DNA & RNA Structure By PresenterMedia.com

Pick Your Brain! What do you already know about DNA? DNA is in the nucleus of every cell Chromosomes contain genes Traits are passed from generation to generation in the form of genes

Make a connection! DNA coils into chromosomes during prophase of mitosis and meiosis I A gene is an area of DNA

Deoxyribonucleic Acid (DNA) Structure of DNA – The twisted ladder General Structure Double Stranded Double Helix (Twisted Ladder) Components: Base pairs are held together by Hydrogen Bonds Phosphate Groups Sugar Groups (Deoxyribose) Nitrogen-containing bases Adenine (A) Guanine (G) Cytosine (C) Thymine (D)

Structure of DNA DNA is a molecule that contains genetic information. DNA coils and condenses to become CHROMOSOMES. The DNA molecule can be described as a “twisted ladder,” but the structure is actually called a DOUBLE HELIX..

Structure of DNA There are three components of DNA: 1) phosphate groups, 2) sugars called DEOXYRIBOSE, and 3) nitrogen-containing bases. There are four different bases in DNA. They are: adenine, guanine, THYMINE, and cytosine

Structure of DNA The sides of the ladder, or the backbones, are made of the sugar and phosphate group. The steps are made of 4 nitrogen base pairs which are connected to each other by a hydrogen bond

Structure of DNA The bases pair in a specific way. Adenine (A) pairs only with THYMINE Guanine (G) pairs only with CYTOSINE. This is called complementary base pairing. These base pairs are held together by HYDROGEN bonds. G and C are held together by three hydrogen bonds, while A and T are held together by two.

EXAMPLE Suppose you had the following DNA strand: T A T A G G C A C The complimentary strand would be: A T A T C C G T G Recall that DNA is double stranded.

Complete the Strand Below are two incomplete portions of DNA. Practice completing the strand by pairing the correct bases. ……..T A C G A T C T G…….. ….....G G C A T A G T C…….

RNA In order for DNA to be copied, a 2nd nucleic acid is needed. That nucleic acid is RNA (ribonucleic acid) Like DNA, RNA contains a phosphate group, a sugar, and nitrogen-containing bases. However, there are several differences

RNA RNA is a single stranded molecule, unlike the double-stranded DNA molecule. Instead of deoxyribose, RNA contains the sugar RIBOSE. Also, instead of the base thymine, RNA contains URACIL. When DNA is copied to make RNA, URACIL will pair with adenine.

Complete the strand Practice by creating a strand of RNA from the DNA template below: ……..TACGATCTG…….. ……..AUGCUAGAC........

Comparison of DNA and RNA Nucleic Acid Contains phosphate groups Contains deoxyribose sugar Adenine pairs with thymine Guanine pairs with cytosine Double-stranded Cannot leave the nucleus Nucleic Acid Contains phosphate groups Contains ribose sugar Adenine pairs with Uracil Guanine pairs with cytosine Single-stranded Can leave the nucleus

RNA As you know, DNA must be copied in order to make proteins. Proteins are substances that do the following for your body: 1. Protein mainly repairs cells 2. It maintains and replaces tissues in your body. 3. Protein manufactures hemoglobin (red blood cells that carry oxygen). 4. It manufactures antibodies to fight diseases and illnesses. 5. proteins also give you strength

RNA Proteins are made in the cytoplasm. DNA contains the instructions for making proteins, but it can not leave the nucleus because of its nitrogen base, thymine. RNA replaces thymine with uracil, which can leave the nucleus.

RNA In order for RNA to make a copy of the DNA instructions for a protein, the two DNA strands must separate or “unzip” Once the strands unzip, RNA makes a copy of the instructions and takes them to the cytoplasm. The DNA strands zip back up.

RNA The RNA strand is called mRNA or “messenger” RNA because it takes the “message” or instructions for building a protein, to the cytoplasm.

RNA Lets assume we have the following DNA strand: T A C G G C A T A The mRNA strand would be: A U G C C G U A U Remember, there is no thymine in RNA. Everywhere a thymine would be, uracil takes its place.

You Try It Complete the mRNA strand for the following DNA strands: G G C A A T T A C C C C A A T G T A