The Unity of Life

Historical Background  Robert Hooke (1600’s)- examined slices of cork with a magnifying glass and observed box-like structures which he called cells.

Improvement in microscopes in the last four centuries has allowed scientists to better develop the cell theory.

Cell Theory 1. All living things are composed of cells. 2. Cells are the structural and functional units of living things. 3. All cells arise from preexisting cells.

Brain Pop! tics/cells/ tics/cells/

Two Exceptions to the Cell Theory: 1. Viruses are not made up of cells contain genetic material they can reproduce only within a living cell.

Exceptions to the Cell Theory 2. The first cell could not have arisen from a previously existing cell

Life’s greatest question Since the beginning of man we have been trying to identify why we are here, how we got here, and how it all came to be Different theories: Science – hot soup theory Intelligent design Mystical religions Modern religions Ancient religions

Or perhaps it’s both?

Based on physical observations through our own senses and developed technology we have come to understand certain principles about ourselves and our environment. This is Biology.

Cells – Two Categories Prokaryotes Eukaryotes Have cell membrane and cytoplasm but do not have a nucleus or organelles Bacteria – E. Coli and Staph aureus  (also called true cells)  Evolved much later  Contain cell membrane and cytoplasm like prokaryotes.  Also contain:  nucleus  organelles  Single cell organism (amoeba), plants, animals, fungi, and other microorganisms

WHAT DO ALL CELLS HAVE IN COMMON? PROKARYOTES AND EUKARYOTES, PLANT AND ANIMAL, RED BLOOD CELLS, NERVOUS CELLS, MUSCLE CELLS

Cell structure! Cell structure! - Cells vary in size, shape, structure, and function; however, most eukaryotic cells possess the following parts or organelles

Small organ-like structures in cells that carry out life functions

1. Cell membrane - Also known as the plasma membrane, it surrounds the cell separating it from the environment - Semi-permeable – selectively regulates the flow of materials to and from the cell maintaining homeostasis within the cell

Regulates transport of materials into and out of the cell Recognition of chemical signals by receptors Cell membrane

Cell Membrane - It is a double-layered, semi permeable membrane composed of lipids and proteins. - The cell membrane is alive.

Structure of the Membrane 1.) receptor – molecules on the surface of the cell membrane which attach to other molecules based on their shape

Structure of the Membrane

2. phospholipid bilayer – separates inside and outside of the cell Structure of the Membrane

3. proteins – allows transport of materials through a channel based on the size and charge of the molecule Structure of the Membrane

2. Cell Wall Found only in plants Composed of Cellulose (carbohydrate!) It is a nonliving supportive structure found outside the cell membrane Primary function is to support and protect the cell

3. Cytoplasm Fluid-like material that fills the space between the cell membrane and the nucleus of the cell Contains the organelles Many biochemical processes occur in the cytoplasm

4. Nucleus Control center of the cell. Directs all activities of cell. Controls cellular metabolism and reproduction. Contains DNA and hereditary material.

Nucleus Surrounded by a nuclear membrane. (sometimes) This membrane controls what can enter and leave the nucleus

5. Nucleolus (nucleoli) Structure that is the site of ribosome synthesis

6. Ribosomes Site of protein synthesis May be found in the cytoplasm or attached to the membrane of the endoplasmic reticulum

7. Endoplasmic reticulum System of fluid-filled canals from the nuclear membrane to the cell membrane Associated with synthesis, storage, and transport of materials within the cell

Ribosomes attached Protein synthesis No ribosomes Lipid synthesis

8. Lysosomes Membrane- bounded sacs that contain digestive enzymes. Lyse = break!

Lysosomes Continued Involved in the digestion of food in unicellular organisms. Destroy damaged or old cell parts in multicellular organisms.

9. Vacuoles Fluid-filled sacs found in the cytoplasm Contain stored materials, such as food and wastes

Types of vacuoles Food vacuole -stores and digests ingested food Contractile vacuole -pumps excess water from cells maintaining homeostasis (especially in uni-cellular organisms)

Plant cells have vacuoles filled with water to help support them

10. Mitochondria Powerhouse of the cell – MIGHTY MITOCHONDRIA! The site of aerobic respiration producing energy for the cell (ATP). Contain their own DNA and therefore can duplicate themselves. Found in large numbers in active cells

Mitochondria 10. Mitochondria

Mitochondria in Past Regents Exam Diagrams

11. Centrioles Found only in animal cells Located near the nucleus Play a role in cell division

12. Chloroplast  Pigment (chlorophyll) containing structures which serve as a site for photosynthesis

Chloroplasts  Found only in plant cells.  Contain green chlorophyll pigment.  Chloroplast, like mitochondria, have their own DNA and are capable of self-replication.

13. Cilia and Flagella  Organelles responsible for cell movement. a) Cilia- usually many and smaller (Paramecium). b) Flagella- usually one or two and larger (Sperm).

14. Golgi Apparatus

Golgi Complex/Apparatus/Body Series of membrane-bound sacs Synthesizes packaging that transports and secretes cellular waste products to the plasma membrane

Golgi body (complex) Golgi body (complex) - usually located near the nucleus

Oranelles – Brain Pop! tics/cellstructures/ tics/cellstructures/

Animal Cell d/1562_a14.htm

Plant Cell _a13.htm