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“ T he. n u c l e us. Chap t er 4:. c o n t rols l i fe.”. t he. f u n c t i o n s. o f.  the. organelle. that. is. resp o nsible. for. heredi t y. and. for. contr o ll i ng. the. fu n ctions. of. the. cell.  the contr o l cell. centre. of. the.  The. n ucleus.

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“ T he

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  1. “The nucleus Chapter 4: controls life.” the functions of

  2. the organelle that is responsible for heredity and for controlling the functions of the cell. thecontrol cell centre of the

  3. The nucleus contains the master set of instructions that determines what each how cell will become, it will function, when it will grow and divide and when it will die.

  4. Trait: a particular feature that can vary in size or to form from individual individual within a species. Inherited parents. from biological

  5. Heredity: the process through which patterns of traits are passed on from an individual to its offspring.

  6. Carries the instructions in the nucleus. A long, double-stranded molecule Forms a helix structure (a twisted ladder).

  7. The DNA Molecule

  8. The sides of the DNA ladder are made of sugar and The four phosphate. steps are made up of nitrogen bases. 1. 2. 3. 4. adenine guanine cytosine thymine (A) (G) (C) (T)

  9. The bases in a DNA molecule always join in a specific way: A G always always joins joins with with T C

  10. When a cell is ready to divide, each strand of loosely coiled DNA folds up further into a compact, structure X-shaped called a chromosome.

  11. Chromosomes within the nucleus pairs. are found in Most pairs humans have 23 of chromosomes including one pair that determines gender.

  12. found small on chromosomes. segments ofDNA located at specific places on a chromosome. store information needed to produce proteins used by body cells.

  13. Genes can vary in to length from hundreds thousands of bases. The arrangement of bases will determine the protein produced. Each chromosome contains thousands of genes.

  14. Proteins determine what body cells will become and howthey will function. Specialize cells will form form tissues; organs. tissues will

  15. Specialized proteins called enzymes speed up the hundreds of chemical reactions that occur within each cell. Ex. Digestive enzymes

  16. Some proteins act as chemical messengers called hormones. Ex. Growth hormone

  17. A gene mutation is a change in the specific order make gene. of up the bases that a particular

  18. A base may be: Added Deleted Substituted for another

  19. 1. Positive Mutation Benefits an individual Ex. Resistance to disease

  20. 2. Negative Mutation individual Harms the Reduce the probability that the individual will or produce offspring survive in their environment.

  21. Ex. Sickle cell anemia

  22. Ex. Cystic Fibrosis

  23. 3. Neutral Mutation Does not affect the individual Ex. Coat Color

  24. Substances or factors that can cause mutations in DNA. Ex. Cigarette smoke, X-rays, pollutants

  25. Nature Ex. Solar radiation Radioactive gases Human Activity Ex. Chemicals Nuclear Radiation

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