Lecture #3 Organelles of the Eukaryotic Cell Unit 2: Cell Energy

Eukaryotic Cells A eukaryote is an organism whose cells have a nucleus, which houses DNA. In addition to the nucleus, Eukaryotes also have several specialized membrane bound structures and compartments (called organelles) that bacterial cells (prokaryotes) lack. This is why they are considered more complex than prokaryotic cells. Organelle- a structure that carries out a specific function in the cell.

The First Eukaryotes First primitive eukaryote evolved approximately 1.5 billion years ago. Modern day descendants are members of the Kingdom Protista. They gave rise to the animals, plants and fungi (all multicelluar organsims).

Single-Celled Eukaryotes Many protists use flagella and cilia for movement. Flagella - threadlike structure that grows out a cell and enables it to move. Cilia - hair-like structures in tightly packed rows that are used for movement.

Kingdoms of Life

The cell is like a factory. People and machines perform functions in a factory. There are parts of a cell that also perform different functions. How does the Cell operate?

All factories produce a product. CELL PRODUCT=PROTEINS Cell’s DNA codes for proteins! Cell Factory

Organelles of the Eukaryotic Cell Nucleus - an internal compartment found in eukaryotes where DNA (hereditary info)is stored. This is the “command center”. Most functions of a eukaryotic cell are controlled by the nucleus. ** Reminder: In Prokaryotes - DNA is suspended in the cytoplasm.

DNA of Eukaryotes vs Prokaryotes Bacterial DNA looks different than ours & other Eukaryotes. Their DNA is circular in shape.

Circular vs Double Helix Bacterial DNA shapeEukaryotic DNA shape

Structure of the nucleus Nuclear envelope – Double membrane that surrounds the nucleus Nuclear pore- small channels through the nuclear envelope. Substances made in the nucleus, such as RNA, travel through these pores to the rest of the cell. Nucleolus - a region of the nucleus where the ribosome’s are partially assembled

Ribosomes (*) Ribosomes - organelle where proteins are made. Ribosomes are found in two places On the Endoplasmic Reticulum (ER) (Only in Eukaryotic cells) In the cytoplasm. These are “free” ribosomes. These make proteins that stay inside the cell (Example – used to make new organelles)

Description-“highway” system throughout inside of cell. Materials can travel on it throughout the cell. Endoplasmic Reticulum

There are 2 types of ER Rough ER ~ the part of the ER that has ribosome’s attached to it. Function - helps to transport proteins that are made by the attached ribosome’s. As a protein in made on a ribosome, it crosses the ER membrane and enters the ER. The portion of ER that contains the completed protein then pinches off to form a vesicle. Vesicle - a small membrane bound sac that transports substances in cells.

ER continued Smooth ER Function- makes lipids, breaks down toxic substances It is called “smooth” because it has no ribosome’s embedded in it.

Golgi Apparatus Description & Function Set of flattened, membrane-bound sacs that serve as the packaging & distribution center of the cell.

What happens at the Golgi Apparatus? After the vesicles containing the newly made proteins leave the ER, they move through the cytoplasm and go to the Golgi apparatus Once inside the Golgi, enzymes modify the proteins. (“Finishing touches”) These modified proteins are then packaged into new vesicles that bud off of the Golgi to go & do their “jobs” in the cell.

Lysosomes One type of modified protein made by the Golgi are Lysosomes. Lysosomes contain the cell’s digestive enzymes which are used to r epair damaged cell parts & break down ones that are beyond repair. the ‘Recycling Center’

Function “storerooms” in plant and animal cells. Plant cells have one large Central Vacuole, animal cells have several smaller ones. Vacuoles

Description- “powerhouse” of the cell where cellular energy (ATP) is generated. Supplies cell with energy through cellular respiration Cells that have a high energy requirement will have more mitochondrion Example- Muscles cells Mitochondria

Description- The process in mitochondria in which carbs (like glucose) and oxygen are consumed, releasing carbon dioxide, water, and energy for life (ATP). C 6 H 12 O 6 (glucose) + O 2 → CO 2 + H 2 O + energy (ATP) This is why we breathe oxygen and how we use carbs to get energy!!! What is Cellular Respiration? Oxygen and glucose in Carbon dioxide, water, and ATP produced

Mitochondrial DNA Mitochondria have their own DNA and ribosome’s. DNA is circular, similar to prokaryotic DNA This supports the theory that primitive prokaryotes are the ancient ancestors of mitochondria. Analyzing this can be useful in deciphering family lines.