DNA Structure and Function THINK PAIR SHARE Teacher

DNA Structure and Function

THINK – PAIR – SHARE Teacher ask question Students think individually Students pair up and combine their best answer 1. Where is DNA located in the cell? 2. What type of macromolecule is DNA? 3. What happens during DNA replication? 4. When does the cell replicate its DNA?

What you need to know……. 1. Structure and function of DNA. 2. Process of DNA replication. 3. How DNA replication is important to passing on genetic information. 4. DNA mutations can lead to different phenotypes. 5. Process of transcription and translation (DNA). 6. How and why DNA is important to all organisms.

What is the essential vocabulary? ü Double helix – the shape of DNA, resembling a twisted ladder ü Nucleotide – a subunit of a nucleic acid molecule that consists of a sugar, sugar a phosphate, phosphate and a nitrogenous base ü Nucleoside – a subunit of a nucleic acid molecule that consists of a sugar and a nitrogenous base

What are the components of DNA? q The backbone of a DNA chain is formed by sugar and phosphate groups of each nucleotide. q The nitrogenous bases stick out sideways from the chain. q The nucleotides can be joined together in any order, meaning that any sequence of bases is possible.

What are the components of DNA? q DNA is a long molecule made up of units called nucleotides. q Each nucleotide is made up of three basic components: q. A 5 -carbon sugar called deoxyribose q A phosphate group q A nitrogenous base q There are four kinds of nitrogenous bases in DNA: q Purines: Adenine and guanine q Pyrimidines: Cytosine and thymine.

Structure Basic structure of DNA is a sugar-phosphate backbone with 4 variable nitrogenous bases. This structure is called a nucleotide. phosphate sugar base Backbone Base

DNA nitrogen Bases Pair P P S Adenine Thymine Cytosine Guanine This Photo by Unknow n Author is Thymine adenine guanine cytosine S

Amino Acid Codons • Every three base pairs is a Codon for one amino acid. • The order of the amino acids forms polypeptides which fold into proteins.

What is DNA’s Function? • Hereditary Instructions • Chemical code for every trait • “Blueprint” for making Proteins

Gizmos – Building DNA Learning Objectives: Students will … q Build a molecule of DNA from a set of components. q Observe how nitrogenous bases bond to form the central “rungs” of the DNA molecule.

+ Home Learning “The same people who never did their homework in high school are still doing that to this very day out in the real world. “ by Jules Shear 1. Gizmos: Activity A

Day 2 of 3 TOPIC 24 – DNA REPLICATION

Bell Ringer (10 minutes) 1. Grab a Biology EOC Exam Preparation Bell Ringer 2. Provide a GIST of the Question. 3. Bubble your answer. 4. Explain why you believe is the correct answer. 5. BE PREPARED TO PARTICIPATE IN CLASS DISCUSSION. 6. After correcting, reflect on our answer.

DNA Replication Duplication of DNA

What is the essential question? How does replication ensure that identical copies of DNA are made?

What is the essential vocabulary? ü Replication – the process of DNA duplication ü Replication fork – Site where DNA strands separate and replication occurs. ü Enzyme – a protein that facilitates a specific chemical reaction in the body. ü Leading strand – DNA strand that forms as a continuous strand during DNA replication.

What is DNA replication? q During DNA replication, the DNA molecule produces two new complementary strands. q Each strand of DNA serves as a template for the new strand. q Described as semiconservative because each DNA molecule has one new strand one original strand.

How does DNA replication work? q A very complex process requiring the assistance of several enzymes and regulatory molecules. q DNA helicases bind to the double stranded DNA and stimulate the separation of the two strands. q Primase initiates replication by adding a short RNA fragment called a primer to the old strands q DNA polymerases join individual nucleotides to produce a new strand of DNA using the old strand as a template. They also carry out DNA proofreading and repair. q Ligase binds the DNA fragments together by addition of phosphates in the gaps that remain in the phophateribose sugar backbone.

Summary: DNA Replication: • Make duplicate DNA Transcription: • Make m. RNA from DNA Translation: Make protein

Gizmos – Building DNA Learning Objectives: Students will … q Explain how DNA replication occurs. q Observe that the result of DNA replication is two identical molecules of DNA.

DNA Replication Overview Right-click slide / select “Play”

DNA Replication Overview A T C G T A A T G C (a) Parent molecule q Each strand of the DNA double helix has all the information needed to reconstruct the other half by the mechanism of base pairing. q Because each strand can be used to make the other strand, they are said to be complementary.

DNA Replication Overview A T C G T A A T G C (a) Parent molecule (b) Separation of strands 1. DNA helicase begins replication by separating the strands and exposing the nucleotide sequence. 2. Primase adds a primer to the DNA molecule to initiate replication 3. DNA polimerases move along the two strands, pairing complementary bases to the exposed nucleotides.

DNA Replication Overview A T A T C G C G T A T A T G C G C (a) Parent molecule (b) Separation of strands (c) “Daughter” DNA molecules, each consisting of one parental strand one new strand 4. DNA ligase seals up the fragments into one long continuous strand 5. Each original strand joins its complementary strand to form a DNA molecule, resulting in two identical DNA molecules.

DNA Replication Overview

What did we learned? DNA, the genetic material of organisms, is composed of four kinds of nucleotides. ü Each nucleotide consists of a sugar, sugar a phosphate group and one of four bases ü ü ü Sugars and phosphates on the outside Nitrogenous bases paired by hydrogen bonds (A with T, T C with G) G form the “rungs. ” The paired strands form a twisted-zipper shape called a double helix ü Before cell division, DNA copies itself in a process called replication ü During replication, DNA separates into two strands, strands and produces two new complementary strands following the rules of base pairing ü

What is the essential question? How does replication ensure that identical copies of DNA are made?

+ Home Learning “The same people who never did their homework in high school are still doing that to this very day out in the real world. “ by Jules Shear 1. Reinforcement: DNA Replication

Day 3 of 3 TOPIC 24 – DNA REPLICATION

Bell Ringer (10 minutes) 1. Grab a Biology EOC Exam Preparation Bell Ringer 2. Provide a GIST of the Question. 3. Bubble your answer. 4. Explain why you believe is the correct answer. 5. BE PREPARED TO PARTICIPATE IN CLASS DISCUSSION. 6. After correcting, reflect on our answer.

DNA Replication DNA Extraction Lab

What are we learning today? Benchmark: ü SC. 912. L. 16. 9 – Explain how and why the genetic code is universal and is common to almost all organisms. Objectives: ü Explain that the basic components of DNA are universal in organisms. ü Explain how similarities in the genetic codes of organisms are due to common ancestry and the process of inheritance.

What is the essential question? Do you think you have ever eaten DNA? Where and when?

Lab – DNA Extraction Purpose: To investigate if DNA is present in plants. Problem Statement: Do you think you have ever eaten DNA? Where and when? q Safety: Handle breakable materials with care. Do not touch broken glassware. If you are allergic to certain plants, tell your teacher before doing activity. Wash your hands when you are finished with the activity. Flammable materials may be present. Make sure no flames, sparks, or exposed heat sources are present. q Vocabulary: decant q q

Lab – DNA Extraction 1. 2. 3. 4. 5. 6. 7. 8. 9. Place two strawberries in a Ziploc baggie. Kneed/mush the strawberries using your fist and fingers for 2 minutes. Careful not to break the bag!!! Add the provided 10 m. L of extraction buffer solution to the bag. Kneed/mush the strawberries/solution mix for an additional 1 minute. Assemble your filtration apparatus as shown in your procedure. Filter strawberry/solution mix through cheesecloth Do not press it. Let gravity work!!! Pour 2 -3 m. L (about 1 cm) of filtrate into a test tube. Decant 4 -6 m. L (about 2 cm) of ice cold ethanol Stir gently with inoculation loop and spool DNA as it clumps at the ethanol/filtrate interface.

Lab – DNA Extraction How is the appearance of your DNA similar or dissimilar to what you have learned about DNA structure? 2. A person cannot see a single strand of cotton thread from 30 meters away. But if thousands of threads are wound together into a rope, the rope can be seen at some distance. How is this statement an analogy to the DNA extraction you did? 3. DNA dissolves in water but not in ethanol. Explain what happened when the ethanol came in contact with the strawberry extract during the DNA extraction. 1.

Lab – DNA Extraction Each step in the procedure aided in isolating the DNA from other cellular materials. Match the procedure with its function PROCEDURE FUNCTION A. Filter strawberry slurry through cheesecloth. B. Mush strawberry with salty/soapy solution C. Initial smashing and grinding of strawberry. D. Addition of ethanol to filtered extract. ___ To precipitate DNA from solution ___ Separate components of the cell ___ Break open the cells ___ Break up proteins and dissolve cell membranes

So, what’s the big deal about DNA? The genetic code is the same in nearly all living organisms. (UNIVERSAL GENETIC CODE) q This supports the view that the code had originated at least by the time bacteria evolved, over 3. 5 billion years ago. q It also provides evidence that all life on Earth evolved from a common origin. q

What is the essential question? Do you think you have ever eaten DNA? Where and when?

+ Home Learning “The same people who never did their homework in high school are still doing that to this very day out in the real world. “ by Jules Shear 1. Complete Formal Lab Report for DNA Extraction Laboratory