Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 1 Exchange with the Environment Objectives Explain the process of diffusion. Describe how osmosis occurs. Compare passive transport with active transport. Explain how large particles get into and out of cells. Chapter 4

Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 4 The Cell in Action

Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 1 Exchange with the Environment What Is Diffusion? Diffusion is the movement of particles from regions of high concentration to regions of lower concentration. Diffusion requires NO NRG! Diffusion of Water The diffusion of water through cell membranes is called osmosis. Chapter 4

Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 1 Exchange with the Environment What Is Diffusion?, continued The Cell and Osmosis Osmosis is important to cell functions. WHY? Remember– cells are surrounded by and filled with fluids made up mostly of WATER! Osmosis allows water to move through the semipermeable (only allows certain substances to pass through!) membrane of cells. Chapter 4

Copyright © by Holt, Rinehart and Winston. All rights reserved. Osmosis

Copyright © by Holt, Rinehart and Winston. All rights reserved. Moving Small Particles Small particles (ex- water, sugar) can cross the cell membrane through passageways called channels. These channels are made of proteins. Particles travel through the channels by either passive or active transport.

Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 1 Exchange with the Environment Moving Small Particles Passive Transport The movement of particles across a cell membrane without the use of energy by the cell is called passive transport. (ex- diffusion & osmosis!) Active Transport A process of transporting particles that requires the cell to use energy (ATP) is called active transport. Chapter 4

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 1 Exchange with the Environment Chapter 4

Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 1 Exchange with the Environment Moving Large Particles Endocytosis The active-transport process by which a cell surrounds a large particle and encloses the particle in a vesicle to bring the particle into the cell is called endocytosis. (ENDO = INTO!) Exocytosis The process in which a cell releases a particle by enclosing the particle in a vesicle that then moves to the cell surface and fuses with the cell membrane is called exocytosis. (EXO = EXIT!) Chapter 4

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 1 Exchange with the Environment Chapter 4

Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 2 Cell Energy Objectives Describe photosynthesis and cellular respiration. Compare cellular respiration with fermentation. Chapter 4

Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 2 Cell Energy From Sun to Cell All cells need energy to live, grow & reproduce. Remember– most of the energy that fuels life processes come from the sun! Photosynthesis- the process by which plants, algae, & some bacteria use sunlight, carbon dioxide, & water to make food. Chlorophyll Plant cells have molecules that absorb light energy. These molecules are called pigments. Chlorophyll, which is found in chloroplasts, is the main pigment used in photosynthesis, & gives plants their green color. Chapter 4

Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 2 Cell Energy From Sun to Cell, continued Chapter 4 Plants use NRG captured by chlorophyll to change carbon dioxide & water into glucose- which can be used later for NRG. Photosynthesis gives off oxygen.

Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 2 Cell Energy Getting Energy from Food Animals cells have different ways of getting NRG from food- they use either cellular respiration or fermentation. 1.Cellular respiration- the process by which cells use oxygen to produce energy from food 2. Fermentation- the breakdown of food without the use of oxygen Chapter 4

Copyright © by Holt, Rinehart and Winston. All rights reserved. Cellular Respiration Cellular Respiration During cellular respiration, food (such as glucose) is broken down into carbon dioxide and water, and energy is released.

Copyright © by Holt, Rinehart and Winston. All rights reserved. Cellular Respiration Remember– Cellular respiration takes place in the mitochondrion of eukaryotic cells– that’s why it’s the POWERHOUSE OF THE CELL!

Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 2 Cell Energy Getting Energy from Food, continued Connection Between Photosynthesis & Respiration During photosynthesis, cells take in carbon dioxide & release oxygen. During cellular respiration, cells use oxygen to break down glucose and release energy & carbon dioxide. Fermentation When muscles can’t get the oxygen for cellular respiration, they use fermentation to get energy. Fermentation is the breakdown of food without the use of oxygen. ( this produces lactic acid– which is why your muscles “BURN” after a tough workout! ) Chapter 4

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Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 3 The Cell Cycle Bellringer Biology is the only science in which multiplication means the same thing as division—at least with regards to cells. Explain what is meant by this statement in your science journal. Chapter 4

Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 3 The Cell Cycle Objectives Explain how cells produce more cells. Describe the process of mitosis. Explain how cell division differs in animals and plants. Chapter 4

Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 3 The Cell Cycle The Life of a Cell The cell cycle begins when the cell is formed & ends when the cell divides & forms new cells. Why do we need to make new cells? To grow & develop To repair damaged cells or tissues To replace cells that have died Chapter 4

Copyright © by Holt, Rinehart and Winston. All rights reserved. Before a cell divides, it must make a copy of its DNA DNA is organized into structures called chromosomes. (copying chromosomes ensures that each new cell will be an exact copy of its parent cell!) Why is this important? – Because each cell must have the correct number of chromosomes, it will not properly function!

Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 3 The Cell Cycle How does a cell make more cells? It depends on what type of cell it is! Prokaryotes- Cell division in bacteria is called binary fission. This is a type of asexual reproduction. Bacteria have a single circular DNA molecule (chromosome). Binary fission results in two cells that each contain one copy of the circle of DNA. Chapter 4

Copyright © by Holt, Rinehart and Winston. All rights reserved. Binary Fission

Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 3 The Cell Cycle The Life of a Cell, continued Eukaryotic Cells - The chromosomes of eukaryotic cells contain more DNA than those of prokaryotic cells. In a eukaryotic cell, chromosomes are found in the nucleus & are made of DNA & protein. Pairs of similar chromosomes are called homologous chromosomes. Chapter 4

Copyright © by Holt, Rinehart and Winston. All rights reserved. Humans have 23 pairs of homologous chromosomes (46 total chromosomes!) … you get 23 chromosomes from your dad and 23 from your mom! (--Just because an organism is more complex- that does not mean it will have more chromosomes– ex- potatoes have 48! )

Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 3 The Cell Cycle The Life of a Cell, continued Eukaryotic Cells The cell cycle has three stages: 1.Interphase: The cell grows & copies its organelles & chromosomes. The two copies of the chromosomes are now called chromatids. 2.Mitosis: The chromatids separate. 3.The cell splits into two identical cells. Chapter 4

Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 3 The Cell Cycle Mitosis and the Cell Cycle Mitosis has four phases: 1.prophase 2.metaphase 3.anaphase 4.telophase Chapter 4

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Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 3 The Cell Cycle Mitosis and the Cell Cycle, continued Cytokinesis is the division of cytoplasm. In animal cells (and other eukaryotes that do not have cell walls), division of the cytoplasm begins at the cell membrane. In plant cells and in other eukaryotes with cell walls, a cell plate forms and the cell splits into two cells. Chapter 4

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The Cell in Action Concept Map Use the terms below to complete the concept map on the next slide. Chapter 4 ATP photosynthesis oxygen water consumers lactic acid producers respiration energy

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Concept Map Chapter 4

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Concept Map Chapter 4

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu End of Chapter 4 Show

Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 2 Cell Energy Chapter 4

Copyright © by Holt, Rinehart and Winston. All rights reserved. Section 2 Cell Energy Chapter 4

Copyright © by Holt, Rinehart and Winston. All rights reserved. Chapter 4 Standardized Test Preparation