1.3.5 - DNA and protein synthesis

Question 1

what do RNAs do?

Answer 1

carry the instructions for a polypeptide
picks up specific amino acids
makes up the bulk of ribosomes

Question 2

what is mRNA?

Answer 2

messenger RNA
formed in the nucleus on the antisense strand of DNA
has instructions for one polypeptide

Question 3

what is tRNA?

Answer 3

transfer RNA
found in cytoplasm
one part has a sequence of three bases that matches genetic code of DNA (the anti-codon)
also has a binding site (picking up amino acids always free in the cytoplasm)

Question 4

what is rRNA?

Answer 4

ribosomal RNA
makes up 50% of the structure of a ribosome
made in nucleus
moves to cytoplasm to bind to proteins to form ribosomes

Question 5

describe the process of transcription in protein synthesis.

Answer 5

DNA directed RNA polymerase attaches to a non-coding section of DNA (in the nucleus)
enzyme separates the two strands
it continues to move along the DNA to reach the coding region of a gene
enzyme adds complementary RNA nucleotides to the template strand
enzyme links the RNA nucleotides together to form a strand of mRNA

Question 6

describe the process of translation in protein synthesis.

Answer 6

strand of mRNA travels out of the nucleus through a nuclear pore
in the cytoplasm, a ribosome (made of rRNA) attaches to the mRNA strand
a tRNA molecule pairs up with each codon
the ribosome joins together the amino acids carried by the tRNA (which has an anti-codon and specific amino acid)
this results in the formation of a polypeptide