5.4 Protein Synthesis, Mutations and Control of Gene Expression Flashcards
Contents of DNA nucleotide?
Pentose sugar DEOXYRIBOSE
Phosphate molecule
Nitrogen containing bases (A T G C)
DNA structure?
Two polynucleotides joined by hydrogen bonding to form alpha helix
How is the orientation of bases useful?
The bases are orientated towards the centre of the helix to protect them from reacting with other chemicals
How do bases match up?
Complementary base pairing
Adenine to Thymine
Guanine to Cytosine
(AG= purine) (TC=pyrimidine)
Difference between RNA and DNA?
The pentose sugar is ribose not deoxyribose
Uracil replaces Thymine for RNA; (AU GC)
mRNA and tRNA are single stranded
Structure and use of mRNA?
Messenger RNA
Linear structure containing codons
Formed in nucleus during transcription
Structure and use of tRNA?
Transfer RNA
20 types of tRNA corresponding to each amino acid
Clover leaf shape (presence of H bonds)
Anticodon (3 unattached nucleotide bases)
Binding site for amino acid attachment
Define: gene
Sections of DNA which contain coded information to determine nature and development of organisms
Where are genes located?
Along chromosomes (thread like structures consisting of DNA and protein)
Define: allele
Different forms of the same gene
Define: locus
The relative position of an allele on a homologous chromosome
Define: homologous
Carry genes controlling same characteristics but not always the same alleles
What is a codon?
Base triplets in mRNA
What is a degenerate triplet code?
When different triplets code for the same amino acid
What is a stop code?
Ending of a polypeptide sequence
