Ch. 4 Cell Structure and Function Intro.-4.2 What are the 7 Characteristics of Life? Intro.-4.2 What are the 7 Characteristics of Life?

/ Cells, organization, reproduction, energy use, response to stimuli, adaptation, growth

I. Cell Discovery Timeline:

Early 17th century Galileo Galilei -among the first to record a biological observation made with a “microscope” Galileo Galilei -among the first to record a biological observation made with a “microscope”

mid 17th century Robert Hooke -coined the term “cell” after observing dead cork cells Robert Hooke -coined the term “cell” after observing dead cork cells

Late 1600s Antony van Leeuwenhoek -observed “animalcules” =small moving creatures Antony van Leeuwenhoek -observed “animalcules” =small moving creatures

1820s Robert Brown -with improvements in lenses, viewed a nucleus Robert Brown -with improvements in lenses, viewed a nucleus

1838 Matthias Schleiden -hypothesized: each cell must develop independently Matthias Schleiden -hypothesized: each cell must develop independently

1839 Theodor Schwann -animals and plants are made of cells which have an individual life of their own Theodor Schwann -animals and plants are made of cells which have an individual life of their own

mid-19th century Rudolf Virchow -every cell comes from an existing cell Rudolf Virchow -every cell comes from an existing cell

II. The Cell Theory 1. Every organism is composed of one or more cells. 2. The cell is the smallest unit having the properties of life. 3. The continuity of life arises directly from the growth and division of single cells. 1. Every organism is composed of one or more cells. 2. The cell is the smallest unit having the properties of life. 3. The continuity of life arises directly from the growth and division of single cells.

4.1 Basic Aspects of Cell Structure Cell- the smallest unit having the properties of life

I. Structural Organization of Cells

Plasma membrane (aka cell membrane) -separates the cell from its environment, allowing substances and signals to move across in controlled ways. *Found in all cells -separates the cell from its environment, allowing substances and signals to move across in controlled ways. *Found in all cells

Nucleus or nucleoid -location of DNA *eukaryotic cell *prokaryotic cell

Cytoplasm -semi-fluid substance in the cell

Prokaryotic cells -lack a membrane- bound nucleus and organelles -Kingdoms: Archaebacteria Eubacteria -lack a membrane- bound nucleus and organelles -Kingdoms: Archaebacteria Eubacteria

Eukaryotic cells -have a membrane- bound nucleus and organelles Kingdoms: Protista, Fungi, Plantae, Animalia -have a membrane- bound nucleus and organelles Kingdoms: Protista, Fungi, Plantae, Animalia

What 3 parts do all cells have?

II. Lipid Bi-layer of Cell Membrane Includes proteins embedded in the membrane which: 1. Act as passive channels for water- soluble substances 2. Pump substances across the bi-layer 3. Act as receptors for hormones and other signaling molecules Includes proteins embedded in the membrane which: 1. Act as passive channels for water- soluble substances 2. Pump substances across the bi-layer 3. Act as receptors for hormones and other signaling molecules

Read pp in Holt Biology book (lion on cover)

III. Cell size and shape Cell size is limited by the surface to volume ratio. If a cell expands in diameter during growth, its volume will increase more rapidly than its surface area. Each unit of the cell’s plasma membrane will have to serve much more cytoplasm making cell transport inefficient. Also, a small cell has more efficient transport within the cell from organelle to organelle.

/ On the next slide you will see: / Largest human cell by volume / Smallest human cell / Longest human cell / On the next slide you will see: / Largest human cell by volume / Smallest human cell / Longest human cell

4.2 Microscopes Micrograph- a photographic image taken through a microscope

I. Light microscope A. Compound light -light must pass through the specimen -ours magnify 1,000X max. A. Compound light -light must pass through the specimen -ours magnify 1,000X max.

B. Stereoscope (aka dissecting microscope) - object is lit from the top and bottom, so can be opaque, 50X B. Stereoscope (aka dissecting microscope) - object is lit from the top and bottom, so can be opaque, 50X

II. Electron Microscopes A. Transmission electron microscope- cannot view living organisms, specimens must be sliced and stained ,000,000X A. Transmission electron microscope- cannot view living organisms, specimens must be sliced and stained ,000,000X

B. Scanning electron microscope- specimens coated with a thin layer of metal, cannot view living, 3-D ,000X B. Scanning electron microscope- specimens coated with a thin layer of metal, cannot view living, 3-D ,000X

C. Scanning tunneling microscope- scans the surface of the object, can view living -up to 100,000,000X C. Scanning tunneling microscope- scans the surface of the object, can view living -up to 100,000,000X

Why are microscopes a critical discovery?