GENETICS AND DNA Genetics is the study of

GENETICS AND DNA • Genetics is the study of how traits are passed from parent to offspring. • Genes - sections of the chromosomes found in cells; control these traits. • DNA is a molecule located on a chromosome that makes up genes and determines traits of all living things.

Genome • Genome: Complete complement of an organism’s DNA. – Includes genes (control traits) and noncoding DNA organized in chromosomes.

CHROMOSOMES Located in Nucleus – Split and Produce New Cells – Contain Genes • BODY CELLS – Make up most of the body’s tissues and organs – 2 of each chromosomes for a total of 46 • SEX CELLS – Can be a sperm cell (male) or an egg cell (female) – Only 1 kind of each chromosome; half as many as chromosomes in body cells

Genes • Eukaryotic DNA is organized in chromosomes. – Genes have specific places on chromosomes.

STRUCTURE of DNA • Holds information needed for cell function and carries information needed to make proteins. • Model looks like a ladder in a twisted shape. • DNA backbone (or sides) are made up of alternating sugars and phosphates. • “Rungs” of the ladder are composed of 4 nitrogen bases (adenine, thymine, cytosine, guanine) which are joined together in a specific order (via a covalent bond which is very strong).

STRUCTURE of DNA • This order is based on our genetic history, and makes up our genetic characteristics (eye, hair color; ear shape and size, etc. ). • These 4 bases form a ‘code’ which spells out a certain ‘message’. • This code is similar to the way the 26 letters in our alphabet combine to form words.

DNA STRAND • A ALWAYS pairs up with T; • C ALWAYS pairs up with G • A-T; C-G

DNA -vs- RNA • DNA • Sugar= deoxyribose • Nitrogen bases a. Adenine • b. Guanine • c. Cytosine • d. Thymine • Double stranded molecule • • RNA Sugar= ribose Nitrogen bases a. Adenine b. Guanine c. Cytosine d. Uracil Single stranded

The making of RNA • RNA is formed from DNA: The strands split at the (weak) hydrogen bonds where needed to make m. RNA. (messenger RNA) • The thymine (T) in DNA is replaced with uracil (U). • This process takes place in the ribosomes within a cell. • Process is referred to as transcription.

TRANSLATION: language of amino acids – creation of a protein • m. RNA is the blueprint that tells the order of amino acids • m. RNA is the CODE composed of a single strand of nucleotides (A, U, C, G) • Nucleotides divided into patterns of 3 letters in a row – (triplet codon) = 1 amino acid • Each codon forms long chain to produce proteins. • STOP codons (UAA, UAG, UGA) tell ribosomes when to stop making a proteins

From Genes to Proteins