2.3 Nucleotides Flashcards
What is semiconservative replication
Two new molecules of DNA are formed, each with one old strand of DNA
Explain DNA replication
DNA helicase unzips two strands of DNA, free nucleotides in the nucleoplasm attach to their complementary base, DNA polymerase creates phosphodiester bonds between bases, Products are identical and contain one original strand
How are Okazaki fragments formed
DNA polymerase can only bind to the 3’ side, so moves from 3’ 5’ direction. The 5’ to 3’ (lagging strand) strand DNA polymerase has to wait until another section has been unwound. (discontinuous replication)
What happens to Okazaki Fragments
Ligase join Okazaki fragments on the lagging strands
What is DNA mutation?
Errors (change in the sequence of bases) created randomly
What is the Genetic code? What are 3 features about it?
DNA coding for an amino acid.
Triplet code - read in threes (codon)
Degenerate - Codons are not overlapping. amino acids can be coded for by many codons
Universal - genetic code is the same for most organisms
What is a start codon?
Met - Codon that starts of DNA translation/transcription, signalling the start of a gene
Put the order of Protein synthesis
Replication, Transcription, Translation
What is the difference between coding and template strands
The strand we want to copy is called the coding strand, The template strand is the one we transcribe
What are the 4 bases of RNA
Adenosine, Uracil, cytosine, Guanine
Explain DNA transcription
RNA helicase unzips DNA. Free RNA nucleotides pair with complementary bases on the template strand. Phosphodiester bonds form on the RNA nucleotides by the enzyme RNA polymerase. mRNA is formed, which is an exact copy of the Coding strand and complementary to the template strand, but with Uracil, instead of Thymine. MRNA detaches from the DNA, and leaves the nucleus through nuclear pores. Double Helix reforms
Nucleotides:
What is ribosomes split into, what does it contain
Small and large subunit, contains ribosomal RNA
Nucleotides:
What is the anticodon on tRNA. What does tRNA do?
Anticodon is complementary to mRNA strand. tRNA brings over amino acid, corresponding to that codon
Nucleotides:
Explain DNA translation
mRNA bonds to small subunit of ribosome, at the start codon. tRNA with complimentary anticodon then binds to the mRNA, only two tRNA can be bound at the same time. Peptide bonds are created between amino acids, catalysed by an enzyme. Ribosome moved down mRNA chain, until it reaches a stop codon, where the primary structure is released. The protein then folds into secondary and tertiary structures
Nucleotides:
What happens to proteins after translation
Protein moves to Golgi apparatus, to be modified
