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

Endomembrane System: Protein Secretion

Anatomy & Physiology

2. Cell Chemistry & Cell Components

Endomembrane System: Protein Secretion

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2:55 minutes

Problem 6

Textbook Question

The nuclear substance composed of histone proteins and DNA is:
a. Chromatin
b. The nucleolus
c. Nucleoplasm
d. Nuclear pores

Verified step by step guidance

Understand the structure and function of the nucleus: The nucleus is the control center of the cell, containing genetic material (DNA) and structures that regulate gene expression and cellular activities.

Learn about chromatin: Chromatin is the combination of DNA and histone proteins. Histones help package the DNA into a compact structure, allowing it to fit within the nucleus and play a role in gene regulation.

Differentiate between the options: a) Chromatin is composed of DNA and histone proteins, b) The nucleolus is a dense region within the nucleus responsible for ribosome production, c) Nucleoplasm is the gel-like substance within the nucleus, d) Nuclear pores are openings in the nuclear envelope that allow transport of molecules.

Focus on the key terms: The question specifically asks for the nuclear substance composed of histone proteins and DNA. This description matches chromatin, as histones are proteins that bind to DNA to form chromatin.

Conclude the reasoning: Based on the definitions and functions of the options provided, chromatin is the correct answer because it is the nuclear substance composed of histone proteins and DNA.

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Key Concepts

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

Chromatin

Chromatin is a complex of DNA and histone proteins found in the nucleus of eukaryotic cells. It serves to package DNA into a more compact, dense shape, allowing for efficient storage and regulation of gene expression. Chromatin exists in two forms: euchromatin, which is less condensed and active in transcription, and heterochromatin, which is more condensed and generally inactive.

Nucleolus

The nucleolus is a prominent sub-structure within the nucleus, primarily responsible for ribosome biogenesis. It synthesizes ribosomal RNA (rRNA) and assembles it with proteins to form ribosomal subunits. While it plays a crucial role in protein synthesis, it is not composed of chromatin, which is the focus of the question.

Nuclear Pores

Nuclear pores are large protein complexes that span the nuclear envelope, allowing for the regulated exchange of materials between the nucleus and the cytoplasm. They facilitate the transport of RNA and proteins, but they do not contain chromatin or contribute to its structure. Understanding their function helps clarify the distinction between nuclear components.