Cells Chapter 7
Robert Hooke - First person to see cells, he was looking at cork and noted that he saw "a great many boxes”. (1665) • Anton van Leeuwenhoek - Observed living cells in pond water, which he called "animalcules" (1673) Early Contributions
Animals vs. Plants!! • Theodore Schwann– zoologist • observed tissues of animals • contained cells (1839) • MattiasSchleiden– botanist • observed tissues of plants • contained cells ( 1845) • Rudolf Virchow • reported that every living thing is made of vital units, known as cells • predicted that cells come from other cells. (1850 )
The Cell Theory • 1. Every living organism is made of one or more cells. • 2. The cell is the basic unit of structure and function. It is the smallest unit that can perform life functions. • 3. All cells arise from pre-existing cells. *Why is the Cell Theory called a Theory and not a Fact?
ALL cells have these parts • Ribosomes – make protein for use by the organism • Cytoplasm – fluid material within cell • DNA – genetic material • Cytoskeleton – internal framework of cell • Cell Membrane – outer boundary, selectively permeable Cell Features
Structure • Core of DNA/RNA surrounded by a protein coat • Reproduction • Lysogenic or lytic cycle • Disease Causing • HIV and influenza • Mimics living cells, but do not have organelles or self-replication Viruses NOT ALIVE!!
Viral Structure
True or false: • Robert Hooke was the first person to see cells.__ • Bacteria cells have a cell membrane.__ • The Cell Theory was developed by a single scientist.__ • Plant cells have cytoplasm.__ • Cells taken from fungi do not have DNA.__ • Cells can only come from pre-existing cells. __ • It only took five years to develop the Cell Theory.__ Comprehension Checkpoint
Got Nucleus? • Cells are classified based on the presence of a membrane bound nucleus “-karyote” • What’s inside the nucleus? • “pro-”=before • “eu-”=true • Prokaryote • Eukaryote
The first cells to inhabit the earth • Simple cells • Bacteria • These cells do NOT have a nucleus, their DNA is circular and floats in the cytoplasm Prokaryote Cells “before a nucleus” Some bacteria have a tail-like structure called a flagella, that helps it to move. A capsule surrounds some bacteria and helps them avoid the body’s immune system
Bacteria Images Bacteria that causes Anthrax. We talked about Anthrax before…remember?
Usually found at center of EUKARYOTIC cell • Has a nuclear membrane & nuclear pores • Contains cell’s DNA in one of 2 forms • chromatin - DNA bound to protein (non-dividing cell) • chromosomes - condensed structures seen in dividing cell • Also contains an organelle called nucleolus - which makes the cell’s ribosomes Nucleus
Mitochondria – this is the cell’s energy center. It turns food into a chemical energy called ATP The mitochondria is sometimes called the “powerhouse” of the cell Cell Organelles
Golgi Apparatus – processes, packages and secretes proteins. It is comparable to a factory or a post office. Cell Organelles *A vesicle forms with Golgi to transport substances outside cell.
Lysosome – Contains digestive enzymes, breaks things down, "suicide sac” Cell Organelles Endoplasmic Reticulum – Transport, "intracellular highway". -Rough ER contains many ribosomes & is involved in protein synthesis -Smooth ER ribosomes not found on surface
Cytoskeleton – Helps cell maintain support & shape and helps with movement a. microtubules-hollow structures; also help build cilia and flagella b. microfilaments-threadlike c. centrioles-only in animal cells; used during cell division (paired) Cell Organelles Vacuole – storage area for water and other substances -Paramecium have a contractile vacuole to get rid of extra water
The cell is like a factory. Its product is protein which goes to body to serve different functions. • DNA has instructions to build protein • These instructions are sent to ribosomes • The ribosomes build protein and send it through ER • The proteins are delivered to golgi where they are completed and “tagged” for export outside cell Protein Production
THE ANIMAL CELL Can you identify the parts?
Cheek Cells Seen Through Microscope
Have additional structures • CELL WALL – surrounds membrane & provides additional support • CHLOROPLASTS– contain green pigment, function in photosynthesis • CENTRAL VACUOLE– large water container in center of cell Plant Cells
PLANT CELL Can you identify the parts?
Mitochondria and chloroplasts have their own DNA (separate from the nucleus) • This supports the ENDOSYMBIOSIS THEORY which states that eukaryotic cells evolved when prokaryote cells engulfed or absorbed other cells. Organelles With DNA
What does “selectively permeable mean? CELL MEMBRANE • Selectively permeable; it regulates what comes into the cell and what leaves the cell • It is composed of a double layer of phospholipids with proteins embedded throughout Lipids again. Told ya.
Cell Membrane Extensions • Cilia assemble and disassemble for cytoplasmic movements that allow cells, such as amoebas, to crawl along surfaces • Intestines have these as well (called villi) • Flagella • Whip-like tails for movement • Bacteria • sperm
