Chapter 4 The Cell in Action...Table of Contents Section 1 Exchange with the Environment Section 2...

Table of Contents

Section 1 Exchange with the Environment

Section 2 Cell Energy

Section 3 The Cell Cycle

Chapter 4 The Cell in Action

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

Section 1 Exchange with the

Environment

What Is Diffusion?

• Diffusion is the movement of particles from regions

of higher density to regions of lower density.

• Diffusion of Water The diffusion of water through

cell membranes is called osmosis.

Chapter 4

Section 1 Exchange with the

Environment

What Is Diffusion?, continued

• The Cell and Osmosis Osmosis is important to

cell functions.

• Plasma surrounds red blood cells and is made up

of water, salts, sugars, and other particles. Osmosis

keeps the concentration of these particles in balance.

• When a wilted plant is watered, osmosis makes the

plant firm again.

Chapter 4

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.

• Active Transport A process of transporting

particles that requires the cell to use energy is called

active transport.

Chapter 4

Section 1 Exchange with the

Environment Chapter 4

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.

• 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.

Chapter 4

Section 1 Exchange with the

Environment

Chapter 4

Section 2 Cell Energy

Objectives

• Describe photosynthesis and cellular respiration.

• Compare cellular respiration with fermentation.

Chapter 4

Section 2 Cell Energy

From Sun to Cell

• Photosynthesis is the process by which plants,

algae, and some bacteria use sunlight, carbon

dioxide, and water to make food.

• Chlorophyll Plant cells have molecules that

absorb light energy. These molecules are called

pigments. Chlorophyll, the main pigment used in

photosynthesis, gives plants their green color.

Chapter 4

Pigments and Spectrum of light

Section 2 Cell Energy

From Sun to Cell, continued

Chapter 4

Section 2 Cell Energy

Getting Energy from Food

• Cellular Respiration During cellular respiration,

food (such as glucose) is broken down into carbon

dioxide and water, and energy is released.

Chapter 4

Section 2 Cell Energy

Getting Energy from Food, continued

• Connection Between Photosynthesis and

Respiration During photosynthesis, cells take in

carbon dioxide and release oxygen. During cellular

respiration, cells use oxygen to break down glucose

and release energy and 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.

Chapter 4

Section 2 Cell Energy Chapter 4

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

Section 3 The Cell Cycle

The Life of a Cell

• The cell cycle begins when the cell is formed and

ends when the cell divides and forms new cells.

• Before a cell divides, it must make a copy of its

DNA which is organized into structures called

chromosomes.

Chapter 4

Cell Cycle G1 Phase S Phase G2 Phase M Phase

Section 3 The Cell Cycle

The Life of a Cell, continued

• Making More Prokaryotic Cells Cell division in

bacteria is called binary fission, which means

“splitting into two parts.”

• 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.

Section 3 The Cell Cycle

The Life of a Cell, continued

•Eukaryotic Cells and Their DNA The chromosomes

of eukaryotic cells contain more DNA than those of

prokaryotic cells.

•In a eukaryotic cell, chromosomes are found in the

nucleus and are made of DNA and protein.

• Pairs of similar chromosomes are called homologous

chromosomes.

Chapter 4

Section 3 The Cell Cycle

The Life of a Cell, continued

The cell cycle has three stages:

1. Interphase: The cell grows and copies its

chromosomes. The two copies are now called

chromatids.

2. Mitosis: The chromatids separate.

3. Cytokinesis: The cell splits into two identical

cells.

Chapter 4

Section 3 The Cell Cycle

Mitosis and the Cell Cycle

• Mitosis has four phases:

1. prophase

2. metaphase

3. anaphase

4. telophase

Chapter 4

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

Section 3 The Cell Cycle Chapter 4

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

Chapter 4 The Cell in Action