Prokaryotic vs Eukaryotic Cells

Prokaryotic vs Eukaryotic Cells

High School

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Learning Objectives

• Define prokaryotic and eukaryotic cells and identify their key characteristics.

• Compare the structural complexity of prokaryotic and eukaryotic cells.

• Describe the four features that are common to all cell types.

• Explain the Endosymbiotic Theory for the origin of eukaryotic cells.

Key Vocabulary

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Prokaryotic Cell

A single-celled organism that lacks a distinct nucleus and other membrane-bound organelles.

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Eukaryotic Cell

An organism with cells where genetic material is contained within a distinct nucleus.

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Nucleus

A membrane-bound organelle in eukaryotic cells that contains the cell's genetic material.

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Organelle

Specialized structures within a eukaryotic cell that perform specific and essential cell functions.

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Endosymbiosis

Theory on eukaryotic origin, where one prokaryote was engulfed by and lived inside another.

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Cytoplasm

The jelly-like substance filling a cell, which contains nutrients and suspends organelles.

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The Fundamentals of Cells

• All living things are composed of one or more cells.

• The cell is the fundamental and basic unit of all life.

• All cells are created from other pre-existing cells through division.

• Every cell has a membrane, cytoplasm, genetic material, and ribosomes.

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Multiple Choice

According to the presentation, what four features are common to ALL prokaryotic and eukaryotic cells?

• Nucleus, Cytoplasm, Ribosomes, and a Cell Wall

• Cell Membrane, Cytoplasm, Ribosomes, and Genetic Material

• A Nucleus, Cytoplasm, Genetic Material, and a Flagellum

• Cell Membrane, Mitochondria, DNA, and Ribosomes

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What Are Prokaryotic Cells?

• They are simple, single-celled organisms without a nucleus or other membrane-bound organelles.

• Their DNA floats in the cytoplasm in a region called the nucleoid.

• They may also have small, independent DNA strands called plasmids.

• Bacteria are common examples and may have a flagellum, capsule, or pili.

Multiple Choice

What is the defining characteristic of a prokaryotic cell?

• Their DNA is organized into complex chromosomes.

• They lack a nucleus and membrane-bound organelles.

• They have a cell membrane and ribosomes.

• They possess a flagellum for movement.

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What Are Eukaryotic Cells?

• They form unicellular or multicellular organisms like protists, plants, and animals.

• ​Their genetic material (DNA) is enclosed within a distinct nucleus.

• The DNA is organized into complex, linear structures called chromosomes.

• They have specialized, membrane-bound organelles that perform specific functions.

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Multiple Choice

What is the key feature that distinguishes eukaryotic cells from prokaryotic cells?

• Their genetic material (DNA) is contained within a distinct nucleus.

• They use ribosomes to synthesize proteins.

• They are filled with a jelly-like cytoplasm.

• They can only be multicellular organisms.

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Key Differences and the Endosymbiotic Theory

• Prokaryotic cells lack a nucleus and other membrane-bound organelles.

• Eukaryotic cells have a true nucleus that houses their DNA.

• The endosymbiotic theory explains the origin of eukaryotic cells.

• Engulfed prokaryotes evolved into organelles like mitochondria and chloroplasts.

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Solved Example 1
A sample of bacteria doubles its population every 20 minutes. If the initial population is 100 cells, how many cells will there be after 2 hours?

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Step 1: Analyze and Sketch the Problem

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Solved Example 1
A sample of bacteria doubles its population every 20 minutes. If the initial population is 100 cells, how many cells will there be after 2 hours?

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Step 2: Solve for the Unknown

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Solved Example 1
A sample of bacteria doubles its population every 20 minutes. If the initial population is 100 cells, how many cells will there be after 2 hours?

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Step 3: Evaluate the Answer

• Checking the calculation confirms the doubling pattern: after 1 hour (60 minutes) there are 800 cells, and after 2 hours (120 minutes) there are 6400 cells.

• The final calculated answer of 6400 cells is consistent with the step-by-step doubling of the bacteria population.

Multiple Choice

What does the Endosymbiotic Theory propose?

• Prokaryotic cells evolved from eukaryotic cells.

• Bacteria are the ancestors of all life on Earth.

• All cells originate from pre-existing cells.

• Eukaryotic cells evolved from a symbiotic relationship between prokaryotic cells.

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Common Misconceptions

Misconception	Correction
Prokaryotes do not have DNA.	All cells have DNA. In prokaryotes, it is found in the nucleoid region.
All single-celled organisms are prokaryotes.	Eukaryotes, like protists, can also be single-celled.
Ribosomes are organelles, so prokaryotes don't have them.	Both cell types have ribosomes, which are not membrane-bound.

Multiple Choice

How does the location and structure of genetic material differ between prokaryotic and eukaryotic cells?

• In prokaryotes, it's in the mitochondria; in eukaryotes, it's in the ribosomes.

• In prokaryotes, it's a circular loop in the cytoplasm; in eukaryotes, it's linear chromosomes in a nucleus.

• Prokaryotes lack genetic material, while eukaryotes have a complete genome.

• Prokaryotes have RNA as genetic material, while eukaryotes have DNA.

Multiple Choice

Based on the provided text, why are prokaryotes considered to have evolved before eukaryotes?

• Because they are all single-celled organisms.

• Because they contain plasmids which can replicate independently.

• Because they are structurally simpler, have no nucleus, and possess fewer genes.

• Because some of them possess a flagellum for movement.

Multiple Choice

A scientist discovers a new fossilized cell. The fossil shows evidence of genetic material and ribosomes, but there is no sign of a membrane enclosing the genetic material. Which conclusion is most likely?

• The organism was a virus, because it has genetic material.

• The organism was a prokaryote, due to the lack of a nucleus.

• The organism was a eukaryotic plant cell, because it had a cell wall.

• The organism was an early animal cell that had not yet formed a nucleus.

Multiple Choice

According to the Endosymbiotic Theory, what was the likely identity of the smaller, engulfed cells that eventually became mitochondria?

• They were free-floating ribosomes.

• They were smaller prokaryotic cells.

• They were small eukaryotic cells.

• They were early viruses.

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Summary

• All living things are made of cells, which arise from pre-existing cells.

• All cells have a cell membrane, cytoplasm, ribosomes, and genetic material.

• Prokaryotic cells are simple and lack a nucleus; eukaryotic cells are complex.

• Eukaryotic cells likely evolved from symbiotic relationships between ancient prokaryotic cells.

Poll

On a scale of 1-4, how confident are you about the concepts covered in today's review?

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