Biology I 10/18/12

HW: Cell Theory – Write & Restate Take out 7.1 Reading Guide

CHAPTER 7 CELL STRUCTURE & FUNCTION

Objectives

Explain what the cell theory is. Describe how researchers explore

the living cell. Distinguish between eukaryotes and

prokaryotes.

7.1 Life is Cellular

Cells are the basic structural and functional units of life.

They differ in structure and complexity

This idea is relatively new Microscopes were first used around mid-

1600’s The invention of microscopes made the

discovery of the cell possible

Robert Hooke

In 1665, Robert Hooke used an early compound microscope to look at cork

Observed that cork was made up of 1000’s of hollow chambers

Dubbed them cells since they looked like the monastery’s tiny rooms called “cellula”.

Late 1600’s- Dutch textile salesman

Created different types of microscopes

Observed pondwater and found living organisms

Discovered over 5,000 types of microscopic life

Lenses were able to magnify up to 300X

Anton van Leeuwenhoek

The Cell Theory

A fundamental concept: a summary of confirmed discoveries

Cells are the most basic unit and structure of life

All living things are made up of cells New cells are produced from existing

cells

More Discoveries

1839 – German biologists Matthias Schleidan & Theodor Schwann proposed that all organisms are made of

cells.

1855 – German physician Rudolf Virchow Proposed that all cells produce more cells

through time

Exploring The Cell

Three major types of microscopes

1. Light Microscope Magnifies 40-1,000

times Used to magnify objects

that light can pass through

Uses slides

2. Electron Microscopes - Uses electrons to illuminate objects

Magnifies from 30,000 to 9 million times Two types

Transmission – Beam of e- pass through thin slice Images are 2-D Useful to study internal cell structures, large proteins

Scanning – beam of e- scan over surface 3-D images Useful to study external structure

Can only be used to look at dead specimens

3. Scanning Probe Microscopes

Traces surface of sample with a probe

View single atoms, DNA, protein molecules

Can view living things

Cells

Cells come in a variety of shapes Range in size from microscopic bacteria

to giant amoeba

All cells have a cell membrane – outer flexible barrier

All cells have (or had) DNA

Chaos carolinensis – Giant amoeba, approximately 1mm in length

Mycoplasma pneumoniae

Cells

Cell membrane

Nucleus- containing DNA

Eukaryotes- have cells that enclose their DNA in a nucleus Prokaryotes- cells that do not enclose their DNA in a

nucleus

2 Main categories of cells

Nucleus: large, membrane-bound structure that contains the cell’s genetic material in the form of DNA

Prokaryotes

Are generally smaller than eukaryotic cells

Have no nucleus Carry out all of life’s processes Ex: bacteria

Bacillus anthracis

Eukaryotes

Are generally larger and more complex than prokaryotes

Contain dozens of membrane bound structures that are specialized

Nucleus separates DNA from rest of cell Come in a variety of shapes and sizes

Ex: protists, fungi, plant, and animal cells

HW: Cell Theory: Write & Restate

1. Write the 1st part of the cell theory

2. Restate the sentence in your own words

3. Draw a picture to describe the statement

4. Repeat steps 1-3 for 2nd and 3rd sentences.

Example: Write: Each day

the temperature is below 32 degrees.

Restate: It’s freezing everyday!

Draw:Sun Mon Tue Wed Thur Fri Sat