Protein Synthesis & Transcription Flashcards
What are the different types of RNA made in the nucleus?
- messenger RNA (mRNA)
- transfer RNA (tRNA)
- ribosomal RNA (rRNA)
What type of RNA is formed in the nucleus in the same way as DNA is replicated?
- mRNA
What is the process of mRNA formation called?
- transcription
What is transcription?
- the process by which DNA makes and codes mRNA
How does the process of transcription start?
- when a small piece of DNA, a gene, unwinds
What catalyses the initial unwinding of a gene in transcription?
- the enzyme RNA polymerase
What does RNA polymerase specifically do?
- causes the 2 strands of DNA to separate
- by breaking the hydrogen bonds between complementary DNA nucleotides
What happens during transcription after the gene unwinds?
- the polymerase attaches to and moves along one of the DNA strands
- causing new nucleotides to pair up with their complementary nucleotides
What happens during transcription after the new nucleotides pair up with their complementary nucleotides?
- the nucleotides join up
- a sugar-phosphate backbone is added
- a new strand of mRNA is formed
What is the sequence of nucleotides in a strand of mRNA determined by?
- the sequence of the template DNA nucleotides
What happens after a completed mRNA strand is formed during transcription?
- it breaks away from the DNA
- the DNA then re-zips
What happens to the newly formed strand of mRNA after transcription has occurred?
- it moves through the pores of the nuclear membrane
- carries the genetic code to the ribosomes
- which are the sites of protein synthesis
What is a protein?
- a long chain (polymer) of small units (monomers) called amino acids
How many different amino acids are there involved in protein synthesis?
- 20
What determines the kind of protein that is made?
- the order in which the amino acids are linked