1. 1.2 DNA: Your Genetic Code Nitrogenous Base  Codon  Gene  DNA  Chromosome Your future is in your “genes”

2. Chromosomes & DNA  the nucleus of almost every cell contains chromosomes  chromosomes act like a master set of instructions that determine:  what each cell’s job is  how it will function  how long it will live before being replaced

3.  chromosomes come in pairs  every plant or animal species that reproduce sexually get 1 chromosome from their mother, 1 from their father  this means you are 50% your mom, 50% your dad  depending on the species, there could be just a few pairs of chromosomes or many  humans have 23 pairs (46 chromosomes)  22 pairs, 1 pair of sex chromosomes  everyone’s chromosomes are a little different, which is why we are all different (except identical twins)  chromosomes are composed of coiled strands of genetic information called DNA

4. How many chromosomes?  Take a look at the difference in # of chromosome pairs:  human  23 pairs (46 chromosomes)  butterfly  190 pairs (380 chromosomes)  elephant  28 pairs (56 chromosomes)  ant  1 pair + (2+ chromosomes)  tomato plant  12 pairs (24 chromosomes)  shark  41 pairs (82 chromosomes)  mosquito  3 pairs (6 chromosomes)

5. Chromosomes of a Human Male Karyotype

6.  The genetic material that acts like a master set of instructions for the organism  Coiled up strands of genetic information that make up a chromosome  Is divided into many genes that control protein production DNA (deoxyribonucleic acid) gene = part of a DNA strand

7. DNA  Made of nitrogen bases, ribose sugars, and phosphate backbones  these 3 parts all together are called a nucleotide  There are 4 nitrogen bases:  adenine  thymine  cytosine  guanine

8.  2 nitrogen bases always pair up:  adenine + thymine  cytosine + guanine  think AT the Golf Course  it’s in the gene sequence that we get differences among individuals  hair colour, how tall you are, what allergies you have, how quickly your fingernails grow, etc.

9. Codons: 3-letter words  the genetic code is like a book that only has words that are 3 letters long  the letters are nitrogen bases (nucleotides)  codons are 3-letter words that code for a certain protein to be made  ex: CAT, GAG, TAG, …  the sequence of codons decides which protein is produced  if there’s a mistake in the sequencing of a codon, we get what we know as a mutation  ex: CAT, GCG, TAG, …

10. Comparing Genetic Information to a Book Book component Biological equivalent Letters Words Sentences Paragraph Chapters Book Nucleotides (nitrogen bases) Codons Genes DNA Chromosomes Organism (human, butterfly, ant)