THE STRUCTURE AND FUNCTION OF DNA
1. DNA is our genetic code!!! It is passed from generation to generation. It carries information that controls the functions of our cells. DNA stands for deoxyribonucleic acid
3. DNA s Structure: a) It is a polymer made of nucleotides! Nucleotides: building blocks of the DNA molecule. Every nucleotide has three parts: 1. sugar group 2. phosphate group 3. nitrogenous base
***The only variation among the nucleotides is what base is attached to each. b) The four nitrogenous bases in DNA are Adenine (A) Thymine (T) Cytosine (C) Guanine (G)
c) The shape of a DNA molecule is a double helix. Sugar and phosphate Bases *Bases form the rungs of the ladder. *Sugars and phosphates form the sides of the ladder.
WATSON AND CRICK DETERMINED THE THREE- DIMENSIONAL STRUCTURE OF DNA BY BUILDING MODELS. They realized that DNA is a double helix that is made up of a sugar-phosphate backbone on the outside with bases on the inside.
Watson and Crick s discovery built on the work of Rosalind Franklin and Erwin Chargaff. Franklin s x-ray images suggested that DNA was a double helix of even width. Chargaff s rules stated that A=T and C=G.
d) Other important information: Chargaff s Rule: in every DNA double helix the #A = #T and the #C = #G. Example: -A-G-C-A-A-T-C-T-G- -T-C-G-T-T-A-G-A-C-
e) Chargaff s rule teaches us that adenine always bonds to thymine. guanine always bond to cytosine.
BE ABLE TO IDENTIFY -THE DEOXYRIBOSE GROUPS -THE PHOSPHATE GROUPS -THE NITROGENOUS BASES -THE HYDROGEN BONDS
4. Genes: Sections of DNA that hold the information for making one particular thing (protein) by the cell. Examples of information contained on one gene: *making the enzyme for fat digestion *making the enzyme for starch digestion *protein for eye color etc..etc..etc!
5. Chromosomes: Bundles of DNA that are made up of genes that carry information for the entire cell. a) Humans have 46 chromosomes in each cell that hold about 25,000 genes. Human Chromosomes
QUESTION #6: DESCRIBE THIS DIAGRAM IN WORDS. Nucleotides DNA Genes Chromosomes
HUMAN GENOME The order of bases on all 23 pairs of human chromosomes. This allows us to know the specific location on a chromosome at which the DNA codes for a specific protein.
EXPLAIN DNA REPLICATION In a sample of yeast DNA, 31.5% of the bases are adenine (A). Predict the approximate percentages of C, G, and T. Explain.
DNA REPLICATION DNA Replication When DNA makes a copy of itself! 2 complete and identical sets of genetic information are produced. The cell does this process before it divides
STEP 1: A. ENZYMES BEGIN TO UNZIP THE DOUBLE HELIX. B. HYDROGEN BONDS ARE BROKEN C. THIS PROCESS PROCEEDS IN 2 DIRECTIONS AT THE SAME TIME.
Step 2: Each existing strand of the DNA molecule is a template for a new strand. Free-floating nucleotides pair up with exposed bases on each template strand. DNA polymerases bond these nucleotides together to form new strands.
VOCAB: DNA POLYMERASES Enzymes that form bonds between nucleotides during replication.
Step 3: 2 identical double-stranded DNA molecules are produced. Each DNA molecule contains an original strand and one new strand.
WHAT IS AN ORIGIN OF REPLICATION? The origin of replication is/are region (s) of DNA necessary for replication of DNA to begin. It is usually designated by a specific sequence of nitrogenous bases that a DNA polymerase will eventually start its work. Step 1: Primase is used to create a RNA primer (a section of RNA that complementary base-pairs to a specific DNA sequence: THE ORIGIN!) Step 2: This DNA polymerase starts to complementary base-pair DNA nucleotides down the DNA molecule. https://www.slideshare.net/anilkumarcgowda/dna-a-genetic-materialreplication-damage-and-repair Step 3: The primase is replaced by DNA nucleotides.
REPLICATION IS FAST AND ACCURATE In human cells, about 50 nucleotides are added every second to a new strand of DNA at the point of replication. DNA polymerase proof-reads DNA sequences and replaces bad nucleotides.