Video Transcript
The diagram provided shows the
basic structure of an egg cell, ovum. Where in the ovum are most of the
nutrients contained? (A) The cytoplasm, (B) the jelly
coat, (C) the nucleus, (D) the corona radiata.
To answer this question, we must
recall what we know about the different functions of the various structures of the
ovum. The ovum, or egg cell, is a
spherical cell measuring about 0.1 to 0.2 millimeters in diameter. This is roughly the same size as a
single grain of table salt, making the ovum one of the largest human cells and
visible to the unaided human eye. This large size of the ovum is
because several structures of the ovum are used to store nutrients that support the
development of the egg cell after fertilization. Let’s review the different
structures of the ovum and how they store nutrients to nourish the ovum.
The outermost structure of the ovum
is called the corona radiata. The word “corona” means crown in
Latin and describes how this part of the ovum is made of cells that surround the
ovum like a crown. The corona radiata provides
physical protection to the ovum as well as helping to provide nutrients while the
ovum develops.
Under the corona radiata is the
jelly coat. This structure has two main
functions. First, the jelly coat releases
chemical signals that attract and guide sperm towards the ovum. Second, the jelly coat ensures that
only one sperm cell can fuse with the ovum.
The jelly coat surrounds the
cytoplasm of the ovum. This structure contains most of the
nutrients that nourish the ovum as it develops, so it is the cytoplasm of the ovum
that is largely responsible for the large size of the cell.
The nucleus of the ovum is found
within the cytoplasm. It contains the genetic material
that will be inherited by the offspring from the biological parent that produced the
ovum.
From this review, we now recall
that the cytoplasm is the part of the ovum that contains most of the nutrients that
nourish the ovum. With this information, we are ready
to answer this question. In the ovum, most of the nutrients
are contained in the cytoplasm.
