Gametes are specialized reproductive cells whose structures support fertilization, including sperm motility and oocyte protection, stored resources, and recognition layers.
Coverage 2014–2021 · Updated 15 Jul 2026
Human sperm and egg cells carry haploid nuclei but have contrasting structures adapted for reaching, recognizing and completing fertilization.
A sperm is small and streamlined, with an acrosome containing enzymes, a compact haploid nucleus, a midpiece rich in mitochondria and a flagellum for movement. The egg is large, with abundant cytoplasm, a haploid nucleus and protective extracellular layers.
Sperm membrane proteins participate in recognition and fusion. The egg's zona pellucida helps control sperm binding, and cortical granules release their contents after fusion to modify the egg coverings and reduce polyspermy.
ATP supplied by mitochondria concentrated in the sperm midpiece supports flagellar movement, while the egg's large cytoplasmic volume supports the earliest stages after the two haploid nuclei unite.
These statements apply to human gametes. The egg is not motile like sperm, and mitochondria supply energy but are not located in the sperm head or distributed evenly along the whole cell.
This objective is assessed through multiple choice, commonly using Identify / Draw.
Identify / Draw
Build the answer around this relationship: Sperm mitochondria are concentrated in the mid-piece to support ATP production.
Placing most sperm mitochondria in the head or tail instead of the mid-piece.
Representative question
In which part of a mature spermatozoan are mitochondria most numerous?
The head
The tail
The mid-piece
Mitochondria are evenly spaced throughout the cell
A strong answer identifies the cell, names the structural adaptation, and states the function it improves. Erythrocytes and PCT cells show exchange and transport adaptations; pneumocytes show diffusion versus secretion; muscles show contraction coordination; gametes show fertilization roles.
