence is copied onto mRNA.After DNA unzips free RNA nucleotides line up to form complementary base pairs. one strand acts as a template then rna polymerase forms the mRNA.
Then translation begins where the mRNA moves to the ribosomes. tRNA binds to complementary mRNA. tRNA contains anticodons which bind to the codons from mRNA. Specific amino acids are attached to each tRNA molecule. Peptide bonds form between adjacent amino acids to form the polypeptide
How is a dna molecule replicated
It replicates via semi conservative replication.The dna double helix unwinds and unzips and hydrogen bonds are broken by dna helicase. Both strands are free to act as templates where free dna nucleotides that are complementary to the sequence align and hydrogen bonds form between them. Sugar phosphate backbone is then reformed by polymerase connected by phosphodiester bonds.
Semi conservative replication
One strand is from the original dna and one is the new strand. The original strand is acts as a template for the new strand
Why is complementary base pairing important
It is important so that no mutation occurs and dna replicated without error
What else is present in dna
Dna is part of a nucleotide joined to nitrogenous base and phosphate groups. Phosphate is joined to carbon 5 and base joined to carbon 1. Nucleotide is a repeating unit of dna.
Why does nitrogenous base pairing allow same copies to be made
As A bonds with Tvand G bonds with C. H bonds form between them. Purines bond with pydrimidins as they’re different sized.
What occurs after bases lair in dna replication
DNA polymerase aligns based and sugar phosphate backbone reforms and dna winds into double helix.
How is dna held together
The chains are held by phosphodiester bonds. The strands are held together by hydrogen bonds. There are two bonds between AT and 3 between GC
purines and prymidines
purines contain 2 carbon nitorgen rings AG
pyrimidines conatin 1 carbon nitrogen ring CUT
which feature of dna provides stability
double helix/sugar phosphate backbone held by strong covalent bonds
