Opening Assignment This is a machine that requires several parts to do its job. Think about its job then answer the following: - Are there any parts you can take out and it still function? - Are there any parts that you absolutely cannot remove without changing its function?

Basic Structure of a Cell

Discovery of the Cell Robert Hooke (1665) → examined a slice of cork under the microscope, he saw boxes that he called cells Anton Van Leeuwenhoek (1675) → looked at pond water and found small living organisms – “animalcules”

Formation of the Cell Theory Matthias Schleiden → cells compose every part of plants Theodor Schwann → cells compose every part of animals Rudolph Virchow → cells come only from other cells Rudolph Virchow

The Cell Theory All living organisms are composed of one or more cells In organisms, cells are the basic units of structure and function Cells are produced only from existing cells

History & Discovery Questions What are some ways our knowledge has advanced regarding cells, based on the developments done by these & other scientists? (think of some current research being done and information in the news) Think about the part of the cell theory that states cells are produced only from pre-existing cells. What does this mean? What does it make you think about?

Review of Introduction to Cells Cells are the basic units of organisms Cells can only be observed under microscope Basic types of cells: Bacterial Cell Animal Cell Plant Cell

Number of Cells Organisms may be: Unicellular – composed of one cell Multicellular- composed of many cells that may organize

Cells May be Prokaryotic or Eukaryotic Prokaryotes include bacteria & lack a nucleus or membrane-bound structures called organelles – small single-celled Eukaryotes include most other cells & have a nucleus and membrane-bound organelles (plants, fungi, & animals) – larger than prokaryotes and can be either unicellular or multicellular

Prokaryote & Eukaryote Questions If Prokaryotes don’t have a nucleus does that mean that they do not have any DNA? Eukaryotes have membrane-bound organelles, which are specialized to perform specific cellular tasks. What characteristic of life does this best coincide with?

Prokaryotes Nucleoid region contains the DNA Cell membrane & cell wall Contain ribosomes (no membrane) to make proteins in their cytoplasm

Two Main Types of Eukaryotic Cells Animal Cell Plant Cell

Organelles Very small size Can only be observed under a microscope Have specific functions Found throughout cytoplasm

Organelles & other structures of the cell

Nucleolus

Ribosomes

Proteins

Endoplasmic Reticulum

Golgi Apparatus

Lysosome

Control Organelle Nucleus Controls the normal activities of the cell Bounded by a nuclear membrane Contains chromosomes

More on the Nucleus Nucleus Each cell has fixed number of chromosomes that carry genes Genes control cell characteristics

Cytoplasm of a Cell Cytoplasm Jelly-like substance enclosed by cell membrane Provides a medium for chemical reactions to take place

More on Cytoplasm Cytoplasm Contains organelles to carry out specific jobs Examples: chloroplast & mitochondrion

Surrounding the Cell Cell membrane Lies immediately against the cell wall in plant cells Made of protein and phospholipids Selectively permeable

Cell or Plasma Membrane Cell membrane Living layer Controls the movement of materials into and out of the cell Selectively permeable

Cell Powerhouse Mitochondrion ( mitochondria ) Rod shape Site of Cellular respiration

In Animal Cells: Mitochondria Active cells like muscles have more mitochondria Burn sugars to produce energy ATP

Plant Cell Organelles Chloroplast Contain the green pigment chlorophyll Traps sunlight to make sugars (food) Process called photosynthesis

Plant Cell Cell wall Dead layer Large empty spaces present between cellulose fibers Freely permeable

Plant Cell Cell wall Made of cellulose which forms very thin fibers Strong and rigid Found in plant cells

Plant Cell Cell wall Protect and support the enclosed substances (protoplasm) Resist entry of excess water into the cell Give shape to the cell

Plant Cell Organelles Vacuole Have a large central vacuole Surrounded by tonoplast Contains cell sap Sugars, proteins, minerals, wastes, & pigments

Animal Cell Organelles Near the nucleus Paired structures Help cell divide

Levels of Organization CELLS (muscle cells,nerve cells) TISSUES (muscle, epithelium) ORGANS (heart, lungs, stomach) SYSTEMS (circulatory system) ORGANISM (human)