Structure and Function Gametes Structure and Function

Human Ovum

Human Sperm

How are they adapted? Ova Sperm Smaller cell Sperm has a long tail Large cell Cytoplasm contains large amounts of protein and lipid food reserves Surrounding egg jelly like coating called zona pellucida Releases chemicals after a sperm fuses with membrane Cannot move independently Chemicals released Smaller cell Sperm has a long tail Has large numbers of mitochondria present Has an acrosome in the head which contains digestive enzymes

How are they adapted? Ova USE? Large cell Cytoplasm contains large amounts of protein and lipid food reserves Surrounding egg jelly like coating called zona pellucida Releases chemicals after a sperm fuses with membrane Cannot move independently Chemicals released Contains sufficient resources for early development of embryo Thickens and prevents any further sperm entering egg Wafted by cilia lining oviduct so directed where to move To attract sperm

Uses of adaptations Sperm USE? Smaller cell Sperm has a long tail Has large numbers of mitochondria present Has an acrosome in the head which contains digestive enzymes Move quickly, take sup less space To enable it to move through cervix and uterus To provide energy for tail Breaks down the zona pellucida

Differences between sperm and ova The ovum is much larger than the sperm – the ovum cytoplasm contains protein and lipid food reserves for the early development of the embryo; the small sperm can move easily. The ovum has jelly-like coating; the sperm has no such coating – the ovum coating thickens after the first sperm penetrates, preventing entry of other sperm. The sperm has a tail; the ovum has no tail – this allows the sperm to move through the cervix and uterus to reach the ovum in the Fallopian tube. Sperm have an acrosome (a specialised lysosome); ova do not – this allows sperm to release digestive enzymes which break down the jelly-like coating of the ovum enabling the sperm to penetrate it.  

Fertilisation http://www.snabonline.com/Content/TopicResources/Topic3/Activities/Interactives/3_3/topic_3_3.html