Chapter 7 Biology

Discovery of the Cell In the mid-1600s, Anton van Leewenhook used a single lens light microscope to observe pond water and discovered a world of tiny microscopic organism in the water.

In 1665, Englishman, Robert Hooke used an early compound light microscope to look at a thin slice of cork a plant material.

•He observed thousands of tiny empty chambers, he called cells now considered to be the basic units of life

Development of Cell Theory In 1838, German botanist, Matthias Schleiden concluded that all plants were made of cells.

The next year, German biologists, Theodore Schwann stated that all animals were made of cells.

In 1855, German physician Rudolf Virchow concluded that new cells could only be produced from existing cells

Together the works of these scientist and others led to the development of the cell theory the fundamental concept of biology!

The Cell Theory states: All things are composed of cells

Cells are the basic units of structure and functions

New cells are produced from existing cells

Exploring the Cell In the 1940s, a new type of microscope, the electron microscope was invented

The Electron Microscope uses beams of electrons instead of natural light to magnify images and can do so up to 500,000 x the actual size of the image

The Electron Microscope was better than the Light Microscope because it allowed scientists to see the internal structures within the cell

There are several different types of Electron Microscopes:

Scanning Electron Microscope (SEM): scans the surface within the cell

Fly leg

Transmission Electron Microscope (TEM): allows scientists to see internal structures.

Pine tree

Scanning Tunneling Microscope (STM): uses electrons to investigate the atoms of the surface of molecules

2 Types of Cells With the development and use of the microscopes, scientists were able to discover 2 groups of cells that exists in living organisms all contain:

ribosomeDNAcell membranecytoplasm

1. Prokaryotic Cells: cells that lack internal membrane-bound structures called organelles (little organs)

2. Eukaryotic Cells: cells that contain internal membrane-bound structures or organelles (has a nucleus)

Discovery of the Nucleus Robert Brown, a Scottish scientist, was the first to observe as prominent structure in cells, called the nucleus

Rudolf Virchow later concluded that this structure (nucleus) is responsible for cell division (reproduction) in living organisms

6 Kingdom System (into which living organisms belong):

1. Eubacteria-prokaryotic cells ex: E. coli (bacteria)

2. Archaebacteria- prokaryotic cells ex. Methanogens (bacteria)

3. Protista-eukaryotic cells ex. Amoeba, algae

4. Fungi- eukaryotic cells ex. Mushrooms, athlete’s foot

5. Plants- eukaryotic cells ex. Pine, flowers

6. Animals- eukaryotic cells ex. Sponges, humans

NOTE: THE ONLY Prokaryotes ON EARTH ARE bacteriums (monerans)

Typical Prokaryotic Cell

DNA

Cell membrane

Typical Eukaryotic Cell

Ch 7.2 Biology Notes

Cell Parts (Organelles) •Prokaryotic cells (prokaryotes)-are cells that do not have a nucleus. They are the most ancient (oldest) cells on Earth. Many of these earliest cells do not use oxygen to respire.

They used CO2 in the atmosphere and lived in water and produced O2 gas as a by-product. Prokaryotes are ONLY found in the kingdom Monera. Eubacteria and Archaebacteria Domains. They are bacteria.

Eukaryotic cells (eukaryotes)-are cells that have a nucleus. They are found in all the other kingdoms: Plantae, Animalia, Fungi, and Protista. They are thought to have evolved from two bacteria living together symbiotically (both benefiting).

This is called the Endosymbiotic Theory. You have eukaryotic cells! Mitochondria and Chloroplast have own DNA.

Nucleus-directs all activities of the eukaryotic cell. Surrounded by a nuclear envelope (membrane)

Nucleolus-organelle inside the nucleus that make ribosomes

·Chromatin-is located in the nucleus of the cell; contains strands of DNA. Chromosomes are condensed chromatin.

·    Plasma Membrane-a bilayer (2-layers) of phospholipids joined together to surround the cell. (Fatty acids + Phosphate Group)

Primary Function is to maintain: Homeostasis

Ribosomes-the site of protein synthesis. Ribosomes take amino acids and produce proteins using the instructions from DNA

Cytoplasm-the fluid of the cell. Also called cytosol

Where all chemical reactions of the cell takes place

Endoplasmic Reticulum (ER)-are cellular pathways used to transport proteins

Smooth ER=have no ribosomesRough ER=have ribosomes

Golgi Apparatus-sort, package, process proteins. They are the UPS of the cell. Produces little packages celled vesicles. Not connected to nucleus

Vacuoles-in plant cells they are the largest structure. Responsible for storing large amounts of water. In animal cells, they are much smaller and more numerous. They store food, enzymes, and other materials needed by the cell. Sometimes they store waste products. Some have Contractile vacuole- to maintain Homeostasis.

Lysosomes-recycle cellular parts. They can contain digestive enzymes that break down and reuse worn-out organelles and food particles.

Chloroplasts-are cell organelles Chloroplasts-are cell organelles that that capture light energycapture light energy and and convert it into convert it into chemical energy chemical energy (glucose/food) for plant cells.. (glucose/food) for plant cells.. ChlorophyllChlorophyll is the is the green pigmentgreen pigment used to trap light energy. used to trap light energy. ChlorophyllChlorophyll also gives plants also gives plants their their green colorgreen color (belongs to a (belongs to a group called group called plastidsplastids). NOTE: ). NOTE: The ultimate source of The ultimate source of all energyall energy on Earth is the on Earth is the SUN!SUN!

Mitochondria-the site of Mitochondria-the site of cellular cellular respirationrespiration (ENERGY). They (ENERGY). They transformtransform food into energy in the food into energy in the form of ATPform of ATP (adenosine triphosphate: a useable (adenosine triphosphate: a useable form of energy). Tissues or cells that form of energy). Tissues or cells that use use a lot of energya lot of energy have have large large numbersnumbers of mitochondria. of mitochondria. Muscle cellsMuscle cells have more mitochondria than have more mitochondria than skin skin cellscells. . Powerhouse Powerhouse of the cell.of the cell.

NCSCOS: mitochondria is folded to NCSCOS: mitochondria is folded to increase surface areaincrease surface area (make more room).

Organelle DNAMitochondria and Chloroplast have own

genetic DNA. It is suggested that mitochondria and

chloroplast are descendents of ancient prokaryotes.

Prokaryotes that use oxygen to generate ATP evolved into Mitochondria.

Prokaryotes that carried out photosynthesis evolved into Chloroplast.

Microtubules and Microfilaments-are thin, solid proteins fibers. Many anchor cilia (hair-like) and flagella (whip-like tail) that help one-celled organisms to move.

Cell Wall-an inflexible barrier found in plants. It protects the cell and gives it support it is made up of cellulose and has porous fibers that allows molecules to pass through

Centrioles-found only in animal cells. Aid(appears) in cellular division