What is DNA So what is DNA Remember

What is DNA?

So, what is DNA? Remember biomolecules • DNA is a nucleic acid • DNA stands for Deoxyribonucleic Acid • DNA – is the genetic material inside the nucleus of eukaryotic cells. IT ACTUALLY WINDS UP REALLY TIGHTLY AND FITS INTO CHROMOSOMES!!!

It is made of DNA!

Deoxyribonucleic Acid Segment of DNA NUCLEUS CHROMOSOMES GENES SEGMENTS OF DNA

Which cell organelle is DNA found in (for eukaryotes)? THE NUCLEUS! Do prokaryotes even have DNA? ? ? OF COURSE! But, it is not protected by a nucleus!

Discovering the Structure of DNA Structure was discovered in 1953 by James Watson and Francis Crick We were only able to complete the model after x-rays taken of DNA through a microscope by a woman named Rosalind Franklin revealed the key to determining the true shape…. she was never officially credited with the discovery Watch this!: DNA ANIMATION!

What is the purpose, or function, of DNA? • Stores the genetic information that instructs the cell on which proteins to make. • So, DNA makes PROTEINS (both are biomolecules!) • Responsible for determining all organism’s traits such as eye color, body structure, and enzyme production. Proteins are responsible for most of these traits!

The Components of DNA • DNA is a long molecule made up of repeating individual units of monomers called nucleotides. – Nucleotides are made up of three parts that are held together by covalent bonds: 1. Sugar 2. Phosphate Group 3. Nitrogenous Base Phosphate Deoxyribose. S ugar Nitrogenous Base

In the diagram, what substance is represented by the letter x? A. Ribose sugar B. Deoxyribose sugar C. Phosphate D. Adenine

Nitrogenous Bases • DNA contains four nitrogenous bases: 1. Adenine (A) 2. Guanine (G) 3. Cytosine (C) 4. Thymine (T)

In DNA, Which Bases Pair? • Adenine (A) always pairs with Thymine (T) • Guanine (G) always pairs with Cytosine (C) Watch this!: COMPOSITION OF DNA Covalent bonds

In your notes, write in the base pairs for the following:

These bases are held together by hydrogen bonds 5’ 3’ 3’ 5’

What are Hydrogen Bonds? Hydrogen bonds are weak and they combine the two DNA strands. It is important that these middle bonds are weak! Why do you think? ? ?

Structure of DNA • Phosphate Group & Deoxyribose Sugar –Form the backbone or sides of the ladder. • Nitrogenous Bases –Form the “steps” of the ladder or middle of the molecule.

X makes up the backbone along with which other molecule? A. Ribose sugar B. Deoxyribose sugar C. Base-pairs D. Adenine

• DNA is a DOUBLE HELIX or a twisted ladder.

Pictures Of The Double Helix

THE INSTRUCTIONS ARE IN THE SEQUENCE OF NUCLEOTIDES.

The components that make up the genetic code are common to all organisms!

A T G C A T C G DNA of a horse If we all have the same components of DNA, why do we look different from other people and from other organisms like horses or plants? What is the difference? The difference is in the order of the bases. C G A T G C T A DNA of a human The more alike two organisms are, the more alike their order of bases will be. Information for everything about an organism is carried in the order of bases in their DNA, like a language.

DNA base pairs genes proteins traits This sequence of base pairs is what determines our traits

THE END