Cell Structure and Function Chapter 4

Cell Theory 1) Every organism is composed of one or more cells 2) Cell is smallest unit having properties of life 3) Continuity of life arises from growth and division of single cells

Structure of Cells All start out life with: –Plasma membrane –Region where DNA is stored –Cytoplasm Two types: –Prokaryotic –Eukaryotic –Know table 4.3 –Know figure 4:7

Animal Cell Features Plasma membrane Nucleus Ribosomes Endoplasmic reticulum Golgi body Vesicles Mitochondria Cytoskeleton

Fig. 4.8b, p. 57 microfilaments microtubules components of cytoskeleton plasma membrane mitochondrion nuclear enevelope nucleolus DNA + nucleoplasm NUCLEUS vesicle lysosome rough ER ribosomes (attached to rough ER and free in cytoplasm) smooth ER vesicle Golgi body pair of centrioles

Main component of cell membranes Gives the membrane its fluid properties Two layers of phospholipids Lipid Bilayer

Membrane Proteins Transport proteins Receptor proteins Recognition proteins Adhesion proteins

Fig. 4.4, p. 53 EXTRACELLULAR ENVIRONMENT (cytoskeletal pro- teins beneatch the plasma membrane) ADHESION PROTEIN oligosaccharide groups phospholipid cholesterol LIPID BILAYER RECOGNITION PROTEIN RECEPTOR PROTEIN CYTOPLASM PLASMA MEMBRANE (area of enlargment) TRANSPORT PROTEINS open channel protein gated channel proten (open) active transport protein gated channel proten (closed)

Keeps the DNA molecules of eukaryotic cells separated from metabolic machinery of cytoplasm Makes it easier to organize DNA and to copy it before parent cells divide into daughter cells Functions of Nucleus

Components of Nucleus nuclear envelope nucleoplasm chromatin (DNA + proteins) Nucleolus

Fig. 4.11, p. 62 cytoplasm nucleus plasma membrane nuclear envelope chromatin (DNA + proteins) nucleoplasm nucleus

Nuclear Envelope Two outer membranes (lipid bilayers) Innermost surface has DNA attachment sites Pores span bilayer

Chromatin Cell’s collection of DNA and associated proteins Chromosome is one DNA molecule and its associated proteins Appearance changes as cell divides

Nucleolus Dense mass of material in nucleus Area of intense transcription of rRNA Materials from which ribosomal subunits are built Genes that encode Ribosome's are located in this area

Components of Cytomembrane System Golgi bodies Vesicles Endoplasmic reticulum

Endoplasmic Reticulum In animal cells, continuous with nuclear membrane Extends throughout cytoplasm Two regions - rough and smooth

Rough ER Ribosomes on surface give it a rough appearance. ER is the site of protein synthesis. Some polypeptide chains enter rough ER and are folded and modified

Smooth ER No ribosomes on surface Lipids assembled inside tubules Synthesizes steroids, such as estrogen and testosterone. inactivates wastes, toxic chemicals and drugs

Golgi Bodies Put finishing touches on proteins and lipids that arrive from ER Package finished material for shipment to final destinations outside the cell. Material arrives and leaves in vesicles

Vesicles Membranous sacs that move through the cytoplasm Lysosomes –Digests, recycles materials

Mitochondria ATP-producing powerhouses Double-membrane system These reactions require oxygen

Cytoskeleton Present in all eukaryotic cells Basis for cell shape and internal organization Allows organelle movement within cells and, in some cases, cell motility

Cytoskeletal Elements microtubule microfilament intermediate filament

Cilia and Flagella Cilia and Flagella are made up of microtubules –Cilia functions to move microorganism or the movement of substances in the body Example: Protozoa move through water by beating their cilia as small ores Example: Cilia found in the body moves mucus out of the lungs and oocytes down the oviduct –Flagella functions in the transport of cells

Cilia and Flagella Length of microtubules or microfilaments can change Parallel rows of microtubules or microfilaments actively slide in a specific direction As one side lengthens and the other side contracts it causes the flagella or cilia to bend.