Lab Textbook Chapter 4- The Cell: Anatomy and DIvision Flashcards Preview

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Flashcards in Lab Textbook Chapter 4- The Cell: Anatomy and DIvision Deck (12):
1

Nucleus

  • Contains the genetic material, DNA
  • Often described as the control center of the cell, the nucleus is necessary for cell reproduction
  • Chromatin (genetic material in a threadlike form) is present when the cell isn't dividing
  • When the cell is in the process of dividing, the chromatin coils and condenses to form rod like bodies called chromosomes
  • Nucleus also contains one more more small round bodies called nucleoli, composed primarily of proteins and RNA
  • The nucleus is bound by a double layed porous membrane, the nuclear envelope

2


Nuclear Envelope

  • The nuclear envelope is distinguished by its large nuclear pores.

 

  • They are spanned by protein complexes that regulate what passes through and permit easy passage of protein and RNA molecules

3

Plasma Membrane

  • The plasma membrane separates cell contents from teh surrounding environment
  • Its main structural building blocks are phsopholipids (fats) and globular protein molecules
  • Selective permeability - Plays an active role in determining which substances may enter or leave the cell and in what quantity

4

Ribosomes

  • Are densely staining, roughly spherical bodies composed of RNA and protein
  • They are the actual sites of protein synthesis
  • They are seen floating free in the cytoplasm or attached to a membranous structure (rough ER)

5


Endoplasmic Reticulum (ER)

  • Is a highly foled system of membranous tubules and cisterns (sacs) that extends throughout the cytoplasm
  • The ER is continuous with the nuclear envelope, forming a system of channles for transport of cellular subsances (primarily proteins) from one part of the cell to another
  • Rough ER - studded with ribosomes; its cisterns modify and store the newly formed proteins and dispatch them to other areas of the cell; external face synthesizes phospholipids and cholesterol
  • Smooth ER - has no function in protein synthesis, is a site of steroid and lipid synthesis, lipid metabolism, and drug detoxication

6

Golgi Apparatus

  • Stack of flattened sacs with bulbous ends and associated small vesicles; found close to the nucleus
  • Plays a role in packaging proteins or other substances for export form the cell or incorporation into the plasma membrane and in packaging lysosomal enzymes

7

Lysosomes

  • Various sized membranous sacs containing digestive enzymes including acid hydrolases
  • Functionto digest worn out cell organelles and foreign substances that enter the cell
  • Have the capacity of total cell destruction if ruptured

8

Peroxisomes

  • Small lysosome like membranous sacs containing oxidase enzymes that detoxify alcohol. hydrogen peroxide, and other harmful chemicals

 

9

Mitochondria

  • Generally rod-shaped bodies with a double-membrane wall
  • Inner membrane is thrown into folds, or cristae; contain ezymes that oxidize foodstuffs to produce cellular energy (ATP)
  • Often referred to as "powerhouses of the cell"

10

Centrioles

  • Paired, cylindrical bodies lie at right angles to each other, close to the nucleus
  • As part of the centrosome, they direct the formation of the mitotic spindle during cell division
  • Form the bases of cilia and flagella

11

Cytoskeletal elements; microfilaments, intermediate filaments and microtubules

  • Provide cellular support; function in intracelluar transport
  • Microfilaments are formed largely of actin, a contractile protein, and thus are important in cell mobility, particularly in muscle cells
  • Intermediate filaments are stable elements composed of a variety of proteins and resist mechanical forces acting on cells
  • Microtubules form the internal structure of the centrioles and help determine cell shape

12

Cell Division: Mitosis and Cytokinesis

  • Mitosis is the division of the copied DNA of the mother cell to two daughter cells
  • Cytokinesis is the division of the cytoplasm
  • Phases of mitosis: Prophase, metaphase, anaphase and telophase
  • Interphase is often included in discussions of mitosis but is not part of mitosis
  • Interphase- G1-The centrioles begin replicating; S- DNA is replicated; G2- Final preparations for mitosis are completed and centrioles finish replicating
  • Prophase- chromatin condenses and becomes chromosomes; nucleoli disappear; the two centrosomes separate from each other; nuclear envelope breaks up; allowing spindle to interact with the chromosomes; growing spindle microtubules attach to kinetochores (special protein structures at each chromosomes's centromere)
  • Metaphase- two centrosomes are at opposite poles of the cell; chromosomes cluster at the midline of the cell (metaphase plate); enzymes act to separate the chromatids from each other
  • Anaphase - shortest phase; begins abruptedly as the centromeres of the chromosomes split simultaneously
  • Telophase- begins as soon as chromosomal movement stops (prophase in reverse); identical sets of chromosomes at opposite poles uncoul and become chromatin; a new nuclear envelope forms around each chromatin mass; nucleoli reappear within the nuclei, spindle breaks down and disappears; mitosis has ended, the cell if (for a brief period) binucleate (has two nuclei)
  • Cytokinesis- begins in late anaphase continues beyond telophase; a contractile ring of actin microfilaments forms the cleavage furrow and pinches the cell apart