Protein Synthesis. 5.1 I can explain the steps in the process of transcription, along with where they take place (this includes the role of DNA and mRNA)

Protein Synthesis

5.1 I can explain the steps in the process of transcription, along with where they take place (this includes the role of DNA and mRNA) 5.2 I can explain the steps in the process of translation, along with where they take place (this includes the role of mRNA, tRNA, ribosomes (rRNA), and amino acids) 5.3 I can list the three different types of RNA and describe the function of each. 5.4 I can describe at least three differences between DNA and RNA. 5.5 I can label the following items in pictures of transcription and translation: DNA sense strand, DNA nonsense strand, RNA polymerase, mRNA strand, ribosome, start codon, stop codon, amino acid, polypeptide chain (protein), tRNA, anti-codon, peptide bond 5.6 I can describe at least three different types of mutations in DNA, and their possible effects on the organism.

I can explain the steps in the process of transcription, along with where they take place (this includes the role of DNA and mRNA)

Every cell faces a fundamental problem when making proteins. The instructions for making the proteins are in the nucleus on the DNA. BUT The location for making proteins is outside the nucleus at the ribosomes.

The first part of the solution is a process called TRANSCRIPTION

First, an enzyme called RNA polymerase attaches to DNA at the beginning of a gene. The enzyme unzips the double helix strand and begins to read the instructions, coded in the sequence of the letters A, T, C, and G.

As the enzyme reads the DNA code, it copies it by attaching complementary RNA nucleotides. The result is a strand of mRNA (messenger RNA) which carries the instructions for making a protein. RNA polymerase RNA nucleotide Growing mRNA strand

Well, were making a copy of the DNA, and the DNA can be found where? In the nucleus. The DNA cant leave the nucleus for two reasons: Its too large to get through the pores, and its too precious to send it out into the cytoplasm where digestive enzymes could break off pieces of it.

it leaves the nucleus to go take the DNAs message to a ribosome where the protein will be made. So mRNA solves the problem of getting the information from the nucleus to the cytoplasm. Now to make the protein!!

I can explain the steps in the process of translation, along with where they take place (this includes the role of mRNA, tRNA, ribosomes (rRNA), and amino acids)

The cell has another problem. It has to take the language of nucleic acids (DNA/RNA) and turn it into the language of amino acids (protein). So it needs a translator otherwise known as the ribosome!

First, the mRNA threads into the ribosome, until the start codon AUG, reaches the P site in the ribosome.

Next, the ribosome brings in a tRNA (transfer RNA). On one end of the tRNA is an anti-codon that is complementary to the codon on the mRNA. On the other end of the tRNA is an amino acid.

A tRNA also binds at the A site. A peptide bond forms between the two amino acids, connecting them together. Then the tRNA in the P site leaves (leaving behind its amino acid), and the ribosome moves to the next codon. The process continues this way until it reaches a stop codon.

Once the ribosome reaches a stop codon, everything detaches. The protein finishes its production by folding a certain way so that it can do its job. The ribosome will make another protein. The mRNA gets recycled by digestive enzymes in the cytoplasm. The tRNA will pick up more of their amino acids to help build another protein.

I can list the three different types of RNA and describe the function of each.

1. mRNA (messenger RNA) carries the message of the DNA from the nucleus to the ribosome; created during transcription. 2. tRNA (transfer RNA) transfers amino acids to the growing chain of amino acids in the ribosome during translation. 3. rRNA (ribosomal RNA) what ribosomes are made of.

I can describe at least three differences between DNA and RNA.

DNA: Double-stranded Deoxyribose is the sugar G, C, A, and T are the bases Very long RNA: Single-stranded Ribose is the sugar G, C, A, and U are the bases Much smaller (one gene)

I can label the following items in pictures of transcription and translation: DNA sense strand, DNA nonsense strand, RNA polymerase, mRNA strand, ribosome, start codon, stop codon, amino acid, polypeptide chain (protein), tRNA, anti-codon, peptide bond

DNA nonsense strand mRNA strand DNA sense strand RNA polymerase

tRNA Peptide bond Polypeptide chain Amino acid Stop codon mRNA strand Start codon anticodon ribosome

I can describe at least three different types of mutations in DNA, and their possible effects on the organism.

There are two main categories of mutations that we discuss: Chromosomal mutations, which involve changes in whole genes on a chromosome (we will look at these next unit) Gene mutations, which involve changes in parts of genes.

There are two main types of gene mutations: point mutations, and frameshift mutations. A point mutation is when one base is switched out for another base. It only affects that one amino acid in the sequence. A frameshift mutation is when one base is deleted or added, which shifts all the bases after it, affecting all of the amino acids in the sequence after the mutation.

Lets say the following sentence is a gene, and each word in the sentence is a codon (even though the words have more than three letters): Biology students are really nice people.

For a point mutation, one base is switched for another base. Biology students ate really nice people. We changed the r in are to a t. As you can see, only one word was affected. However, the whole meaning of the sentence has changed.

Look at your codon chart. Is every amino acid coded for by one codon? No! There are repeats, right? So if we changed the last base of the codon, sometimes it would still code for the same amino acid. If this is the case, is there any change in the protein? No we call it a silent mutation because there was no effect on the organism.

In an addition mutation, one base is repeated. So we will add one letter twice. Biology students sar enic epeopl e. We put in an additional s after students. Now, every word (or codon) after the addition is affected because every base afterward is shifted down one.

In a deletion mutation, one base is deleted from the sequence. Biology studenta ren icep eople. We deleted the s at the end of students. Now, it shifts all the bases afterward up one.

Effects of mutations can be minor, or severe. They can be beneficial, harmful, or as weve seen, neutral. Its hard to discuss which type is worse than others, because while frameshifts render the entire protein useless and may appear worse at a glance, point mutations can be equally devastating. Lets take a look at one such case.

Protein Synthesis. 5.1 I can explain the steps in the process of transcription, along with where they take place (this includes the role of DNA and mRNA)

Documents

mrna slide

mrna strand slide

transcription slide

role of dna

protein synthesis slide

role of mrna

strand of mrna messenger

dna code