BIOLOGY 12 - CELL STRUCTURE & FUNCTION: Chapter Notes THE CELL THEORY 1. All living organisms are made up of one or more cells 2. The cell is the basic unit of life 3. All cells come from the division of pre-existing cells Cell size most cells are 0.001 cm in length (10 µm). smallest cells 0.3 µm (microorganism mycoplasma) large cells. giant algal cells (several centimeters long) an ostrich egg is a single cell. Amazing Facts You produce about 2.5 million new red blood cells every second! Each square cm of your skin contains about 150,000 skin cells. Human beings are composed of about 50 to 100 trillion cells. cells carry on all the processes associated with life, such as reproducing and interacting with the environment. EUCARYOTIC CELL STRUCTURE Pop Quiz /4 1. : the thin layer which separates the cell contents from it's environment. Plant cells also have a cell wall surrounding the cell membrane. 2. : specialized structure within the cell which contains DNA and controls cell functioning and reproduction. 3. : small bodies with specific structures and functions within the cell. 4. : the liquid substance between the nucleus and the cell membrane, in which the organelles are located. CELL ORGA ELLES 1 The Cell Membrane (plasma membrane) Cell membrane functions: (1) of materials in and out of cell (2) cell to cell (3) cell to cell (4) maintaining of cells. Please Label this Diagram Page 1
The Fluid Mosaic Model: thin membrane of, and, some carbohydrates cell membrane has properties of a solid and a liquid. " " property due to phospholipids bilayer (lipid bilayer). = solid part (random design due to proteins) phospholipid has a hydrophobic tail and a hydrophylic head. the cell membrane has the consistency of light machine oil. the membrane is (will let some substances in but not others of the same size). 2 Cell Wall Cell Wall found on the outside of the cell membrane of made of fibers also said to be semi-permeable Nu 3 The Nucleus: the Cell s Brain organelle located is the of cell Contains DNA and relplicates DNA DNA produces RNA. DNA is contained in Chromosomes - long strands of DNA tightly wound into coils with proteins called histones. CHROMATIN = chromosomes. Chromosomes only visisble during nuclear division DNA contains which which produce proteins and enzymes The nucleus, therefore, determines the,,,, and of cell. NUCLEOLI dark stained region in the nucleus - site of RIBOSOMAL RIBONUCLEIC ACID (rrna) SYNTHESIS. Nucleus is surrounded by nuclear envelope (nuclear memebrane) - a double membrane (phospholipid bilayer) - contains nuclear for selected molecules to enter and exit (p.52) - is connected to endoplasmic reticulum. - RNA (genetic messages) pass into cytoplasm via nuclear pores Page 2
4 Endoplasmic Reticulum (ER) system of MEMBRANOUS TUBULAR CANALS that begin outside the nucleus and branches to the cytoplasm. Rough ER - ribosomes attached - function = synthesis. Smooth ER - no ribosomes attached - function = synthesis of Lipids needed for - Phospholipids and cholesterol for cell membrane and organelle membranes - used to make - to drugs and chemicals in the cell Rough E.R. Smooth E.R. ER membranes has a HUGE surface area for chemical reactions. channels for storage space of synthesized products transportation routes Immature proteins sent to Golgi apparatus for further processing 5 Ribosomes (p. 514) made of 2 non-identical subunits ribosome subunits made of and rrna produced in nucleolus and joined with proteins nuclear pore cytoplasm for final assembly ribosomes attach to the ER function is site for PROTEIN SYNTHESIS 6 Polysomes (polyribosomes p.515) free-floating ribosomes in the produce proteins that will be used inside the cell (generally) can the production of a protein 7 Golgi Apparatus stacks of flattened, hollow cavities enclosed by membranes, continuous with the membranes of the. found near and. Each sac in the organelle contains enzymes that can proteins Functions = modification, assembly, packaging, storage and secretion of substances. Page 3
Golgi receives newly manufactured protein (from the ER) on it's inner surface. Proteins are sorted out and packaged into vesicles vesicles "pinch off" outer surface of the saccuoles. Vesicles can be transported within the cell or exported outside of the cell (exocytosis) 8 Vacuoles and Vesicles A VESICLE is a small are used for transport and storage of materials vacuoles and vesicles are formed by: 1) pinching off from the apparatus 2) endocytosis of the 3) extension of the membrane Plant cells usually have one large. the plant cell s central vacuole functions in 1) storage 2) storage 3) storage 4) cell is thought to be an extension of the ER membrane 9. Lysosomes special vesicles formed by Golgi. contain powerful enzymes functions in 1) cellular 2) or disposal of damaged cell components like mitochondria 3) breakdown of a cell (by releasing their contents into the cell cytoplasm). known to contain over 40 different enzymes that can digest almost anything in the cell, including proteins, RNA, DNA, and carbohydrates. involved in phagocytosis and pinocytosis (p. G-13). Lysosomes help destroy invading. 10 PEROXISOMES A vesicle Contain peroxisomal - remove H 2 from small molecules and join to O 2 H 2 O 2 H 2 O 2 (hydrogen peroxide) catalase H 2 O + O 2 Page 4
11 Mitochondria: (p.57) 2 nd largest organelle in an animal cell oval-shaped. size of (generally) 1 µm x 7 µm has two membranes - outer like a cell membrane - inner - is convoluted (many folds) =. - enzymes for cellular respiration are on the cristae - where energy is. a. b. Function AEROBIC ENERGY METABOLISM (also called CELLULAR RESPIRATION). Glucose + O 2 CO 2 + H 2 O + ENERGY ( ) 1 glucose can produce molecules of ATP (maximum) Fatty acids can also be used instead of glucose. Other function help control the [ ], [ ] and [ ] in the cytoplasm. Mitochondria have their own molecules (inherited from your mother only) Mitochondria are self-replicating - reproduce by splitting in half (binary fission) Human mitochondrial DNA is a closed, circular molecule (like DNA). 12 Chloroplasts: found in cells only. Is a type of plastid many other types exist - Amyloplasts plant roots - Chromoplasts plant leaves - Leucoplast - algae - Plastids contain membranes and (color) - some plastids are storage bodies for starch, proteins, oils. Chloroplast W = double-membrane bound organelles X = stroma contains chloroplast s own & Y = contain (green chemical) - absorbs energy Z = from the sun.photosynthesis - the opposite of CO 2 + H 2 O + ENERGY (i.e. ATP) Carbohydrate + O 2 Page 5
13 The Cytoskeleton network of filamentous structures Mainly made of microtubules and microfilaments (intermediate filaments as well) Function - - - 14 Microtubules, Microfilaments and Intermediate Filaments (not organelles themselves) Microtubules - hollow, cylindrical tubelike structures - give the cell shape and form - organelle movement - made of 13 rows of globular proteins form a hollow tube - globular protein =. Microfilaments (actin filaments) - 2 filaments arranged in a helical pattern - Filaments = globular proteins (made of ) - anchor organelles and move them within the cell - cell movement - pseudopod like an amoeba - cell structures moved microvilli extended and shortened Intermediate Filaments - Rope-like structures - Support nuclear membrane and cell membrane 15 Centrioles Found in animal cells Two short cylindrical bodies - lying at right angles located near the. 9+0 pattern of microtubular triplets assist in the formation of the spindle apparatus in cell. centrioles can become. Basal bodies direct the formation of and 9 + 0 CENTRIOLES & BASAL BODIES 9 + 2 CILIA AND FLAGELLA Page 6
16 Cilia membrane-bound cylinder, with 9+2 arrangement of microtubules. Microtubules are doublets short, hairlike projections beat stiffly, like oars function in cell movement or particle movement (e.g. Paramecium, cells of human respiratory tract) 17 Flagella Same structure as cilia but than cilia beat in undulating whip-like fashion function in cell movement (e.g. sperm cells, Euglena) ENDOSYMBIOTIC HYPOTHESIS (p.63) Endo = Symbiotic = Invagination of the PM accounts for formation of nucleus and other organelles. Mitochondria (aerobic bacterium), chloroplasts (cyanobacterium) and flagella (spirochete) were derived from prokaryotes that were taken in (endocytosis) by the larger eukaryotic cell and formed a symbiotic relationship. Evidence: 1) Size: mitochondria chloroplasts 2) mitochondria and chloroplasts are bound by a membrane - outer from engulfing vesicle - inner from PM of original prokaryote 3) M and C contain small amount of DNA (DNA is like prokaryotes - circular loop) 4) M and C have their own ribosomes that produce some proteins (resemble prokaryotes 5) RNA base sequence of ribosomes in C and M resemble prokaryotes Page 7