-Connection Between Photosynthesis and Respiration-during ...

Chapter Four: The Cell in Action Teacher Notes

Lesson One: Exchange with the Environment -What is Diffusion? -Diffusion-the movement of particles from regions of higher density to regions of lower density. -Diffusion of Water -Osmosis-the diffusion of water through a semipermeable membrane. -Semipermeable-means that only certain substances can pass through. -The Cell and Osmosis -Osmosis helps maintain balance in cells -Can occur in plant cells (when a plant wilts and then gets water and firms up again) -Moving Small Particles -Passive Transport-the movement of substances across a cell membrane without the use of energy by the cell. -usually moves from an area of high concentration to an area of low concentration. -Active Transport-the movement of substances across the cell membrane that requires the cell to use energy. -usually involves particles moving from an area of low concentration to high concentration. -Moving Large Particles -Endocytosis-the process by which a cell membrane surrounds a particle and encloses the particle in a vesicle to bring the particle into the cell. -Exocytosis-the process in which a cell releases a particle by enclosing the particle in a vesicle that then moces to the cell surface and fuses with the cell membrane.

Lesson Two: Cell Energy -From Sun to Cell -Photosynthesis-the process by which plants, algae, and some bacteria use sunlight, carbon dioxide, and water to make food. -pigment-molecules that absorb light energy -chlorophyll is the green pigment found in plants and is located in the chloroplasts. -Getting Energy from Food -Cellular Respiration-the process by which cells use oxygen to produce energy from food. -is a chemical process that occurs in cells -food is broken down into carbon dioxide and water and energy is released -most is used to maintain body temperature and some provides energy for cell activities. -most takes place in the cell membranes of prokaryotic cells. -in eukaryotes it mostly takes place in the mitochondria

-Connection Between Photosynthesis and Respiration-during photosynthesis carbon dioxide is taken in and oxygen is released; in respiration oxygen is used by cells to break down sugar and release carbon dioxide. -Fermentation-occurs when cells can't get enough oxygen for respiration

-may occur when muscles produce lactic acid -some occurs in types of bacteria and in yeast

Lesson Three: The Cell Cycle -The Life of a Cell -Cell Cycle-the life cycle of a cell -begins when the cell is formed and ends when the cell divides and forms new cells -before a cell divides it makes a copy of its DNA which is organized in chromosomes. -copying chromosomes ensures that each new cell will be an exact copy or its parent cell -Chromosome-in a eukaryotic cell, one of the structures in the nucleus that are made up of DNA and protein; in a prokaryotic cell, the main ring of DNA -Making More Prokaryotic Cells -binary fission-splitting into two parts -results in two cells that each contain one copy of the circle of DNA -Eukaryotic Cells and Their DNA -homologous chromosomes-chromosomes that have the same sequence of genes and the same structure. -Making More Eukaryotic Cells -The cell cycle includes three stages -stage one-interphase-the cell grows and copies its organelles and chromosomes. After each chromosome is duplicated the two copies are called chromatids which are held together at a region called the centromere. They twist and coil and condense into an X shape. -stage two-mitosis-a process of cell division that forms two new nuclei, each of which has the same number of chromosomes. It is divided into four phases. -third stage-the cell splits into two cells; the cells are identical to each other and to the original cell. -Mitosis and the Cell Cycle -Cytokinesis-the division of the cytoplasm of a cell -Mitosis -Stage One-Interphase-chromosomes are copied. There are two chromatids. -Stage Two-Prophase-Mitosis begins. The nuclear membrane dissolves. Chromosomes condense into rodlike structures.

-Stage Three-Metaphase-Chromosomes line up along the equator of the cell. Hologous chromosomes pair up. -Stage Four-Anaphase-Chromatids separate and move to opposite sides of the cell. -Stage Five-Telophase-A nuclear membranes forms around each set of chromosomes, and the chromosomes unwind. Mitosis is complete. -Stage Six-Cytokinesis-Cell walls pinch in two.

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