Biology

Function of the Nucleus the organelle that is responsible for heredity and for controlling the functions of the cell. the control centre of the cell

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

Draw Diagram of a Cell indicating the placement of the nucleus and that DNA, genes, and chromosomes are located in the nucleus of a cell.

Keep this in mind as you learn the definitions of DNA, Gene and Chromosome Bill Nye Example Blue Jeans tied together – each pair of jeans represents a gene and all of them tied together represents DNA. All of this tightly packed in a suitcase called a chromosome.

DNA – Deoxyribonucleic acid Carries the master set of instructions in the nucleus. A long, double-stranded molecule which forms a double helix structure (a twisted ladder). Discovered by James Watson & Francis Crick

DNA Molecule

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

The bases in a DNA molecule always join in a specific way: A always joins with T G always joins with C This arrangement is known as the DNA message. In humans, a single DNA molecule can be several million base pairs in length

Figure 4.7 Page 116 DNA exists in the nucleus in a loosely coiled form until it is ready to divide When a cell is ready to divide, each strand of loosely coiled DNA folds up further into a compact, X-shaped structure called a chromosome.

Draw Picture of Chromosome Text Page 118

Chromosomes Chromosomes within the nucleus are found in pairs. Each chromosome can contain thousands of genes Most humans have 23 pairs of chromosomes including one pair that determines gender. Textbook Page 117

Genes small segments of DNA (can vary from hundreds to thousands of bases) located at specific places on a chromosome that instruct the nucleus to produce a specific protein. The types of proteins produced determine traits that will be manifest in the individual person.

How Does it All Come Together

Text: Page 120 “Glowing Genes” Explain the term Recombinant DNA Explain how this may be used by scientists in the future.

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

Dominant vs Recessive Traits

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

Trait Survey Hairline Tongue Rollers Ear Lobes

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

For the mutation to happen; A base may be: Added Deleted Substituted for another

Effects of Mutations 1. Positive Mutation Benefits an individual Ex. Resistance to disease

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

Ex: Sickle Cell Anemia

Ex: Cystic Fibrosis

3. Neutral Mutation Does not affect the individual Ex. Coat Color, Eye Color

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

Mutations can be caused by; Nature Ex. Solar radiation, UV rays, gamma rays etc Human Activity Ex. Chemicals – cleaning products, industrial wastes, cigarette smoke

Correcting Mutations Drugs, surgery Gene Therapy – replace a mutated gene with a healthy copy of the gene Page 127 Figure 4.17 Ashanti DeSilva

Activity Page 138 From one cell to many cells #1-5 and 4a in what did you find out