DNA Protein Synthesis Structure of DNA n n

Structure of DNA n n n Double stranded helix Structure determined in 1953 by

Nucleotides n n Composed of sugar, phosphate, and nitrogen base Sugar-Phosphate Backbone – Deoxyribose

Nucleotides continued. . . n Nitrogen base – Adenine – Thymine – Cytosine –

DNA Replication n Enzyme breaks hydrogen bonds that hold the nucleotides together DNA unzips.

Animation n http: //www. stolaf. edu/people/giannini/bi ological%20 anamations. html

DNA Replication n n T-A-C-G Complementary strand?

Genes and Proteins n DNA determines your: amino acid sequence protein production. RNA: helper

3 Types of RNA “WORKERS” n n n m. RNA Messenger RNA (m. RNA):

Step 1: Transcription n DNA making a m. RNA in the nucleus so genetic

Step 2: Translation: 1. Changes m. RNA message to amino acids 2. Amino acids

The Genetic Code n n Proteins determine ALL of your characteristics!!! Protein = Amino

Mutation: A Change in DNA n Simple error environmental chemical or radiation n Can

Two types of gene mutations: n Point mutation – change in a single nitrogen

Chromosomal Mutations n n Nondisjunction organism has one more or one less chromosome than

Causes of Mutations n Mutagens - agent that causes change in DNA. – Radiation

Repairing DNA n Often occurs naturally by the enzymes of the organism. However, if

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DNA & Protein Synthesis

Structure of DNA n n n Double stranded helix Structure determined in 1953 by Watson and Crick. Composed of nucleotides.

Nucleotides n n Composed of sugar, phosphate, and nitrogen base Sugar-Phosphate Backbone – Deoxyribose sugar – Phosphate group

Nucleotides continued. . . n Nitrogen base – Adenine – Thymine – Cytosine – Guanine }pai r } pai n n r Weak hydrogen bonds hold nitrogen bases together Sequence of nucleotides determines

DNA Replication n Enzyme breaks hydrogen bonds that hold the nucleotides together DNA unzips. n Free nucleotides pair with exposed nucleotides on both strands.

Animation n http: //www. stolaf. edu/people/giannini/bi ological%20 anamations. html

DNA Replication n n T-A-C-G Complementary strand?

From DNA to Protein. . .

X X

Genes and Proteins n DNA determines your: amino acid sequence protein production. RNA: helper n n Single strand Ribose sugar, not deoxyribose sugar. Uracil (nitrogen base) replaces Thymine of DNA, bonding with Adenine

3 Types of RNA “WORKERS” n n n m. RNA Messenger RNA (m. RNA): carries genetic info. from nucleus to cytoplasm Ribosomal RNA (r. RNA): attach to m. RNA; assemble the amino acids in order. Transfer RNA (t. RNA): transfers amino acids to the ribosome to be assembled into protein.

Step 1: Transcription n DNA making a m. RNA in the nucleus so genetic message can get to cytoplasm

Animation n http: //www. stolaf. edu/people/giannini/bi ological%20 anamations. html

Step 2: Translation: 1. Changes m. RNA message to amino acids 2. Amino acids form a protein - t. RNA carrying an amino acid, binds to m. RNA.

Translation

The Genetic Code n n Proteins determine ALL of your characteristics!!! Protein = Amino Acid + … There are 20 amino acids = “gazillion” proteins. Each set of 3 nitrogen bases forms a triplet, U A – called a codon on m. RNA – called an anticodon on t. RNA n Start and Stop: – AUG is the start codon. – UAA, UGA, UAG are the stop codons. G

Genetic Code

Animation n http: //www. stolaf. edu/people/giannini/bi ological%20 anamations. html

Genetic Changes. . .

Mutation: A Change in DNA n Simple error environmental chemical or radiation n Can happen in all cells n n Melanoma

Two types of gene mutations: n Point mutation – change in a single nitrogen base pair in DNA – Results in the change of one amino acid of a protein. n Frameshift mutation – – One nitrogen base is added or deleted – results in a drastic change in the amino acid sequence.

Point & Frameshift Mutations

Types of Mutations

Chromosomal Mutations n n Nondisjunction organism has one more or one less chromosome than it should. Piece of chromosome could break away and become lost, or it could rejoin upside

Causes of Mutations n Mutagens - agent that causes change in DNA. – Radiation - x-rays, ultraviolet nuclear – Chemicals asbestos formaldehyde tobacco

Repairing DNA n Often occurs naturally by the enzymes of the organism. However, if the exposure to the mutagen is very high, the chance for repair is slim.