GenEd: Lesson 19 Homologous and Analogous Structure | Free LET Reviewer and Drill

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General Education

 Lesson 19: Homologous &Analogous Structure

The study of body structures and how they are used helps scientists understand evolution, adaptation, and how organisms are related. In this lesson you will learn about homologous structures, analogous structures, and how humans use biotechnology to modify living things and solve problems.

• We will compare body parts that are similar or different, and then see how people use biotechnology to change or use living things on purpose.

 

Homologous Structures

Image from ThoughtCo.

What are homologous organs?

Homologous organs are organs having similar structure but different functions.

They come from a common ancestor, but over time they have changed to perform different jobs in different organisms.

• Same basic bone pattern or layout.
• Often found in species that are evolutionarily related.
• Show divergent evolution – one ancestral structure becomes different forms for different uses.

Examples of homologous structures:

• Human arm – used for lifting, carrying, and manipulating objects.
• Cat leg – used for walking and running on four legs.
• Seal flipper – used for swimming in water.
• Bat wing – used for flying.

Even though a human arm, cat leg, seal flipper, and bat wing all do different jobs, their bone arrangement (humerus, radius, ulna, wrist, fingers) is very similar.

Homologous organs have the same basic design on the inside, but are used for different jobs in different animals.

 

Analogous Structures

Image from ThoughtCo.

What are analogous organs?

Analogous organs are organs having similar functions but different structures.

They do the same job, but they do not come from the same ancestral structure.

• Same function, different design.
• Often found in species that are not closely related.
• Show convergent evolution – different ancestors evolve similar solutions to the same problem.

Example of analogous structures:

• Butterfly’s wings – made of thin membranes stretched over veins; attached to the exoskeleton; no bones.
• Bat’s wings – made of skin stretched between long finger bones; attached to a vertebrate skeleton.

Both butterfly wings and bat wings are used for flying, but their structure and origin are very different.

Analogous organs look and work the same on the outside (same job), but are built differently on the inside and come from different ancestors.

 

(Click to Unblur)

 

• Homologous - same design, different use.
• Analogous - same use, different design.

 

Why These Structures Matter in Biology

• They help scientists reconstruct evolutionary history.
• Homologous structures suggest that organisms share a common ancestor.
• Analogous structures show how environmental pressures can shape different species in similar ways.
• Both concepts support the idea of adaptation and natural selection.

By comparing body parts, scientists can tell who is “related” and who only looks similar because they live in similar environments.

 

Introduction to Biotechnology

What is biotechnology?

Biotechnology is the modification of biological processes through human intervention.

It means people use living organisms, or parts of them, to make products, improve plants and animals, or solve problems.

• Uses cells, enzymes, DNA, and whole organisms.
• Found in medicine, agriculture, food production, and environmental cleanup.

Biotechnology is when humans use or change living things on purpose to do useful things.

 

Genetic Engineering and GMOs

Image from MIT

Genetic engineering

Genetic engineering is a type of biotechnology where scientists change an organism’s DNA directly.

• Specific genes can be cut out, copied, or inserted.
• This can give the organism a new trait, such as disease resistance or the ability to make a useful protein.

GMO / Transgenic organism

• A GMO (genetically modified organism) or transgenic organism has had its genes altered or had new genes added by humans.
• The new gene might come from a different species.

Examples you might hear about (in general):

• Crops engineered to resist insects or herbicides.
• Bacteria engineered to produce human insulin for diabetes treatment.

In genetic engineering, scientists edit an organism’s DNA, and the result is a GMO that has traits it did not have before.

 

Bioremediation

Image from Springer Link

What is bioremediation?

Bioremediation is the use of biotechnology to solve environmental problems.

It uses living organisms to clean up pollution or break down harmful substances.

• Often uses bacteria, fungi, or plants.
• These organisms use the pollutant as a food source or change it into something less harmful.

Example: Oil-eating bacteria

• Oil-eating bacteria are used in cleaning up oil spills.
• These bacteria can break down oil molecules into simpler substances that are less dangerous.
• They help restore oceans and coastlines after accidents.

Bioremediation uses living things, like oil-eating bacteria, to clean up messes in the environment.

 

Homologous and Analogous Structure Quiz: click here

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