1 Unit 2 Reproduction Pages

2 Section 4-1 Function of the Nucleus Within the Cell Pages

Recognize that the nucleus of a cell contains genetic information and determines cellular processes. Nucleus is the organelle responsible for 1. Storing heredity information 2. Controlling functions of cells

continued… 3. Contains master set of instructions that determines a. what each cell becomes b. how it functions c. when it will grow and divide d. when it will die

Define traits Particular feature that can vary in size or form from individual to individual within a species Passed on from one generation to another Inherited from biological parents

continued… Examples of traits: Dominant TraitsRecessive Traits Finger hairNo finger hair FrecklesNo freckles Attached ear lobesunattached lobes Widow’s peakNo widow’s peak

Define heredity.  Process through which patterns of traits are passed on from an individual to its offspring

Explain the role of the nucleus and its contents in determining traits and controlling cell division. Instructions in nucleus are carried in long, two stranded molecules called deoxyribonucleic acid. Commonly referred to as DNA

continued… DNA information Carries the instructions in the nucleus Long, stranded double- stranded molecule Forms a helix structure (Greek word: to wrap)

continued…

continued… Sides of DNA are made up of sugar and phosphate Steps are made up of four nitrogen bases: 1. adenine (A) 2. guanine (G) 3. cytosine (C) 4. thymine (T)

continued…  Bases in a DNA molecule always join in a specific way: A always joins with T G always joins with C

Explain the importance of using the terms gene and chromosome properly. The terms gene and chromosomes are often used to mean the same thing but they have very different meanings. Gene is a section of DNA Chromosomes are made up of genes

continued… ture=related ture=related Diagram of THE CHROMOSOME EXPRESS train (page 118)

continued… 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.

continued… Chromosomes within the nucleus are always found pairs Humans…23 pairs (46) of chromosomes One pair determines gender (M/F) XX male XY female

continued… Genes are found on chromosomes Stores information needed to produce proteins used by the body cells Vary in length from hundreds to thousands of bases Arrangement of bases determines the protein produced

continued… Each chromosomes contains thousands of genes Proteins determine what body cells will become and how they will function Specialize cells will becomes tissues; tissues will form organs

continued… Specialized proteins called enzymes speed up the hundreds of chemical reactions that occur within each cell Example: Digestive enzymes

continued… Some proteins act as chemical messengers called hormones Examples: Growth hormone

Define gene.  Small segments of DNA located on specific places on a chromosome

Describe chromosomes as being composed of numerous genes.

Example of knowledge of cellular functions has resulted in the new technologies. See wild, weird, wonderful Text page 120

24 Section 4.2 Mutations Pages

Discuss factors that may lead to changes in a cell’s genetic information. See notes to

Define mutation. A gene mutation is a change in the specific order of the bases that make up a particular gene Change in order of A, T, G, and C DNA sequence read in groups of three bases. Example: CAT or GCC

continued A base may be Added…an extra base is added Deleted…one base is missing Substituted…one base is substituted for another

Example: Added (Inserted) 28

Example: Deleted 29

Examples: Substitution 30

Video for genetics source/tdc02.sci.life.repro.lp_inher it/ source/tdc02.sci.life.repro.lp_inher it/ dna/index.html dna/index.html 31

continued… Types of Mutation 1. Positive mutations Benefits an individual -Resistance to diseases (see text page 124 for example of HIV resistant individuals)

continued… 2. Negative Mutation a. Harms the individual b. Reduces the chance that an individual will produce offspring or survive in the environment Examples: Sickle cell anemia Cystic Fibrosis

continued… 3. Neutral Mutation Does not affect the individual Example: Coat color of animals such as the Spirit Bear in British Columbia

Define mutagen. Substance or factors that can cause mutations in the DNA of organisms. Examples: – Cigarette smoke – X-rays – Pollutants

Give examples of causes mutations 1. Nature -Solar radiation -Radioactive gases

continued… 2. Human Activity -Chemicals such as chloroform and mustard gas -Nuclear radiation