Describe the structure of egg and sperm cells with diagram.
Answers
Explanation:
The male and female reproductive gametes (sperm and egg) have specialised structures which reflect their functions. The male gamete (sperm) is small and motile and only contributes the male’s haploid nucleus to the zygote. The female gamete (egg) is large and non-motile and .
Answer:
male and female reproductive gametes (sperm and egg) have specialised structures which reflect their functions
The male gamete (sperm) is small and motile and only contributes the male’s haploid nucleus to the zygote
The female gamete (egg) is large and non-motile and contributes all the organelles and cytoplasm to the zygote
Sperm
A typical human spermatozoa can be divided into three sections – head, mid-piece and tail
The head region contains three structures – a haploid nucleus, an acrosome cap and paired centrioles
The haploid nucleus contains the paternal DNA (this will combine with maternal DNA if fertilisation is successful)
The acrosome cap contains hydrolytic enzymes which help the sperm to penetrate the jelly coat of the egg
The centrioles are needed by a zygote in order to divide (egg cells expel their centrioles within their polar bodies)
The mid-piece contains high numbers of mitochondria which provide the energy (ATP) needed for the tail to move
The tail (flagellum) is composed of a microtubule structure called the axoneme, which bends to facilitate movement
Egg
A typical egg cell is surrounded by two distinct layers – the zone pellucida (jelly coat) and corona radiata
The zona pellucida is a glycoprotein matrix which acts as a barrier to sperm entry
The corona radiata is an external layer of follicular cells which provide support and nourishment to the egg cell
Within the egg cell are numerous cortical granules, which release their contents upon fertilisation to prevent polyspermy
Although diagrams of egg cells commonly include a haploid nucleus, no nucleus will form within the egg until after fertilisation has occurred (the egg cell is arrested in metaphase II until it becomes fertilised by a sperm)
Explanation:
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