Life is Cellular 7-1

1660’s Anton van Leewenhoek invented the first microscope.

1665 Robert Hooke used an early microscope to look at cork and named the small chambers he saw “cells.”

What is a cell? Cells are the basic unit of structure and function of all living things.

Cell Theory 1) All living things are made of cells. 2) Cells are the basic unit of structure and function in living things. 3) New cells come from existing cells.

A) A cell membrane B) cytoplasm C) DNA D) ribosomes All cells have. . . A) A cell membrane B) cytoplasm C) DNA D) ribosomes

A. Cell membrane A thin, flexible barrier around the cell. Controls what enters and leaves the cell

B. Cytoplasm Jelly-like substance that fills the cell. Site of many chemical reactions

C. DNA Stores the genetic information for the organism Like a cookbook for making proteins

Use the instructions from DNA to make protein. D. Ribosomes Use the instructions from DNA to make protein.

Different types of cells There are two types of cells: Prokaryotic cells Eukaryotic cells

How are they different? Prokaryote Eukaryote No nucleus Nucleus No organelles Organelles Relatively small Relatively large

Nucleus (eukaryotes) Controls the cell Stores the genetic material (DNA)

What types of organisms are prokaryotes? Bacteria

What types of organisms are eukaryotes? Plants, animals, fungus, and protists (Everything except bacteria)

Multicellular vs. Unicellular Organisms Multicellular – cells develop in particular ways for different functions. i.e. humans Unicellular – aka single celled. The one cell IS the organism. Perform all of the functions in just one cell. i.e yeast

An instrument that produces magnified images of tiny structures Microscope An instrument that produces magnified images of tiny structures

Compound Light Microscope Most common microscope Uses light Compound = contains more than one lens

Electron Microscope More powerful than compound microscope. Uses a beam of electrons to examine something.

Scanning Probe Microscope Trace the surfaces of a sample with a tiny tip known as a probe

Viruses

What are viruses? Viruses are not cells. They consist of DNA or RNA wrapped in a protein coat (capsid)

Viruses are NOT alive!!! They inject their DNA/RNA into a cell and force it to make copies of the virus Since they cannot reproduce on their own, they are not considered to be living.

Lecture Review Questions Why was the invention of the microscope important? How is the original definition of the cell different from today’s definition? Virus are not living organisms, or cells, because they do not reproduce. How does their inability to reproduce go against Cell Theory?