Standard 5: DNA Structure and Replication 2014 Team: Science!

Objectives Generalize that the genetic information in DNA is determined by the order of nucleotides Relates the importance of the sequence of DNA to the function of proteins Explain the steps of DNA replication (unzipped and copied). Describe that DNA is replicated during interphase to ensure each cell receives an identical copy of genes

What is DNA?

DNA = Uniqueness You are unique….actually all organisms that sexually reproduce are unique to that type of species because of their DNA. DNA is what makes an organism the organism that it is. DNA is found in the nucleus of all eukaryotic organisms and as a single loop centered in prokaryotic organisms.

What does DNA look like? It’s a “twisted ladder” or “spiral staircase” that holds the genetic information for an individual. That shape is called the double helix. We’ll talk a bit more of what it looks like in a bit…

DEOXYRIBONUCLEIC ACID!!!!! What does DNA stand for? DEOXYRIBONUCLEIC ACID Huh? DEOXYRIBONUCLEIC ACID! DEOXYRIBONUCLEIC ACID!!!!!

Well what is the deoxyribose part? and What is the nucleic acid part? Deoxyribose is a type of sugar… Nucleic acid are molecules like DNA, RNA, and ATP and are made up of 3 components- a phosphate, a sugar, and a base. What are they?

What are nucleic acids made of? Nucleic acids (DNA & RNA) are long chains of nucleotides Each nucleotide is made of three parts (Nitrogenous) Base Phosphate Group Sugar

What does the nucleotide look like in the DNA strand?

So what does DNA look like? The sequence of nucleotides are what determine our unique genetic information Nucleotide

So what does the DNA look like? (cont.) The shape of DNA, the double helix is formed by the alternating sugars and phosphates (the “backbone”) with the nitrogen bases bonded in the middle. Then the entire DNA is twisted. Like a twisted ladder.

The pattern of the DNA sequence Genetic information is determined by the sequence (order) of bases Just as a word is determined by the sequence of letters There are 4 (Nitrogenous)Bases Adenine Thymine Guanine Cytosine

Base Pairing Rule Adenine ALWAYS pairs with Thymine Guanine ALWAYS pairs with Cytosine Bonded with hydrogen bonds

Base-pairing rule  AKA Chargaff’s Rule Chargaff was the scientist who discovered: -The amount of adenine equals the amount of thymine. -The amount of guanine equals the amount of cytosine. Structure of DNA Erwin Chargaff

What else is the sequence of the bases important for? Strands of unique sequence of bases along the DNA strand also code for genes which code for proteins. Some genes make single proteins while other genes code for groups of proteins. What is a gene? Proteins are important for: Body structure (muscle, bone, hair, skin, etc.) Acting as enzymes to speed up chemical reactions Fighting diseases- these proteins are called antibodies Carrying oxygen through the blood- this protein is called hemoglobin

Quick Check 1. What is the name for the shape of DNA? 2. DNA is made of a “twisted ladder” of alternating ___________________. 3. What 3 things make a up a nucleotide? 4. How many nitrogen bases are there? What are their names? 5. Describe the base-pairing rule. 6. How are proteins important?

So what’s the point of replication? WHY does DNA need to replicate- what is the purpose? DNA needs to replicate so that when cells divide, there are two identical copies of the DNA- one for each new cell.

So when is DNA copied? Interphase DNA is copied during Interphase of the Cell Cycle. DNA is copied then because otherwise the cell will divide and there needs to be an identical copy of DNA in each new celll! Interphase

How does DNA replicate? Helicase DNA Polymerase Uncoils (straightens strand out) the DNA strand and then “Unzips” the DNA strand by breaking the hydrogen bonds between the bases. DNA Polymerase Moves along each individual strand and adds on a new nucleotide by using the complementary base pair rule

What ‘s the Final product What ‘s the Final product? 2 identical copies of the original DNA molecule

Here is how DNA replication works: =DNA Polymerase: the enzyme that adds nucleotides back on and “proofreads” the new strands = Helicase: the enzyme that “unzips” the DNA strand

DNA Replication Video Clip

Quick Check 1. What is the point of DNA replication? 2. What is the enzyme that “unzips” the DNA strand? 3. What does DNA Polymerase do? 4. How many copies of the DNA are made? 5. Why is DNA unique to an organism? 6. When is DNA copied? Why?

Protein Synthesis (How proteins are made!) Objectives: -know the functions of all the different types of RNA (B) -know the function of a protein (B) -understand the steps of protein synthesis (P) -understand that the order of the amino acids in a protein determine the shape and function of the protein (message read right, protein put together correctly…) (P)

Overall this is how proteins are made(Protein synthesis) Flow of Information DNA RNA Proteins (Transcription) (Translation)

But 1st……What are Proteins? Proteins come from the genetic code found on the DNA strand. So what is a gene? Let’s find out: John Perry answers…. What is a gene? Examples of different shapes of proteins 

Before we cover how a protein is made, let’s conquer: DNA vs RNA

DNA vs RNA DNA <------Type of molecule-----> RNA <------ Type of Helix-----> <------ Type of Sugar-----> <------ Types of Bases----->

So now you know what RNA is, let’s discuss the 3 Types of RNA Messenger RNA(mRNA) - RNA molecules that carry copies of genetic instructions Transfer RNA (tRNA) - transfers each amino acid to the ribosome as it is specified by “messages” of mRNA Ribosomal RNA (rRNA) - part of the ribosome structure

3 types of RNA Messenger RNA (mRNA) Transfer RNA (tRNA) Ribosomal (rRNA)

Before we move on…can you tell the difference between DNA and RNA Before we move on…can you tell the difference between DNA and RNA? Now Let’s discuss PROTEIN SYNTHESIS: There are two main steps: Transcription and Translation

Transcription and Translation Video Why it's important that we talk about making proteins.....

There are 2 main steps to how a protein is made: Transcription and Translation (use the word bank on your notes to fill in the blanks) Baking a Cake Analogy for Protein Synthesis

Lets Bake a Cake What all do you need to do or gather before you can bake a cake? Recipe Book Kitchen Pantry Recipe Index Card Kitchen Counter Ingredients Keebler Elves Cake!

Let’s use an analogy of baking a cake to understand it: = -DNA is a large book of recipes(the entire DNA strand) that is too large to leave the pantry(nucleus) in the kitchen(the whole cell). -So a copy of the DNA strand, so therefore a copy of the recipe (mRNA) is written from the DNA strand. This process of copying and writing the recipe on an index card would be (transcription). -The copied recipe on the index card (mRNA), must now leave the pantry (nucleus) and go to the countertop(the ribosome) where it can be read(translation) and the cake (protein) can be assembled. The process of assembling the cake would be (protein synthesis).

Well how is the cake(protein) assembled Well how is the cake(protein) assembled? Ingredients (amino acids) are needed! So all of the ingredients—the flour, oil, eggs, sugar, water, baking soda, icing------ (the amino acids), are transferred to the countertop(ribosome) from your helpers the Keebler Elves (tRNA). One by one the Keebler Elves(tRNA) bring the correct ingredient(amino acid) to the countertop(ribosome) according to what is written on the recipe index card (mRNA). So as the recipe card is read (translation), the cake (protein) is being made! Later that cake (protein) is baked in the oven (another cell in the body) that needs that cake (protein).

Transcription Transcription

Translation Translation