oranelles presentation a

8/14/2019 Oranelles Presentation A

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CELLS

Continued!!!Structures and Functions



Basic Parts of the Cell

• Plasma membrane – barrierbetween in and outside of cell

•Cytoplasm – everything inside cell• Cytosol – includes molecules and small

particles but not organelles

4. Genetic material

6. Ribosomes



Organelles!Eukaryotic Cell

Nucleu

s



The Nucleus• Most obvious structure (5 μm)

• Most eukaryotic cells contain a nucleus

• Function:

• Houses and protects geneticinformation

• Controls most functions of cell

4. Structure:

• Nuclear envelope – double membranelayer contains genetic contents; porous– materials enter and exit

• Nucleoplasm – jelly like fluid filling



1.Processes:

• Cell Division

Normal state - DNA exists aschromatin: long, thin

structures

During division - DNA

condenses to formchromosomes• Transcription – DNA converted toRNA in the nucleus



CellDivision

Chromatin

Chromosome



Mitochondria



Mitochondria• Size: 1-10 μm long

• Function: • Transfer energy from organic

molecules to adenosine

triphosphate (ATP) – powers mostcellular reactions

3. Structure: inner & outermembrane

• Outer – separates mitochondriafrom cytosol

• Inner – many folds (cristae) that

capture and store energy



1. Processes:

• Cellular respiration – formation of ATP by extracting energy fromfood sources



Ribosomes



Ribosomes• small, spherical (< 25 nanometers)

• Function:• Build proteins

• Free ribosomes – make proteins

used in cytosol (Ex: enzyme)

• Bound ribosomes – make proteinsused in membranes, packaging,

and elsewhere in body3. Structure:

• Manufactured partly in nucleolus,

completed in cytoplasm



EndoplasmicReticulum



(ER)

• System of cisternae - membranous

tubes & sacs• Function – move molecules from one

part of cell to another

• Structure– Rough ER – covered with ribosomes;

makes certain proteins and

phospholipids• Secretory proteins – secreted in vesicles

(Ex: digestive enzymes)

•Membrane proteins – inserted inmembranes



GolgiApparatus



Golgi Apparatus• System of cisternae stacked up

• Function:a. Manufactures, stores, sorts, ships

b. Modify contents of nearby vesicles, give“address label,” transport to other partsof cell

3. Structure:– Distinct polarity – membranes on

opposite ends have different thickness &molecular composition

– Two poles:•

Receiving – near ER• –



Vesicles

• Small, spherical shaped sacs

• Function:

a. Migrate to and merge with cellmembrane

b. Release contents outside of cell

3. Structure:a. Single membrane

b. Different types (lysosomes,peroxisomes)



Lysosomes

• Structure – bud from Golgi,

contain digestive enzymes• Function – Break down

macromolecules (proteins,

carbohydrates, nucleic acids)• Processes:

– Autophagy – Digestion of worn-out

organelles– Autolysis – Digestion of damaged or

extra cells



Vesicles



Peroxisomes

1. NOT produced in Golgi, containdifferent enzymes

3. Neutralize oxygen ions

5. Detoxify alcohol and other drugs

7. Break down fatty acids



Vacuole

1. Membrane bound storagestructures, contains fluid

3. Types:

– Food – stores nutrients

– Contractile – contract, dispose of excess water

Vacuoles



Vacuoles

Centriole



Centrioles

1. Animal cells ONLY!2. Organize cell structure during

division

3. 2 short cylinders of microtubules



Part of cytoskeleton

k l



Cytoskeleton• Provides shape and support

• 3 structural elements

– Microtubules – hollow tubes made of

maintain cell shape, hold organelles inplace

– Microfilaments - 2 strands intertwined;used in cell movement, musclecontraction, cell division

– Intermediate fibers – anchor nucleus and

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