Genetics Unit Genetic Materials Terms to know: - DNA- genome - RNA- double helix - Chromosome- karyotype - Chromatin - Sister chromatid - Gene - Bases - Nucleotide - Proteins

Watson and Crick - Discovered structure of DNA in Nobel prize 1962 Watson’s book

Rosalind Franklin ( ) X-ray diffraction patterns of DNA Her essential work was not recognized by the Nobel Committee in 1962

DNA structure -DNA is made up of two strands arranged in a double helix structure - The 2 strands of DNA run anti- parallel to one another DNA = deoxyribosenucleic acid

DNA structure (cont.) The building block of DNA is called a nucleotide which is made of 3 parts: - A phosphate group - A 5-carbon deoxyribose sugar - A nitrogen- containing base (A,T,G,and C)

Nitrogen-containing bases of DNA - All organisms have the same 4 bases: Adenine Guanine Thymine Cytosine - A connects with T via 2 hydrogen bonds (A=T) - G connects with C via 3 hydrogen bonds (G≡C) - Only 4 bases but unlimited ways to code for proteins (proteins are products of genes)

The double helix staircase in Vatican, Italy Visualizing the double helix structure of DNA

Where is DNA? In the nucleus Human cell: 23 pairs of chromosomes in every non-sex cell dna-is-packaged-basic.html

Chromosomes= super-coiled DNA - Male 46 chromosomes = 23 pairs - Karyotype = a picture of chromosomes arranged in pairs

DNA vs. RNA (ribose nucleic acid) RNA: single stranded The nitrogenous bases in DNA are: A, T, C, G The nitrogenous bases in RNA are: A, U, C, G

Molecular Visualizations of DNA 1ZvsYDTxc8&feature=related (Part 1) 1ZvsYDTxc8&feature=related DJ8FWA&feature=related (Part 2) DJ8FWA&feature=related

Gene - Genes are small segments on DNA that code for proteins -Proteins are the products of genes - A gene can range from 1,000 bases to 1 million bases in humans. - DNA can have thousands of genes. - Genes can overlap each other

Examples of Proteins ProteinsFunctions InsulinEnzyme for sugar metabolism HemoglobinOxygen transport in blood KeratinForms hair, nails and skin Actin, myosinMovement AntibodiesBody immune system

Genome = is an organism’s complete set of DNA, including all of its genes Numbers of Pairs of Chromosomes in Different Species of Plants and Animals Common nameSpeciesNumber of chromosome pairs MosquitoCulex pipiens 3 HouseflyMusca domestica 6 Garden onionAllium cepa 8 RiceOryza sativa 12 FrogRana pipiens 13 AlligatorAlligator mississipiensis 16 CatFelis domesticus 19 House mouseMus musculus 20 HumanHomo sapiens 23 PotatoSolanum tuberosum 24 DonkeyEquus asinus 31 HorseEquus caballus 32 DogCanis familiaris 39 ChickenGallus domesticus 39 CarpCyprinus carpio 52

Recall cell cycle and cell division Mitosis (PMAT)

Before a cell can divide It must duplicate its chromosome number (i.e. making 2 copies of each) e.g. if the cell has 2 chromosomes, after DNA duplication it should have 4 chromosomes Diploid cells: have 2 sets of chromosomes; often are non-sex or somatic cells; represented as 2n e.g. Human skin cells contain 2n=46 chromosomes --> they are diploid cells Haploid cells: have 1 set of chromosomes; are sperm & egg cells; represented as n e.g. Human sperm and egg cells contain n= 23 chromosomes --> they are haploid cells

2n = 46 e.g. Skin, heart cells n = 23 e.g. sperms, eggs