Basics of Genetics Part 1

Introduction Cells come from existing cells – the cell theory “Like produces like” – dogs produce pups not kittens But how??????? Heredity- transmission of traits from one generation to the next Genetics- the science of heredity usually dealing with the molecular basis

DNA Genetics: Study of heredity and DNA Discovered in the late 1800’s (not known as genetic material yet.) (Proteins) Limited by technology Located inside nucleus of cell (also in mitochondria, chloroplast, virus and bacteria). Purpose of DNA is to code for proteins. Made up of a phosphate, sugar and nucleotide bases. Arranged in a double helix (twisted ladder). Watson and Crick (1953)

II. DNA A. Structure Nucleotide Phosphate group + Sugar + Nitrogen base

DNA cont. Four nucleotide bases: Adenine A always pairs w/ T Thymine Guanine G always pairs w/ C Cytosine Complimentary base pairs 2-3 billion base pairs in DNA Chargraff’s ratio: #A = #T and #G = #C

Diagram of DNA

RNA Acts as an intermediary between DNA and protein. Common in cytoplasm of the cell. Transfers code from DNA to ribosome (where protein is made). Made of phosphate, sugar and nucleotide bases. Single stranded.

RNA cont. Four nucleotide bases: Adenine A always pairs w/ U Uracil (replaces thymine) Guanine G always pairs w/ C Cytosine

RNA cont. Three types of RNA mRNA- (messenger) carries information from DNA to ribosome tRNA- (transfer) carries amino acids to ribosome rRNA- (ribosomal) assembles amino acids to make protein

3 Important Processes Replication: DNA making copies of itself Transcription: DNA makes RNA Translation: Protein synthesis (making proteins)

Comparing DNA and RNA DNA RNA Deoxyribose (sugar) Double stranded Thymine Located in nucleus RNA Ribose (sugar) Single stranded Uracil Found in cytoplasm

After amino acids have bonded, the tRNA leaves. Continues until STOP codon Protein synthesis is done New protein is released

Sickle Cell Anemia A genetic disease passed down through families. Abnormal protein (hemoglobin – carries oxygen) causes red blood cells to be sickle shaped rather than round. Results in blood clots and fatigue from lack of oxygen passing through blood stream.

Sickle Cell Anemia

DNA code CAT ______________ _______________ mRNA codon _____________ GUU _______________ tRNA anticodon _____________ ______________ _______________ Amino acid ____________ ______________ methionine

DNA code TGA ______________ _______________ mRNA codon _____________ UCU _______________ tRNA anticodon _____________ ______________ _______________ Amino acid ____________ ______________ tryptophan