Warm-up: DNA What does DNA stand for? Where do we find DNA? How do crime scene investigators use DNA to solve crimes?

NUCLEIC ACIDS Flow of biological information: DNA RNA protein trait DNA deoxyribonucleic acid carries the genetic code (stores and transmits the genetic information from one generation to the next) parents offspring DNA is a type of organic compound and an example of a Nucleic Acid Definition organic compound: compound containing Carbon & made from a living organism B. Chromosomes are made of DNA and are located in the nucleus only

Model of DNA: The model was developed by James Watson and Francis Crick. They received a Nobel Prize in 1962 for their work. First picture of DNA (X-ray) – Rosalind Franklin The model looks like a twisted ladder – double helix

Watson Crick Died in 2004

RECALL… Nucleotides are the building blocks (monomer) of DNA (polymer) One Phosphate + one Sugar + one Base = one nucleotide Nucleotides are the building blocks (monomer) of DNA (polymer)

Untwisted it looks like this: The sides of the ladder are P = phosphate group S = deoxyribose sugar   The steps of the ladder are C, G, T, A = nitrogenous bases (contain Nitrogen) Purine Pyrimidine A and G = purines T and C = pyrimidines Nucleotide

2 H bonds pairs A = adenine T = thymine 3 H bonds pairs C = cytosine G = guanine

When would your body need more cells? How do we get more or new cells?

II. DNA Replication A. Cell division produces 2 daughter cells that are genetically identical to each other and genetically identical to the parent cell B. Remember that for this to happen, DNA in the parent cell must be replicated (copied) before cell division

STEP 1 STEP 2 Hydrogen bonds between base pairs are broken by the enzyme Helicase and DNA molecule unzips DNA molecule separates into complementary halves

STEP 3 Nucleotides match up with complementary bases Free nucleotides abundant in nucleus

STEP 4 New Strand Original Strand Nucleotides are linked into 2 new strands of DNA by the enzyme, DNA polymerase—DNA Polymerase also proofreads for copying errors New Strand Original Strand

III. Ribonucleic acid – RNA -- acts as a III. Ribonucleic acid – RNA -- acts as a messenger between DNA and ribosomes, and carries out the process by which proteins are made from amino acids. Protein = polymer Amino Acids = monomer   A. Different from DNA: 1. RNA’s sugar -- ribose DNA’s sugar – deoxyribose 2. RNA – single strand of nucleotides DNA – double strand of nucleotides (double helix)

3. RNA has uracil instead of – thymine When RNA pairs with DNA to get its code: RNA cytosine (C) pairs with DNA – guanine (G) RNA guanine (G) pairs with DNA – cytosine (C) RNA adenine (A) pairs with DNA – thymine (T) RNA uracil (U) pairs with DNA – adenine (A)    4. RNA found – inside and outside nucleus (small – single strand) DNA found – inside nucleus only (large – double strand)

B. 3 types of RNA involved in Protein Synthesis– mRNA messenger RNA tRNA transfer RNA rRNA ribosomal RNA

found in and out of nucleus Complete the chart by reading each term or phrase and placing a check in the appropriate column. DNA RNA Both Deoxyribose  Ribose double stranded single stranded nucleotides found in nucleus only found in and out of nucleus Cytosine Guanine Adenine Thymine Uracil double helix replication