Chap4.1 Eukaryotic Cell

7/29/2019 Chap4.1 Eukaryotic Cell

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CHAPTER 4

EUKARYOTIC CELL

STRUCTURE & FUNCTION

External Structures

Internal Structures


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Overview of Eukaryotic CellStructure

Eukaryote: Protozoa, Algae, Fungi larger than prokaryotic cell

more complex than prokaryotic cell

contains membrane-bound organellesthat perform specific functions


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Protozoa, Algae, Fungi


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Eukaryotic Cell Structure


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1. Cilia motility

5-20 m long

shorter and more numerous

than flagella

beat with two phases

2. Flagella

motility

100-200 m long

longer than cilia

eukaryotic flagellum moveslike a whip


7/29Ciliated protozoa Oxytrichasp.


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Structure of Flagella and Cilia membrane-bound cylinders ~2m in diameter

9 pairs of microtubule doublets circle around 2 central tubules

9 + 2 arrangement called axoneme

basal body

at base of flagellum or cilium directs synthesis of flagella and cilia


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3. Pellicle a thin layer supporting plasma membrane in various protozoa

not as strong or rigid as cell wall

provides characteristic shape to cell

Epidinium caudatum Pellicle of a mushroom


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4. Cell Wall

rigid covering outside plasma membrane

variable compositions in eukaryotes

Algae - ?

Diatoms - ? Fungi - ?


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Cellulose cell wall of algae Volvoxsp.


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Silica shell of diatoms


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Chitin & cellulose of fungi


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5. Plasma Membrane almost as similar as prokaryotes

Fluid-mosaic structure

greater variety oflipids, includephosphoglycerides, sphingolipids andcholesterol

contains sterols that adds rigidity toplasma membrane


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(1) is standard lipid bilayer(2) is a lipid raft.

Plasma Membrane

eucaryotic membranes contain

microdomains called lipid rafts

enriched for certain lipids and proteins

participate in a variety of cell processessuch as cell movement and transduction
http://upload.wikimedia.org/wikipedia/commons/c/c6/Lipid_raft_organisation_scheme.svg


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Eukaryotic Cell InternalStructures

Nucleus

EndoplasmicReticulum

Golgi Apparatus

Mitochondria

Chloroplast

Ribosome

Lysosome Peroxisome

Vacuoles

Cytoplasmicmatrix

Cytoskeleton


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Eukaryotic Cell Structure


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Nucleus

largest organelle ineucaryotic cell

contains geneticmaterial

enclosed by nuclear

envelope contains chromatin

and nucleolus


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Nucleus

Chromatin

dense fibrous materialwithin nucleus

contains genetic DNA

condenses to formchromosomes during cell

division mitosis/meiosis (refer

Prescotts Microbiology

pg. 92-94)

Nuclear envelope

double membrane (inner

& outer) structure that

surrounds nucleus

has nuclear pores

pores allow materials

to be transported intoor out of nucleus


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Nucleus

Nucleolus

1 nucleolus per nucleus

not membrane-enclosed

important in ribosome synthesis

directs synthesis and processing of rRNA directs assembly of rRNA and ribosomal

proteins to form ribosomes


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Endoplasmic Reticulum (ER)

consists of networkof membranous

tubules andflattened sacs calledcisternae

internalcompartment of ER= cisternal space


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Two types of ER:

rough ER

ribosomes attached, rough texture

smooth ER

lack of ribosomes, smooth texture

Endoplasmic Reticulum (ER)

Functions of ER: major site of cell membrane synthesis

transports proteins, lipids, and other materials to

Golgi apparatus

synthesis of lysosomes


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Golgi Apparatus

membranous organellemade of cisternae stacked

on each other dictyosomes

stacks of cisternae

involves in modification,packaging, and secretionof materials throughsecretory vesicles


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cis face (associated with ER)

trans face

cis face differs from trans face in thickness,enzyme content and vesicle formation

movement ofmaterial

Chap4.1 Eukaryotic Cell

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