UNIT 1UNIT 1

Chapter 1: Cells and More Cells

Chapter 2: Plants: From Cells to Systems

Chapter 3: Animals: From Cells to Systems

Tissues, Organs, and Systems of Living Things

Tissues, Organs, and Systems of Living Things

Cell StructureCell Structure• One of the first structures to be seen clearly through a microscope

was the nucleus.

• The nucleus is the organelle that controls the cell’s activities.• Organelles are specialized structures within a cell.

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The Cell TheoryThe Cell Theory

The Cell Theory was proposed by German scientists in the late 1830s. Theodor Schwann and Matthias Schleiden used their studies of plants and animals to formulate the first two ideas. In 1855 Rudolph Virchow added the final one. The theory states that:

1. All living organisms are made of one or more cells.2. The cell is the basic organizational unit of life.3. All cells come from pre-existing cells.

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Animal and Plant Cell OrganellesAnimal and Plant Cell Organelles

The cytosol (the fluid material between the cell membrane and the nucleus) is filled with many specialized organelles.

Each organelle has specific functions that it performs in the cell. Together the organelles and fluid are called the cytoplasm.

There are some important differences between the organelles found in plant and animal cells.

Copyright © 2010 McGraw-Hill Ryerson Ltd.

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Animal Cell

nucleolus

chromatin

nucleoplasm

ribosome

lysosome

mitochondrion

cell membrane

cytoplasm

rough endoplasmic reticulum

Golgi apparatus

Golgivesicle

vacuole

centrioles

nuclear membrane

nuc

leu

s

smooth endoplasmic reticulum

Plant Cell

nucleolus

chromatin

nucleoplasm

ribosome

mitochondrion

cell membrane

cytoplasm

rough endoplasmic reticulum

vacuole

cell wall

chloroplast

Cell Organelles

cell membrane – separates the inside of the cell from the external environment; controls the flow of materials into and out of the cell

cytoplasm – includes the cytosol, the organelles, and other life-supporting materials, such as sugar and water, all contained by the cell membrane

mitochondria – (singular: mitochondrion) where energy is released from glucose to fuel cell activities

ribosomes – help to produce proteins, which make up much of a cell’s structure and are required for activities necessary for the cell’s survival; some ribosomes float in the cytoplasm, and others are attached to the endoplasmic reticulum

Cell Organelles

endoplasmic reticulum – a network of membrane-covered channels that transport materials made in the cell; is connected to the nucleus

vesicles – membrane-covered sacs that transport and/or store materials inside the cell and sometimes help these materials cross the cell membrane to enter or exit the cell

Golgi body – sorts and packages proteins and other molecules for transport out of the cell

vacuoles – contain water and other materials and are used to store or transport small molecules; plant cells tend to have one large vacuole; animal cells may have several smaller vacuoles

Cell Organelles

lysosome - contains enzymes (type of proteins) that can break down molecules (food, bacteria, wastes, the cell itself)

cytoskeleton – filaments and tubules that provide a framework for the cell, helping it maintain its structure and providing “tracks” along which vesicles and organelles can move

cell wall – a tough, rigid structure lying just outside a plant cell’s membrane; provides support for the cell

chloroplasts – found only in plant cells; trap energy from the Sun to make glucose, which is broken down in the mitochondria to power cell activities (animals must get glucose from the food they eat)