DNA: Structure and Function Chapter 12 Section 1

Deoxyribose Nucleic Acid The Architect of Life The Molecule of Heredity The Blueprint of Life The First three-dimensional xerox machine Life Instruction Manual

DNA

Why Study DNA? TTo truly understand genetics, biologists first had to discover the chemical structure of the gene TThis would then help them understand how genes control the inherited characteristics of living things GGene expression is what enables cells of the same organism to take on so many different sizes, shapes and functions ((even though just about every cell in an individual contains the same DNA)

1.What organelle is known as the control center of the cell? 2.What structures are found in the nucleus? 3.What are short segments of chromosomes? 4. What are genes/chromosomes composed of? 5. How do genes/chromosomes control the activity of the cell? Review nucleus chromosomes genes DNA produce proteins that regulate cell functions and become cell structures

Review

History 1 Friedrich Miescher – “discovered” DNA in nucleus 1 Frederick Griffith – Identified DNA as source of genetic material using bacteria 11930’s - Oswald Avery, Colin MacLeod and Maclyn McCarty - Confirmed that genes made of DNA 1 Alfred Hershey and Martha Chase confirmed DNA is the biochemical of heredity using radioactive markers bacteriophages 11952- Maurice Wilkins and Rosalind Franklin X-rayed DNA to show repeating nucleotide structure 11953- James Watson and Francis Crick combined data to create a 3-D model of structure called the double helix Oswald Avery Maclyn McCarty Martha Chase Alfred Hershey Rosalind Franklin X-ray of double helix James Watson Francis Crick Frederick Griffith

Watson-Crick Model

Bell Work Compare the ratio for mono hybrid and dihybrid crosses. 2. Define natural selection and artificial selection then state an example of each. 3. Describe macroevolution and describe 3 of the 6 examples of change. 4. Do assignment on Study Island LT 34 I can explain the process of DNA replication and transcription.

What is LT? Agenda 1. BW / LT / Study Island 2. DNA structure and function

DNA Function What are the building blocks of nucleic acids? Nucloetides What does DNA Stand for? Deoxyribose Nucleic Acid Where is DNA located? Nucleus What are the small pieces of a DNA molecule that determine genetic traits? GENES!!!

P - the Phosphate group Is important because it links the sugar on one nucleotide with the phosphate of the next nucleotide to make a polynucleotide Nucleotides are connected to each other via a covalent bond Nucleotide sugar base P

Deoxyribose (like ribose) is a sugar with 5 carbon atoms in a ring Oxygen is one of the ring members In Deoxyribose, one of the OH groups is missing and replaced with hydrogen Thus deoxy = - 1 oxygen Nucleotide sugar base P OH H

Adenine double ringed Guanine Thymine single ringed Cytosine Bases

DNA Function What does DNA stand for? Deoxyribose Nucleic Acid Located? Nucleus Sections of DNA that determine genetic traits? Genes!!

Scientists wondered how DNA worked. They knew genes do these critical things: Carry information from one generation to another Put information to work to determine an organism’s characteristics Can be easily copied Store and transmit genetic information needed for all cell functions In order to do these things it had to be a special molecule! DNA Function

DNA Structure What is the sugar found in DNA? Deoxyribose

Is a polymer of 1000’s of nucleotide monomers Is a double strand of covalently bonded nucleotides in twisted ladder shape twisted ladder shape = double helix DNA Structure

Adenine double ringed = Guanine Thymine single ringed = Cytosine Bases purines pyrimidines

Four nitrogen-containing bases Adenine Guanine Cytosine Thymine Bases

Double helix: 2 spirals wound around each other DNA Shape But joined in the middle

Adenine double ringed = Guanine Thymine single ringed = Cytosine Bases purines pyrimidines

Nucleotide- Individual unit of DNA. Made of three parts: Deoxyribose (5-carbon sugar) Phosphate group A nitrogen-containing base Nucleotide Complimentary Base Pairing

Bases are paired together in specific manner Because of chemical structure and shape Adenine only pairs with Thymine Guanine only pairs with Cytosine Exactly enough room for only one purine and one pyramide base between the two strands of DNA ‘Base Pairing Rule’

Bases held together in ‘rungs’ by weak hydrogen bonds 2 hydrogen bonds between A & T 3 hydrogen bonds between C & G ‘Base Pairing Rule’

DNA

Is a polymer of 1000’s of nucleotide monomers Is a double strand of covalently bonded nucleotides in twisted ladder shape twisted ladder shape = double helix ‘Rungs’ of ladder = nitrogen bases ‘Sides’ of ladder = sugar & phosphate groups (also called the DNA backbone) DNA Molecule Sugar Phosphate Backbone

DNA Diagram But joined in the middle

Our knowledge of DNA put to use: Inheritance/ Genetic Counseling Cell function/protein synthesis Embryonic development/gene regulation Evolution/ phylogenetic relationships Medicine/genetic diseases Genetic engineering/ recombinant DNA Understanding DNA

Structure of DNA Review Hydrogen bonds Nucleotide Sugar-phosphate backbone Key Adenine (A) Thymine (T) Cytosine (C) Guanine (G)

Structure of DNA Review AdenineGuanineCytosine Thymine Phosphate group Deoxyribose Purines Pyrimidines Bases

To get an idea of the size of the human genome present in each of our cells, consider the following analogy: If the DNA sequence of the human genome were compiled in books, the equivalent of 200 volumes the size of a Manhattan telephone book (at 1,000 pages each) would be needed to hold it all. It would take about 9.5 years to read out loud (without stopping) the 3 billion bases in one person's genome sequence, calculated on a reading rate of 10 bases per second, equaling 600 bases/minute, 36,000 bases/hour, 864,000 bases/day, 315,360,000 bases/year. DNA’s Size Human Genome Project

Structure of DNA Review

DNA How Am I Packaged? Nitrogen bases 1. Are like letters in the code 2. Put them in different order make a different gene A G T C

DNA Package Genes 1. Are like words made up of letters 2. A group of nitrogen bases that makes sense 3. Tells the cell to do something CAT DOGHAT A A T C

DNA strand 1. Are like sentences made up of words 2. A long line of genes on each DNA strand DNA Package The cat sat. One dog ate. The big hat.

DNA Package Chromosomes 1. Are like books full of sentences 2. DNA strand twists around and around itself

DNA Package Nucleus 1. Is like a bookcase 2. Inside the cell, where all the chromosomes are stored

So what would a library full of rows and rows of bookcases represent? many cells together which is a tissue DNA Package