DNA, RNA & Protein Synthesis Packet 7

Notes DNA Structure

DNA Structure DEOXYRIBONUCLEIC ACID DNA stands for – What group of organic molecules does DNA belong to? DNA is responsible for storing & transferring from one generation to the next. It also contains the codes for making all the in your body. NUCLEIC ACIDS GENETIC INFORMATION PROTEINS 1. DNA Structure 2. Journey into DNA 3. DNA to Protein

DNA Structure The building blocks of DNA are Look at the 12 different nucleotides given to your group. What are the three parts in a nucleotide? NUCLEOTIDES DEOXYRIBOSE (SUGAR), PHOSPHATE, NITROGEN BASE

DNA Structure What are the TWO common parts of the nucleotides? In other words what two parts are identical between all the pieces? Notice one of the words ends in –ose. What type of molecule is this? What group of organic compounds does this belong to? What is the ONE part of a nucleotide that is DIFFERENT among the nucleotides in your group? List the letters for the four nitrogen bases: DEOXYRIBOSE (SUGAR) AND PHOSPHATE SUGAR CARBOHYDRATE NITROGEN BASE (A) – ADENINE (G) – GUANINE (C) – CYTOSINE (T) - THYMINE

DNA Structure DOUBLE HELIX DEOXYRIBOSE (SUGAR) AND PHOSPHATE Your completed model should look like a ladder. Besides being shaped like a ladder, a DNA molecule is twisted. It looks like a spiral staircase. However, your paper model cannot show this shape. This shape is known as a If DNA is “ladder like,” which two molecules of a nucleotide form the sides or upright portion of the ladder? Which molecules form the rungs of the ladder? What is the pairing arrangement of the nitrogen bases? This kind of pairing is called complementary. The base pairing rule states that:   If four guanine bases appear in a DNA model, how many cytosine bases should there be? DOUBLE HELIX DEOXYRIBOSE (SUGAR) AND PHOSPHATE NITROGEN BASE __A____ pairs with ___T___ ___C___ pairs with ___G____ FOUR

Purines vs pyrimidines Notice that the nitrogen bases are different sizes. are larger and are made of 2 rings or units and are called purine bases. are smaller and are made of only 1 ring or unit and are called pyrimdine bases. A purine base always pairs with a base. ___A____ and ___G___ ___T____ and ___C___ PYRIMIDINE

DNA Structure 2 3 HYDROGEN P The bases pairs in the double helix are held together by weak bonds. A and T are held together by (#)_________ hydrogen bonds C and G are held together by (#)_________ hydrogen bonds The backbone of DNA is made up of alternating (D) and (P) molecules which are held together by strong bonds. The two opposing strands are said to be since by knowing one half you can figure out the other) What is the same about DNA between all organisms? What is different about DNA between all organisms? HYDROGEN 2 3 DEOXYRIBOSE PHOSPHATE COVALENT COMPLEMENTARY THE SAME 4 NUCLEOTIDES ARE IN ALL ORGANISMS. THEY ARE MOSTLY THE SAME EXCEPT FOR THE ORDER OF THE NUCLEOTIDES, THE NUMBER OF CHROMOSOMES AND THE EXPRESSION OF THE GENES.

DNA Replication

DNA Replication 1. DNA Replication 2. Short Clip of Replication 3. DNA to Protein 4. DNA Replication Use the puzzle pieces to construct a strand of DNA 6 nucleotides long. Write down the sequence of the strands here. You can just list the letters of the bases. Original Strand 1: T T G C G C Original Strand 2: A A C G C G Since the strands are complementary each strand can serve as a for a new DNA molecule. Separate the two strands of DNA between the base pairs. You will get 12 new nucleotides. Manipulate these nucleotides to find the best fit with the 12 nucleotides in your Parental Strands. (Unzip DNA) TEMPLATE

DNA Replication T T G C G C A A C G C G A A C G C G T T G C G C YES The new strand of the six nucleotides you just joined together is called a copy of your Parental Strand. Daughter Strand #1 is base-pairing to Parental Strand #1 and Daughter Strand #2 is base-pairing to Parental strand #2. (Enzyme helps with this chemical reaction) In the space below, write the sequence of your nucleotides in each strand. (Your sequence will not be the same as below. P#1 & D#2 = Identical; D#1 & P#2 = Identical) Parental strand #1: Daughter strand #1: Parental strand #2: Daughter strand #2: Do the two new molecules contain the same number of rungs?   Are the two DNA molecules exact copies of each other? COMPLEMENTARY T T G C G C A A C G C G A A C G C G T T G C G C YES YES

DNA Replication This mode of replication is called replication because each parental strand is used as a model (or template) for the generation of the new daughter (or complementary) strand. Color the backbone of original strand blue and the newly formed strand red. Identify the parts of the DNA molecule below as the original strand or the new strand. SEMICONSERVATIVE 4. ORIGINAL 5. NEW 6. ORIGINAL 7. NEW

Steps of DNA Replication An ENZYME (called comes in and breaks the bonds between the base pairs which causes the strand of DNA to split or “unzips” (what is left looks like a ladder cut in two). The appropriate NUCLEOTIDE are then matched up (by another enzyme called . What you are left with is identical strands of DNA. HELICASE HYDROGEN POLYMERASE TWO

DNA Replication Why are the bonds between the nitrogen bases in DNA weak? Specifically when and why would DNA have to replicate? SO DNA CAN SPLIT TO REPLICATE. WHEN NEW CELLS ARE MADE SO EACH NEW CELL HAS A COPY OF DNA

DNA vs RNA & Protein Synthesis

DNA vs RNA & Protein Synthesis RNA also belongs to the group of organic molecules. The building blocks of RNA are NUCLEIC ACID NUCLEOTIDES 1. RNA Structure 2. Transcription

DNA vs RNA & Protein Synthesis Stands for DEOXYRIBONUCLEIC ACID RIBONUCLEIC ACID Function STORES GENETIC INFORMATION & HAS CODE FOR MAKING PROTEINS HELPS MAKE PROTEINS Structure (how many strands?) TWO ONE Sugar in each DEOXYRIBOSE RIBOSE Nitrogen bases in each A, T, C, G A, U, C, G Location NUCLEUS MADE IN NUCLEUS BUT FOUND IN RIBOSOME AND CYTOPLASM Picture of a nucleotide

DNA vs RNA & Protein Synthesis Three types of RNA: RNA (mRNA)– carriers the code from the DNA in the to the in the cytoplasm. Every three mRNA nucleotides is a How many are in the mRNA pictured below? MESSENGER NUCLEUS RIBOSOME CODON FOUR mRNA Codon

DNA vs RNA & Protein Synthesis RNA (rRNA) combines with proteins to make up the Made up of two subunits that snap together around the mRNA. RIBOSOMAL RIBOSOME rRNA (& protein)

DNA vs RNA & Protein Synthesis RNA (tRNA) is the complement to the mRNA. Its job is to bring to the ribosome to make the protein. The 3 letters on the tRNA is called an How are codons related to anticodons? TRANSFER AMINO ACIDS tRNA ANTICODON THEY ARE COMPLEMENTS OF EACH OTHER

Protein Synthesis

Protein Synthesis 1. DNA & Protein Synthesis 2. Translation Protein Synthesis is the joining of in a specific sequence in order to form a protein or . There are only different amino acids. AMINO ACIDS 20 POLYPEPTIDE

What does an amino acid look like? There are 20 different R groups. This is what makes each amino acid different.

Enzymes Hemoglobin Cellular Respiration ATP Insulin Integral proteins So why do we even need to make proteins???? Here are several important proteins. ________________ - help with the chemical reactions in your body (metabolism). __________________ - covers the red blood cells and helps carry oxygen to all the cells in your body. Remember your body needs oxygen to undergo __________________________ to produce 38 __________ molecules giving your body energy. ________________ - helps maintain blood sugar homeostasis. Excess glucose is stored as glycogen in the muscles and liver. ______________________ - Forms channels in the cell membrane to help transport substances in and out of the cell ________________ - These help with growth and development Makes up your muscles that help your body move. Is every protein made at all times within an organism? Enzymes Hemoglobin Cellular Respiration ATP Insulin Integral proteins Hormones No, this would be a waste of time & energy. Proteins are made when needed.

NUCLEUS RIBOSOME Flow chart of Protein Synthesis (Label the arrows with the 2 steps). TRANSCRIPTION TRANSLATION protein DNA mRNA The DNA contains the code for making proteins. But DNA cannot leave the safety of the ______________. Therefore, mRNA is formed from the DNA and leaves the nucleus taking the message out to the ___________________ where proteins are made. NUCLEUS RIBOSOME

Protein Synthesis First Step = Transcription Occurs in the 1. DNA & Protein Synthesis Rap 2. Interactive DNA Replication & Protein Synthesis First Step = Transcription Occurs in the is used to form Second Step = Translation Occurs at the The tRNA picks up a specific in the cytoplasm and ‘travels’ to the mRNA (which is attached to the ). The tRNA attaches to the mRNA. When 2 tRNA molecules are next to one another at the ribosome a bond forms between the 2 amino acids. NUCLEUS DNA mRNA RIBOSOME AMINO ACID RIBOSOME PEPTIDE

Result – long chain of amino acids making the protein or ________________________. The protein is functional when it folds and changes shape. (See your teachers telephone cord demo). POLYPEPTIDE

Diagram of Protein Synthesis (Transcription + Translation) Label Name A NUCLEUS C RIBOSOME B mRNA D tRNA E ANTICODON F CODON G H AMINO ACID H

Protein Synthesis C A G G U C Glutamine

Protein Synthesis

Mutations

Mutations Mutation – A CHANGE IN THE DNA Sentence Analogy: Original Sequence Definition Example Point – one base is replaced with a different base aka Substitution Silent change in DNA strand that does not change the amino acid No disease Missense causes one a.a. to change that is important to protein function Sickle cell anemia Nonsense codon for an a.a. is changed into a stop codon so get a protein that is short and nonfunctional Cystic fibrosis (protein produced has only the first 493 amino acids of the normal chain of 1480) Frameshift – a base is inserted or deleted so the entire sequence is changed from that point on. Insertion an entire base is inserted Huntington’s Disease (degeneration of brain cells) Deletion An entire base is deleted. some forms of muscular dystrophy Sentence Analogy: Represents the Normal sequence: The red cat ate the fat rat. SILENT The red cat ate the fat rat. MISSENSE The red hat ate the fat rat. NONSENSE The red hat ate the INSERTION The reb dca tat eth efa tra t DELETION The rec ata tet hef atr at

Mutations Causes of Mutations: Random errors in DNA replication 1. DNA Mutation Causing Cancer 2. How Mutations Work 3. Mutations 4. Mutations - sickle shaped cells Causes of Mutations: Random errors in DNA replication mutagens – physical or chemical agents that cause mutations Ex: x-rays, UV rays Mutations are not always bad –they are a source of genetic diversity