Types of Cells: Prokaryotes, Plants, and Fungi

Do Now 11/171. Take out homework for checking.

2. Classify the following organisms as prokaryotes or Eukaryotes:

Apple treeDuck

MushroomE. coli

Thermus aquaticus, a unicellular organism that lives in very hot water near deep-sea vents.

Prokaryotes: Simple, yet Diverse• Of the structures we

have discussed, prokaryotes have ONLY:– Cell membrane– Ribosomes– Flagella / cilia– Cell wall***

• Prokaryotes contain NO internal membrane structures

Prokaryotes are Small• Prokaryotes are generally 10 to 100 times smaller than typical

eukaryotic cells.

• Eukaryotic cells have specialized compartments where required materials can be kept, while prokaryotes must depend on diffusion to get materials throughout the cytoplasm where they need to be.

Many Prokaryotes Have Cell Walls• Many prokaryotic

cells have rigid cell walls for support and defense

• Most are made of a glycoprotein (amino acids + sugars) called peptidoglycan, very different from the cellulose-based cell walls of plants.

Prokaryotes are Very Diverse• Biologists estimate that 98% of the different metabolic

pathways in life occur in prokaryotes.

• In other words, if every single species of eukaryote went extinct, 98% of the reactions done by cells on Earth would remain.

• Prokaryotes have been found in EVERY terrestrial and aquatic ecosystem of Earth, without exception.

• Some prokaryotes can live in very difficult environments, from the Dead Sea to deep underground, to boiling hot springs.

Plant Cells

• Plants are multicellular eukaryotes, and typically contain the following parts that animal cells lack:– Chloroplasts / plastids– Large, central vacuoles– Cell walls (cellulose)

Chloroplasts Absorb Light Energy… But NOT Green Light!

Free-living chloroplasts?Not quite…

Chloroplast(from eukaryotic plant cell)

Cyanobacterium(prokaryote)

Other Plastids

What else is so special about plant cells?

Large, Central

Vacuoles can take up most ofThe cell!

It stores water,And some minerals

Anything Else? Yup – The Cell Wall

SUPER IMPORTANT: Cell wall

**not in animal cells**

Structure: Hard outer covering made of cellulose fibers

Function: provides support and strength to plant cells

Think wood.

When you hear “Plant Cell Wall,” think Cellulose!

Fungi: The other Multicellular Heterotrophs

• Generally, fungal cells are more similar to animal cells than other cell types.

• The most important difference is the presence of cell walls made of chitin, a polysaccharide.

Fungal Diversity

• There is great variation in kingdom fungi, ranging from the smallest eukaryotes to the largest…

And that’s just the beginning…

• We have not even begun to appreciate biological diversity, for several reasons:– 1. We are considering only gross differences in

cell types, NOT the diversity found in multicellular organisms

– 2. We have not considered MANY different types of cells, especially protists

– 3. There is an exception to nearly every rule in biology.

Recap:• Prokaryotes are small and simple: they contain

NO internal organelles with membranes; everything happens right in the cytoplasm. Many have peptidoglycan cell walls.

• Plant cells contain several unique features: chloroplasts, large vacuoles, and a cellulose cell wall.

• Fungi cells are similar to animal cells in many ways, but most have chitin cell walls.

• Cellular diversity is huge! And most of it is prokaryotic…