12-3 Notes

RNA and Protein Synthesis

12-3 Vocabulary

• Messenger RNA- (mRNA)– RNA molecule that carries

copies of instruction for the assembly of amino acids into proteins from DNA to the rest of the cell.

• Ribosomal RNA- (rRNA)– Type of RNA that makes up

the major part of the ribosomes.

12-3 Vocabulary• Transfer RNA (tRNA)

– Type of RNA molecule that transfer amino acids to ribosomes during protein synthesis.

• Transcription-– Process in which part of the

nuclotide sequence of DNA is copied into complemetary sequence in RNA.

RNADNA

RNApolymerase

Adenine (DNA and RNA)Cystosine (DNA and RNA)Guanine(DNA and RNA)Thymine (DNA only)Uracil (RNA only)

12-3 Vocabulary

• RNA polymerase-– Enzyme similar to DNA

polymerase that binds to DNA and separates the DNA strands during transcription.

• Promoter– Region of DNA that indicates to

an enzyme where to bind to make RNA.

12-3 Vocabulary

• Intron-– Intervening sequence of DNA; does not code

for a protein.

• Exon-– Expressed sequence of DNA; codes for a

protein.

1. The Structure of RNA

a. It consists of long chains of nucleotides, like DNA

b.There are three main differences from DNA

RNA DNA

1) Sugar is ribose Sugar is deoxyribose

2) Single stranded Double stranded

Contains uracil Contains thymine

2.Types of RNAa. Main function is protein synthesisb. There are three main types of RNA

1) Messenger RNA (mRNA): carry copies of instructions for assembling amino acids

2) Ribosomal RNA (rRNA): located on ribosomes, where proteins are assembled

3) Transfer RNA (tRNA): transfers each amino acid to the ribosome as specified by mRNA

3. Transcriptiona. Transcription: the DNA

nucleotide sequence is copied into a complementary RNA sequence

b. The DNA strands unzips, and assembles nucleotides to form an RNA strand from the DNA template

c. mRNA is edited before leaving the nucleus

d. Introns (intervening sequences not needed in the code) are cut out leaving exons (expressed sequences needed in the code)

e. mRNA is sent to the ribosome