Chapter 7 Cell Structure and Function

Objectives Explain what the cell theory is. Explain what the cell theory is. Describe how researchers explore the living cell. Describe how researchers explore the living cell. Distinguish between eukaryotes and prokaryotes. Distinguish between eukaryotes and prokaryotes.

What is a common structure that makes up every living thing? THE CELL

The Discovery of the Cell Advances in technology led to the discovery of the cell: INVENTION OF MICROSCOPE.

MID-1600s: Robert Hooke Used an early compound microscope to look at cork. Used an early compound microscope to look at cork. Noticed empty “chambers” in cork. Noticed empty “chambers” in cork. Named chambers “cells.” Named chambers “cells.”

Anton van Leeuwenhoek Used single-lens microscope to observe pond water. Observed microorganisms.

CELLS BASIC UNITS OF LIFE BASIC UNITS OF LIFE

CELL THEORY Proposed by 3 scientists: Proposed by 3 scientists: Schleiden: “All plants are made of cells” Schleiden: “All plants are made of cells” Schwann: “All animals are made of cells” Schwann: “All animals are made of cells” Virchow: “New cells are produced only from the division of existing cells” Virchow: “New cells are produced only from the division of existing cells”

** Proposals were confirmed by other biologists and make up the cell theory: 1. All living things are composed of cells. 2. Cells are the basic units of structure an function in living things. 3. New cells are produced from existing cells.

Exploring the Cell Microscopes are still used to explore cells. Microscopes are still used to explore cells. Technology is more advanced now and more powerful microscopes have been built to observe cells. Technology is more advanced now and more powerful microscopes have been built to observe cells. Confocal Light Microscope Confocal Light Microscope Electron Microscope Electron Microscope Scanning Electron Microscope Scanning Electron Microscope Scanning Probe Microscope Scanning Probe Microscope

Confocal Light Microscope Scans cells with a laser beam Makes it possible to build 3-D images of cells and parts.

Electron Microscope Focuses beam of electrons on image. Able to reveal images 1000 times smaller than light microscopes can reveal.

Scanning Electron Microscope Produces 3-D images of preserved cells and tissues. Cells and tissues must be placed in a vacuum.

Scanning Probe Microscope Can operate in ordinary air Can show samples in solution. Can image DNA and protein molecules.

Prokaryotes and Eukaryotes All cells have 2 characteristics in common: All cells have 2 characteristics in common: Cell membrane Cell membrane DNA: at some point in their lives. DNA: at some point in their lives.

2 Types of Cells Depending on whether or not they contain a nucleus: Depending on whether or not they contain a nucleus: Prokaryote Prokaryote Eukaryote Eukaryote

Prokaryotes Smaller and simpler than eukaryotic cells. Genetic material is not contained in a nucleus. Bacteria

Eukaryotes Larger and more complex than prokaryotes. Larger and more complex than prokaryotes. Contain a nucleus with DNA. Contain a nucleus with DNA. Plants, animals, fungi, and protists. Plants, animals, fungi, and protists.