Molecular Genetics 3.01

Information The sequence of nucleotides in DNA codes for proteins. Proteins are the central key to cell function.

Structure of DNA Deoxyribonucleic Acid is Double helix Made of monomers called nucleotides. Deoxyribose sugar Phosphate group Nitrogen bases (4) Adenine Thymine Guanine Cytosine P Sugar N-Base

Complimentary Base Pairing Rule Adenine always base pairs to Thymine. Guanine always base pairs to Cytosine

A A A A C C C G G G T T T T G G G C C C

Bonds Covalent bonds hold the backbone (phosphate/sugars) together. Covalent bonds hold the backbone (phosphate/sugars) together. Keeps code intact. Keeps code intact. Hydrogen bonds allows nucleotides to link in the center. Hydrogen bonds allows nucleotides to link in the center. Allows for access to information. Allows for access to information. Covalent Bond Hydrogen Bond

DNA Replication The process allows daughter cells to have an exact copy of parental DNA. Replication occurs during interphase of the cell cycle before mitosis.

DNA Replication

The Big Picture DNA Protein 1 Gene = 1 Protein 1 Protein = A Segment of DNA

DNA must stay in the nucleus. DNA must stay in the nucleus. Proteins are made at the ribosome in the cytoplasm. Proteins are made at the ribosome in the cytoplasm. There has to be a molecule that works as an in-between. There has to be a molecule that works as an in-between.

RNA Ribonucleic Acid Ribonucleic Acid is Single Stranded Made of monomers called nucleotides. Ribose sugar Phosphate group Nitrogen bases (4) Adenine Uracil Guanine Cytosine

RNA Cont. There are 3 types of RNA, each with a specific function. There are 3 types of RNA, each with a specific function. mRNA: messenger RNA mRNA: messenger RNA Carries the code of DNA from the nucleus to the ribosomes. Carries the code of DNA from the nucleus to the ribosomes. tRNA: transfer RNA tRNA: transfer RNA Carries amino acids from the cytoplasm to the ribosomes. Carries amino acids from the cytoplasm to the ribosomes. rRNA:ribosomal RNA rRNA:ribosomal RNA Holds ribosome together during the process of protein synthesis. Holds ribosome together during the process of protein synthesis.

Protein Synthesis Occurs in 2 stages: Transcription Produces an RNA copy of DNA in the nucleus mRNA travels to the ribosome Translation mRNA is fed into the ribosome and read 3 bases at a time (codon) tRNA supplies appropriate amino acids Amino acids linked by peptide bonds to form a polypeptides (protein)

The Big Picture Protein DNAtranscriptionmRNA translation

Codon Charts AUG 1. First Base 2. Second Base 3. Third Base

Mutations Point Mutation: a change in 1 nucleotide. Normal --> Cats eat big rat. Point mutation --> Cats eat big hat

Mutations cont. Frame-shift Mutation: a nucleotide is added (insertion) or subtracted (deletion) Normal --> Cats eat big rat Add an additional letter A to the beginning, and the reading frame changes Frameshift Mutation--> Aca tse atb igr at

Frameshift Mutation