Why do cells need to signal?
To respond to changes in their environment and to communicate with other cells.
How do cells communicate with one another?
By producing signals that are detected by target cells through receptors, leading to a response.
What are the three main types of signaling distances?
- Direct contact
- Short-distance
- Long-distance
Which types of signaling are short-distance?
- Autocrine signaling
- Paracrine signaling
Which type of signaling is long-distance?
Endocrine signaling.
What is direct contact signaling?
Communication through cell junctions or surface proteins binding directly to receptors on another cell.
What are the three stages of cell signaling?
- Receptor activation
- Signal transduction
- Cellular response
What happens during receptor activation?
A signaling molecule binds to a receptor, causing a conformational change.
What happens during signal transduction?
The signal is relayed through intracellular pathways, often using cascades or second messengers.
What happens during the cellular response stage?
The cell changes its activity, such as turning genes on/off, altering enzyme activity, or modifying structural proteins.
Why is ligand-receptor binding important?
It is specific and noncovalent, ensuring the right signal binds the right receptor quickly and effectively.
What are examples of cellular responses to signaling?
- Gene expression changes
- Enzyme activity regulation
- Structural protein modifications
What is a signal transduction cascade?
A sequence of molecular events (often phosphorylation steps) that amplify and relay a signal inside the cell.
What is a kinase?
An enzyme that adds a phosphate group to a protein, often activating it.
What is a phosphatase?
An enzyme that removes a phosphate group from a protein, often deactivating it.
Why are kinases and phosphatases important?
They regulate signaling pathways by turning proteins on or off, controlling cell responses.
What are the two main categories of receptors?
- Transmembrane (cell surface) receptors
- Intracellular receptors
What are the three main types of transmembrane receptors?
- Enzyme-linked receptors
- G-protein coupled receptors (GPCRs)
- Ligand-gated ion channels
Where are intracellular receptors found?
In the cytosol or nucleus, binding small or hydrophobic molecules that cross the membrane.
What is the function of enzyme-linked receptors?
They have extracellular and intracellular domains and often act as kinases to activate signaling pathways.
How do G-protein coupled receptors (GPCRs) work?
Ligand binding activates a G-protein, which exchanges GDP for GTP and triggers downstream effects.
How do ligand-gated ion channels function?
Ligand binding opens the channel, allowing ions to flow across the membrane and change cell activity.
What is the role of second messengers in signaling?
They relay signals inside the cell, amplify responses, and allow fast activation of pathways.
Give an example of a second messenger.
cAMP or Ca²⁺.
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Chapter 1 (1.5)22
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Chapter 2 (2.1 & 2.2)35
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Chapter 2 (2.4 & 2.5)26
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Chapter 3 (3.1 - 3.5)36
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Chapter 4 (Section 4.3-4.5)24
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ndomembrane system and protein sorting/ endosymbiotic theory25
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Chapter 5 (Membrane structure & transport)44
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Cell Communication25
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Chem Reactions and Energy33
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Chapter 5 metbalolsim24
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Cell Respiration18
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Chapter 1130
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Chapter 1650
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Chapter 1725
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Gene Regulation41
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Chapter 1520
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Gene Expression74
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Exam 2 Questions40
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Exam 3 Questions40
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Exam 4 Questions39
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Chapter 2231
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Chapter 2337
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Chapter 2430
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Chapter 2526
