STRAND 1: Molecules and CellsBiology Standard 2 Students shall demonstrate an understanding of the structure and function of cells
The Goals • MC.2.B.1 • Construct hierarchy of life from cells to ecosystems • MC.2.B.2 • Compare and contrast prokaryotes and eukaryotes • MC.2.B.3 • Describe the role of subcellular structures (organelles, ribosomes, cytoskeleton) in the life of the cell. • MC.2.B.4 • Relate the structure of the cell membrane to its function • MC.2.B.5 • C/C the structures of an animal cell with a plant cell • MC.2.B.6 • C/C the functions of autotrophs with heterotrophs
The Goals continued • MC.2.B.7 • C/C active and passive transport mechanisms (diffusion, osmosis, exocytosis, endocytosis, phagocytosis, pinocytosis) • MC.2.B.8 • Describe the main events of the cell cycle, including differences in plant and animals (interphase, mitosis, cytokinesis) • MC.2.B.9 • List in order and describe the stages of mitosis (prophase, metaphase, anaphase, telophase) • MC.2.B.10 • Analyze the meiotic maintenance of constant chromosome number from one generation to the next. • MC.2.B.11 • Discuss homeostasis using thermoregulation as an example
Getting to Where We Are Now • Microscopes began being used to study small things in the 1600s. • 1665 – Englishman Robert Hooke observes the bark of the cork oak and notices small open spaces that he calls “cells”. • After that Holland man Anton von Leeuwenhoek finds first living cells in pond water and in samples from human mouths.
Developing Cell Theory • 1805 – Lorenz Oken suggests that cells may be coming from other cells. • 1838 – Matthias Schleiden concludes that all plants are made of cells. • 1839 – Theodor Schwann concludes that all animals are made of cells. • 1855 – Rudolf Virchow verifies Oken’s hypothesis that all cells come from pre-existing cells.
Current Cell Theory • All living things are composed of cells. • Cells are the basic units of structure and function within an organism. • Cells come from pre-existing cells.
Microscope Function • All microscopes work by focusing either light or electron beams to produce an image. • Light microscopes can magnify an object up to 1000x. • Since individual cells are mostly clear they are stained in order to better observe certain parts of the cell.
Electron Microscopes • Can view objects up to 1µm or 1 millionth of meter. • 1µm is called 1 micrometer or 1 micron.
Electron Microscopes • Offer much better resolution. • Sample must be placed within a vacuum to keep electrons from scattering in all directions. • Samples must be non-living due to: • Placement in vacuum to be hit with electron beam. • Removal of all water from specimen prior to placement in vacuum. • Coating/preserving of specimen to be viewed with SEM. • Sample must be ultra thin for TEM.
Types of Electron Microscopes • SEM – SCANNING electron microscope: shows a 3-D view of outer surface of specimen. Electron beam is bounced off or scanned across a coated surface. • TEM – TRANSMISSION electron microscope: shows internal parts of specimen. Electron beam passes through or transmits through the specimen.
MC.2.B.1 • Construct a hierarchy of life from cells to ecosystems
MC.2.B.2 • C/C prokaryotes and eukaryotes
MC.2.B.3 • Describe the role of sub-cellular structures in the life of a cell • Organelles • Ribosomes • Cytoskeleton
NUCLEUS • Controls most functions of the cell • Filled with liquidynucleoplasm • Houses/protects genetic info/DNA • Surrounded by a double membrane nuclear envelope • Covered in protein lined holes called pores • RNA and others enter and leave here • Nucleolus is where DNA is concentrated and rRNA is made.
Vacuoles • Many cells contain large, saclike, membrane-enclosed structures called • vacuoles that store materials such as water, salts, proteins, and • carbohydrates.
CENTRAL VACUOLE • Large reservoir in plants that stores water, enzymes, waste, and other material • Forms as smaller vacuoles fuse together • Makes up to 90% of plant cell’s volume • Pushes organelles into a thin layer against plasma membrane • Pressure helps give plant cells their rigidity to support
OTHER VACUOLES • Some store toxic materials • Vacuoles in acacia trees store poisons for defense • How do these defend the tree? • Tobacco plants store the toxin nicotine in a vacuole • Rose’s are colorful due to pigments found in vacuoles of the petal
LYSOSOMES • Is a digestive vesicle • Come from Golgi • Breaks down proteins, NA, carbs, phospholipids • In liver they break down glycogen to realease glucose into blood • White BC use them to break down bacteria • Digest worn out organelles in process called autophagy • Break down cells when cell is dying in process called autolysis • They play large role in organisms overall health…how?
Peroxisome • Vesicle • Not produced by Golgi • High in liver and kidney cells • Neutralize free-radicals which are oxygen ions that do lots of damage • Detox alcohol and drugs • Named after hydrogen peroxide which is what they release when breaking down alcohol and killing bacteria • Breaks down FA which mitochondria can use for energy
OTHER VESICLES • GLYOXYSOMES • Found in plant seeds • Break down stored fats to nourish developing plant embryo • ENDOSOMES • Material engulfed by cell and surrounded w/ a membrane pocket • Will fuse with lysosome to be digested • FOOD VACUOLES • Store nutrients for a cell • CONTRACTILE VACUOLES • Contract to dispose of excess water in cell
CYTOSKELETON • Thin tubes and filaments that crisscross the cytosol • Give shape and support to cell • Acts as internal tracks that allow things to move around on • 3 main types • Microtubules • Microfilaments • Intermediate filaments
MICROTUBULES • Hollow protein tubes made of tubulin • Radiate out away from the nucleus at a point called centrosome • Hold organelles in place • Maintain cell shape • Guide organelles and molecules around cell • Arranged in a pattern called 9+2
MICROFILAMENTS • Long threadlike w/ beadlike proteins called actin • Allow cell movement • Crawling of white BC and contraction of muscle
INTERMEDIATE FILAMENTS • Rods that anchor nucleus and other MBOs in place in cell • Maintain shape of nucleus • Make up the shaft of hair/hair follicles
CENTRIOLES • Two short cylinders of microtubules perpindicular to each other • Found in animal cells
RIBOSOMES • Partly spherical • Responsible for building proteins • No membrane • Made of protein and RNA • Made partly in nucleus and completed in cytoplasm
ENDOPLASMIC RETICULUM • Called ER • System of membranous tubes and sacs called cisternae • Acts as an intracellular highway • Moves molecules from one area to another • Amount of ER depends on how active the cell is • Two types: Smooth and Rough
ROUGH ER • System of connected flattened sacs covered w/ ribosomes • Produces proteins and phospholipids • Proteins made here are incorporated into the cell’s membranes • Makes digestive enzymes that are stored in the rough ER until needed to be used/released • Most abundant in digestive glands and antibody-producing cells
SMOOTH ER • Lacks ribosomes • Most cells have little SER • Builds lipids like cholesterol • Produces steroid hormones in ovaries and testes • Releases Ca in skeletal and heart muscles which causes contractions • Lots in the liver and kidneys where it helps detox drugs/posions • Alcohol/drug abuse causes increase of SER which leads to drug/alcohol tolerance
GOLGI BODY • System of flattened membrane sacs • Sacs closest to nucleus receive vesicles from ER • Travel from one part of GB to next transporting substances as they go • Sacs modify contents as it moves • Proteins get “address labels” that direct them to their destination in cell
CELL MEMBRANE • Composed of phospholipidbilayer • Acts more like a fluid than a solid • Has proteins embedded within it • Marker proteins extend only from one side • Receptor and transport proteins go all the way through • Proteins going all the way through can detect changes in envi and then adapt • Marker proteins help similar cells ID and link • Also allows viruses to ID and enter cell
FLUID MOSAIC MODEL • Current idea of cell membrane is that it allows proteins in the PLBL to move around like boats on the water, so the picture (mosaic) of the cell membrane is constantly changing
Cilia/Flagella • Hairlike extending from surface of cell • Assisst in movement • Cillia is in inner ear and vibrate due to sound • Cilia on protists row to move them