Chapter 3 Cells

Objectives Identify the structure of a typical cell Define the function of each component of a typical cell Relate the function of cells to the function of the body Describe the processes that transport materials in and out of a cell Describe a tumor and define cancer Define the key words that relate to this chapter

Cells The cell is the basic unit of structure and function of all living things Cell or plasma membrane

Nucleus Most important organelle within the cell Function Control the activities of the cell and facilitate cell division DNA and chromatin Chromosomes Nuclear membrane or nuclear envelope Regulates transport of substances into and out of the cell Nucleoplasm A clear, semi-liquid medium that fills the spaces around the chromatin and the nucleoli

Cell Organelles Nucleolus Ribosomes Cytoplasm Centrosome Serves at site for protein synthesis Cytoplasm Cytoplasm is the background for all chemical reactions that take place in a cell, such as protein synthesis and cellular respiration Embedded in the cytoplasm are organelles, or cell structures that help a cell to function Centrosome Centrioles found in the centrosome function in cell reproduction by aiding in the equal distribution of chromosomes to the new daughter cells

Cell Organelles Endoplasmic reticulum Mitochondria Golgi apparatus Provides passage through which transport of substances occurs in cytoplasm Mitochondria Serves as sites of cellular respiration and energy production; stores ATP Golgi apparatus Manufactures carbohydrates and packages secretions for discharge from the cell Lysosomes Serve as center for cellular digestion

Cell Organelles Pinocytic vesicles Cilia and flagella Perioxisomes Enzymes oxidize cell substances Cytoskeleton Forms internal framework Pinocytic vesicles Method by which large molecules can enter the cell Cilia and flagella Create movement

Cellular Metabolism Chemical reactions occur within the cells Energy supplied by ATP ATP created from CHO, proteins, and fats we eat

Cell Division Meiosis Mitosis Involves reproduction Involves growth and maintenance of cells

Meiosis Process of cell division of the sex cell or gamete Ovum and spermatozoa reduce chromosomes from 46 to 23 Fertilization Zygote is formed from two sex cells to obtain full set of 46 chromosomes

Mitosis Cell division Division of the nucleus Division of the cytoplasm Mitosis essentially is an orderly series of steps by which the DNA in the nucleus of the cell is equally distributed to two daughter, or identical nuclei All cells do not reproduce at the same rate

Mitosis Stages Phase I Phase II Phase III Phase IV Phase V Interphase (resting stage) Phase II Prophase Phase III Metaphase Phase IV Anaphase Phase V Telophase Cycle back to interphase

Cell Death Necrosis Apoptosis

Stem Cells Embryonic stem cells Adult stem cells Umbilical cord blood stem cells

Protein Synthesis Cells produce proteins DNA RNA Determines the kinds of proteins that are produced RNA Carries instruction for protein synthesis form the DNA to the ribosome in the cytoplasm Transports amino acid molecule in the cytoplasm and takes it to the ribosome where they combine to form a specific protein

Movement of Materials Across Cell Membranes Passive transport Do not require an energy source Active transport Require an energy source

Passive Transport Diffusion Osmosis Filtration A physical process whereby molecules of gases, liquids or solid particles spread or scatter themselves evenly through a medium Osmosis Osmosis is the diffusion of water or any other solvent molecule through a selective permeable membrane from a region of higher concentration of water molecules to a region of lower concentration of water molecules Filtration Filtration is the movement of solutes and water across a semipermeable membrane as a result of some mechanical force such as blood pressure or gravity

Active Transport Phagocytosis Pinocytosis Cell eating Cell membrane engulfs a particle to form a vesicle in the cytoplasm where digestive enzymes destroy the entrapped substance Pinocytosis Cell drinking Formation of pinocytic vesicles which engulf large molecules in solution then ingest the nutrients for its own use

Specialization Nerve cells Red blood cells Specialize in response Red blood cells Specialize in oxygen transport May lose some functions, such as reproduction Interdependence among cells

Aging Aging is a phase of normal development Older person may have 30% fewer cells Cells may change in ability to perform specialized tasks

Disorders of Cell Structure Atrophy Hypertrophy Hyperplasia Metaplasia Dysplasia Neoplasia

Tumor When cell division does not occur in the usual pattern Also called neoplasms Benign tumors Malignant tumors