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Transcript
Pg. 68 Observed the first cells; dead plant cells (cork) Coined the term “cell” First person to observe living cells Ground microscope lenses with precision Called the organisms, animalcules (We call them protists.) Cell-the basic unit of life 1) All living organisms are composed of one or more cells. 2) Cells are the basic unit of structure and function in an organism. 3) Cells come only from other cells. M. Schleiden- “All plants are composed of cells” T. Schwann-”All animals are composed of cells.” Cell division There is a large variety of cells: Skin cells Nerve cell Bacterial cell Onion cells There are 1000 micrometers in one millimeter!! WHY ??? As a cell grows its volume increases much faster than its surface area. If the cell’s volume were too large, it’s surface area would not be able to meet the cell’s needs. How would you answer this? As a cell becomes smaller, its surface area-to- volume ratio ___________________. A. increases B. decreases C. stays the same D. becomes less important Cell Diversity “Form follows function” - the shape of a cell is often related to its function The long extensions of a nerve cell are specialized for sending and receiving impulses Cell Size Most cells are between 10-50 micrometers The smaller the cell the more efficient it is at moving materials across its membrane How many cells would fit on the head of a pin that is 2mm in diameter??? Two Basic Types of Cells Prokaryotes… …include bacteria Eukaryotes… …include plant and animal cells What’s the difference? PROKARYOTES EUKARYOTES 1) no nucleus 1) have a nucleus 2) no membrane-bound 2) membrane-bound organelles 3) smaller 4) no mitochondria organelles 3) larger 4) have mitochondria Colonial Organisms A collection of identical cells living in a colony, NOT a multicellular organism Volvox Regulates movement of substances into and out of cells; outer boundary of the cell Composed of proteins, carbohydrates, and lipids *All important in the functioning of the membrane 1 ) They serve as attachment sites for molecules in the extracellular fluid 2) Transport materials across the cell membrane Helps cells recognize each other 1) forms vesicles with cell membrane 2) provides a boundary between cell and surroundings 3) transports substances into and out of the cell S.A. = 4πr2 2µm cell = 12. 56 20 µm cell= 1256 Increased by 100 times -controls cell functions -houses (holds) DNA/ chromosomes Contains: 1) Nuclear Envelope- contains pores that serve as passageways for RNA to enter and leave 2) Nucleolus- the site where ribosomes are made