Cells June 2, 2015

Cells I. Cells = building blocks of all life A. Discovered in 1600’s 1. After Microscope was invented 2. Named by Hooke

Cells II. Cell Theory A. All living organisms are made of cells 1. One or more Humans, elephants, redwood trees, amoebas, bacteria, mushrooms B. Cells = basic unit of structure in function of organism Bone cells Fat cells Muscle cells Leaf cells C. All cells come from other cells 1. Reproduction = cell division 2. We start as one cell = fertilized egg

Cells III. Types of cells (types of organisms) A. Prokaryotic 1. Most primitive life form = bacteria and blue green bacteria 2. Oldest fossils = 3.75 billion years old 3. Do not have nucleus 4. Do not have organelles with membranes 5. DNA is in form of loop or ring

Cells B. Eukaryotic 1. More advanced/complex – have nucleus 2. Includes protists,fungi, plants, and animals 3. Oldest fossils = 1.9 billion years old 4. Have nucleus a) Double membrane b) DNA enclosed inside 5. Have organelles made of membranes a) Mitochondria b) Chloroplasts c) Vacuoles d) Many others 6. DNA is in linear form

Cells

IV. Geography of Eukaryotic Cell A. Plasma membrane 1. Outer layer of cell 2. Controls what goes in or out of cell B. Nucleus – Has double membrane with pores 1. Center of cell 2. Contains DNA = control center of cell C. Cytoplasm 1. Region a)Area between nucleus and cell membrane b)Filled with cytosol (jelly) and organelles

Cells V. How cells are studied A. Microscopy 1. Principle of the Light Microscope: a) Light is focused on specimen b) Light passed through specimen c) Magnification = how much larger an object is made to appear compared to its larger size d) Resolving power = minimum distance between two points that can still be seen e) Resolution of a light microscope is limited by the wavelength of light -Highest magnification in a light microscope = 1500X

Cells 2. Principle of a Transmission Electron Microscope (TEM) a) Electron beam is aimed at a thin section of specimen b) Electrons are focused by using electromagnetic lenses c) Image is focused into screen or film d) Used to study internal cellular ultra-structure e) Resolving power is inversely related to wavelength 3. Principle of a scanning electron microscope a) Electron beams scans the structure of the specimen and gives a 3D image 4. Cell Fractionation = centrifuging broken cells at various speeds to isolate parts of different sizes a. Heavier organelles sink to bottom

Cells VI. The Nucleus A. Structure 1. Nuclear membrane a. Double Membrane b. Has pores 2. Chromosomes a. Long threads of DNA b. Each species has certain amount Humans = Nucleolus = spherical region in the nucleus a) Makes ribosomes b) May have two or more per cell B. Function 1. Control Center 2. Stores DNA

Cells VII. Ribosomes A. Structure 1. Made of protein + RNA B. Function 1. Help make proteins C. Made in the nucleolus D. Free ribosomes = ribosomes in cytosol E. Bound ribosomes = ribosomes attached to E.R.

Cells VIII. Endoplasmic Reticulum (ER) A. Structure 1. Extensive network of membranes, tubules, and sacs – highly folded 2. Connected with the outer membrane and the nuclear membrane B. Smooth ER 1. Lacks ribosomes 2. Makes lipids, phosolipids and steroids C. Rough ER 1. Has ribosomes 2. Makes proteins for export

Cells

IX. The Golgi Apparatus A.Structure 1.Made of membrane sacs 2. Arranged in stacks B. Function 1. Package materials for export (secretion) 2. Makes carbohydrates

Cells X.Lysosomes A. Membrane sac filled with digestive enzymes 1. Break down food vacuoles 2. Break down worn out cell parts 3. Break down worn out cells

Cells XI. Vacuoles A. Membrane-enclosed sac B. Types 1. Food vacuole 2. Contractile vacuole 3. Central vacuole = found in most mature plant cells a) Stores materials

Cells XII. Mitochondria A. Structure 1. Has two membranes a) Smooth outer membrane b) Highly folded inner membrane B. Function 1. Site of cellular respiration = powerhouse 2. Site where ATP is made

Cells XIII. Chloroplasts A. Structure 1. 3 membranes Inner Outer Thylakoid B. Function 1. Site of photosynthesis 2. Found in eukaryotic algae, leaves and other green plants

Cells XIV. The Cytoskeleton = A network of fibers throughout the cytoplasm that forms a framework for support and movement A. Mechanical Support B. Enables a cell to change shape C. Associated with cell movement 1. Microtubules -Straight hollow tubes -Separation of chromosomes during cell division -Make up centrioles in animal cells

Cells

2.Centriole = composed of nine sets of triplet microtubules arranged in a ring 3.Cilia and Flagella a)May propel single-celled organisms b)Draw fluid across the surface of cells c)Structure of cilia and flagella: i.Are extensions of plasma membrane with a core of microtubules

Cells XV. Endosymbiosis (Endosymbiotic Hypothesis) A. States that eukaryotes arose from groups of prokaryotes “living together” 1. Many examples of symbiosis in nature E. coli in large intestine Skin mites 2. Some present day organelles may have arose from ancient prokaryotes