Cell Theory
Cell Theory Understanding of cells required Improvement of microscopes Hundreds of years of research and observations The Cell Theory states All living things are made of cells Cells are the basic units of structure and function in living things Cells come from pre-existing cells
Exceptions to cells theory Where did the first cell come from? Viruses: non-living genetic material; need to act as parasites to reproduce Mitochondria and chloroplasts have their own DNA; partially reproduce on their own
Cell Theory Timeline 1590s: Zacharias Janssen worked with his father and invented the first compound microscope 1665: Robert Hooke observes cork under a microscope and names the tiny boxes he saw “cells” 1673: Anton von Leeuwenhoek observed single-celled organisms and blood cells
Cell Theory Timeline 1801: Robert Brown discovers the nucleus of the cell 1838: Matthias Schleiden (ShLY-dun) says all plants are made of cells Theodor Schwann says all animals are made of cells 1855: Rudolph Virchow (FUR-koh)says cells only come from other cells http://learn.genetics.utah.edu/content/begin/cells/scale/
Cell scale cell scale http://learn.genetics.utah.edu/content/begin/cells/scale/
Levels of organization Cells: Smallest structural and functional unit of an organism E.g. Skin cells, Nerve cells Tissues: a group of similar cells that perform particular functions E.g. Nerve, muscle, connective, epithelial Organs: groups of tissues working together E.g. Heart, Kidney Organ systems: a group of organs working together E.g. Digestive system, nervous system
Basic Cell Structure The cell membrane: A thin, flexible barrier around the cell. Cell wall: Many cells also have a strong layer around the cell membrane. Cell membranes and cell walls support and protect cells, while allowing them to interact with their surroundings
Basic Cell Structures Nucleus (plural: nuclei): A large structure that contains the cell’s genetic material and controls the cell’s activities. The cytoplasm: The material inside the cell membrane but not including the nucleus. The cytoplasm contains many important structures.
Two basic cell types 1. Prokaryotic (Pro=before, karyon=nucleus) a. no nucleus or organelles except ribosomes b. unicellular (one-celled) c. e.g. bacteria Anthrax Strep throat E. coli
Two basic cell types 2. Eukaryotic (True nucleus) a. have a nucleus and organelles b. unicellular and multicellular c. e.g. animals, plants, fungi, protists yeast Ameba, a protists
Prokaryotic Vs. Eukaryotic