PROTEIN SYNTHESIS copyright cmassengale 1 Protein Synthesis DNA

PROTEIN SYNTHESIS copyright cmassengale 1

Protein Synthesis • DNA ‘s code must be copied and taken to the ribosomes. • In the ribosomes, this code must be read so amino acids can be assembled to make proteins. • This process is called PROTEIN SYNTHESIS copyright cmassengale 2

RNA copyright cmassengale 3

Roles of RNA and DNA • DNA is the MASTER PLAN • RNA is the BLUEPRINT (copy) of the Master Plan copyright cmassengale 4

RNA Differs from DNA • RNA has a sugar ribose DNA has a sugar deoxyribose copyright cmassengale 5

Other Differences • • RNA contains the base uracil (U) DNA has thymine (T) RNA molecule is single-stranded DNA is doublestranded copyright cmassengale DNA 6

Structure of RNA copyright cmassengale 7

Remember the Complementary Bases On DNA: A-T C-G On RNA: A-U C-G copyright cmassengale 8

. Three Types of RNA • Messenger RNA (m. RNA) copies DNA’s code & carries the genetic information to the ribosomes • Ribosomal RNA (r. RNA), along with protein, makes up the ribosomes • Transfer RNA (t. RNA) transfers amino acids to the ribosomes where proteins are synthesized copyright cmassengale 9

Messenger RNA • Long Straight chain of Nucleotides • Made in the Nucleus • Copies DNA & carries info to ribosomes. copyright cmassengale 10

Ribosomal RNA (r. RNA) • Globular in shape • Are part of the ribosomes actual structure. • Site of protein Synthesis (where the proteins are made) copyright cmassengale 11

Transfer RNA (t. RNA) • Clover-leaf shape • Single stranded molecule. • Attachment site at one end for an amino acids. • Opposite end has three nucleotide bases called the anticodon. copyright cmassengale 12

Transfer RNA amino acid attachment site U A C anticodon copyright cmassengale 13

Codons and Anticodons • The 3 bases of an anticodon are complementary to the 3 bases of a codon • Example: Codon ACU Anticodon UGA copyright cmassengale UGA ACU 14

Transcription and Translation (The actual making of a protein. ) copyright cmassengale 15

Protein Synthesis § The production or synthesis of proteins. § Two phases: Transcription & Translation copyright cmassengale 16

Transcription • The process of copying the sequence of one strand of DNA, the template strand. • m. RNA copies the template strand. copyright cmassengale 17

Transcription • During transcription, RNA polymerase binds to DNA and separates the DNA strands • RNA Polymerase then uses one strand of DNA as a template to assemble nucleotides into RNA copyright cmassengale 18

Transcription • Promoters are regions on DNA that show where RNA Polymerase must bind to begin the Transcription of RNA Called the TATA box. copyright cmassengale 19

Transcription • Specific base sequences act as signals to stop Called the termination signal. • Once the Polymerase is done it falls off, the DNA re-zips up and the m. RNA escapes out the nucleus. copyright cmassengale 20

m. RNA Transcript • m. RNA leaves the nucleus through its pores and goes to the ribosomes. copyright cmassengale 21

Translation • Translation is the process of decoding the m. RNA into a protein. • Ribosomes read m. RNA three bases or 1 codon at a time and construct the proteins copyright cmassengale 22

Step 1 - Initiation • m. RNA enters the ribosome and attaches to the t. RNA. The t. RNA has an anticodon that matches with the three “start” nucleotides. 23

Initiation amino 2 -t. RNA 1 -t. RNA anticodon hydrogen bonds U A C A U G codon aa 2 G A U C U A C U U C G A copyright cmassengale m. RNA 24

Step 2 - Elongation • The ribosome moves down the m. RNA strand. • The first t. RNA detaches and leaves it’s amino acid. • Two new t. RNA with their amino acids move into position (positions are called A and P) • The new t. RNAs have the correct amino acid for that specific codon. Each copyright cmassengale 25 amino Acid forms a bond.

Amino 1 peptide bonds Amino 2 Amino 4 Amino 3 4 -t. RNA 2 -t. RNA A U G 3 -t. RNA G C U G A A C U U C G A A C U m. RNA copyright cmassengale 26

Amino 1 peptide bonds Amino 5 Amino 2 Amino 3 Amino 4 5 -t. RNA U G A 3 -t. RNA 4 -t. RNA G A A G C U A C U U C G A A C U m. RNA copyright cmassengale 27

Termination • t. RNA’s will continue to read m. RNA and hook up amino acids until “stop” codon is reached. • A “stop” codon is three nucleotides on the m. RNA that t. RNA does not have an anticodon for. copyright cmassengale 28

Dissaembly • When the stop codon is reached the ribosome falls off, the protein goes into the body, and the t. RNAs go out to find more amino acids. • The ribosome will go find another strand of m. RNA and the 29 whole process starts over.

End Product –The Protein! • The end products of protein synthesis is a primary structure of a protein • A sequence of amino acid bonded together by peptide bonds 2 1 3 4 5 199 copyright cmassengale 200 30