Cytology

Studying Cells Cell Theory: Four Basic Concepts 1. Basic building blocks of all animals and plants 2. Smallest functional units of life 3. Products of cell division 4. Basic homeostatic units

Studying Cells The Diversity of Cells in the Human Body Figure 3-1

Studying Cells Overview of Cell Anatomy Extracellular (interstitial )fluid - outside cell Cell Membrane a. Cytosol = intracellular fluid b. Organelles = “little organs” structures that perform special functions for cell Cytoplasm - stuff inside (not including the membrane & nucleus) Nucleus

Studying Cells Figure 3-2 Anatomy of a Representative Cell

The Cell Membrane Functions of the cell membrane Physical isolation Regulation exchange of materials Sensitivity - receptors allow cell to recognize & respond to specific molecules in environment Support

The Cell Membrane Figure 3-3

The Cell Membrane Table 3-2

The Cell Membrane Membrane is Selectively permeable = chooses what can pass through based on Size Electrical charge Shape Lipid solubility Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Cell Membrane Membrane Transport Processes Passive transport - no energy needed Diffusion (including Osmosis) Facilitated diffusion - diffusion with help of a protein channel Active Transport - uses ATP energy Sodium-potassium exchange pump Phagocytosis - cell eating Exocytosis - sending materials out

The Cell Membrane Membrane Transport Definitions Diffusion Movement of materials from higher to lower concentration (tries to even out) Osmosis Diffusion of water across a membrane to where there is more solute (less water)

The Cell Membrane Figure 3-4 Diffusion

The Cell Membrane Diffusion Across Cell Membranes Figure 3-5

Osmosis & Solutions That Affect It Isotonic = cell maintains balance Hypotonic = water moves in to where there is more solute - cell swells & bursts (hemolysis in RBC’s) Hypertonic = water moves out of cell to where there is more solute - cell shrivels

The Cell Membrane Facilitated Diffusion Figure 3-8

The Cell Membrane Figure 3-9 The Sodium- Potassium Exchange Pump

Figure of 8 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Cell membrane of phagocytic cell Phagocytosis A phagocytic cell comes in contact with the foreign object and sends pseudopodia (cytoplasmic extensions) around it. Pseudopodium (cytoplasmic extension) EXTRACELLULAR FLUID CYTOPLASM Foreign object Vesicle Lysosomes Undissolved residue The pseudopodia approach one another and fuse to trap the material within the vesicle. The vesicle moves into the cytoplasm. Lysosomes fuse with the vesicle. This fusion activates digestive enzymes. The enzymes break down the structure of the phagocytized material. Residue is then ejected from the cell by exocytosis. Phagocytosis

Figure of 7 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Endoplasmic reticulum Transport vesicle Golgi apparatus (a) Membrane renewal vesicles Secretory vesicles Lysosomes CYTOSOL EXTRACELLULAR FLUID Cell membrane Vesicle Incorporation in cell membrane (b)Exocytosis

Cell Structures - Organelles Figure 3-2 Anatomy of a Cell

The Cytoplasm Organelles Microvilli - Surface projections increase surface area for absorption Cilia - Move fluids across cell surface Flagella - Moves cell through fluid Ribosome - proteins factories Lysosomes - “janitors” - hold digestive enzymes to get rid of wastes & bacteria Mitochondria - “power plant” - make ATP energy

The Cytoplasm Key Note Mitochondria provide most of the energy needed to keep your cells (and you) alive. They use oxygen and organic compounds, such as glucose, and make carbon dioxide and ATP. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Nucleus = Control Center Nuclear envelope surrounds nucleus Nuclear pores Allows movement of materials in & out (but NOT DNA)

The Nucleus Chromosome Structure Figure 3-17 DNA makes up 23 pairs of chromosomes contained in nucleus

The Nucleus Key Note The nucleus contains DNA, the genetic instructions within chromosomes. The instructions tell how to synthesize the proteins that determine cell structure and function. THEREFORE - the nucleus controls everything else by regulating (controlling) protein synthesis! Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Nucleus The Genetic Code Triplet code = Sequence of 3 nitrogen bases (codon) which code for a certain amino acid A Gene = All the amino acids needed to make 1 protein

Protein Synthesis Problem: DNA can’t leave nucleus & protein factories (ribosomes) are in the cytoplasm Solution: Make a copy of DNA & send it out Protein Synthesis: 1. Transcription = DNA is copied to make mRNA 2. Translation = Info from mRNA is used to make a protein with help of tRNA TranscriptionTranslation DNA RNAProtein In Nucleus In Cytoplasm

The Cell Life Cycle Interphase - Most of a cell’s life performing normal function - time between cell division Includes DNA replication Mitosis - When copied chromosomes split apart & the 2 nuclei divide Cytokinesis - the last part of mitosis when the cytoplasm divides to create 2 new cells

The Cell Life Cycle Note: some cells never divide - apoptosis = genetically programmed cell death Occurs in Somatic Cells = all cells in body aside from sex cells (sperm & eggs) Involves: Interphase, Mitosis & Cytokinesis

The Cell Life Cycle DNA ReplicationThe Cell Life Cycle Figure 3-21

Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Nucleus Mitosis begins Centrioles (two pairs) Spindle fibers Centromeres Chromosome with two sister chromatids Cytokinesis Daughter cells Cleavage furrow Daughter chromosomes Metaphase plate Early prophaseLate prophase MetaphaseAnaphaseSeparationTelophase Interphase Figure of 8

The Cell Life Cycle Cell Division and Cancer Tumor (neoplasm) - a mass or swelling made by abnormal cell growth & division Malignant Tumor = when it no longer responds to normal control mechanisms & spreads into surrounding tissues Cancer = illness from effects of malignant cells

The Cell Life Cycle Key Note Cancer results from mutations that disrupt the control mechanism that regulates cell growth and division. Cancers most often begin where cells are dividing rapidly, because the more chromosomes are copied, the greater the chances of error. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Cell Diversity and Differentiation Somatic Cells All have same genes Some genes inactivate during development Cells thus become functionally specialized Specialized cells form distinct tissues Tissue cells become differentiated Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings