dna & genetics

• cell division

  the process where one cell splits to create new cells
• cell division

  • allows organisms to replace dying or damaged cells
  • new cells can only be made when pre-existing cells divide
  • allows organisms to grow
• an adult human loses roughly 60 billion cells per day
• the number of cells in an adult body stays roughly the same over time
• an adult produces 60 billion new cells each day by cell division
• mitosis

  cell division for growth and repair
• meiosis

  cell division for the production of sex cells
• mitosis occurs during the division of all cells in the body except in the production of sex cells
• without mitosis your bones and hair would not grow and you would quickly lose cells due to damage
• Skin cells are replaced every 10 to 30 days
• Mitosis


  1. One cell splits in half to create two new cells

  2. The cell that divides is called the parent cell

  3. The two new cells are called daughter cells
• Each daughter cell has its own nucleus, which contains the DNA it needs to grow and function
• in mitosis, the daughter cells are genetically identical to each other and to the parent cell that made them
• The process of replacing dead or damaged cells


  Is depended directly on mitosis
• the growth of an organism is depended directly on mitosis
• a parent cell divides into two daughter cells, resulting in two cells in all
• daughter cells are genetically identical to their parent cells
• To grow in size from an embryo to a teenager all of your cells had to go through many cycles of cell division
• The cell cycle


  1. The daughter cells produced by cell division grow and divide, producing new daughter cells

  2. This repeated process of growth and division
• With each cell cycle, the total number of cells double
• During interphase, the strands of DNA are all jumbled together in the nucleus, a bit like a bowl of spaghetti
• There are 46 separate strands of DNA in most human cells, called chromosomes
• Cell division by mitosis


  1. The cell copies its DNA while it is still in interphase

  2. When each chromosome is copied, the new strand of DNA remains attached to the old one in a single bundle

  3. The number of chromosomes remains the same, but each one changes from single stranded to double stranded
• dna stands for deoxyribonucleic acid
• dna determines what organs and parts should develop, the order in which these parts should be assembled and how they should work together.
• the blueprint for a living thing is the genetic information contained in the cells that make it up
• nearly every cell in an organism's body contains exactly the same genetic information
• in animal and plant cells, the genetic information is stored in the cell's nucleus
• DNA is a type of molecule made up of thousands of atoms bonded together
• the genetic information in DNA determines how an organism develops and whether or not an organism will grow legs or wings
• dna determines how parts of an organism work together
• DNA is a very long, thin molecule made up of thousands of atoms. It consists of two chains or "backbones" that twist around each other. This structure is known as a double helix.
• Base


  Two smaller molecules that make up each "rung" of the DNA ladder
• DNA bases


  • Adenine (A)
  • Thymine (T)
  • Guanine (G)
  • Cytosine (C)
• Adenine (A)


  Joins with Thymine (T) to form a base pair
• Guanine (G)


  Joins with Cytosine (C) to form a base pair
• Base pair


  An A-T or G-C combination
• Genetic information is passed down from one generation to the next in packets or units known as genes
• A gene is a section of a DNA molecule that provides instructions for building a specific protein. Humans have about 20,000 genes.
• a single strand of DNA contains thousands of genes