CHAPTER 3 OBJECTIVES: CELLS

1. Sketch a typical cell membrane, label the components, name a term that describes the permeability of this membrane, and describe the factors that determine whether a substance/ particle will pass through the cell membrane.

Selectively permeable

2. Distinguish between integral and peripheral membrane proteins and list the functions of each.

Integral proteins are firmly inserted into and extend across the lipid bilayer.

1. Most are glycoproteins;

2. They serve as either channels (pores), transporters (carriers), receptors (recognition sites) or enzymes.

Peripheral proteins lie loosely on the inner surface of the cell membrane.

1. They serve as cytoskeletal anchors.

3. Identify each of a "generalized" human cell's components on a diagram or model.

4. List a function(s) for each cellular component and/or organelle.

CELL COMPONENT	DESCRIPTION/ STRUCTURE	FUNCTION(S)
CELL MEMBRANE	Bilayer of phospholipids with proteins dispersed throughout	cell boundary; selectively permeable (i.e. controls what enters and leaves the cell; membrane transport)
CYTOPLASM	jelly-like fluid (70% water)	suspends organelles in cell
RIBOSOMES	RNA & protein; dispersed throughout cytoplasm or studded on ER	protein synthesis
ROUGH ER	Membranous network studded with ribosomes	protein synthesis
SMOOTH ER	Membranous network lacking ribosomes	lipid & cholesterol synthesis
GOLGI	“Stack of Pancakes”; cisternae	modification, transport, and packaging of proteins
VESICLE	Cylindrical membrane sacs	Storage and transport
MITOCHONDRIA	Kidney shaped organelles whose inner membrane is folded into “cristae”.	Site of Cellular Respiration; “Powerhouse”
LYSOSOMES	Membranous sac of digestive enzymes	destruction of worn cell parts (autolysis) and foreign particles
PEROXISOMES	Membranous sacs filled with oxidase enzymes (catalase)	detoxification of harmful substances (i.e. ethanol, drugs, etc.)
CENTROSOMES	paired cylinders of microtubules at right angles near nucleus	aid in chromosome movement during mitosis
CILIA	short, eyelash extensions; human trachea & fallopian tube	to allow for passage of substances through passageways
FLAGELLA	long, tail-like extension; human sperm	locomotion
MICROVILLI	microscopic ruffling of cell membrane	increase surface area
CYTOSKELETON	Protein strands that makeup cellular frame	Provide shape of cell, locomotion
OTHER STRUCTURES	Accumulations of substances	storage
NUCLEUS	Central control center of cell; bound by lipid bilayer membrane; contains chromatin (loosely coiled DNA and proteins)	controls all cellular activity by directing protein synthesis (i.e. instructing the cell what proteins/enzymes to make).
NUCLEOLUS	dense spherical body(ies) within nucleus; RNA & protein	Ribosome synthesis
CHROMATIN	DNA wrapped in protein forming nucleosomes	Protection of genetic material

5. Describe the structure of each cellular organelle. See above.

6. Name the cellular organelle that contains cisternae (Golgi), and the one that contains cristae (mitochondria).

7. Explain what a vesicle is, and name the organelle that is always surrounded by them. See above

8. Describe the process of autolysis, and name the organelle that accomplishes this process.

Autolysis is the process by which worn cell parts are digested by autophagy.

Lysosomes

9. Name the human organ that is rich in peroxisomes. liver

10. Name the organelle where cellular respiration occurs. mitochondria

11. Distinguish between microvilli, cilia, and flagella.

Microvilli	cilia	flagella
See above

12. Name the human cell type(s) that possess a flagellum (sperm) or cilia (trachea).

13. Describe what a nuclear pore is and explain its function.

Nuclear envelope is a double membrane that separates the contents of the nucleus from the cytoplasm;

At various points, these two membranes fuse = nuclear pore.

14. Distinguish between chromatin and chromosomes.

chromatin	chromosomes
loosely coiled fibers of DNA and histone proteins present in the nucleus	These fibers of chromatin would be condensed into tightly coiled chromosomes if the cell were preparing to divide.

15. Define the term nucleosome.

Nucleosome = fundamental unit of chromatin; spherical clusters of eight histone proteins connected like beads on DNA string.