TRANSCRIPTION AND TRANSLATION

Bell Ringer (5 MINUTES)1. Have your homework (any missing

work) out on your desk and ready to turn in

2. Draw and label a nucleotide.3. Summarize the steps of DNA

replication.

TURN AND TALK

❑ If DNA is universal, then why do we as humans look different from other living things?

PART 1: TRANSCRIPTION

To transcribe means to put information into a written form

Benchmark Objectives✓ Compare and

contrast RNA and DNA.

✓ Describe the processes of transcription and translation.

What are we learning today?

SC.912.L.16.5 – Explain the basic processesof transcription and translation, and how theyresult in the expression of genes.

Introduction

• From DNA to protein• https://www.youtube.com/watch?v=gG7uCsk

UOrA

What is the essential vocabulary?

✓ RNA polymerase – enzyme that binds to DNA and separates the DNA strands during transcription.

✓ Transcription – Process during which RNA molecules are producedby copying part of the nucleotidesequence of DNA.

✓ Intron – sequence of DNA that is notinvolved in coding for a protein.

✓ Exon – sequence of DNA that isinvolved in coding for a protein.

How is DNA like or not like RNA?

❑ RNA and DNA are nucleic acids.❑ RNA, like DNA consist of a

long chain of nucleotides.❑ There are three main

differences between RNA and DNA:❑ The sugar in RNA is

ribose, the sugar in DNAis deoxyribose.

❑ RNA is single stranded, DNA is double stranded.

❑ RNA contains uracil (U)DNA contains thymine (T)

What are the three types of RNA?

Abbrev. Name Function Structure

mRNA Messenger RNA

Carries instructions for making proteins from DNA to ribosomes.

Single-stranded

tRNA TransferRNA

Reads mRNA sequence and transfers each amino acid to the ribosome.

A clover leaf

rRNA Ribosomal RNA

Binds amino acids together to make a peptide chain (protein)

Complex, with

proteins

How does transcription works?

❑ RNA molecules are produced by copying part of the nucleotide sequence of DNA into a complementary sequence in RNA during a process called transcription.

❑ Transcription requires an enzyme known as RNA polymerase.

❑ RNA polymerase onlybinds to regions in DNA known as promoterswith specific basesequences.

❑ Promoters are signalsin DNA that indicateto the enzyme whereto bind to make RNA.

How does transcription works?

1. Initiation: RNA polymerase binds to DNA and separates the DNA strands.

2. Elongation: RNA polymerase uses one strand of DNA as a template to add nucleotides, making a strand of RNA.

3. Termination: When RNA polymerase reaches a stop signal in the DNA, the DNA and new mRNA are released.

How does transcription work?

A certain gene has the following sequence of nucleotides. From left to right, write the sequence of the mRNA molecule transcribed from this gene.

DNA 3’ GACAAGTCCACAATC 5’

mRNA

Intron Exonsnucleotides NOT involved with coding proteins-cut out of RNA molecules while they are still in the nucleus

nucleotides that code for proteins

Draw in your notebook

PART 2: TRANSLATION

To translate is to express meaning in a different

language or to move something from one place

to another

What is the essential vocabulary?

✓ Genetic code – Instructions needed to convert DNA into proteins.

✓ Codon – Three consecutive nucleotidesthat in mRNA that specify a single aminoacid.

✓ Anticodon – Three adjacent nucleotideslocated on tRNA that binds tothe mRNA codon

✓ Translation – Protein synthesis using mRNA as a template.

What is the essential vocabulary?

✓ Amino acid – building block, or monomer,of all proteins.

✓ Ribosome – organelle in the cell that is in charge of producing proteins

✓ Polypeptide chain – a group of amino acids joined together that form proteins

How do proteins function?❑ Proteins are made by joining amino acids together into long

chains, called polypeptides chains. ❑ Each polypeptide contains a combination of any or all of

the 20 different amino acids.❑ The properties of a protein are determined by the specific

amino acids in a polypeptide chain and the order in which different amino acids are joined together.

amino acid + amino acid Protein

What is the genetic code?

❑ The “language” of mRNA instructions is called the genetic code.

❑ RNA contains four different bases:A, U, G, C.

❑ The genetic code is read three letters at a time, each three-letterword is known as a codon.

❑ There are 64 possible three-base codons.

Genetic Code Chart

How does a cell interpret DNA?

❑ Consider the following RNA sequence:

5’UCGCACGGU3’

❑ This sequence will be read three bases at a time as:

UCG – CAC – GGU

❑ The codons represent the following amino-acids.

Serine – Histidine – Glycine

How does a cell interpret DNA?

Consider the following RNA sequence and identify the amino acids it will code for.

5’AUGCGCUUCUAA3’

Consider the following DNA sequence and identify theamino acids it will code for.

3’CTTGGAATG5’

What is translation?

❑ The decoding of an mRNA message into a polypeptide chain is known as translation.

❑ Translation takes place on ribosomes.

❑ During translation, or protein synthesis, the cell uses information from mRNA to produce proteins.

❑ The cell uses all three main forms of RNA during translation.

How does translation work?

❑ Messenger RNA is transcribed in the nucleus and then enters the cytoplasm for translation.

How does translation work?

1. INITIATIONA ribosome attaches to an mRNA molecule in the cytoplasm and a tRNA molecule carrying methionine (start codon = AUG) binds to ribosome.

How does translation work?

2. ELONGATIONAs the ribosome reads each codon of mRNA, it directs tRNA with the matching anticodon to bring the specific amino acid into the ribosome. One at a time, the ribosome attaches each amino acid to the growing chain.

How does translation work?

3. TERMINATIONThe polypeptide chain continues to grow until the ribosome reaches a “stop” codon (UGA, UAA, UAG) on the mRNA molecule.

How does translation work?

4. DISASSEMBLYRibosome falls apart, releasing both the newly formed polypeptide and the mRNA molecule, completing the process of translation

Let’s Recap What We Learned

• https://www.youtube.com/watch?v=gG7uCskUOrA

Partner Work 25 MIN.• READ ALL THE INSTRUCTIONS!!!• Stay with your partner at your lab

table and DO NOT walk around the room

• Before you ask for help, try to find the answer on your own by looking in your notes

Independent Practice 15 MIN.

-On my website www.mahoneybiology.wordpress.com

SILENTLY AND INDEPENDENTLY

Exit Ticket

-On my website www.mahoneybiology.wordpress.com

SILENTLY AND INDEPENDENTLY

Home Learning• Make Frayer Models for

the processes of transcription and translation (one Frayer Model for each)

• For each process include:

1. Definition2. Illustration3. Steps4. Importance in living

things