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 & otherEukaryotes.

Their DNA is circular in shape.

Circular vs Double Helix

Bacterial DNA shape Eukaryotic DNA shape

Structure of the nucleus Nuclear envelope –Double membrane thatsurrounds 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 thenucleus where the ribosome’sare partially assembled

Ribosomes (*)Ribosomes - organelle whereproteins are made. Ribosomes arefound in two places On the Endoplasmic Reticulum (ER) (Only in Eukaryotic cells) In the cytoplasm. These are “free”ribosomes. These make proteinsthat 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’sembedded in it.

Golgi Apparatus

Description & FunctionSet of flattened,membrane-bound sacsthat serve as thepackaging & distributioncenter of the cell.

What happens at the Golgi Apparatus?

After the vesicles containing the newly made proteinsleave the ER, they move through the cytoplasm and go tothe 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 modifiedprotein made by theGolgi are Lysosomes.

Lysosomes containthe cell’s digestiveenzymes which are usedto repair damaged cellparts & break down

onesthat are beyond repair.

the ‘Recycling Center’

Function“storerooms” inplant and animalcells.

• 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).

• C6H12O6 (glucose) + O2 → CO2 + H2O + 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 ATPproduced

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 theancient ancestors of mitochondria.  Analyzing this can be useful in deciphering family

lines.