Table of contents

1. Introduction to Anatomy & Physiology5h 43m
2. Cell Chemistry & Cell Components12h 36m
3. Energy & Cell Processes10h 6m
4. Tissues & Histology10h 3m
5. Integumentary System2h 20m
6. Bones & Skeletal Tissue2h 16m
7. The Skeletal System2h 35m
8. Joints2h 17m
9. Muscle Tissue2h 33m
10. Muscles1h 11m
11. Nervous Tissue and Nervous System1h 35m
12. The Central Nervous System1h 6m
- Introduction to the Central Nervous System
  18m
- The Cerebrum
  48m
13. The Peripheral Nervous System1h 26m
14. The Autonomic Nervous System1h 38m
15. The Special Senses2h 41m
16. The Endocrine System2h 48m
17. The Blood3h 22m
18. The Heart3h 42m
19. The Blood Vessels3h 35m
20. The Lymphatic System3h 16m
21. The Immune System14h 37m
22. The Respiratory System3h 20m
23. The Digestive System2h 5m
24. Metabolism and Nutrition4h 0m
25. The Urinary System2h 39m
26. Fluid and Electrolyte Balance, Acid Base Balance37m
27. The Reproductive System2h 5m
28. Human Development1h 21m
29. Heredity3h 32m

2. Cell Chemistry & Cell Components

Mitochondria & Chloroplasts

Anatomy & Physiology

2. Cell Chemistry & Cell Components

Mitochondria & Chloroplasts

Previous problemNext problem

3:12 minutes

Problem 1

Textbook Question

What are three attributes of mitochondria and chloroplasts that suggest they were once free-living bacteria?

Verified step by step guidance

Identify the concept of endosymbiotic theory, which suggests that mitochondria and chloroplasts originated from free-living bacteria that were engulfed by ancestral eukaryotic cells.

Recognize that both mitochondria and chloroplasts have their own circular DNA, similar to bacterial DNA, which supports the idea that they were once independent organisms.

Note that mitochondria and chloroplasts have double membranes, which is consistent with the engulfing mechanism described in the endosymbiotic theory, where the inner membrane is derived from the original bacterial membrane and the outer membrane from the host cell.

Understand that mitochondria and chloroplasts replicate independently of the cell cycle through a process similar to binary fission, which is how bacteria reproduce.

Consider that both organelles have their own ribosomes, which are more similar in size and structure to bacterial ribosomes than to the eukaryotic ribosomes found in the cytoplasm of the host cell.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above

Video duration:

Play a video:

Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Endosymbiotic Theory

The endosymbiotic theory posits that mitochondria and chloroplasts originated from free-living bacteria that were engulfed by ancestral eukaryotic cells. This theory explains how these organelles have retained their own DNA and replicate independently of the cell, suggesting a symbiotic relationship that evolved over time.

Double Membrane Structure

Both mitochondria and chloroplasts are surrounded by a double membrane, which is a characteristic feature of prokaryotic cells. The inner membrane is thought to be derived from the original bacterial membrane, while the outer membrane may have originated from the host cell's membrane, indicating their prokaryotic ancestry.

Genetic Material and Ribosomes

Mitochondria and chloroplasts contain their own circular DNA, similar to bacterial genomes, and possess ribosomes that resemble those of prokaryotes. This genetic similarity supports the idea that these organelles were once independent bacteria, as they can produce some of their own proteins, further reinforcing their evolutionary history.