DNA, RNA, and Proteins

DNA and Protein Synthesis-REPEAT DNA contains 4 bases. They are: Adenine (A)-pairs with Thymine only Thymine (T)-Pairs with adenine only Guanine (G)-pairs with cytosine only Cytosine (C)-pairs with guanine only DNA contains the genetic information to make amino acids Amino acids combine to make proteins These proteins determine the physical traits of an organism and control cellular functions. Proteins do everything, and DNA gets all the credit! Think of them as tiny minions who do all the work

Codon: three bases code for a specific protein: ex: AAA = Lysine DNA and Protein Synthesis Codon: three bases code for a specific protein: ex: AAA = Lysine The codons code for 20 amino acids Just like the alphabet has 26 letters to make all the words we know, the 20 amino acids make all the different proteins found in living organisms This makes it possible to have 64 different combinations for amino acids The codons are the template for protein synthesis Protein synthesis is the production of protein which takes place on the ribosomes in the cytoplasm **Protein is very important because it triggers many cell processes as we learned earlier

But… How does the information get from the DNA to the cytoplasm? DNA and Protein Synthesis But… How does the information get from the DNA to the cytoplasm? mRNA

RNA DNA must be decoded to work The structure of RNA is similar to DNA but has 3 differences Sugar in RNA is Ribose RNA is single-stranded Uracil replaces thymine

3. Three main types of RNA Messenger RNA (mRNA)-This contains instructions for joining amino acids to make proteins; three consecutive nucleotides make up a codon (a single amino acid). The complimentary trio is an anticodon Ribosomal RNA (rRNA)-Assembles proteins into ribosomes Transfer RNA (tRNA)-carries each amino acid to the ribosome according to a coded message from mRNA

Bring amino acids to ribosome RNA Concept Map Section 12-3 RNA can be Messenger RNA Ribosomal RNA Transfer RNA also called which functions to also called which functions to also called which functions to mRNA Carry instructions rRNA Combine with proteins tRNA Bring amino acids to ribosome from to to make up DNA Ribosome Ribosomes

Transcription-The process of copying DNA into RNA (for decoding of DNA) making it possible for a gene in DNA to be copied hundreds of times The DNA strands separate or “unzip”) Nucleotides of RNA match up and join the DNA strand-they are creating mRNA **Bases pair up the same way except uracil binds with adenine instead of thymine c. The completed RNA strand is released and moves into the cytoplasm

RNA polymerase DNA RNA Adenine (DNA and RNA) Cystosine (DNA and RNA) Guanine(DNA and RNA) Thymine (DNA only) Uracil (RNA only) Adenine (DNA and RNA) Cystosine (DNA and RNA) Guanine(DNA and RNA) Thymine (DNA only) Uracil (RNA only) RNA polymerase DNA RNA

DNA G A T T A C A C U A A U G U mRNA DNA and Protein Synthesis Practice making mRNA using the DNA template DNA G A T T A C A C U A A U G U mRNA

5. Translation -RNA is a molecule that contains instructions for making proteins. This process occurs on the ribosome. mRNA moves into the cytoplasm and attaches to a ribosome (rRNA) The rRNA decodes the message and sends out tRNA to pick up an amino acid Each codon has an anticodon brought in by tRNA to compliments or pair up (CGA pairs with GCU) forming bonds (like puzzle pieces) tRNA breaks away to allow another one to bring in a new anticodon A long chain is built until a stop codon is reached (there are three possible types)

Translation

The Genetic Code Wheel

Codons and amino acids: This is the message from mRNA and is translated by rRNA and it tells tRNA what amino acid to pick up and add to the protein chain Name the Amino Acid for each anticodon: UAU CCG AGU GCA Tyrosine Proline Serine Alanine What do you think the DNA codon was for these anticodons?

Journal ; Determining the Sequence of a Gene DNA contains the code of instructions for cells. Sometimes, an error occurs when the code is copied. Such errors are called mutations. 1. Copy the following information about Protein X: Methionine—Phenylalanine—Tryptophan—Asparagine—Isoleucine—STOP. 2. Use the Genetic Code Wheel to determine one possible sequence of RNA to code for this information. Write this code below the description of Protein X. Below this, write the DNA code that would produce this RNA sequence.

3. Now, cause a mutation in the gene sequence that you just determined by deleting the fourth base in the DNA sequence. Write this new sequence. 4. Write the new RNA sequence that would be produced. Below that, write the amino acid sequence that would result from this mutation in your gene. Call this Protein Y. 5. Did this single deletion cause much change in your protein? Explain your answer.

12-4: Mutations Mutations are changes in the genetic material. A. Kinds of Mutations 1. gene mutations-mutations that produce changes in a single gene a. point mutations- Gene mutations involving a change in one or a few nucleotides that occur at a single point in the DNA sequence. 1. substitutions-one base replaces another.

2. Frameshift Mutations a 2. Frameshift Mutations a. The effects of insertions or deletions are more dramatic. b. The addition or deletion of a nucleotide causes a shift in the grouping of codons. c. Types 1. insertions- an extra base is inserted into a base sequence 2. deletions- loss of a single base is deleted and the reading frame is shifted

3. chromosomal mutations- mutations that produce changes in the number or structure of chromosomes. a. Types 1. Deletion-the loss of all or part of a chromosome. 2. Duplication- produce extra copies of parts of a chromosome. 3. Translocation-occurs when part of one chromosome breaks off and attaches to another 4. Inversion- reverse the direction of parts of chromosomes.

B. Significance of Mutations Many mutations have little or no effect on gene expression. Some mutations are the cause of genetic disorders. Beneficial mutations may produce proteins with new or altered activities that can be useful. Example: Polyploidy is the condition in which an organism has extra sets of chromosome