Genetics
Pine seeds grow into pine trees Nile crocodiles raise baby Nile crocodiles
Why? In all living organisms, offspring resemble their parents because they inherit their parents’ genes
What is a gene? A gene is a section of DNA that contains the instructions for making a protein. In eukaryotes, DNA is found in the nucleus and is packaged in chromosomes Human cell – 7 ft of DNA Histones (proteins) keep it from tangling
Structure of DNA Double helix Backbone made of alternating molecules of deoxyribose sugar and phosphate Held together by covalent bonds
Four different nitrogenous bases adenine (A) pairs with thymine (T) cytosine (C) pairs with guanine (G) Bases are held together by hydrogen bond bonds
A single nitrogenous base bound to a single molecule of sugar and a single phosphate is called a nucleotide
DNA Replication DNA has to be copied before cell division Process is called replication DNA spiral “unzips” Each strand serves as a template for building new partner
Free nucleotides bind to complementary nucleotides Attached by enzymes called DNA polymerase DNA molecules are identical to the original
How does DNA provide instructions for cells to build proteins? Processes of transcription and translation Key molecule – Ribonucleic acid (RNA)
RNA Single-stranded Sugar – ribose Base is uracil (U) instead of thymine (T)
Transcription – DNA is used as a template for building a molecule of RNA Translation – RNA molecule is used to assemble proteins
Recall that proteins provide structure function in cell signaling protect organisms from disease initiate chemical reactions (enzymes)