The most joyful moment in every family is the birth of a baby. What we normally hear is:
“Is it a girl or a boy?”
Gender refers to whether somebody is a boy/male or girl/female. This is naturally determined from the moment of fertilization and depends on the sperm from the father that fertilizes an egg from the mother.
Even though we should embrace whatever comes our way as a blessing from the Almighty, many sad stories have been heard about how some women have suffered episodes of abuse, rejection and even divorce for having too many girls rather than boys.
Interestingly, no one has control over these natural events; and if we do in one way or the other, women have no control over the gender of a baby; men do!
The gender of a baby is genetically determined and fundamentally based on a natural phenomenon involving:
*Egg cells
*Sperm cells
*Chromosomes
*DNA
*Genes
WHAT IS A CELL?
A cell is the basic unit of life.
Living things, also called organisms are made up of one or more cells. Basically, cells are the building blocks of living things, ranging from bacteria made up only one cell to humans, cows, cats and dogs made up of many cells. Plants are also living things made up of cells.
The word “cell” was coined in 1665 by an English Scientist called Robert Hooke. He is credited as the first scientist to investigate living things and their components using a microscope he manufactured himself.
His interesting observation was that: all the objects he observed had smaller components that could not be seen with the naked eye; that is, an eye without a microscope or a magnifying device. He called these microscopic structures “CELLS”, which also had sub-cellular structures most of which were not clearly seen in the light microscope he had manufactured.
These sub-cellular structures are now called organelles an example of which is the NUCLEUS.
Plant and animal cells, specifically, human cells, except for matured red blood cells contain an organelle called NUCLEUS, among others.
The nucleus houses DNA which is the chemical responsible for the transmission of genetic information from parents to children, also called offspring from generation to generation.
DNA is what enables humans to give birth to human babies, dogs to give birth to puppies and cats to give birth to kittens from generation to generation. This goes for all living things in order for procreation to make their own kind as ordained by God in Genesis 1:28. “Be fruitful and increase in number”.
ADAM AND EVE
Besides Adam and Eve, we do not hear about any other humans created directly by God. Instead, our wise God placed DNA in the cells of Adam and Eve to transmit human characteristics to humans. All living things were also made in opposite pairs to execute this divine instructions at the appropriate time.
Scientists have discovered that it is DNA that enables living things to procreate to make copies of themselves through cell division and differentiation.
More information on DNA as you read on.
WHAT ARE EGG CELLS?
Egg cells are cells from the ovaries of the mother (female) which, when fertilised by a sperm from the father (male) will form a zygote (fertilized egg) which eventually develops through cell division and differention to form a baby which may be born within a period of 9 months.
WHAT ARE SPERM CELLS?
Sperm cells (Spermatozoa) are cells produced by the testes in males.
For pregnancy to occur, the DNA in the nucleus of a sperm has to fuse or mix with the DNA in the nucleus of an egg.
Scientists have not yet come out with any other way of beginning a human life but to mix the DNA from a sperm and an egg or their derivatives.
WHAT ARE CHROMOSOMES?
Chromosomes are
condensed forms of DNA and histone proteins.
Chromosomes develop just before a cell divides to make copies of itself for growth to occur, to replace damaged cells for wound healing or for making sex cells for procreation or reproduction.
Different organisms have different number of chromosomes. Humans have 46 chromosomes in the nucleus of all their cells, except for the sperm cells in males and egg cells in females which have 23 chromosomes in the nucleus. The rationale behind this is that each sperm and each egg will supply 23 chromosomes during fertilization to make a human baby with 46 chromosomes.
Fertilization is basically the mixing of DNA from two opposite organisms to produce an offspring with half of its DNA from the mother and half from the father.
Chromosomes contain DNA, the genetic material of living things.
During fertilization in humans, the genetic material of one sperm cell with 23 chromosomes fuses or mixes with the genetic material of one egg cell with 23 chromosomes to form a zygote which is a baby-to-be with 46 chromosomes.
THE X AND Y CHROMOSOMES IN BODY CELLS AND IN THE SEX CELLS
In genetics all human cells are described as body cells or somatic cells, also called autosomes. However, the sperm cells and the egg cells are described as sex cells or gametes. The nucleus of all body cells, with the exception of matured red blood cells contain 46 chromosomes in 23 pairs. One of each pair of chromosomes comes from each parent.
The chromosome pairs are numbered 1-23. Chromosome pairs number 1-22 are the autosomes or body chromosomes and the pair number 23 is the sex chromosomes which determine the gender of the baby.
Each pair of chromosomes from both parents are referred to as: homologous chromosomes.
Chromosomes are denoted as X and Y chromosomes.
The 46 chromosomes that are associated with humans contain all the characteristics inherited from both parents.
The nucleus in the body cells in males contains both X and Y chromosomes. To be precise, there are 23 X chromosomes and 23 Y chromosomes, making a total of 46 chromosomes in the nucleus of all the body cells in males. The 23 Y chromosomes were inherited from the father and the 23 X chromosomes were inherited from the mother. Hence the male genoype is denoted as XY.
However, in the nucleus of the body cells in females, there are 46 X chromosomes; 23 from the mother and 23 from the father to make the total of 46 chromosomes, hence the female genotype is denoted as XX.
As DNA is our genetic material which determines our characteritics and the chromosomes are made up of DNA, it implies that the chromosomes contain the chacteristics of individuals located in genes which are segments of the DNA or chromosome structure that code for a particular characteristic or a particular protein such as insulin.
Of each characteristic located in the genes, children inherit two copies of each gene from both parents. So, essentially, genes come in pairs whereby each chromosome from the homologous pair contains the same genes as the other, except for the gender chromosomes or chromosome number 23.
These pairs of genes in chromosome pairs 1-22 from both parents are called alleles. They are genes controlling the same characteristics such as eye colour in both parents.
GENOTYPES AND PHENOTYPES
Genotypes are the types of genes inherited from both parents with reference to particular characteristics. Phenotypes are the observable or experienced characterstics as a result of the genotype. For example:
If a sperm cell containing X chromosomes in the nucleus fertilises an egg the genotype of the baby is XX and the phenotype is a girl or a female.
If a sperm cell with Y chromosomes fertilises an egg, the genotype is XY and the phenotype is a boy or a male.
Remember that all the egg cells have 23 X chromosomes in the nucleus, but some sperm cells have 23 X chromosomes and some have 23 Y chromosomes.
This highlights the fact that the father has the upper hand with reference to the gender of the baby, because, naturally females have 23 X chromosomes in all their eggs, but males have 23 X chromosomes in the nucleus of some of the sperm cells but 23 Y chromosomes in the nucleus of some sperm cells.
So the fathers who wage war against their wives for having too many girls or too many boys should go and say apologize!
WHAT IS DNA?
DNA stands for deoxyribonucleic acid. It is the chemical for genetic inheritance that enables humans to give birth to humans, not cats; and cats to give birth to cats, not dogs, mango seeds to develop into mango fruits not oranges and orange seeds to develop into oranges not tomatoes etc, etc.
Thankfully, such is the power of DNA!
Basically, organisms give birth to their own kind as much as possible.
WHAT ARE THE COMPONENTS OF DNA?
DNA is a biochemical molecule which contains the following elements:
*Oxygen (O)
*Hydrogen (H)
*Carbon (C)
*Nitrogen (N)
*Phosphorus (P)
Carbon, oxygen and hydrogen bond together to form a five carbon sugar or pentose sugar called deoxyribose, carbon, oxygen, hydrogen and nitrogen bond to form nitrogenous bases and oxygen and phosphorous bond to form a phosphate group. There are four different nitrogenous bases in DNA namely:
*Adenine (A)
*Cytosine (C)
*Guanine (G)
*Thymine (T)
One phosphate group, one deoxyribose sugar and one nitrogenous base bonded together constitute a nucleotide.
Nucleotides are the basic units of the DNA structure.
THE DOUBLE HELIXA double helix refers to 2 strands of molecules twisted into a spiral shape.
DNA is a double stranded giant molecule twisted into a spiral shape.
To form the double stranded DNA structure, the nitrogenous bases have to bond with their appropriate partners using hydrogen bonds.
The correct bonding of the nitrogenous bases is important for DNA to maintain its structure and function as a molecule that transmits genetic information from parents to children from generation to generation.
Scientific research has shown that A bonds with T (A-T), using two hydrogen bonds and G bonds with C (G-C) using three hydrogen bonds. These base pairing should always be the same in order to maintain the authenticity of the DNA structure and function as the molecule of inheritance.
The wrong base pairing such as T-G or A-C constitutes a mutation or a change in the base pairing which can result in a disease such as sickle cell anaemia or cystic fibrosis.
Mutation is a complex aspect of genetics as some mutations are useful whilst some are harmful. In some cases, mutations occur in the DNA structure to bring about variations in organisms.
Simply stated, DNA is the blueprint of life.
WHAT IS A GENE?
Genes are segments of the DNA or chromosome structure which code for particular proteins such as insulin and haemoglobin or characteristics such as nose shape and eye colour.
Genes for nose shape and eye colour may mutate to bring about variations in eye colour such as blue eyes green eyes, brown eyes and pointed nose or flat nose shapes.
The genes found in the chromosones or DNA and the chromosome numbers of different organisms set organisms apart as humans, dogs, cats, plants, sheep, cows, bacteria, mosquitoes, snakes etc, etc.
Naturally, the combination of the 23 chromosomes in the nucleus of one sperm cell and the 23 chromosomes in the nucleus of each egg cell which occurs as a result of copulation between males and females is a requirement for pregnancy.
However, modern scientific pursuits have channeled techniques such as artificial insemination and in-vitro fertilisation which allow individuals to have biological children without any physical contact between a male and a female.
Most importantly, pregnancy can only be achieved through the fusion of an egg and a sperm.
In artificial insemination, a sperm is injected into the fallopian tube (oviduct) at an appropriate time to wait for an egg to be released during ovulation for fertilization to occur.
Ovulation is the release of a matured egg 12-14 days from the first day of menstruation.
Artificial insemination has different forms but they all involve the introduction of a sperm into the woman’s fallopian tube to fertilise an egg within the body.
In-vitro fertilization on the other hand involves the sperm and egg cells made to fuse in a glassware to form a zygote outside the body before placing the embryo in the womb of the mother where the embryo will continue its development.
THE VIRGIN BIRTH
The Virgin Birth refers to the birth of Jesus by a Virgin Mary who was said to be a virgin, but yet got pregnant with Jesus after an Angel had prophesied to her.
These new complex reproductive techniques beg the question of the Virgin Birth which has created many doubts in many people both Christians and non-Christians.
In my humble opinion, the All-knowing God has allowed humans to perform all these complex acts in order to clear the doubts about the Virgin Birth, but l’m sure a good number of people may have missed the point.
If we as humans with our feeble minds can perform such acts to cause a woman to be pregnant without having sexual contact with a man, why can’t the creator of the universe in its entirety cause a virgin to be pregnant?
Food for thought!
THE END
ARTICLE 3: BY DR. AGNES BOATENG: BIOLOGY LECTURER, UK
