Packet 7 Notes DNA stands for DEOXYRIBONUCLEIC ACID

Packet 7

Notes

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

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

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

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 DOUBLE HELIX If DNA is “ladder like, ” which two molecules of a nucleotide form the sides or upright portion of the ladder? DEOXYRIBOSE (SUGAR) AND PHOSPHATE Which molecules form the rungs of the ladder? NITROGEN BASE What is the pairing arrangement of the nitrogen bases? This kind of pairing is called complementary. The base pairing rule states that: __A____ pairs with ___T___ ___C___ pairs with ___G____ If four guanine bases appear in a DNA model, how many cytosine bases should there be? FOUR

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

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

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 Original Strand 2: A A C G Since the strands are complementary each strand can serve as a TEMPLATE 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)

The new strand of the six nucleotides you just joined together is called a COMPLEMENTARY 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: TTGCGC AACGCG TTGCGC Do the two new molecules contain the same number of rungs? YE S Are the two DNA molecules exact copies of each other? YES

This mode of replication is called SEMICONSERVATIVE 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. 4. ORIGINAL 5. NEW 6. ORIGINAL 7. NEW

1. 2. 3. An ENZYME (called HELICASE comes in and breaks the HYDROGEN 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 POLYMERASE. What you are left with is TWO identical strands of DNA.

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

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

DNA RNA Stands for DEOXYRIBONUCLEIC ACID Function STORES GENETIC INFORMATION & HAS CODE FOR MAKING PROTEINS HELPS MAKE PROTEINS Structure (how many strands? ) TWO ONE Sugar in each DEOXYRIBOSE 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

Three types of RNA: 1. MESSENGER RNA (m. RNA)– carriers the code from the DNA in the NUCLEUS to the RIBOSOME in the cytoplasm. Every three m. RNA nucleotides is a CODON How many are in the m. RNA pictured below? FOUR m. RNA Codon

2. RIBOSOMAL RNA (r. RNA) combines with proteins to make up the RIBOSOME Made up of two subunits that snap together around the m. RNA. r. RNA (& protein)

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

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

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

So why do we even need to make proteins? ? Here are several important proteins. Enzymes - help with the chemical reactions in your body • ________ (metabolism). Hemoglobin - covers the red blood cells and helps carry • _________ oxygen to all the cells in your body. Remember your body needs Cellular Respiration to produce 38 oxygen to undergo _____________ ATP _____ molecules giving your body energy. Insulin - helps maintain blood sugar homeostasis. Excess • ________ glucose is stored as glycogen in the muscles and liver. Integral proteins - Forms channels in the cell membrane to • ___________ help transport substances in and out of the cell Hormones - 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? No, this would be a waste of time & energy. Proteins are made when needed.

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

First Step = Transcription Occurs in the NUCLEUS DNA is used to form m. RNA 1. DNA & Protein Synthesis Rap 2. Interactive DNA Replication & Protein Synthesis Second Step = Translation Occurs at the RIBOSOME The t. RNA picks up a specific AMINO ACID in the cytoplasm and ‘travels’ to the m. RNA (which is attached to the RIBOSOME ). The t. RNA attaches to the m. RNA. When 2 t. RNA molecules are next to one another at the ribosome a PEPTIDE bond forms between the 2 amino acids.

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

Label A B Transcription Name NUCLEUS m. RNA Label C Translation Name RIBOSOME D t. RNA E ANTICODON F CODON G m. RNA H AMINO ACID H

C A G G U C Glutamine

Mutation – A CHANGE IN THE DNA Original Sequence Point – one base is replaced with a different base aka Substitution Frameshift – a base is inserted or deleted so the entire sequence is changed from that point on. Definition Example 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 Cystic fibrosis (protein produced has only the first 493 amino acids of the normal chain of get a protein that is short and nonfunctional Insertion an entire base is inserted 1480) Huntington’s Disease (degeneration of brain cells) Deletion An entire base is deleted. some forms of muscular dystrophy Sentence Analogy: Represents the Normal sequence: SILENT MISSENSE NONSENSE INSERTION DELETION The red cat ate the fat rat. The red hat ate the The reb dca tat eth efa tra t The rec ata tet hef atr at

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