Biological Molecules 2 Flashcards
Semi Conservative replication
Dear molecules unravel due to hydrogen bonds breaking. This Is catalysd by DNA helices
The exposed bases attract free DNS nucleotides an d new hydrogen bond form between matching bases. Dna polymerase catalyses the linking of the nucleotides along the template strands
Dna ligaments catalyses the formation of ohsphoduetsrr bonds between two strands of DNA
Dna automatically coils
Genes
A sequence of Bases on DNQ molecule that codes for a specific sequence of amino cids on polypeptide chain
Structure of mrna
Contains a sugar and phosphate held together by phsophideter bonds
Formed in the nucleus
Structure of trna
Clover shape help it carry its function and held together by hydrogen bonds
Each trna contains a Anticodon with a Complementary shape to the codon of the mrna
Contains a biding site which can bind to an specific amino acid.
Function of trna
Form proteins
Last stage of transcirption
Free nucleotides line up on template strands by Complementary base pairing and adjacent nucleotides joined together by phsophodiester bonds forming mrna . Catalysed by RNA polymerase
Nature of genetic code
Non overlapping: a single base cannot take part I t he formation of more than one codon. The triplet cam only be read once and does not share its bases
Degenrate: more than one triplet can code for a single amino acid. So if dna base sequence changes it can code for the amino acid. Reduce the effect of mutations
Universal
Start and stop codon
Define gene mutation
One or a small number of nucleotide is miscopied during g translation
Point mutatikn
A change in a small number rof nucleotide which could affect a single gene
How is sickle cell disease caused
One base is changed in dna
One codon is changed in mrna
One amino acid is changed
Polypeptide forms a different shape. Amino acid phe replaced by leu so bond cannot be formed to from shape of active site
Enzyme cannot function. Lack of enxyme causes genetic disease
