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

Proteins

Anatomy & Physiology

2. Cell Chemistry & Cell Components

Proteins

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2:32 minutes

Problem 7

Textbook Question

Why are proteins not considered to be a good candidate for the first living molecule?a. Their catalytic capability is not sufficient for most biological reactions.b. Their amino acid monomers were not likely present in the prebiotic soup.c. They cannot serve as a template for replication.d. They could not have polymerized from amino acid monomers under early Earth conditions.

Verified step by step guidance

Identify the key functions required for a molecule to be considered a candidate for the first living molecule. These functions typically include the ability to catalyze chemical reactions, self-replicate, and form under prebiotic conditions.

Evaluate the statement in option (a) regarding proteins' catalytic capabilities. Proteins, as enzymes, are actually highly efficient catalysts for biological reactions, which contradicts the statement.

Consider the statement in option (b) about the availability of amino acids in the prebiotic soup. Research suggests that amino acids could indeed form under early Earth conditions, making this statement less likely to disqualify proteins.

Analyze the statement in option (c) concerning proteins' ability to serve as a template for replication. Proteins do not have the ability to store genetic information or replicate themselves; this function is typically associated with nucleic acids like DNA and RNA.

Review the statement in option (d) about the polymerization of proteins from amino acids under early Earth conditions. While there are challenges, it is not entirely implausible that amino acids could polymerize to form proteins under certain early Earth conditions.

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Key Concepts

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

Catalytic Capability of Proteins

Proteins, while they can act as enzymes to catalyze biochemical reactions, often lack the versatility and efficiency required for the complex reactions necessary for the origin of life. Early life forms would have needed a molecule that could facilitate a wide range of reactions, which proteins alone may not have been able to provide.

Prebiotic Soup and Amino Acids

The prebiotic soup theory suggests that the early Earth contained a mixture of organic compounds, including amino acids, which are the building blocks of proteins. However, the specific amino acids required to form proteins may not have been present in sufficient quantities or diversity in this primordial environment, limiting the potential for proteins to emerge as the first living molecules.

Template for Replication

For a molecule to be considered a candidate for the first living entity, it must be able to replicate itself. Proteins do not possess the ability to serve as templates for their own replication, unlike nucleic acids such as RNA, which can store genetic information and replicate, making them more suitable candidates for the origin of life.