DNA, RNA and protein synthesis Flashcards
Name the properties of eukaryotic DNA
Linear DNA molecules
Chromosomes found in nucleus
Very long, wound up to fit in the nucleus
Wrapped around histones
Chloroplasts and mitochondria has own DNA
Name the properties of prokaryotic DNA
Carry DNA as chromosomes
Shorter and circular
Supercoils to fit in cell
Define what a gene is
A sequence of DNA bases coding for either a polypeptide or functional RNA
What are introns and exons?
Introns are non coding sections of DNA, exons are coding
What does mRNA do?
Made during transcription
Carries genetic code
What does tRNA do?
Involved in translation Carries the necessary amino acids to ribosomes Folded into clover shape H bonds between specific bases Three bases at one end Has amino binding site
How does transcription work?
RNA polymerase attaches to binding site at start of gene
DNA helicase breaks hydrogen bonds between the two strands, exposing bases
RNA polymerase lines up free floating nucleotides and forms the phosphodiester backbone
H bonds reform of DNA strand
RNA polymerase detaches at the stop signal
mRNA moves out of the nucleus and attaches to ribosome
How does translation work?
mRNA attaches to a ribosome and tRNA carries amino acids (bonded using ATP)
tRNA has an anticodon which is complementary to the first codon on mRNA, they bind
The next mRNA does the same
The two amino acids are bonded by a peptide bond
The tRNA molecule moves away
The process repeats until a stop codon is reached
Describe genetic code in three ways
Degenerate, lots of combinations and more than one codon can code for the same amino acid
Universal, the same base triplets code for the same amino acid in all organisms
Non-overlapping, each triplet code is read once
Name the base pairs of DNA
Adenine and Thymine
Cytosine and Guanine
Name the base pairs of RNA
Adenine and Uracil
Cytosine and Guanine
