1. Introduction to Biology

2. Chemistry

3. Water

4. Biomolecules

5. Cell Components

6. The Membrane

7. Energy and Metabolism

8. Respiration

9. Photosynthesis

10. Cell Signaling

11. Cell Division

12. Meiosis

13. Mendelian Genetics

14. DNA Synthesis

15. Gene Expression

16. Regulation of Expression

17. Viruses

18. Biotechnology

19. Genomics

20. Development

21. Evolution by Natural Selection

22. Evolution of Populations

23. Speciation

24. History of Life on Earth

25. Phylogeny

26. Prokaryotes

27. Protists

28. Plants

29. Fungi

30. Overview of Animals

31. Invertebrates

32. Vertebrates

33. Plant Anatomy

34. Vascular Plant Transport

35. Soil

36. Plant Reproduction

37. Plant Sensation and Response

38. Animal Form and Function

39. Digestive System

40. Circulatory System

41. Immune System

42. Osmoregulation and Excretion

43. Endocrine System

44. Animal Reproduction

45. Nervous System

46. Sensory Systems

47. Muscle Systems

48. Ecology

49. Animal Behavior

50. Population Ecology

51. Community Ecology

52. Ecosystems

53. Conservation Biology

[BOOK BIO] CLUTCH

Golgi Apparatus

Endomembrane System: Protein Secretion

Endomembrane system | Structure of a cell | Biology | Khan Academy

Most of the proteins that enter the nucleus possess a nuclear localization signal (NLS), even if they are small enough to pass through the nuclear pore complex unhindered. Why would a small protein have an NLS, when it naturally diffuses across the nuclear pore complex without one?

Endomembrane System

Endoplasmic Reticulum

Which structure is part of the endomembrane system?
(A) mitochondrion
(B) Golgi apparatus
(C) chloroplast
(D) centrosome

The Endomembrane System- Moving Proteins inside a Cell

Molecular zip codes direct molecules to particular destinations in the cell. How are these signals read?
a. They bind to receptor proteins.
b. They enter transport vesicles.
c. They bind to motor proteins.
d. They are glycosylated by enzymes.

Cells that line your intestines are known to possess a large number of membrane proteins that transport small molecules and ions across the plasma membrane. Which of the following cell structures would you expect to be required for this characteristic of the cells?
a. the endoplasmic reticulum
b. peroxisomes
c. lysosomes
d. the cell wall

Nucleus

Describe the pathway of the protein hormone insulin from its gene to its export from a cell of your pancreas.

Endomembrane System: Protein Secretion Practice 1

BioFlix: Endomembrane System

In which cell would you find the most smooth ER?
a. pancreatic cell that secretes digestive enzymes
b. ovarian cell that produces estrogen (a steroid hormone)
c. muscle cell in the thigh of a long-distance runner
d. white blood cell that engulfs bacteria

Which structure is not part of the endomembrane system?
a. nuclear envelope
b. chloroplast
c. Golgi apparatus
d. plasma membrane

Protein Secretion

In which cell would you find the most rough ER?
a. pancreatic cell that secretes digestive enzymes
b. ovarian cell that produces estrogen (a steroid hormone)
c. muscle cell in the thigh of a long-distance runner
d. white blood cell that engulfs bacteria

No. Most of the proteins synthesized in the mitochondria stay in the mitochondria.

No. Proteins made on free cytoplasmic ribosomes do not end up in the membranes of the endomembrane system.

No. Although the smooth endoplasmic reticulum is part of the endomembrane system, it lacks ribosomes and therefore is not involved in protein synthesis.

No. Proteins that function in the plasma membrane are synthesized in the same place as all of the other membranes of the endomembrane system.

Consider the flow of materials in the endomembrane system.

A protein that ultimately functions in the plasma membrane of a cell is most likely to have been synthesized __________.

Endomembrane System Summary

Which part of the nucleus is responsible for assembling ribosomes and ribosomal RNA?

The Endomembrane System: Difference between Transport and Secretory Vesicles

The Endomembrane System

Which of the following results provided evidence of a discrete nuclear localization signal somewhere on the nucleoplasmin protein?
a. The nucleoplasmin protein was small and easily slipped through the nuclear pore complex.
b. After cleavage of the nucleoplasmin protein, only the tail segments appeared in the nucleus.
c. Removing the tail from the nucleoplasmin protein allowed the core segment to enter the nucleus.
d. The SRP bound only to the tail of the nucleoplasmin protein, not the core segment.

No. The smooth ER is the primary site where the cell produces lipids.

No. Although the protein ends up in the plasma membrane, any modifications were most likely made before the protein arrived at the plasma membrane.

No. Transport vesicles function to move membrane and proteins between the organelles of the endomembrane system.

No. The protein was originally synthesized on ribosomes of the rough ER, but modification occurs elsewhere.

Consider the functions of the various components of the endomembrane system.

A researcher made an interesting observation about a protein made by the rough endoplasmic reticulum and eventually found in a cell's plasma membrane. The protein in the plasma membrane was actually slightly different from the protein made in the ER. The protein was probably altered in the __________.

In the aqueous interior of a lysosome, functioning as a digestive enzyme

No. Proteins that are inserted into the rough ER membrane are membrane proteins, not soluble proteins.

In the cytoplasm, functioning as an enzyme in carbohydrate synthesis

No. Cytoplasmic proteins are synthesized on free cytoplasmic ribosomes.

In the internal space of the Golgi apparatus, being modified before the protein is excreted

No. Proteins that are inserted into the rough ER membrane are membrane proteins, not soluble proteins to be excreted.

In a mitochondrion, functioning in ATP synthesis

No. Mitochondria are not part of the endomembrane system.

Embedded in the plasma membrane, functioning in the transport of molecules into the cell

Consider the flow of materials through the endomembrane system.

Consider a protein that is made in the rough endoplasmic reticulum. You observe that when the synthesis of the protein is completed, the protein is located in the ER membrane. Where else in the cell might this protein be found?

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