The Question is from neet-zoology human-reproduction , and it was created by the author K SUNKANNA

Question

A male patient presents with infertility and upon examination, it is found that he has immotile sperms. Genetic analysis reveals a mutation affecting a specific protein crucial for dynein arm function within the sperm flagella. Which of the following proteins is MOST likely affected by this mutation?

K SUNKANNA · Accepted Answer

## CORE INFORMATION
✓ **Answer**: B
## CONCEPT FRAMEWORK
 **Primary Concept**: Sperm motility and flagellar function
 **Related Topics**: Cilia and flagella structure, molecular motors, genetic basis of infertility
 **Prerequisites**: Understanding of eukaryotic cell structure, protein function, and the role of dynein in microtubule-based movement.
## SOLUTION PATHWAY
**Given Information**:
  * Male patient with infertility.
  * Immotile sperm.
  * Genetic mutation affecting a protein crucial for dynein arm function in sperm flagella.
**Method & Steps**:
 1. Identify the structure responsible for sperm motility: Sperm motility is driven by the flagellum, a whip-like structure composed of microtubules.
  Reasoning: The question states that the sperm are immotile, indicating a problem with the flagellum's function.
  Formula/Rule: None directly applicable.
 2. Identify the motor protein responsible for flagellar movement: The movement of flagella is powered by the motor protein dynein.
  Working: Dynein arms, located on microtubules within the axoneme (the core structure of the flagellum), generate the force for flagellar beating.  A mutation affecting dynein would directly impair this movement.
  Key Point: Dynein is a molecular motor that uses ATP hydrolysis to move along microtubules.
 3. Determine the most likely affected protein: Given the mutation affects dynein arm function, the most likely affected protein is axonemal dynein.
  Result: Axonemal dynein
  Verification: The question directly links the mutation to dynein arm function within the sperm flagella.  Axonemal dynein is the specific dynein isoform found in the axoneme.
 ## OPTION ANALYSIS
[A] :x: Tubulin: Tubulin is a component of microtubules, the structural elements of the flagellum, but it is not the motor protein responsible for movement.
[B] ✓: Axonemal dynein: This is the motor protein responsible for the movement of the sperm flagellum. A mutation affecting it would directly cause immotile sperm.
[C] :x: Actin: Actin is involved in various cellular processes, but not directly in the motility of sperm flagella.
[D] :x: Myosin: Myosin is a motor protein involved in muscle contraction and other cellular processes, but not primarily in flagellar movement.
 ## LEARNING AIDS
 **Common Mistakes**:
  1.Confusing the roles of tubulin and dynein: Tubulin forms the structural framework, while dynein provides the motive force.
   [How to avoid]: Clearly understand the difference between structural proteins and motor proteins.
  2.Overlooking the specificity of axonemal dynein:  There are different isoforms of dynein;  the question specifies a defect in the sperm flagellum, requiring the axonemal form.
   [How to avoid]: Pay attention to the context of the question and the specific location (sperm flagella) of the defect.
 **Quick Tips**:
  1.Remember the key players in flagellar movement:  Microtubules, dynein, and ATP.
  2.Associate immotile sperm with defects in the flagellar motor protein, dynein.

K SUNKANNA · Answer

Tubulin

K SUNKANNA · Answer

The correct Option is "Axonemal dynein"

K SUNKANNA · Answer

Actin

K SUNKANNA · Answer

Myosin

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