Proteins
We generally tend to think of proteins only from a dietary lens, as a component of what we eat. However, they are among the most important and abundant organic macromolecules in the human body, with diverse structures and functions. Every cell contains thousands and thousands of proteins, each with specific functions. Some help in the formation of cellular membrane or walls, some help the cell to move, others act as messages or signals and flow seamlessly from one cell to another, carrying information.
Protein Expression
The method by which living organisms synthesize proteins and further modify and regulate them is called protein expression. Protein expression plays a significant role in several types of research and is highly utilized in molecular biology, biochemistry, and protein research laboratories.
3B
![Evidence Question #5
1. Cholesterol is abundant in the plasma membrane. Would you expect cholesterol to flip
between the two leaflets of the membrane faster than phospholipids, or slower, or at
the same rate? Explain.
3. Many neurons contain "delayed" voltage-gated K+ channels. Compared to voltage-
gated Na+ channels, the voltage-gated K+ channels respond more slowly to changes in
membrane potential. When the voltage-gated K+ channels are open, they make the
plasma membrane even more permeable to K+.
a) Why does neuronal function require the voltage-gated K+ channels to open more
slowly than the voltage-gated Na+ channels?
b) How would you expect the voltage-gated K+ channels to affect the shape of the
action potential?
3. Mitochondrial DNA encodes key proteins of the electron transport system in the
mitochondrial inner membrane. Certain yeast strains carry mitochondrial DNA
mutations that selectively inactivate the electron transport system, but these mutant
cells are viable when grown in the presence of glucose.
a) How do yeast cells lacking the electron transport system make ATP?
b) Yeast cells lacking the electron transport system still have a weak membrane
potential across the mitochondrial inner membrane. How do these cells generate
a membrane potential?](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F4bb26d64-bb49-4ec5-afc7-ea9f4d31dfb0%2F455c415c-b719-4070-8635-e0f2f7119703%2F4dspi6d_processed.jpeg&w=3840&q=75)
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