3.1 Transcription and Translation

Transcription and Translation- Making proteins from DNA

Here is the slideshow from this week: 3.1 Transcription and Translation

What I will be learning....

I will be learning how proteins are made

Why I will be learning this......

The way I look, the way I feel, and the way I function are the responsibility of proteins.

How I will know I learned it

I will be able to describe the steps of Transcription and Translation, and the basics of how a protein is made.

The whole purpose of DNA is to make the proteins. 

Where do fireflies get the chemical luciferin make your structures like bones and ears and hair, and to help run the body with important worker proteins , like hemoglobin that carries oxygen in your blood.

Phenomenon: Watch this  1 minute Video of  fireflies

Fireflies produce light through a process called bioluminescence, a chemical reaction within their bodies that converts chemical energy into light energy.  This reaction occurs in specialized light-producing organs in their abdomens, where the chemical Luciferin reacts with oxygen and an enzyme called luciferase in the presence of oxygen to make light.  

1. When a molecule name ends with "ase" it indicates its a special kind of protein that helps chemical reactions speed up. What is that type of protein?

2.  Where are the instructions for making the protein Luciferase?

3. What would happen to a firefly that couldn't "light-up"?

Making Proteins

DNA has the instructions to make RNA.  RNA has the instructions to make proteins.  A funny term, Central Dogma,  means just that.  "Dogma" is a set of beliefs.  Scientists once believed that the creation of proteins always went in this order DNA is used to make RNA.  RNA is then used to make proteins. Since the early study of DNA and Proteins, we have learned that there are exceptions to this rule, but for the most part  Central Dogma is true.  DNA is used to make RNA.  Then RNA is used to make proteins.  Making RNA from DNA is called TRANSCRIPTION.  Making proteins from RNA is called TRANSLATION. Trasncription happens in the nucleus of the cell.  Translation happens in the cytoplasm of the cell on an organelle called a ribosome.  

THREE DIFFERENCES BETWEEN RNA AND DNA

There are three differences between RNA and DNA

1. DNA uses the sugar DEOXYRIBOSE and RNA uses the sugar RIBOSE in the nucleotide bases. They are exactly the same except for one oxygen atom.  See if you can spot it.

2. RNA IS A SINGLE STRAND

3. RNA uses URACIL for a nucleotide base instead of Thymine

THREE TYPES OF RNA

The RNA can be made into different shapes, and used in different ways.  The three main type of RNA are mRNA, which means messenger RNA, tRNA, which means transfer RNA, and rRNA, which means ribosomal RNA. 

RNA and Protein Synthesis

Your DNA, or deoxyribonucleic acid, contains the genes that determine who you are. How can this organic molecule control your characteristics? DNA contains instructions for all the proteins your body makes. Proteins, in turn, determine the structure and function of all your cells.

What determines a protein’s structure? It begins with the sequence of amino acids that make up the protein.  Amino acids are the small molecules, the monomers, that are bonded together to make long chains we call a protein. Protein chains are then folded up into the different shaped molecules your body needs.

Protein video

Instructions for making proteins with the correct sequence of amino acids are encoded in DNA. DNA is found in chromosomes. The chromosomes in your cells always remain in the nucleus, but proteins are made at ribosomes in the cytoplasm. How do the instructions in DNA get to the site of protein synthesis outside the nucleus? Another type of nucleic acid is responsible. This nucleic acid is RNA, or ribonucleic acid. RNA is a small molecule that can squeeze through pores in the nuclear membrane. It carries the information from DNA in the nucleus to a ribosome in the cytoplasm and then helps assemble the protein.

The structure of RNA is similar to the structure of DNA, but they are not identical. RNA contains three of the same bases as DNA, but does not include thymine.Instead, RNA has the base uracil (U). The other major difference between DNA and RNA is that RNA is single stranded, instead of double stranded like DNA. This means that the bases of RNA are available to bond with other nucleotides. This part of RNA’s structure is very important to its function in making proteins. There are three types of RNA directly involved in protein synthesis: ● Messenger RNA (mRNA) carries the instructions from the nucleus to the cytoplasm. mRNA is produced in the nucleus, as are all RNAs. ● The other two forms of RNA, ribosomal RNA (rRNA) and transfer RNA (tRNA), are involved in the process of ordering the amino acids to make the protein.

Ribosomal RNA becomes part of the ribosome, which is the site of protein synthesis, and tRNA brings an amino acid to the ribosome so it can be added to a growing chain during protein synthesis. There are numerous tRNAs, as each tRNA is specific for an amino acid. The amino acid actually attaches to the tRNA during this process. The process of protein synthesis is summarized in the diagram below. DNA produces an RNA template which then directs the amino acids to be introduced into the growing protein chain in the proper sequence. A specific transfer-RNA (tRNA) attaches to each specific amino acid and brings the amino acid to the RNA for incorporation.

The first step in the process is transcription, the unfolding of DNA and the production of a messenger-RNA (mRNA) strand. This step takes place in the nucleus of the cell. The DNA uncoils and provides the pattern for the formation of a single strand of mRNA.

TRANSCRIPTION

1. A single stranded RNA molecule is built against the DNA, inside the nucleus. When the RNA detaches from the DNA, the DNA winds back up. 

2. The RNA strand is then processed.  Introns are cut out and the finished mRNA strand is ready to go.  An intron is a non-coding section of DNA/RNA.  

3. The mRNA leaves the nucleus through a pore in the nuclear membrane.

TRANSLATION

4. In the cytoplasm it settles on a ribosome (rRNA),which will read the mRNA in sections of three, called codons. 

5. The codons are an actual code.  The three nucleotide bases in the codon bond with the three bases on tRNA ( transfer RNA).  Those three nucleotide bases in tRNA are called the ANTI-CODON.  The anticodon brings one specific amino acid with it, that those three letters "code for" .  There are 20 amino acids.

The order of amino acids determines the final shape of the protein, so it is important that the amino acids are in the right order. Use the figure below to study the relationship between the order of bases in the mRNA and the order of the amino acids. The process of protein synthesis is fairly fast. Amino acids are added to the growing protein at a rate of about 3-5 amino acids per second. A small protein (100-200 amino acids) can be produced in a minute or less.  

Learn Genetics Transcription and Translation

How to Use a Codon Chart

Each set of three bases on mRNA code for a specific amino acid.  A codon chart helps use to read the mRNA, so we can know which of the 20 amino acids its codons match to.  There are a couple kinds of codon chart, rectangular and a wheel shape.  They are both good to use.  Watch this video to understand how to use your codon chart. Amoeba Sisters Codon Charts

Now you try decoding:

mRNA  UUA

mRNA  UAU

mRNA GCU

Back to Fireflies- Watch this video Utah Learn Genetics: How do Fireflies Glow