Eukaryotic Cells

What are the main objectives of the Eukaryotic Cell lecture?

Discuss eukaryotic cell origin; list eukaryotic cell components; describe plasma membrane structure/function (transport); describe cell wall/flagella/cilia/cytoplasm; identify membrane-bound organelles and their functions.

What types of organisms are eukaryotes?

Unicellular: algae, protozoa, yeasts. Multicellular: algae, molds, helminths (worms), plants, animals, humans.

What is the typical size range of eukaryotic cells?

About 10–100 µm (larger than prokaryotes).

List the main components of a eukaryotic cell.

Plasma membrane; cell wall (+/-); flagella/cilia (+/-); cytoplasm with cytosol, cytoskeleton, ribosomes, and membrane-bound organelles including nucleus.

What is the structure of a eukaryotic plasma membrane?

Phospholipid bilayer with proteins and sometimes sterols.

What are the main functions of the eukaryotic plasma membrane?

Protects/forms border; semipermeable barrier; senses environment; transport.

What are 2 transport processes eukaryotes use that prokaryotes don’t mainly rely on?

Endocytosis and exocytosis.

What is exocytosis?

Transport process where materials are moved OUT of the cell using vesicles that fuse with the plasma membrane.

What is endocytosis?

Transport process where materials are brought INTO the cell by forming vesicles from the plasma membrane.

What is pinocytosis and what is its nickname?

“Cell-drinking” — uptake of fluids into the cell via vesicles.

What is phagocytosis and what is its nickname?

“Cell-eating” — uptake of large particles/microbes into the cell via vesicles.

What are the 2 theories for the origin of eukaryotic cells?

Membrane infolding and endosymbiotic theory.

What is the endosymbiotic theory (basic idea)?

Eukaryotic cells formed when early cells engulfed bacteria that became organelles like mitochondria and chloroplasts.

What evidence supports endosymbiosis: binary fission?

Mitochondria and chloroplasts replicate independently by binary fission similar to bacterial division.

What evidence supports endosymbiosis: ribosomes?

Eukaryotic cytoplasm has 80S ribosomes, but mitochondria and chloroplasts have 70S ribosomes (like prokaryotes).

What evidence supports endosymbiosis: DNA?

Mitochondria and chloroplasts contain their own circular DNA distinct from nuclear linear chromosomes.

What is the eukaryotic cell wall made of (and what is it NOT made of)?

It provides support in algae/plants/fungi and it is NOT peptidoglycan.

What is the main function of the eukaryotic cell wall?

Support and protection (helps maintain structure).

What are eukaryotic flagella and cilia made of?

Microtubules covered by plasma membrane.

What powers eukaryotic flagella and cilia?

ATP (energy required for movement).

What are the main parts of eukaryotic cytoplasm?

Cytosol, cytoskeleton, ribosomes, and membrane-bound organelles.

What type of ribosomes do eukaryotic cells have?

80S ribosomes made of 60S + 40S subunits.

What is the nucleus and its function?

Membrane-bound organelle that contains DNA.

What is the nuclear envelope?

The membrane surrounding the nucleus.

What is the nucleolus and what does it do?

Region inside nucleus involved in making rRNA (and building ribosomes).

What is the function of mitochondria?

Produces ATP (energy).

Why do mitochondria have a double membrane and inner cristae?

Cristae increase surface area for Electron Transport Chain (ETC) proteins to maximize ATP production.

What is found in the mitochondrial matrix?

Metabolic enzymes (Krebs cycle), mitochondrial DNA, and 70S ribosomes.

Why do mitochondria support the endosymbiotic theory?

They have their own DNA and 70S ribosomes like bacteria.

What is the function of chloroplasts?

Make ATP in plants/algae (energy production similar to mitochondria).

How are chloroplasts similar to mitochondria?

Both are energy-related organelles and support endosymbiotic theory traits (similar structure/function).

What is the endoplasmic reticulum (ER)?

A series of flattened, hollow, interconnecting sacs.

What is the rough ER and what does it do?

Has ribosomes; receives/transports/stores proteins.

What is the smooth ER and what does it do?

Synthesizes/transports/stores lipids.

What is the Golgi apparatus (complex)?

A series of sacs independent of ER that assembles raw materials and routes end-products.

Describe vesicle transport between ER and Golgi.

ER → Golgi complex; Golgi complex → final destination (inside cell, outside cell, or plasma membrane).

What are lysosomes and what do they do?

Vesicles with digestive enzymes that digest microbial invaders and old organelles; common in phagocytes.

Where do lysosomal digestive enzymes come from?

They are produced in the cell and packaged into vesicles (lysosomes) for digestion functions.

Which organelle is thought to have originated as a bacterial cell, and what is its function?

Mitochondria; produces energy (ATP).

What is the eukaryotic cell cycle?

A regulated sequence of growth and division where the nucleus divides so each daughter cell receives identical linear chromosomes, followed by cytoplasm division.

What is the main point of nuclear division in eukaryotes?

To ensure each daughter cell receives an identical set of linear chromosomes.

What happens after the nucleus divides in a eukaryotic cell?

The cytoplasm divides to physically separate the two new cells.

What special division process produces gametes?

Germ cells undergo two rounds of division to produce haploid gametes for sexual reproduction.