Nucleotides and Nucleic acids Flashcards
Briefly summarise the process of DNA replication
- Double Helix unwinds
- Hydrogen bonds are broken
- Enzyme DNA helicase breaks these H-bonds between complementary base pairs on the 2 strands of DNA
What is Semi conservative replication?
each new DNA molecule is made up of one parent strand (see next point) from the original DNA molecule, and one new, daughter strand.
What does DNA Polymerase.
Works in the 5’ to 3’ direction
reads” the parental strand, and catalyses the addition of the free-floating nucleotides.
since DNA strands are antiparallel but DNA polymerase can only work in one direction, replication has to occur in opposite directions on the two strands.
What does DNA ligase do?
DNA ligase catalyses condensation reactions between the new nucleotides to create a polynucleotide chain.
What is DNA made up of?
A phosphate group, deoxyribose sugar and 4 nitrogenous bases (A,C,T,U) that connect the two strands in DNA
What is RNA made up of?
Single stranded and has one polynucleotide chain
Ribose sugar
Uracil instead of thymine
What are the types of RNA?
Messenger RNA
Transfer RNA
Ribosomal RNA
Where is the phosphodiester bonds?
Between the phosphate group and the sugar molecule.
What is the genetic code?
- codons are non-overlapping
- codons are degenerate
- genetic code is universal
- triplet nature
What is a codon?
Every 3 bases - a single gene is a sequence of codons
What does it mean when codons are non-overlapping?
Each codon codes only for its particular amino acid.
What does it mean when codons are degenerate?
some of the twenty amino acids that our bodies use to make proteins can be specified by more than one codon
What does it mean that the genetic code is universal?
some of the twenty amino acids that our bodies use to make proteins can be specified by more than one codon
Summarise the process of transcription.
At the start of transcription, the DNA molecule is separated into two strands by RNA polymerase.
Transcription begins at the promoter region.
The opposite strand to the strand that should be copied serves as the template.
RNA polymerase builds the RNA molecule- works in a 5′ – 3′ direction.
The RNA polymerase will then release the completed mRNA strand
Summarise the process of translocation.
Translation begins at the start codon.
Another tRNA joins to the next codon of the mRNA
Ribosome catalyses the peptide bond formation.
The tRNA are released and the process repeats.
Translation ends at the stop codon.
