CH 17: Gene Expression Flashcards
DNA
double stranded, its a polymer of 4 different nucleotide monomers. they are C, G, A, T
RNA (the messenger)
single stranded, its a polymer of 4 different nucleotide monomers. they are C, G, A, U
Protein
Polymer of 20 different amino acid monomers
transcription happens
in the nucleus (for eukaryotes)
translation happens
in the cytoplasm on a ribosome
Ribosomes are made up of rRNA. they make….
proteins
nucleotide
a molecule that has 3 sections
polymerase copies in which direction
3’ to 5’
on the leading strand,
DNA replication moves along with the replication fork, requires on the initial primer
on the lagging strand,
polymerase has to go one chunk at a time, as new template is made available. the templates are called OKAZAKI Fragements,
DNA Polymerase I
swaps the primer nucleotides for DNA nucleotides on the lagging strand
ligase
makes sure all the nucleotides are connected
In transcription,
enzymes use of one the strands of DNA as a template to produce mRNA
how does DNA produce messenger RNA
RNA polymerase (with the help of proteins called transcription factors), binds to a specific sequence within the gene, which is called the promoter, and pries the two strands apart. One of the strands will serve as the template (antisense strand), and the other is the nontemplate (sense strand).
Does RNA polymerase need a primer?
No, it simply initiates mRNA synthesis at the start of the codon, and then moves downstream along the gene in a process called elongation, synthesizing the mRNA as it goes.
