CHAPTER 3 CELLS3.2 Cell Organelles

KEY CONCEPT Eukaryotic cells share many similarities.

Cells have an internal structure.

• The cytoskeleton has many functions• supports and shapes• cell helps position and

transport organelles• provides strength• assists in cell division• aids in cell movement

• Three main types of fibers make up the cytoskeleton.• Microtubules – long hollow tubes

Give cell shape Act as “tracks” for the

movement of organelles• Intermediate filaments

Smaller then MicrotubulesGive cell strength

• MicrofilamentsSmallest of 3Tiny threads that help cell

move and divideRecall that Cytoplasm also

helps shape the cell

• Cytoplasm aids in structure• The fluid portion mostly

water is called cytosol• Gives structure to cells

by exerting pressure on the cell walls of plants

Several organelles are involved in making and processing proteins.

• Much of the cell is dedicated to making proteins• Recall proteins are made

from 20 amino acids

• Proteins are very powerful because of their almost limitless variety of shapes and interactions

• Proteins carry out many critical functions• Need to be made correctly

• Nucleus• Control center “brain of cell”• Stores genetic information - DNA.

• Nucleolus• Dark spots in nucleus

Ribosomes are made here

• Endoplasmic reticulum• Interconnected network of thin folded membranes • Transports materials throughout the cell• Produce lipids and proteins

Two Types of ER• Rough ER• Contains ribosomes• Makes and transports proteins

• Smooth ER• NO ribosomes• Makes and transports lipids

• Golgi apparatus• Closely layered stacks of

membrane enclosed spaces

• Looks like a stack of pancakes

• Proteins are sorted, processed, and delivered

• Packaging and distribution center of the cell

• Ribosomes• Ribosomes link amino acids to form proteins.

• Proteins synthesis – they’re made here!

• Vesicles• Vesicles are membrane-bound sacs that hold and

transport materials.

Other organelles have various functions.

• Mitochondria• Supply energy to the cell.• Via respiration – glucose + oxygen = energy

• Vacuoles• Fluid-filled sacs that hold materials.

• Lysosomes• Break down worn out cell parts• Contain enzymes to digest material (bacteria).

• Centrioles • Centrosomes small regions in

cytoplasm

• Tubes found in the centrosomes.• Centrioles help divide DNA• Centrioles form cilia and flagella

Plant cells differ slightly from animal cells.

• Plant cells have:• Cell walls• Chloroplasts• Central vacuole

• Cell wall• Protects, supports and shapes cell• Made of cellulose – (what is that?)

• Chloroplasts• Chloroplasts convert solar energy to chemical energy.

How? Photosynthesis

Magnified

• Food for thought! • Chloroplast/Mitochondria

• Both have their own DNA and ribosomes• Were they once separate organisms???????