GENETICS DNA Basics 1 What makes them different

GENETICS DNA Basics 1

What makes them different? DNA

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Rosalind “Rosy” Franklin 1920 -1958 5

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DNA: The Molecule of Heredity DNA = Deoxyribonucleic acid; a type of nucleic acid The building blocks (monomers) of DNA are nucleotides A nucleotide is composed of: Deoxyribose (a sugar compound) A phosphate group A nitrogen base Ringed compound that 7

Review: Which of the following is the monomer of DNA? A. ) phosphate group B. ) nucleotide C. ) RNA D. ) deoxyribose 8

Review: Which of the following is the monomer of DNA? A. ) phosphate group B. ) nucleotide C. ) RNA D. ) deoxyribose 9

Review Nucleotides are made of: A. ) a sugar B. ) a phosphate group C. ) a nitrogen base D. ) all of the above 10

Review Nucleotides are made of: A. ) a sugar B. ) a phosphate group C. ) a nitrogen base D. ) all of the 11

Review The people credited with discovering DNA’s structure are: A. ) Avery and Chase B. ) Mendelsohn and Stahl C. ) Watson and Crick D. ) All of the above 12

Review The people credited with discovering DNA’s structure are: A. ) Avery and Chase B. ) Mendelsohn and Stahl C. ) Watson and Crick 13

Nitrogen bases in DNA In DNA, there are four possible Nitrogen bases Adenine Guanine Cytosine Thymine 14

The Double Helix The three parts of DNA (sugar, phosphate, and nitrogen base) come together to form NUCLEOTIDES The nucleotides will link together to form two long strands The two strands will connect at the nitrogen bases and twist forming a DOUBLE HELIX The linking occurs with “complimentary base pairing”… Adenine will pair with Thymine Guanine will pair with Cytosine The link that holds the bases together is a Hydrogen bond 15

Chargaff’s RULES This is NOT on Your note page, you need to find a place on the sheet to write this. 1. % of C’s will = % of G’s in DNA (This also applies to A’s = T’s) 2. ) These % will vary for different species. 16

DNA Double Helix 17

Prokaryotic DNA The DNA in bacteria is different from the DNA in eukaryotic cells. In bacteria, the DNA is a single circular strand of DNA. Kind of looks like “spaghetti-ohs”. 18

Review Which of the following is not found in DNA? A. ) Deoxyribose B. ) Phosphate C. ) Adenine D. ) Protein 19

Review Which of the following is not found in DNA? A. ) Deoxyribose B. ) Phosphate C. ) Adenine D. ) Protein 20

Review The sides (backbone) of DNA are made of: A. ) Deoxyribose sugar and adenine B. ) complete nucleotides C. ) sugar and phosphate D. ) Nitrogen bases, sugar and phosphate 21

Review The sides (backbone) of DNA are made of: A. ) Deoxyribose sugar and adenine B. ) complete nucleotides C. ) sugar and phosphate 22

Review In DNA, Adenine bonds with: A. ) Adenine B. ) Guanine C. ) Cytosine D. ) Thymine 23

Review In DNA, Adenine bonds with: A. ) Adenine B. ) Guanine C. ) Cytosine D. ) Thymine 24

Review What holds one base to another? A. ) hydrogen bonds B. ) the sugar C. ) phosphate groups D. ) ionic bonds 25

Review What holds one base to another? A. ) hydrogen bonds B. ) the sugar C. ) phosphate groups 26

Review The following is one side of a DNA strand: A-T-G-T-C-C-A-T Which of the following would be the complementary (other side of the )DNA strand? A. ) A-T-G-T-C-C-A-T B. ) T-A-C-A-G-G-T-A C. ) A-T-G-G-A-C-A-T D. ) None of the above 27

Review The following is one side of a DNA strand: A-T-G-T-C-C-A-T Which of the following would be the complementary (other side of the )DNA strand? A. ) A-T-G-T-C-C-A-T B. ) T-A-C-A-G-G-T-A C. ) A-T-G-G-A-C-A-T 28

RNA vs DNA There are THREE main differences between DNA & RNA The sugar In DNA it’s DEOXYribose sugar In RNA it’s Ribose sugar Number of strands DNA is usually double stranded RNA is ONLY single stranded Nitrogen Bases DNA Adenine pairs with Thymine Guanine pairs with Cytosine RNA Adenine pairs with Uracil Guanine pairs with Cytosine 29

Why DNA? Segments of DNA code for proteins Each set of three base pairs codes for a particular amino acids The three bases are called the codon Amino acids are the building blocks for proteins Since 3 bases pairs are involved, the DNA code is often called the triplet code There are 64 possible codon combinations given the four nitrogen bases combined into triplets 30

DNA & Chromosomes When comparing the chromosomes of two different organisms, you’ll find that both contain DNA with the same bases The ORDER of the nucleotides is what makes the organisms different The more closely related two organisms are, the more alike their order of nucleotides will be 31

Genes & Chromosomes Genes Small pieces of DNA that code for a specific trait Chromosomes Collection of genes that are wound in the shape of an X (when ready for cell division) Half of a chromosome – a chromatid 32

Chromosome 33

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Review Which of the following could be a nucleotide of DNA? A. ) Deoxyribose, uracil, phosphate B. ) Ribose, adenine, phosphate C. ) Adenine, Thymine, phosphate D. ) Guanine, phosphate, deoxyribose 36

Review Which of the following could be a nucleotide of DNA? A. ) Deoxyribose, uracil, phosphate B. ) Ribose, adenine, phosphate C. ) Adenine, Thymine, phosphate D. ) Guanine, phosphate, 37