Unit 2 Lesson 5 Homeostasis and Cell Processes Copyright © Houghton Mifflin Harcourt Publishing Company 1

Unit 2 Lesson 5 Homeostasis and Cell Processes Florida Benchmark SC.6.L.14.3 Recognize and explore how cells of all organisms undergo similar processes to maintain homeostasis, including extracting energy from food, getting rid of waste, and reproducing. Copyright © Houghton Mifflin Harcourt Publishing Company 2

Stayin’ Alive What is homeostasis? Unit 2 Lesson 5 Homeostasis and Cell Processes Stayin’ Alive What is homeostasis? Homeostasis is the maintenance of a constant internal state in a changing environment. Cells obtain and use energy, make new cells, exchange materials, and eliminate wastes in response to a changing environment. Copyright © Houghton Mifflin Harcourt Publishing Company 3

Unit 2 Lesson 5 Homeostasis and Cell Processes What is homeostasis? Unicellular organisms exchange materials directly with the environment. Multicellular organisms have systems that transport materials to other places within the organism. The cardiovascular system in humans and xylem and phloem in plants are transport systems. Copyright © Houghton Mifflin Harcourt Publishing Company 4

Get Growing! How do cells get energy? Unit 2 Lesson 5 Homeostasis and Cell Processes Get Growing! How do cells get energy? Cells get energy by breaking down materials. Plants, algae, and some bacteria make their own food from the sun by photosynthesis. Carbon dioxide and water are converted to sugar and oxygen in the chloroplasts. Copyright © Houghton Mifflin Harcourt Publishing Company 5

Unit 2 Lesson 5 Homeostasis and Cell Processes How do cells get energy? Plants and animals use oxygen during cellular respiration to produce energy from food. Sugars and oxygen are converted to water, carbon dioxide, and energy during respiration. Photosynthesis and respiration are linked because each one depends on the products of the other. Copyright © Houghton Mifflin Harcourt Publishing Company 6

Unit 2 Lesson 5 Homeostasis and Cell Processes How do cells divide? Cells grow, divide, and die at different rates and for different reasons. In eukaryotes, DNA is copied before a cell can divide. The nucleus and the rest of the cell divide to make two new cells. Copyright © Houghton Mifflin Harcourt Publishing Company 7

Unit 2 Lesson 5 Homeostasis and Cell Processes How do cells divide? Mitosis is cell division that forms two new nuclei that are identical to each other. DNA is packaged as chromosomes in the cell. During mitosis, the chromosomes are separated and genetic material is split evenly between the new genetically identical cells. Copyright © Houghton Mifflin Harcourt Publishing Company 8

Move It! How do cells exchange materials? Unit 2 Lesson 5 Homeostasis and Cell Processes Move It! How do cells exchange materials? Cell membranes are semipermeable, allowing only certain particles to move into or out of the cell. The movement of materials across a cell membrane without the use of energy is called passive transport. Copyright © Houghton Mifflin Harcourt Publishing Company 9

How do cells exchange materials? Unit 2 Lesson 5 Homeostasis and Cell Processes How do cells exchange materials? Diffusion is the movement of molecules from high concentrations to low concentrations. Osmosis is the diffusion of water through a semipermeable membrane. Large molecules move into and out of cells through protein channels. Copyright © Houghton Mifflin Harcourt Publishing Company 10

How do cells exchange materials? Unit 2 Lesson 5 Homeostasis and Cell Processes How do cells exchange materials? At some point, the movement of tea out of the bag stops or slows down considerably. Why? Copyright © Houghton Mifflin Harcourt Publishing Company 11

How do cells exchange materials? Unit 2 Lesson 5 Homeostasis and Cell Processes How do cells exchange materials? Active transport is the movement of particles against a concentration gradient and requires energy. Endocytosis and exocytosis are forms of active transport that move large particles into and out of cells. Copyright © Houghton Mifflin Harcourt Publishing Company 12

How do cells exchange materials? Unit 2 Lesson 5 Homeostasis and Cell Processes How do cells exchange materials? Why are both active and passive transport necessary to move materials into and out of cells? Copyright © Houghton Mifflin Harcourt Publishing Company 13

How do cells exchange materials? Unit 2 Lesson 5 Homeostasis and Cell Processes How do cells exchange materials? Endocytosis is a process in which cells use energy to surround and enclose a particle in a vesicle to bring the particle into the cell. Exocytosis is a process in which particles are enclosed in a vesicle in a cell and released from the cell. Copyright © Houghton Mifflin Harcourt Publishing Company 14

How do organisms respond to the environment? Unit 2 Lesson 5 Homeostasis and Cell Processes How do organisms respond to the environment? Cells and whole organisms must work to maintain homeostasis in a constantly changing environment. Some animals adapt their behavior to control body temperature. Trees can show seasonal responses to changes in the environment. Copyright © Houghton Mifflin Harcourt Publishing Company 15