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Unformatted text preview: Biology 11 Outline of Unit 3: Genetics Unit 3: Genetics Topic Outline: What is a cell? Cell theory- Fundamental ideas in biology established through research and now accepted to be true- 1. All living things are composed of one or more cells- 2. The cell is the smallest entity that retains the properties of life- 3. New cells arise from prexisting cells 3 key components of all cells- 1. Cell membrane:- Outer barrier of skin of cell- Isolates one cell from another- Site of cell communication (everything enters and exits the cell via membrane)- 2. Cytosol:- insides of a cell, including cytoplasm- May contain organelles like ribosomes- 3. Genetic materials:- DNA (deoxyribonucleic acid)- DNA carries the information necessary for normal cellular function- DNA forms a double helix and may be organized into chromosomes 2 main types of cells (text 6.2)- 1. Prokaryotic:- Primitive cells- No nucleus- No organelles- No chromosomes; just a single loop of DNA- Very small (1-10um in diameter)- E.g. bacteria - 2. Eukaryotic:- Advanced cells- Nucleus- Organelles- Chromosomes- Can be plant or animal cells- A little larger than prokaryotic cells (10-100um in diameter)- E.g. humans Cell cycle (text 12.2)- The cell lifespan Biology 11 Outline of Unit 3: Genetics- 1. Interphase:- When the cell lives its life, does its specialized cell job and grows- There are three stages in interphase; G1, S, and G2- In G1 it is the first growth phase, the cell performs its cell job- In S (synthesis) DNA is duplicated- In G2 the second growth phase occurs- 2. Cell division:- When the cell divides to make 2 daughter cells at the end of its life Reasons for cell division (including surface to volume ratio activity) (Text Chapter 12 overview)- 1. They may receive a signal from outside (via the blood, often in the form of a hormone) to grow bigger, repair damage, or replace other cells that have died- 2. They may be getting too old - 3. They may be getting too large to function efficiently Mitosis (text pages 232-233 is excellent!!!) Mitosis- Interphase versus mitosis- Phases: Prophase, prometaphase, metaphase, anaphase and telophase (and how to draw & identify them)- 1. Prophase:- Nucleolus fades and chromatin (replicated DNA and proteins) condense into chromosomes- The two chromatids begin to contract to form a tightly coiled appearance - In animal cells, the centrioles separate and move apart, and bundles of fibers appear around them- Both duplicated chromosomes compromises two chromatids which both have the same genetic info- Microtubules of the cytoskeleton which hold the cell shape and are attached during interphase are disassembled- Components of the microtubules are used to grow the mitotic spindle from the centrosomes- 2. Prometaphase: - No longer a recognizable nucleus as the nuclear envelope is broken down to allow the chromosomes to spread out- The spindle is fully formed- Individual chromosomes appear as dark Xs due to their dense packing...
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