Cell Processes SUGAR BASE Phosphate Group

Looking Inside Cells Cell Wall Cell Membrane Nucleus Mitochondria Endoplasmic Reticulum Ribosomes Golgi Bodies Chloroplasts Vacuoles Lysosomes Look Inside a Cell-1 Look Inside a Cell-2

Nucleus Nuclear Membrane Chromatin Nucleolus Journey into the Nucleus

D N A DNA – the blueprint of life DNA is a nucleic acid found in the chromatin in a cell’s nucleus DNA holds all the information that the cell needs to carry out its functions DNA Replication A cell makes a copy of its DNA before mitosis occurs ensures that each replicated cell will have all of the genetic information it needs to carry out its activities Journey into DNA

Why Do We Study DNA Chromosomes & DNA Central importance to all life on Earth Medical benefits such as cures for diseases Better food crops. Chromosomes & DNA Our genes are on our chromosomes Chromosomes are made up of a chemical called DNA.

DNA-Deoxyribonucleic Acid Made up of nucleotides (DNA molecule) in a DNA double helix It looks like a twisted ladder or a spiral stair staircase Nucleotide: 1. Phosphate group 2. 5-carbon sugar 3. Nitrogenous base ~2 nm wide

DNA Double Helix P P G C T A Mitosis Review O “Rungs of ladder” 1 2 3 4 5 P O 1 2 3 4 5 Nitrogenous Base (A,T,G or C) “Rungs of ladder” G C “Legs of ladder” Phosphate & Sugar Backbone T A Mitosis Review

DNA Building Block phosphate The backbone of the molecule is alternating phosphates and deoxyribose sugar The teeth are nitrogenous bases Adenine Thymine Guanine Cytosine deoxyribose bases

Structure of DNA The two sides of the DNA ladder are made of molecules of a sugar called deoxyribose nucleic acid- (DNA) --alternating with molecules known as phosphates Each rung of the DNA ladder is made of a pair of molecules called nitrogen bases Four kinds of nitrogen bases Adenine - A Thymine - T Guanine - G Cytosine - C Structure of DNA

DNA Replication Process DNA replication begins when two sides of the DNA molecule unwind and separate, like a zipper unzipping The molecules separate between the paired nitrogen bases Nitrogen bases that are floating pair up with bases on each half of the DNA molecule Rules of Pairing: A always binds with T G always binds with C

DNA Replication Process Once bases are attached, two new DNA molecules are formed. The order of the bases in each new DNA molecule will exactly match the order in the original DNA molecule Tour of DNA

Interesting DNA facts Each cell has about 2 m of DNA The average human has 75 trillion cells The average human has enough DNA to go from the earth to the sun more than 400 times DNA has a diameter of only 0.000000002 m The earth is 150 billion m or 93 million miles from the sun. Extraction of DNA