Molecular Biology Principles Flashcards
(26 cards)
DNA structure
2 polynucleotide chains, double helix, sugar phosphate back bone,
How are nucleotides joined together?
phosphodiester linkage
hydroxyl group of 3 carbon phosphate group of 5 carbon
What are nucleotides?
phosphate, sugar, base
What are nucleosides?
base and sugar
How are the base and sugar joined together?
peptidic bond
How many hydrogen bonds does G+C have?
3
How many hydrogen bonds does A+T have?
2
How does DNA replication occur?
- ORI region (AT bases)
- DNA gyrase and helicase make DNA unwind
- DNA polymerase - synthesises template DNA
What enzymes promote the unwinding of DNA in DNA replication?
DNA gyrase and helicase
What is the core enzyme in Transcription?
RNA polymerase
What happens in transcription?
Coding strand is transcribed into mRNA
Where does transcription start?
At a promotor 10 bases up form start site
-10 TATAAT and -35 TTGACA
What is the transcriptional terminator?
inverted repeats forming a stem loop in the mRNA
What is the core enzyme in translation?
Ribosomes
What is the function of a ribosome?
to incorporate charged tRNA in the A site following the mRNA template
How are genomes organised in eukaryotes?
Several linear DNA molecules are present within the membrane enclosed nucleus
How are genomes organised in prokaryotes?
circular chromosome is packed into a structure called nucleoid
also contain plasmids
What does a genome contain?
genes, RNA, regulatory RNA regions, noncoding DNA regions
which genome is larger; bacterial or mammals?
mammals
How many genes are in 2 Mb genome?
2,000
How do prokaryotes replicate DNA?
bidirectional replication - two replication forks
from ORI to Ter
How is GC Skew measured?
GC skew = (G-C) /( G+C)
What is the GC skew used for?
to identify leading and lagging strand in bacterial chromosome
Which strand, leading or lagging, has more G+T?
leading
