Unit 4: Genetic Information, Variation and Relationships between Organisms Lesson 4 tRNA and TranslationTHE STRUCTURE OF MOLECULES OF MESSENGER RNA (MRNA) AND OF TRANSFER RNA (TRNA).TRANSLATION AS THE PRODUCTION OF POLYPEPTIDES FROM THE SEQUENCE OF CODONS CARRIED BY MRNA. THE ROLES OF RIBOSOMES, TRNA AND ATP.

Starter: Where we left off: Look at this sequence of DNA bases on the sense strand:

(3’) TTACGTAGCCTGGTATAGCCC (5’)

1. Draw the antisense strand (1 mark)2. Draw the mRNA sense strand (1 mark)3. How many amino acids can be made from this

strand? (1 mark)4. Why might that number of Amino acids actually be

fewer? (2 marks)5. Explain fully how the mRNA strand is synthesised

from the DNA antisense strand (4 marks)

Learning Outcomes:

The structure of molecules of messenger RNA (mRNA) and of transfer RNA (tRNA).

Translation as the production of polypeptides from the sequence of codons carried by mRNA.

The roles of ribosomes, tRNA and ATP.

Learning Outcomes:

The structure of molecules of messenger RNA (mRNA) and of transfer RNA (tRNA).

Translation as the production of polypeptides from the sequence of codons carried by mRNA.

The roles of ribosomes, tRNA and ATP.

Off to the ribosomes we go!

mRNA is single stranded and so can fit through pores in nuclear membrane. It will leave the nucleus and go towards the rough ER/ribosomes.

Learning Outcomes:

The structure of molecules of messenger RNA (mRNA) and of transfer RNA (tRNA).

Translation as the production of polypeptides from the sequence of codons carried by mRNA.

The roles of ribosomes, tRNA and ATP.

tRNA - anticodons Learning Outcomes:

The structure of molecules of messenger RNA (mRNA) and of transfer RNA (tRNA).

Translation as the production of polypeptides from the sequence of codons carried by mRNA.

The roles of ribosomes, tRNA and ATP.

tRNA (transfer RNA) is coded for by DNA and produced the same way that mRNA is (by transcription). This type of RNA doesn’t act as a message for amino acid coding.

It has 3 sections:1 – the main body that is a sequence of bases that interact to form the structure seen2 - An amino acid attachment site3 – an anticodon

tRNA - anticodons Learning Outcomes:

The structure of molecules of messenger RNA (mRNA) and of transfer RNA (tRNA).

Translation as the production of polypeptides from the sequence of codons carried by mRNA.

The roles of ribosomes, tRNA and ATP.

Translation Is the production of a polypeptide from an mRNA template using tRNA and attached amino acids. This happens in the ribosomes.

Learning Outcomes:

The structure of molecules of messenger RNA (mRNA) and of transfer RNA (tRNA).

Translation as the production of polypeptides from the sequence of codons carried by mRNA.

The roles of ribosomes, tRNA and ATP.

https://www.youtube.com/watch?v=Ikq9AcBcohA

Summary Learning Outcomes:

The structure of molecules of messenger RNA (mRNA) and of transfer RNA (tRNA).

Translation as the production of polypeptides from the sequence of codons carried by mRNA.

The roles of ribosomes, tRNA and ATP.

Initiation:1. The mRNA enters the ribosome 3 codons at a time2. A tRNA with an antocodon to match frist mRNA codon join up by complentary base

pairing.3. The attached amino acid is lined up. 4. A second tRNA anticodon that matches the second mRNA joins. The second amino

acid in the chain lines up.5. Peptidyl transferse uses GTP to join the 2 amino acids in the correct arder. 6. The frist tRNA leaves the ribosome. Elongation:1. The process repeats one amino acid at a time until all amino acids are joined in

order. Termination:1. A stop codon on the mRNA is reached and no amino acid is joined this time. 2. The mRNA disconnects from the ribosome and so does the completed polypeptide.3. The polypeptide is sent to the golgi apparatus for further processing

AGU

SERINE

CUC

LEUCINE

CAC

HISTAMIN

E

UUU

PHENYLALAN

INE

ACG

THREONIN

E

AUA

ISOLEUCINE

CCA

PEPTIDYL TRANSFERASE AND GTP/ATP

Peptide bond

Peptide bond

Peptide bond

Peptide bond

Peptide bond

Peptide bond

Peptide bond

Peptide bond

Peptide bond Peptide bond

Peptide bond

Peptide bond

Peptide bond

Peptide bond

Peptide bond

Peptide bond

Peptide bond

Peptide bond

Peptide bond Peptide bond