Transcription and Translation

Transcription and Translation

By Jackie Cates

Objective

Describe how proteins are made via the processes of transcription and translation. 

Science| Genetics​

Multiple Choice

What is responsible for the creation of proteins?

• DNA

• Nuclei

• Cytoplasm

• RNA

Protein Synthesis

• Development, function and structure of an organism are controlled by proteins. 

• Proteins are large, complex molecules made of subunits called amino acids. 

• Amino acids are linked together in specific sequences to form different proteins.

Multiple Choice

What are proteins made of?

• Amino Acids

• Chromosomes

• DNA

• Super Glue

Protein Synthesis

• The sequence of nucleotides in DNA determines the sequence of amino acids of a protein. 

• Specifically, the sequence of nucleotides in a gene - a segment of DNA that codes for a trait - codes for a protein, which controls that trait. 

With your table partner, answer this question...

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What do genes use to "create" the traits they code for?​

Protein Synthesis

• The process of decoding DNA to make a protein is called protein synthesis. 

• Protein synthesis is a two-step process. 

  1. The first step is called transcription. 

  2. The second step is called translation. 

Multiple Select

Which two of these processes are responsible for the creation of proteins?

• Transpiration

• Translation

• Transcription

• Transportation

Transcription

• The first step of protein synthesis is transcription.

• During transcription, a DNA nucleotide sequence (a gene) is transcribed into mRNA.

• Transcription takes place in the nucleus of the cell. 

• During transcription, the DNA molecule unwinds and unzips at the gene that will be transcribed. 

Multiple Choice

Where does transcription take place?

• Nucleus

• Cytoplasm

• Ribosome

• Mitochondria

Transcription

• Free RNA nucleotides “line up” along the gene that is to be transcribed. 

• They line up in a manner similar to the base pair rule, except there is no thymine in RNA – RNA has uracil. 

• Whenever there is an adenine nucleotide in DNA, a uracil nucleotide matches it.

Transcription

• The mRNA molecule is complementary to the DNA segment, the gene, on which it formed. 

• The RNA nucleotides bind together to form a molecule of mRNA. Once complete, the mRNA moves out of the nucleus and into the cytoplasm.

Please find the RNA Transcription practice link in Google Classroom and follow it. Then try to complete an mRNA sequence.

Transcription

Translation

• The second step of protein synthesis is translation.

• During translation, mRNA is translated into a protein (amino acid sequence).

• Translation occurs at ribosomes in the cytoplasm.

• tRNA brings free amino acids in the cytoplasm to the ribosome to help assemble the protein. 

Multiple Choice

In which part of the cell does translation occur?

• DNA

• Nucleus

• Ribosome

• Mitochondria

Translation

• The ribosome reads a sequence of three nucleotides at a time. The group of three nucleotides is called a codon. A codon codes for an amino acid. 

• There are 64 possible codons, but only 20 amino acids. Therefore, multiple codons code for the same amino acid. 

Multiple Choice

Which of these "codes" for an amino acid?

• RNA

• DNA

• Codon

• Anticodon

• A codon chart lists all the different codons and the amino acids they code for. 

• In order to translate the mRNA code into a protein, you must use this chart.

Translation

• Translation always begins with an AUG codon. This codon is called the start codon and codes for the amino acid methionine. Methionine is abbreviated met. Any nucleotides before AUG are ignored – they do not code for amino acids. 

Translation

• Translation ends with a stop codon. The codons UAA, UAG and UGA are the stop codons. A stop codon actually codes for nothing – it does NOT code for a “stop” amino acid. Because it codes for nothing, translation ends. Any nucleotides after the stop codon are ignored – they do not code for amino acids.

Translation

Protein Synthesis

• You can transcribe and translate a gene to determine the protein for which that gene codes. 

Step 1: Transcribe mRNA using the base-pair rule. Because there is no T in RNA, transcribe a U every time you come across an A in the DNA segment. 

DNA: T A C C C C G T G C A T A T A T C A T A T A G C A C T 

RNA: A U G G G G C A C G U A U A U A G U A U A U C G U G A

Step 2: Use the codon chart to translate the mRNA into an amino acid sequence. Start with AUG. Ignore nucleotides before the start codon. End with a stop codon. Use “–” to show that the amino acids link together.

RNA: A U G G G G C A C G U A U A U A G U A U A U C G U G A

Protein:   met - gly – his – val – tyr – ser – ile – ser

Amoeba Sisters time!!!!

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https://www.youtube.com/watch?v=oefAI2x2CQM​

Go to Gizmos and practice building proteins! :)