B2 Nucleic Acids Flashcards
What is DNA
codes for the sequence of amino acids in the primary structure of a protein, which in turn determines the final 3D structure and function of a protein.
It’s essential therefore that cells contain a copy of this genetic code & that it can be passes onto new cells without being damaged.
DNA polymer = double helix
What is a dna nucleotide monomer made up of
DNA monomer = nucleotide
made up of deoxyribose (a pentose sugar), nitrogenous base and 1 phosphate group.
What’s a polymer of nucleotides called
Polynucleotide
How is a polynucleotide made
via condensation reaction
between the deoxyribose sugar and the phosphate group, creating a phosphodiester bond.
Phosphodiester bonds (strong covalent bonds) - help ensure that genetic code isn’t broken down
What is the name of the structure that holds a polynucleotide (polymer) together
a sugar-phosphate ‘backbone’
This’s describing the strong CBs between sugar and phosphate groups that hold polymer together.
How is the double helix structure of dna created
DNA polymer occurs in pairs that’re joined together by HBs between bases.
This’s how double helix structure’s created, as 2 chains twist.
HB in dna
HBs can only form between complementary base pairs.
This’s the term given to the fact that the base cytosine can only form HBs with guanine and adenine can only bond with thymine.
The number of HB between bases in DNA
Adenine and thymine form 2 HBs
cytosine and guanine can form 3 HBs
This complementary base pairing is important to help maintain order of genetic code when DNA replicates.
How the structure relates to the function in DNA
Stable structure due to sugar-phosphate backbone (CBs) and double helix.
Double stranded so replication can occur using 1 strand as a template.
Weak HBs for easy unzipping of 2 strands in double helix during replication.
Large molecule to carry lots of info
Complementary base pairing allows identical copies to be made.
What’s RNA made of
polymer of nucleotide formed of ribose, nitrogenous base and phosphate group.
bases are adenine, guanine, cytosine and uracil.
How is rna different to dna (talk about rna only)
RNA has base uracil instead of thymine
In comparison to DNA, RNA is relatively short polynucleotide chain & it’s single stranded.
What’s the function of RNA
function of RNA is to copy & transfer genetic code from DNA in nucleus to ribosomes.
Some RNA is also combined with proteins to create ribosomes.
What are the 3 types of RNA
(Messenger) mRNA
(Transfer) tRNA
(Ribosomal) rRNA
What is mRNA
A copy of a gene from DNA
Where is mRNA created
in nucleus and it then leaves nucleus to carry copy of genetic code of 1 gene to a ribosome in cytoplasm.
Why is mRNA able to leave the nucleus but DNA can’t
DNA too large to leave nucleus and would be at risk of being damaged by enzymes, therefore destroying the genetic code permanently.
mRNA much shorter (its only length of1 gene, and can therefore leave nucleus)
Why is mRNA short lived
mRNA is short lived as only needed temporarily to help create protein, therefore by time any enzymes could break it down it would’ve already carried out its function.
mRNA is single stranded and every 3 bases in sequence code for specific amino acid, these 3 bases are called codons.
Where is tRNA found
Only in cytoplasm
What’s rRNA
The type of RNA that makes up bulk of ribosomes.
Describe the shape of tRNA
single stranded, but folded to create shape that looks like cloverleaf.
This cloverleaf shape is held in place by HBs
What’s the function of tRNA
function = to attach to 1 of 20 amino acids & transfer this AA to ribosome to create polypeptide chain.
Specific AAs attach to specific tRNA & this’s determined by 3 bases found on tRNA which’re complementary to 3 bases on mRNA.
These are called anticodon, because they’re complementary to codon on mRNA.
Differences between DNA and RNA monomers:
DNA contains base thymine, RNA contains uracil
DNA contains pentose sugar deoxyribose, RNA contains pentose sugar ribose.
Differences between polymers DNA & RNA
DNA is much larger because it contains approx 23,000 genes (entire genome), RNA is much shorter because it’s only length of 1 gene
DNA is double stranded, RNA is single stranded
What does ATP stand for
Adenosine tri phosphate
What is ATP
An immediate source of energy for biological processes