Eukaryotic Cell Eukaryotic Cell StructureStructure

7.37.3

Human Cell

NucleusNucleus• Nuclear Envelope- double membrane that

surrounds the nucleus

• nuclear pores - regulates what enters andleaves the nucleus

• Chromatin- long strands of DNA that formchromosomes (grainy-looking in a cell)

• Nucleolus- spherical structures inside thenucleus, functions in making ribosomes

NucleusNucleus

Plasma MembranePlasma Membrane

• Found in all cells

• Flexible boundary:– Outer boundary in

animal cells

• Function: - regulates what enters and leaves the cell

Cell BoundariesCell Boundaries

Cell Wall:

-Found in bacteria, some protists, fungi and plants

Functions:-forms a rigid, strong boundary

-when present, it is outside the cell membrane

Cell WallCell Wall

• In plants, the cell wall is composed of cellulose

CytoplasmCytoplasm

• Jelly-like substance found between the plasma membrane and the nucleus

1. Suspends the cell organelles (membrane-bound structures)

2. Area where cell metabolism occurs

Organelles: Assembly, transport and store Organelles: Assembly, transport and store materialsmaterials

1. Ribosomes

-spherical structures where proteins are synthesized

-free-floating groups or attached to ER

2. Endoplasmic reticulum (ER)

-folded system of membranes

a. folds increases the exposed surface area

b. forms sheet-like and tube-like areas

c. functions to make and transport materials

Rough ER (RER)

Smooth ER (SER)

Rough ER (ER that has ribosomes attached)-’sheet-like’ area-proteins made here are secreted out of the cell

or incorporated into cell membranes

Smooth ER (no attached ribosomes)-’tube-like’ area-site of lipid and carbohydrate production-toxins and drugs broken down here

Endoplasmic Reticulum (ER)

3. Golgi Apparatus

-series of stacked, flattened sacs

-functions to process and packageproteins, lipids and carbohydrates

-some are stored in the cell and othersare secreted out of the cell

4. Vacuole (membrane sac)-functions to store food and waste*contractile vacuole – pumps out excess

cell water from unicellular animals

5. Plastids – (plants only)-store pigments and starchs

6. Lysosome- sac of digestive enzymes -break down old organelles and foreign bodies

Energy TransformersEnergy Transformers

1. Mitochondria-“power house of the cell” -site of Cellular Respiration

-Foods are converted into useable energy using oxygen

-double membranes-Inner membrane is folded to increase surface area-has own DNA and ribosomes

2. Chloroplast (plants only)-contains Chlorophyll-traps light energy then transforms CO2

and H2O into sugar.

-double membranes

-inner membrane forms stacks called grana

-fluid-filled space between the grana is called the stroma

-has own DNA and ribosomes

CytoskeletonCytoskeleton- - support structure support structure withinwithin the cytoplasm or “ skeleton of the the cytoplasm or “ skeleton of the cell”cell”

1. Microtubules

-thin hollow cylinders-give rigid support-can transport material (on the outside)

2. Microfilaments

–thin, solid helical fibers

-Contractile (contract to change cell shape)

3. Cilia - short, hair-like projections for:

-movement in free-swimming cells

-capture food in free-swimming animal cells

-moving materials across the surface of fixed cells (mucus in the lungs)

- composed of series of microtubules

4. Flagella- long, whip-like structure-for locomotion-composed of microtubules arranged

in the same pattern as in cilia

Centriole

-cell component that producesmicrotubules that are usedinside animal cells

-centrioles are not visible inplant cells