4.1,4.2 Flashcards
Dna in prok and euk similarities
Deoxyribose attached to phosphate and base
Adjacent nucleotides joined by phosophodiester bonds and comp bases by hydrogen bonds
Dna in mitochondria and chloroplasts have a similar structure to dna in prokaryotes
Differences in euk dna and prok dna
Euk dna longer
Euk dna is linear and prok is circular
Euk dna is associated with histones and prok isn’t
Euk dna contains introns prok doesn’t
Chromosome
Long linear dna associated with histones
In the nucleus of euk cells
Gene
Sequence of dna bases that codes for
Amino acid sequence of polypeptide
Or functional RNA
Locus
Fixed position a gene occupies on particular dna molecule
Triplet code
Sequence of 3 dna bases that code for a specific amino acid
Universal
Same triplet of bases code for same amino acid in all organisms
Non coding base sequences
Dna that doesn’t code for an amino acid
Between genes
Or within genes which are introns
How are tRNA and mRNA similar
Both single polynucleotide strands
Differences between mRNA and tRNA
tRNA folded into a soviet leaf shape
mRNA is linear and straight
tRNA has hydrogen bonds between paired bases but mRNA doesn’t
tRNA shorter and fixed length but mrna is long and variable length
Trna has an anticodon mRNA has codons
Trna has an amino acid binding site mrna doesn’t
Transcription
Hydrogen bonds between dna bases break
Only one dna strand acts as a template
Free RNA nucleotides align next to complementary bases on template strand
I’m rna uracil is replaced by thymine
RNA polymerase joins adjacent nucleotides forming phosphodiester bonds via condensation reactions
Pre mRNA spliced to remove introns = mRNA
How is production of mRNA different in prok to euk
Pre mRNA is formed in euk whereas mRNA is produced directly in prokaryotic cells
Because genes in prokaryotes don’t contain introns so no splicing is required
Translation
mRNA attaches to ribosome
Ribosome moves to start codon
tRNA brings specific amino acid
tRNA anticodon binds to complementary mRNA codon
Ribosome moves along to next codon and another tRNA binds so 2 AA can be joined by a condensation reaction forming a peptide bond
Using energy from hydrolysis of ATP
tRNA released after amino acid joined polypeptide
Ribosome moves along
mRNA to form polypeptide till stop codon reached
Role of atp in translation
Hydrolysis of atp to adp and pi
So amino acids join tO tRNA and peptide bonds form between amino acids
tRNA
Attaches to and transports a specific amino acid in relation to its anticodon
tRNA anticodon is complementary base pairs to mrna codom forming hydrogen bonds
2 trna bring amino acids together so peptide bonds can form
