Nucleotides and nucleic acids Flashcards
(12 cards)
state the components of a DNA nucleotide (3)
- deoxyribose sugar
- phosphate group
- purine/pyrimidine base
Describe how the structure of RNA differs from that of DNA (2)
has ribose ;
uracil / U, instead of, thymine / T ;
single stranded ;
3 forms / AW ;
Describe how a DNA molecule is replicated (7)
untwist / unwind ;
unzip / described ;
H bond breaks ;
both strands act as template ;
(aligning of) free (DNA) nucleotides ;
complementary, base / nucleotide, pairing ;
C to G and T to A / purine to pyrimidine ;
hydrogen bonds reform ;
sugar-phosphate back bone forms ;
(using) covalent / phosphodiester, bond ;
semi-conservative replication ;
DNA polymerase ;
Suggest how changing the sequence of DNA nucleotides could affect the final product the DNA codes for (2)
There will be a different sequence of amino acids (primary structure) which leads to a different protein forming. This means the protein may no longer function or have a different function
State the role of a gene (1)
codes for a specific polypeptide
Explain how the structure of DNA allows replication
DNA is double stranded (both strands act as a template). hydrogen bonds easily break/form between bases. which leads to complementary base pairing. purines are only able to bind to pyrimidines. There is H bonds between A, T (2 H bonds) and C, G ( 3 H bond)
How do tRNA molecules contribute to the process of translation during protein synthesis, and what role do the ribosome and rRNA play in this process?
In the cytoplasm, there are free molecules of tRNA (transfer RNA)
These tRNA molecules have a triplet of unpaired bases at one end (known as the anticodon) and a region where a specific amino acid can attach at the other
The tRNA molecules bind with their specific amino acids (also in the cytoplasm) and bring them to the mRNA molecule on the ribosome
The triplet of bases (anticodon) on each tRNA molecule pairs with a complementary triplet (codon) on the mRNA molecule
Two tRNA molecules fit onto the ribosome at any one time, bringing the amino acid they are each carrying side by side
A peptide bond is then formed (via a condensation reaction) between the two amino acids
This reaction is catalysed by the rRNA subunits of the ribosome
where does transcription and translation occur
transcription occurs in the nucleus but translation occurs in the cytoplasm!
how is the genetic code degenerate
multiple codons can code for the same amino acid
how is the genetic code non-overlapping
each base is only read once in the codon it is part of
describe how dna strands are structered
DNA molecules are made up of two polynucleotide strands lying side by side, running in opposite directions – the strands are said to be antiparallel
