Eukaryotic Cell Eukaryotic Cell StructureStructure

Chapter 7.2

The Eukaryotic Cell

• Divided into two major parts:

1. The nucleus

2. The cytoplasm

Portion of the cell outside the nucleus

Contains the organelles

OrganellesOrganelles

• Functional components of the cell

Each carries out a specific job

Determines the job of the cell

Work together to make the cell function

• Typically surrounded by a membrane– Same membrane structure that surrounds the

cell– Allows incorporation between organelles and

the cell membrane

How these notes work

• RedRed = Cell structure

• GreenGreen = Function

• PurplePurple = Other information

• Picture = Structure (separate slide)

The Nucleus

• The nucleusnucleus holds nearly all of the cell’s DNA holds nearly all of the cell’s DNA and with it the coded instructions for making proteins and other important molecules• ccontrol center of the cellontrol center of the cell

– Surrounded by a double membrane with pores in it nuclear envelope nuclear envelope outer boundary of the nucleusouter boundary of the nucleus

• Houses genetic material and nucleolus– Genetic material = DNA and proteins– NucleolusNucleolus makes ribosomesmakes ribosomes

The Nucleus

Genetic Material

• ChromatinChromatin– Tangles mass of protein and DNATangles mass of protein and DNA

• ChromosomeChromosome– Highly organized and compact mass of Highly organized and compact mass of

protein and DNAprotein and DNA

Chromatin becomes a chromosome Chromatin becomes a chromosome before cell divisionbefore cell division

ChromatinChromatinChromosomeChromosome

RibosomesRibosomes

Site of protein synthesisSite of protein synthesis

Composed of RNA and proteinComposed of RNA and protein

Can be attached or free-floatingCan be attached or free-floating

Most common organelleMost common organelle- found in prokaryotes as well

Endoplasmic Reticulum (ER)

• The site where lipid components of the cell membrane are assembled; along with proteins and other materials that re exported from the cell

• Two types

– Smooth ER Smooth ER – no ribosomes attached to itno ribosomes attached to itContains collections of enzymes that perform specialized Contains collections of enzymes that perform specialized

tasks (makes membrane lipids and detoxifies drugs)tasks (makes membrane lipids and detoxifies drugs)

– Rough ER Rough ER – has ribosomes attached to ithas ribosomes attached to itPortion of ER where protein synthesis occursPortion of ER where protein synthesis occurs

– Newly made proteins enter the ER and are modifiedNewly made proteins enter the ER and are modified

Golgi ApparatusGolgi Apparatus

• The function of the Golgi Apparatus is to modify, sort, and package proteins and modify, sort, and package proteins and other materials from the ER for storage other materials from the ER for storage in the cell or secretion outside the cellin the cell or secretion outside the cell

LysosomesLysosomes

Small organelles filled with digestive Small organelles filled with digestive enzymesenzymes

– Digestion of macromolecules into small Digestion of macromolecules into small molecules that can be used by the rest of the cellmolecules that can be used by the rest of the cell

– Breakdown of organelles that have outlived their Breakdown of organelles that have outlived their usefulnessusefulness

– Cell suicide organellesCell suicide organelles

Lysosomes

VacuolesVacuoles

Store materials such as water, salts, Store materials such as water, salts, proteins, or carbohydratesproteins, or carbohydrates

– One large vacuole is found in plant cellsOne large vacuole is found in plant cells• Allows the plant to grow tallAllows the plant to grow tall

– Found in some single celled organisms and Found in some single celled organisms and in some animalsin some animals• Used to control the amount of water in the Used to control the amount of water in the

organismorganism– Homeostatic mechanismHomeostatic mechanism

MitochondriaMitochondria

Convert the chemical energy stored in Convert the chemical energy stored in food into compounds that are more food into compounds that are more convenient for the cell to useconvenient for the cell to use– Enclosed by two membranesEnclosed by two membranes

• Inner membrane is highly folded Inner membrane is highly folded – Called cristaeCalled cristae

• FYI = All mitochondria come from your mother

ChloroplastChloroplast

Capture the energy from sunlight and Capture the energy from sunlight and convert it into chemical energy in a convert it into chemical energy in a process called photosynthesisprocess called photosynthesis

• Mostly found in plants (some other single Mostly found in plants (some other single celled organisms)celled organisms)– Surrounded by two membranesSurrounded by two membranes

• Highly stacked internal membraneHighly stacked internal membrane– Called the thylakoidCalled the thylakoid– Holds chlorophyllHolds chlorophyll

Mitochondria and Chloroplast

• Both contain their own DNA

• Endosymbiotic theory– Lynn Margolis suggested that ancient

mitochondria and chloroplasts were independent prokaryotes

• Created a symbiotic relationship with early eukaryotes

CytoskeletonCytoskeleton

Network of protein filaments that help Network of protein filaments that help the cell to maintain its shapethe cell to maintain its shape– Also involved in movementAlso involved in movement

• Principle protein filamentsPrinciple protein filaments– MicrofilamentsMicrofilaments– MicrotubulesMicrotubules

Centrioles / Cilia / Flagella

• Centrioles, cilia, and flagella are all made of microtubules

• CentriolesCentrioles Help to organize cell divisionHelp to organize cell division

• Only in animal cellsOnly in animal cells

• Cilia / FlagellaCilia / FlagellaHair-like projections that enable cells to Hair-like projections that enable cells to

“swim” in a liquid environment“swim” in a liquid environment