Wednesday, February 26, 2014

No Mitosis without Meiosis

For animals and plants, including humans, cell division resulting from mitosis results in growth, repair, and renewal of the body and its tissues. Our posts have recently discussed gestation--prenatal events up until birth. During this interval mitosis produces startling growth of body mass. A body cell may duplicate itself in 24 hours. Growth multiplies geometrically during gestation from the initial production of the diploid zygote following fertilization. Over 200 different types of body cells are built coherently into the human frame. The construction activity taking place in the body during gestation is a source of wonder and awe, not to mention the growth, repair, and renewal of body tissue for the remainder of one’s life following birth.

We focus on another term equally familiar to students of biology. The term is meiosis. Our study of meiosis reveals significant differences from mitosis. Both terms involve division of cells. Mitosis results in the generation of all the somatic cells of our body, every body cell, and the transmission of all genetic information passed on by the DNA contained in each cell. Both mitosis and meiosis transmit genetic information as body cells divide. Mitosis is linked primarily with growth, while meiosis is associated with reproduction of an entirely new organism. Mitosis is a continuous lifetime event. For the origin of any one organism, however, meiosis is a once in a lifetime event.

Events of meiosis differ from mitosis. After mitosis, the two daughter cells produced are identical to the original cell and have received the same DNA. Two resulting diploid cells are genetically identical. Growth is the outcome of this cell division process. In contrast, meiosis results in production of a new organism. The first step replicates the DNA in maternal and paternal pairs of chromosomes. Two separate divisions follow--meiosis I and meiosis II. First, each pair of chromosomes separates. The second division separates each pair again into haploid sister chromatids. These are unreplicated cells, two maternal and two paternal cells. These four daughter cells have only half as many chromosomes as the parent cell and each is genetically distinct from each other and from the parent cell. The full number of chromosomes is restored when the zygote forms at fertilization.

Because each daughter cell is genetically distinct, no two humans alive (except identical twins) are exactly alike. God apparently endows each member of humanity with uniqueness. A new life is formed by the joining of female and male gametes, ova and sperm, formed in the manner described above. Thereafter, mitosis generates all the somatic cells of the body.

We conclude this series of posts on prenatal events with a personal expression of worship. A recent conversation with a director of our local pro-life pregnancy center triggered a thoughtful perspective on this breathtaking process. Recently refined ultrasound technology for viewing the developing physical child supplements the knowledge we have gained about cellular growth and organ building processes during gestation in the womb of the mother. We know intricate detail about the growth process of mitosis as well as how male and female gametes are formed during the reproductive process of meiosis. Viewing ultrasound images of the forming baby including its beating heart is wonderfully effective in dissuading prospective mothers from terminating the lives of their unborn children. Beyond the ultrasound, there are more rewards for our inquiry: discovery of the microscopic and molecular reality of gametes, chromosomes, and DNA molecules, not to mention how life development processes occur. The beauties of God’s gift of life come ever more clearly into focus.

As we examine the multifaceted panorama of life itself we find it difficult to deny the exquisite signature of the Master Designer. Prospective mothers and every discerning living person should be loathe to deny that signature. The more we understand how our lives unfold from formation of a one celled zygote to our days of maturity and decline, the more we exult in the beauty and love of our Creator.

Thursday, February 20, 2014

Mitosis Memories

Flashback to memories of your early courses in biology. One term--mitosis--may come to mind. Perhaps you even recall diagrams or animations of chromosome pairs organizing themselves along an imaginary plane equidistant from the cell’s poles, followed by impressive parting and separation of the chromosome pairs. Two identical pairs of chromosomes are produced from one.

Mitosis occurs in stages termed prophase, metaphase, and anaphase. Real time anaphase proves to be the shortest but most impressive event. In only a few minutes the paired chromosomes are seen to separate and move toward opposite ends of the cell. Soon there are two new duplicate cells, each with a nucleus. All phases of mitosis are completed in just one hour. The new cells begin production of proteins and organelles. Growth of cells predominates over cell duplication.

Wondrous events of prenatal development during human gestation all depend on successful mitosis events. Campbell and Reese in their AP textbook Biology state, “As a human develops from a zygote to a sexually mature adult, mitosis generates all the somatic cells of the body. Both chromosome sets in the zygote and all the genes they carry are passed on with precision to our somatic cells.” (Somatic cells include virtually every biological cell forming the body of an organism.)

The single-celled diploid fertilized egg, the zygote, becomes a fully formed human being in only nine months. During that time the process of mitosis generates all cells of the newly formed, functional human being. The newborn baby, complete with an integrated organ system, is a tribute to the Creator’s planning and Intelligent Design.

Naturalistic evolutionists and theistic evolutionists alike denigrate Intelligent Design. The creation of a human being from the union of two gametes, one sperm and one egg, forming a one-celled zygote, is an example of Intelligent Design--the Creator’s design! When details of human reproduction are described many think the handiwork of God is apparent whether the term ID is used or not. Rejection of the term might relate to rejection of the concept that the Creator initiates supernatural events on occasion. Do we understand how God accomplishes such supernatural events? No, we do not. This is not an excuse, however, to reject the intelligent workings of the Deity either to initiate life forms or to design a method of reproduction.

Intelligent Design has come under fire. Both ID and creationism have been attacked as unscientific. In the past few decades the tendency to diminish ID and creationism is to curry favor with the community of naturalistic and theistic evolutionary scientists who pledge allegiance to the mystique of science. Even theistic evolutionists implore their young followers in the church community to “get on board with science.”

Lest we are misunderstood, we stress our enthusiastic respect for the discoveries and benefits of science. Never should science distort our understanding of the miraculous workings of the Deity in the world we observe. With a correct interpretation of both Scripture and the discoveries of science, we posit there is no disagreement.

Friday, February 14, 2014

Mystery of Reproduction

Our posts on human reproduction have focused on only one of earth’s species. The total species count is variously estimated to number in the millions. According to one new study by UNEP, the United Nations Environmental Programme, the number has been pegged at 8.7 million, of which over 1.2 million appear in the “Catalog of Life,” an index of the world’s species. Biology textbooks have included man as but a single species among Earth’s 8.7 million. Our single species of focus is unique and very special according to Genesis because he is created in the Image of God. With this qualification, man is not merely another species on the continuum of life. He occupies an extraordinary position on the continuum.

In secular textbooks modern humanity, Homo sapiens sapiens, is touted as an evolutionary vestige and the only remaining species of hominids, a branch of animals, according to the evolutionary view, which began to walk erect and exhibit some cultural advances such as simple tool-making. Secular biology texts’ matter-of-fact treatment, accurate from a taxonomic standpoint, does not treat the uniqueness of man from a theological standpoint. Most often biology texts describe man from an evolutionary viewpoint.

Modern humanity is a very recent arrival on Earth. The historical “cultural explosion” of humans is identified by secular scientists as originating only several tens of thousands of years ago. Advanced tool-making and weaponry, sculpture, painting, jewelry making, and even long distance trade appeared quite suddenly. Creationists see the rapid onset of advanced humanity as harmonious with scripture’s account of the special creation of man in the Image of God.

A highlight of the Genesis account is the creation of man. Little detail is given in Genesis. For example, in Chapter One, the initial mention of the vast array of the creation of life forms concludes with, “So God created man in his own image, in the image of God he created him, male and female he created them.” (Genesis 1:27 NIV) When we read ahead to the next verse, we see Scripture’s first mention of reproduction. God said, “Be fruitful and increase in number.”

Millions of species created in the eons preceding man’s creation were “fruitful” and “increased in number.” Their reproduction strategies were identical with living things of our day. God’s original plan for reproduction was utilized anew when modern man arrived. Most species have depended on sexual reproduction, the creation of a new organism by combining the genetic material of two other organisms, one male, one female.

Secular biologists admit many phenomena of reproduction of living things are a mystery. In particular, sexual reproduction, the union of haploid male sperm and haploid female ovum into a diploid zygote capable of generating a new individual is a “major evolutionary puzzle.” The explanations for this phenomenon are “controversial,” according to evolutionists. From a scientific standpoint, explanations are inadequate. However, from a theological standpoint, Genesis 1:27 characterizes male/female reproduction as a divine plan originating in the mind of the Creator. Details of reproduction of Earth’s living things are matters of intensive study and ongoing discovery.

Sunday, February 9, 2014

Imageries of Building

Building projects supply instructive imageries to illustrate life’s important lessons. Imageries use figurative language to make a point. As a classroom teacher, one of my favorite instructional imageries supplied students with advice for construction of their “life house.” For instance, we must build our life house using good construction materials. Good diet and healthy exercise must be incorporated into the building of our bodies. Wholesome reading materials help build our moral and ethical “life house.”

Pastors often use building imagery in their pulpit instruction. Recently our pastor concluded a series on the Sermon on the Mount with the text of Matthew 7:24-28. In that familiar passage the foundations of two homes were contrasted. One home was built on a foundation of rock; the other was built on sand. Of course, the success of the structures depended largely on the planning and choices of the house builders with respect to their foundations.

Other building imageries reminding us of the necessity of intelligent planning come to mind. During my adult life I have been involved in the construction of three new personal family dwellings. The first two were building projects joined “in progress.” The home designs had been chosen by our builder before we entered into contract with him. We had only to select various options for woodwork, flooring, colors, and other minor design features.

In contrast, our most recent home building venture involved personal goals and prudent planning--selection and purchase of a building lot, engagement of an architect, and hiring of a building contractor. My wife’s insightful design concepts were particularly manifest in the kitchen and other rooms where the woman’s touch produced results approaching creative genius. Many other details of the building process are chronicled and preserved in family lore.

We avoid taking credit for our dwelling more than we deserve, even though our guests are informed that the home’s basic design concepts and decorating schemes are our very own. Our chosen professional designer deserves the lion’s share of credit for producing the blueprints. Our builder and his sub-contractors executed the actual production. In similar manner, the appearance of our children and the perfection of their body systems is a gift from the Lord beyond our control.

Recent post topics relate to the miracle of reproduction and the process of gestation. Details of this story inspire awe and wonder. All involved--young people, prospective parents, parents, grandparents, indeed, all of humanity--are invested in this grand saga. When we understand the mind-boggling reality of the wonder of genetic inheritance and the intricate process of reproduction, we tremble with awe. The signature of God is manifest in multiple ways.

Building projects provide lessons in integrated construction strategies. Quality building materials must be selected. Construction materials must be utilized at the proper time and place and in the appropriate manner. For an effective result, all factors must operate in concert. Applying this imagery to human reproduction, the formation of an embryo, its transition to a fetus and finally, the arrival of the birth of a child are events which are coordinated precisely by the Creator. A home building project demands intelligent human control. Likewise, the human body building gestation process demands intelligent divine guidance during pregnancy. For the most part the process is beyond the control of prospective parents except to monitor the mother’s physical condition and reverently preserve and care for the developing new life.

This tiny corner of the universe has been bestowed with life by the Creator. So far as scientists can tell, life’s existence occurs solely on our unique planet. Life has been endowed with the capacity to reproduce itself. Man, the highest form of life, is endowed with consciousness. We are enabled, therefore, to contemplate the reality of life and its reproductive ability. Our enablement is one of God’s multiple gifts to humanity created in God’s image.

Wednesday, February 5, 2014

Plotting Prenatal Progress

The astonishing beginning and subsequent development of the human embryo and its transition to the category of fetus at roughly eight weeks is known to medical scientists in stunning detail. For forty weeks these events are hidden from the outside world. At birth the child makes its grand entry to the vision of outside observers, the world of conventional photography, and the world of unmuffled sound. The newborn experiences an immediate need for an independent food and air supply. With dramatic suddenness the infant transitions from the silent prenatal development venue to the bustling activity of the world of the nursery.

The first eight weeks are crucially important. The foundation for cellular organization is laid in the tiny embryo during the first few weeks following conception. This is an incredibly eventful and delicate time interval. At four weeks the embryo is smaller than a grain of rice. Many of the 220 types of body cells navigate their way to their proper positions in the newly forming human body. At eight weeks every body organ is in place. Bones have begun to replace cartilage, fingerprints form, and the baby can begin to hear. The baby has grown to one inch in length and “humanity now covers the embryo’s countenance.”

The body structure at eight weeks is visibly locked in place. Hereafter the fetus mainly increases in size and completion of already formed bodily features. The National Right to Life Committee (NRLC) website link on “Fetal Development” details the transition from one inch in length and 1/8 ounce in weight to the average birth length of 18-20 inches and average body weight of seven pounds.

In the following paragraphs we quote information published by NRLC on fetal development prior to birth.

During weeks nine and ten teeth begin to form. The baby can turn its head, frown, and hiccup. Weeks ten and eleven find the baby able to “breathe” amniotic fluid and urinate. Objects placed in its hand may be grasped. All organ systems are functioning. The baby has a skeletal structure and circulation.

In week twelve the baby is three inches long, weighs one ounce, and has all the parts necessary to experience pain, including nerves, spinal cord, and thalamus. Its vocal cords are complete. The baby can suck its thumb. At fourteen weeks the heart pumps several quarts of blood through its body every day. At sixteen weeks the baby is four to five inches long, weighs three ounces, possesses a complete skeleton, and has an adult’s taste buds.

At the close of the fourth month the baby has grown to eight to ten inches in length and weighs one half pound. Bone marrow is beginning to form. The heart is pumping 25 quarts of blood each day. The baby recognizes its mother’s voice at twenty weeks. During months five and six the baby practices breathing by inhaling amniotic fluid into its developing lungs. The baby grasps at the umbilical cord when it feels it. A mother feels movements from her baby which has achieved twelve inches in length and a weight of one and one-half pounds.

During months seven through nine the baby opens and closes its eyes. It makes use of four of its five senses--vision, hearing, taste, and touch. It knows the difference between waking and sleeping and can relate to the moods of the mother. The baby’s skin begins to thicken, and a layer of fat is produced and stored beneath the skin. Antibodies are built up, and the baby’s heart pumps 300 gallons of blood per day.  Approximately one week before birth the baby stops growing and descends, head down, into the pelvic cavity.

The first eight weeks of gestation is the time frame most shrouded in mystery. Professionals in embryology have written voluminously on chemical and physical processes taking place in the miniscule, kernel-sized embryo of the first month of pregnancy. In the first four weeks the embryo becomes ten thousand times larger than the fertilized egg but it remains barely visible. We repeat the colorful imagery in one volume on reproduction: “Nothing so puzzles embryologists as the way in which cells outfit themselves and trek about to settle different regions of the embryo.” We hasten to explain the cells’ “trek” occurs in a tiny piece of embryological tissue.

At the end of two months the embryo stage concludes and the fetus stage begins. The foundation of the human frame has been laid. The seven-month fetus stage mostly builds on a structure already in place after two months. Interrupting the events of a healthy pregnancy at any stage is a procedure bringing grief to ethical parents who think profoundly. More significant is the grief this procedure brings to the Creator who planned and created life and sustains it from moment to moment.