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IB Bio SL Topic 3- 3.1-3.6
Adapted from Mr. Faure; reviews water, organic compounds and DNA replication, transcription and translation.
Terms in this set (36)
Strong covalent bonds.
What links the sugar to the base and phosphate?
Adenine, thymine, cytosine, guanine.
Four bases in DNA.
Complementary base pairing (A-T, C-G), where the 2 sugar phosphate chains are anti-parallel. Weak hydrogen bonds form between the bases to hold the chains together.
How does the double helix form?
Pyramidine nucleotide bases.
Cytosine and thymine.
Adenine and guanine.
One is 5'-3', the other is 3'-5'.
Direction of DNA strands.
Both replicated DNA contain one strand of the old DNA and one new strand.
DNA helicase unwinds the DNA double helix by breaking the bonds between the bases; this forms the replication fork.
First step of DNA replication?
It adds nucleotides to the 3' end to create the complementary strand of DNA.
Function of DNA polymerase III.
The linear sequence of bases.
By complementary base pairing.
How is the genetic code preserved?
5' to 3'.
Direction of DNA replication.
RNA is single stranded, has the base uracil instead of thymine, and has the sugar ribose instead of deoxyribose.
3 structural differences between RNA and DNA.
Only one strand of the DNA is copied, RNA nucleotides are used (there is a pool of these in the nucleoplasm), the enzyme RNA polymerase is used.
3 main differences of transcription compared to DNA replication.
DNA is unzipped by RNA polymerase, RNA polymerase builds mRNA by pairing mRNA nucleotides onto the strand of DNA opposite the desired gene, mRNA is released and leaves the nucleus.
3 key steps of transcription.
How many RNA bases code for one amino acid?
How many codes are there for stop codons?
Markers of the end of the 'message' on mRNA.
How many codons are there in total?
When two codons code for the same amino acid.
What is degeneracy?
Because all organisms use this same code.
Why is the DNA code universal?
The process used to make a polypeptide chain from the mRNA code.
A specific sequence of DNA bases at the start of a gene on the sense strand where RNA polymerase binds.
Adds nucleoside triphosphates using base pairing to the DNA template.
Sequences of mRNA that are not translated into part of the protein, and must be removed.
They make up the mature RNA.
What do the exons do?
Where does the post-transcriptional modification of mRNA take place?
Ribosomal RNA and protein, in two subunits.
Composition of ribosomes.
Binds to the mRNA.
Function of small ribosomal subunit.
Has three binding sites to bind to tRNA.
Function of large ribosomal subunit.
In the nucleolus within the nucleus.
Where are ribosomes manufactured?
Initiation, elongation, translocation and termination.
4 stages of transcription?
The small ribosome subunit binds to mRNA and the first charged tRNA binds to the start codon.
The large ribosome subunit attaches. The second charged tRNA binds in the second binding site A peptide bond is formed between the two amino acids.
A bond between amino acids.
The ribosome reaches the stop codon. There are no tRNAs with an anticodon for a stop codon. The ribosome subunits break free and the polypeptide is released.