BIOLOGICAL
BEGINNINGS
CRISTY O.BENAMER
Discussant
SALVACION M. MAGISTRADO
Professor
GENETIC FOUNDATIONS OF CHILD DEVELOPMENT
CHROMOSOME
Rodlike structure that resides in
the nucleus of every cell of the body
and contains genes that guide growth
and development; each chromosome is
made up of DNA and other biological
instructions.
DNA
GENES
Basic unit of heredity in a
living cell; genes are made up of
DNA and contained on
chromosomes.
A spiral-staircase–shaped molecule
that guides the production
of proteins needed by the body for
growth and development; short for
deoxyribonucleic acid.
cell
chromosome
DNA
Gene
Segment of DNA
Operation of Genes
Among these universal genes are those that
make it possible for children to develop basic human
abilities, such as communicating with language,
walking and running, and forming social relationships.
The remaining (small) proportion of
genes varies among children. Genes that vary
predispose individual children to be relatively
tall or short, heavy or thin, active or sedentary, eager to
learn new things or content to rely
on existing knowledge, emotionally agreeable or
combative, and healthy or vulnerable to
disease.
..Operation of Genes
Both universal and
individual genes
initiate chains of
events for the
child.
Formation of Reproductive Cells
Normal human cells contain
46 chromosomes. There is an important
exception: Male and female
reproductive cells, called gametes ,
have only 23 chromosomes each—half
of each chromosome pair. Gametes,
which take the form of sperm in men
and ova in women, are created in a
process of cell division called meiosis
Gender
When one sperm and one ovum unite at
conception, the 23 chromosomes from each parent
come together and form a new being (the zygote ) with
46 chromosomes. The 23rd chromosome
pair determines the gender of the individual: Two X
chromosomes (one each from the mother and father)
produce a female, and a combination of an X
chromosome and a Y chromosome (from the mother
and father, respectively) produces a male.
How Twins Are Created
Occasionally, a zygote splits into two separate
cell clusters, resulting in two offspring instead of one.
Identical, or monozygotic twins , come from the
same fertilized egg and so have the same genes. At
other times, two ova simultaneously unite with two
sperm cells, again resulting in two offspring. These
dizygotic twins , also known as fraternal twins, are
as similar to one another as ordinary siblings. They
share some genetic traits but not others.
Genetic Basis of Individual Traits
Genes that vary among children are
transmitted through systematic patterns of
inheritance as well as by
less common mechanisms and biological errors
during meiosis and later cell divisions.
Common Mechanisms of Genetic Transmission
When the two sets of 23 chromosomes combine into matched
pairs during conception, the corresponding genes inherited from each
parent pair up. Each gene pair includes two forms of the protein-coding
instructions—two alleles —related to a particular physical characteristic.
Sometimes the two genes in an allele pair give the same instructions. At
other times they give very different instructions. When two genes give
different instructions, one gene is often more influential than its
counterpart. A dominant gene manifests its characteristic, in a sense
overriding the instructions of a recessive gene with which it is paired. A
recessive gene influences growth and development primarily when its
partner is also recessive. For example, genes for dark hair are dominant
and those for blond hair are recessive. Thus a child with a
dark hair gene and a blond hair gene will have dark hair, as will a child
with two dark hair genes.
…..Common Mechanisms of Genetic Transmission
However, when two genes of an allele pair disagree, one gene
doesn’t always dominate completely. Sometimes one gene simply has a
stronger influence than others, a phenomenon known as codominance.
In reality, the influence of genes is often even more complex.
Many physical traits and most psychological ones are dependent on
multiple genes rather than on a single pair of alleles and are further
influenced by specific factors in the environment. With a multifactorial trait
, many separate genes work together with environmental factors in the
expression of the characteristic. Height and vulnerability to certain
illnesses, including some kinds of diabetes, epilepsy, and cancer, are
determined by several genes acting together and interacting with such
environmental influences as nutrition, activity, and toxins.
Problems in Genetic Instructions
2 primary types of genetic disorders
• chromosomal abnormality may have an extra
chromosome, a missing chromosome, or a
wrongly formed chromosome.
• single-gene defect from one or both parents resulting
physical problems tend to be more specific and
subtle than those caused by chromosomal
abnormalities.
…Problems in Genetic Instructions
All children require individualized care, but those
with chromosomal abnormalities, single-gene defects, and
other genetic conditions and birth defects may need
interventions tailored to their specific conditions.
Increasingly, parents and teachers have realized that
these accommodations can usually be made in the regular
classroom. In a practice called inclusion , children and
adolescents with exceptional needs are educated within
the general education classroom for all or part of the
school day.
The Blending of Heredity and Environment
In addition to responding to maturational states inside the
child, genes attend to conditions that originate in the outside
environment. Children who obtain nutritious meals, attention from
loving caregivers, and exposure to challenging activities generally
reach their full genetic potential.
The tendency for a child’s genes to be dynamically
influenced by numerous internal and external factors means that
few developmental outcomes can be anticipated with certainty. In
other words, genes make particular characteristics likely but not
guaranteed. The actual characteristics a child ends up with depend
on the full complement of genes the child has and the child’s
ongoing experiences.
Acknowledging Nature and Nurture in
Children’s Lives
Evidence of strong environmental influences should inspire
dults’ optimism about their ability to exert beneficial effects on
children. We offer the following recommendations:
• Expect and make allowances for individual differences
• Remember that environmental factors influence virtually
every aspect of development
• Intervene when children struggle
• Be mindful of your own reactions to challenging
temperaments in children
• Encourage children to make growth-promoting choices
PRENATAL DEVELOPMENT
period of growth between conception and birth, a
simple, single cell is transformed into a complex human
being. During this remarkable developmental
journey, the new being undergoes a series of changes,
takes nourishment from
the mother, and grows in an environment especially
suited to its fragile capabilities.
Phases of Prenatal Growth
●zygote During the middle of a woman’s menstrual cycle, an
ovum (female gamete) emerges from one of her two
ovaries
●embryo During prenatal weeks 2 through 8, the
developing offspring that is in the process of forming major
body structures and organs
●fetus During prenatal week 9 until birth,
the developing offspring that is growing in size and weight
and in sensory abilities, brain structures, and organs
needed for survival
Preparing for Pregnancy
A woman can increase her chances of having a healthy infant by caring
for herself before becoming pregnant. Physicians and nurses advised of a
woman’s wish for a child may suggest that she watch her diet, take approved
vitamin supplements, exercise moderately, and avoid alcohol and drugs. They
may also review her prescriptions and over-the-counter medicines, because
some can be harmful to fetuses.
A man and woman concerned about conceiving a child with significant
birth defects may consult a genetic counselor. Prospective parents are most
likely to work with a genetic counselor when they have had several
miscarriages; have given birth to a child with a genetic defect or chromosomal
abnormality; have a particular concern that can be addressed with
investigations
into genetic risk; or are aware of a family history of a genetic disorder,
intellectual disability, or birth defects.
Supporting Parents, Protecting Babies
If you have the opportunity to work with prospective parents, you
can educate them about prenatal development and their future child’s need
for protection. Here are some specific tactics to take:
• Encourage women to evaluate their health before becoming pregnant
• Remind sexually active women and men to take care of themselves
• Urge pregnant women to seek medical care
• Use well-researched strategies when trying to reach women who are at
risk for late or no prenatal care
• Advise pregnant women about nutritional resources
• Urge pregnant women to stay clear of teratogens
• Ask pregnant women to speak their minds
• Ask fathers to talk about their experiences
• Advise new parents about appropriate care when children have been
exposed to teratogens
BASIC DEVELOPMENTAL ISSUES
ISSUE
GENETIC FOUNDATIONS
PRENATAL DEVELOPMENT
Nature & Nurture
Nature forms gametes (the sperm & ovum) and fuses them to
form a future child with a unique genetic makeup. Nurture is
evident in environmental effects on the parents’ chromosomes,
as can occur when radiation and illness create errors in
reproductive cells. During and after prenatal development,
nature and nurture work in concert: Genes do their work in
collaboration with the offspring’s physiology, nutrition, and
experience.
Nature and nurture are closely intertwined during the
offspring’s prenatal development. The effects of nature are
evident in predictable, ordered changes to body structures and
in the formation
and operation of supporting physical structures, such as the
placenta. The effects of nurture are seen with nutrition,
protection from harmful substances, and the mother’s stress
management.
Universality &
Diversity
The vast majority of children are born with 46 chromosomes.
Most genes take the form of uniform instructions for necessary
proteins to build human bodies and brains. Some genes vary
systematically across children and permit individual differences
in height, weight, physical
appearance, motor skills, intellectual abilities, and
temperament. Errors in chromosomes and genes are another
source of diversity.
In healthy prenatal beings, there is considerable universality in
the sequence of changes. The small being proceeds through
phases of the zygote, embryo, and fetus, and ultimately is born
after approximately 9 months. Diversity occurs because of
variations in mothers’ health and exposure to harmful
substances, the genetic vulnerabilities of the fetus, and the
efficiency with which physical structures in the womb sustain
life.
Qualitative &
Quantitative
Change
Qualitative changes are made possible by the careful
sequence with which particular genes are triggered. At
appropriate times, selected genes spring into action and
create qualitative changes in the child’s body, such as the
makeovers of puberty. When genes direct the body to mature
and grow larger, they also permit quantitative changes, as
occurs in steady increases in height and weight.
The future baby undergoes a series of predictable qualitative
transformations. As a zygote it moves through the fallopian
tubes, grows new cells, and burrows into the inside wall of the
uterus; as an embryo it creates many new cells, which form the
basic organs and structures of the body; and as a fetus it builds
and refi nes these preliminary structures, activating
physiological processes needed for survival. Quantitative
changes are present in the rapid production of new cells,
particularly in the brain and
body prior to birth.
BIRTH OF THE BABY
Childbirth is a complex bioecological
occasion. The events that culminate in a birth
are affected by the health of mother and baby;
support the mother receives from family, friends,
midwives, medical personnel, and other
members of the community; the mother’s
preferences for coping with the physical strains
of labor and delivery; and her cultural traditions
and beliefs.
Preparation for Birth
A human childbirth provokes a range of feelings in parents—
excitement, fear, pain, fatigue, and joy, to name a few. The events of birth
are managed best when families prepare ahead of time,
take advantage of adequate care, and hold reasonable expectations about
the baby’s abilities.
Health care providers and family educators can give useful
information and reassurance to parents during the pregnancy. They may
teach relaxation techniques; offer tips for posture, movement, and
exercise; and persuade women to eliminate potentially risky behaviors.
In Western societies, prepared childbirth classes are common. These
programs typically include the following elements:
…Preparation for Birth
• Information about changes in, and nutritional needs of, the prospective
baby
• Preparation for the baby’s arrival, including arrangements for the baby at
home and decisions about breast or bottle feeding
• Relaxation and breathing techniques that encourage the mother to stay
focused, manage pain, reduce fear, and use muscles effectively during
the various phases of the labor
• Support from a spouse, partner, friend, or family member who coaches
the mother throughout labor and delivery, reminds her to use the breathing
techniques she has learned, massages her, and otherwise encourages
her
The Birth Process
SEQUENCE OF EVENTS THAT CONSTITUTES THE BIRTH PROCESS
• As the pregnancy advances, the mother experiences Braxton Hicks
contractions .
• In most cases (95%), the baby settles in a head-downward position,
which facilitates its
passage through the birth canal
• A few events may occur in the days immediately before labor begins
• In the first stage of labor , the mother experiences regular uterine
contractions that widen the cervix opening
• In the second stage of labor , the cervix is fully dilated, the baby proceeds
down the birth canal, and the child is born.
• In the fourth stage of labor , 1 to 4 hours after birth, the mother’s body
begins to readjust after its considerable exertion.
Babies at Risk
Two categories of babies require special care
• Babies born early
-premature infant is born before the end of 37 weeks after
conception
• Babies born small for date
- Some infants are small and light given the amount of time
they have had to develop in the mother’s uterus.
Developmental Care for Babies at Risk
GUIDELINES ARE RECOMMENDED FOR THOSE WHO CARE FOR A FRAGILE
INFANT
• Reduce the infant’s exposure to light and noise.
• Regulate the amount of handling of the infant by medical staff.
• Position the baby to increase circulation.
• Encourage parents to participate in the care of the infant.
• Inform parents about the infant’s needs.
• Arrange diapering, bathing, and changing of clothes so that interruptions to sleep
and rest are minimized.
• Encourage parents to cuddle with the infant and carry him or her often and for long
periods.
• Swaddle the baby in a blanket or with arms bent and hands placed near the mouth
to permit sucking on fingers or hands.
• Massage the baby.
• Educate parents about caring for the child as he or she grows older.
Enhancing Parents’ Sensitivity to Newborn Infants
• Reassure new mothers that they will be able to find the necessary
energy and insight to
take good care of their baby
• Share what you know about infants’ sensory and perceptual abilities
• Point out the physiological states of newborn infants
• Encourage families to watch infants’ responses to particular stimuli
• Discuss the kinds of stimulation infants might find soothing
• Model sensitive interactions with infants
• Show parents how to care for the baby
• Offer early and continued support to parents of fragile infants
Thanks!
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