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Genetics, Prenatal
Development, and Birth
Chapter 2
Robert S. Feldman
Copyright © 2011 Pearson Education, Inc. All rights reserved.
1, 2, 3…Go!
Module 2.1: Earliest development and genetics
Module 2.2: Interaction of heredity and
environment
Module 2.3: Prenatal growth and birth
Module 2.1
Earliest Development and the
Foundations of Genetics
Beginning of Life
Gametes from male and female join
Ovum and sperm
Fused gametes create zygote
The Code of Life
Genes
DNA
Chromosomes
Rod-shaped DNA portions
in 23 pairs
Contain genetic blueprint
for individuals
Replicate through mitosis
Figure 2.1. The Contents of a
Single Human Cell
And baby makes two or three or more!
Multiple births
• Monozygotic
• Dizygotic
What causes multiple births?
Fertility drugs
Racial, ethnic, and national differences
Mixing and Matching of Traits
• Basics of genetics
– DOMINANT TRAITS
– RECESSIVE TRAITS
Just the right type
GENOTYPE
Homozygous
Heterozygous
PHENOTYPE
Genetic Information
Transmission
Let’s turn to Figure 2-4 in
the text to examine PKU
probabilities
Figure 2-4. PKU Probabilities
Cracking the Genetic Code
• The Human Genome
• National Human Genome
Research Institute
• (http://www.genome.gov/)
Figure 2.5. Uniquely Human?
In what ways do you think
information from the Human
Genome Project can affect
your life?
When Development Deviates
Causes
Genetics
Spontaneous mutation
Environmental insult
When Development Deviates
Consequences
Down Syndrome
Fragile X Syndrome
Sickle-cell Anemia
Tay-Sachs Disease
Klinefelter’s Syndrome
Genetic Counseling
Can you name three diseases for which DNAbased gene tests are available?
(Hint: see Table 2-2)
Table 2-2. Some Currently Available DNA-Based Gene Tests
Prenatal Testing
Amniocentesis
CVS embryoscopy
FBS
Sonoembryology
Sonogram
Ultrasound sonographyregular ultrasound
From Research to Practice
Should pre-implantation sorting be
available to all families?
Review and Apply
REVIEW
In humans, the ____ sex cell (sperm) and the ____ sex
cell (ova) provide the developing baby with 23
chromosomes each.
A ____ is the underlying combination of genetic
materials present in an organism, but invisible; a
____ is the visible trait, the expression of the
genotype.
The field of ____ ____, a combination of psychology
and genetics, studies the effects of genetics on
behavior.
Review and Apply
REVIEW
Several inherited and genetic disorders are due to
damaged or mutated genes.
____ ____ use a variety of data and techniques to
advise future parents of possible genetic risks to
their unborn children.
Review and Apply
APPLY
How can the study of identical twins who were separated at
birth help researchers determine the effects of genetic and
environmental factors on human development?
If genetic testing revealed that you had what is almost always a
fatal disease, what use would the information have for you?
Would it change your career goals? Chosen partner? Choice of
college?
Module 2.2
The Interaction of Heredity
and Environment
What do you think?
A given behavior is not caused exclusively by
genetic factors, nor is it caused solely by
environmental factors.
Can you restate that in regular words?
How about an example?
Range of Possibilities
Figure 2-6. Possible Sources of Intelligence
Studying Development
Nonhuman animal studies
Controlling genetics and environment
Human studies
Adoption
(What do we know abt natural parents and how that affects kids who grow up in diff
environment)
Twin studies
(Look at fraternal and identical in same envio ornot to determine nature vs nurture)
Family studies
( Look at relationship/ average genetic relationness between family on average)
Do you have your mother’s eyes?
Family resemblances
More genetically similarity more likely to
share physical characteristics
Nature, Nurture, and Intelligence
Relative contributions of nature and nurture
highly researched
Closer genetic link = greater correspondence of
overall IQ scores
Figure 2-2. Genetics and I.Q.
Do we inherit our personality?
What evidence supports this
claim?
Figure 2-8. Inheriting Traits
A link look
Two* of “Big Five” personality traits linked to
genetic factors:
– Neuroticism*
– Extroversion*
– Agreeableness
– Conscientiousness
– Openness
What about environmental
influences?
Culture
-Influences you to think this is “the only way things can be”
-What your parents have taught you and you learned from others around you
Parental encouragement
- Ex: if you’re shy and your parents don’t push you to socialize you will always be shy
Any other?
- Birth order
-Parents are inexperienced at first and also freak out easily when kids get hurt but as
time goes on they become more comfortable
-Socio Economic Status
- Able to provide material w/ more $ and more opportunities
-
Gene-environmental Influence
Sandra Scarr suggests three ways that a child’s
genetic predisposition may influence his or
her environment:
Active
-Child actively tries to surround themselves by an enviro that fits w their genes
Passive
- Ex: parent doesn’t fix the problem for their kid and gives advice for them to act actively
Evocative
– Kids draw certain responses from adults
– (Ex: cute kids gets attn from adults which increases their resiliency)
Review and Apply
REVIEW
Human characteristics and behavior are a ____ ____ of
genetic and environmental factors.
Genetic influences have been identified in ____ ____,
____, ____ ____ and _behaviors_.
There is some speculation that ___ ____ may be
predisposed genetically toward certain types of
philosophical viewpoints and attitudes.
Review and Apply
APPLY
How might an environment different from the one you have
experienced have affected the development of personality
characteristics that you believe you inherited from one or
both of your parents?
Some people have used the proven genetic basis of intelligence
to argue against strenuous educational efforts on behalf of
individuals with below-average IQs. Does this viewpoint make
sense based on what you have learned about heredity and
environment? Why or why not?
Module 2.3
Prenatal Growth and Birth
Fertilization
Moment of
conception
Joining of sperm and
ovum = zygote
Stages of Prenatal Development
• Germinal (Zygote Stage)
• Embryonic (After implantation)
• Fetal (When most organ systems are well developed-fuzzy distinction)
(See Table 2-3 for a concise review)
Stages of Prenatal Period
Germinal Stage
Fertilization  two weeks
– Shortest stage
– Fertilized egg now called blastocyst
– Travels to and implants in uterus
– Characterized by methodical cell division
– With division comes cell specialization
Embryonic Stage
2 weeks  8 weeks
– Organism firmly secures to uterus and called an embryo
– Development of major organs and basic anatomy
– Can see where arms, teeth, eyes and lips are
– Has a small tail: looks like a fish
Three distinct layers that ultimately form different set
of structures:
– Ectoderm (sensory)
– Endoderm (internal organs and respiratory system)
– Mesoderm (muscle, bones and circulatory)
Figure 2-9. Body Proportions
During fetal period,
body proportions
change dramatically.
Can you see the
differences?
Fetal Stage
8 weeks  Birth
– Formally starts when differentiation of major
organs has occurred
– Organism now called fetus
– Characterized by rapid development
Autism and the Toddler Brain
causes remain unknown
• New research (Whaken et al., 2009)
•
Autistic Spectrum Disorder
– ASD might be related to problems with structure
or functions of amygdala
– Amygdala larger in brains of toddlers with ASD
and smaller in adult brains of people with ASD
So should all toddlers be screened to
test for ASD?
Pregnancy Problems
Infertility
– Artificial insemination (Either stick a needle with sperm into egg or into womb)
– In vitro fertilization (IVF) (outside the body in a Petri dish)
– Surrogate mother (either bears the child w their egg or the mother’s)
Miscarriage
-Spontaneous abortion or simply losing the child out of your actions
Abortion
Threats to Development
Prenatal environment
– Teratogen
(See Figure 2.11-15 for a teratogen sensitivity timeline)
Figure 2.11.Teratogen Sensitivity
Timeline
Mother’s Prenatal Influence
Diet
Age
Prenatal support
Health
Drug use
Alcohol
Tobacco
Father’s Prenatal Influence
Relatively little research
Tobacco use
Drug use
Alcohol use
Treatment of mother
Becoming an Informed Consumer
Optimizing the Prenatal Environment
Avoid X-rays and birth control pills; get
rubella vaccination
Eat well and take prenatal vitamins
Avoid alcohol use and other drugs
Monitor caffeine intake.
Avoid smoking and exposure to
secondhand smoke
Exercise regularly
Labor: The Process of Birth Begins
Release of CRH (including oxytocin)
Contractions
– Braxton-Hicks
– Labor initiation
Figure 2-12. Three Stages of Labor
From Fetus to Neonate
Some things to ponder…
When is the moment of birth?
What causes a baby to cry after birth?
What cultural differences surround the birth of
children worldwide?
Approaches to Childbirth
Variety of strategies and approaches
No universally accepted single procedure
No conclusive research evidence that one
procedure significantly more effective than
another
REMEMBER: Everyone has advice.
Get information, reflect, and make your own
decision!
What birthing procedures would
you choose?
Alternative Birthing Procedures
Lamaze birthing techniques
Bradley Method
Hypnobirthing
Childbirth Attendants: Who Helps?
Obstetrician
Midwife
Doula
Pain and Childbirth
Interpretation of pain is subjective
– Amounts of pain varies, including perceived pain
– Many factors affect pain perception, including
cultural ideas of childbirth, fear (raises pain),
number of previous births, fetal presentation,
birthing position, and a woman's natural pain
threshold
Do neonates feel pain during birth?
Objective indications of neonate pain at
birth:
•
•
•
•
•
•
Crying
Facial expressions
Body movement
Vital signs
Serum cortisol, tissue and blood oxygen levels
Neurobehavioral assessments
Use of Anesthesia and PainReducing Drugs
Kinds
Effects
– Mother
– Neonate
What do you think?
Why is infant survival less likely in the
United States than in other, less
developed countries?
(poor ppl don’t have insurance to cover
prenatal care)
Problems During Labor and
Delivery
Preterm infants: when a baby is born early
Low birth-weight infants:
most premies are low-birth but there are also babies born on time who are too small b/c they
didn’t fully develop in the womb
Small-for-gestational-age infants
Very low birth-weight infants
Most vulnerable; immaturity of their organ
systems
Weigh less than 1250 grams (around 2 1/4
pounds)
What causes preterm and lowbirth-weight deliveries?
• Half of births unexplained
• Difficulties related to mother’s reproductive
system
• Immaturity of mother’s reproductive system
• General health of mother
Factors Associated with Increased Risk
of Low Birth weight
•
•
•
•
•
•
Demographic risk
Medical risks predating pregnancy
Medical risks in current pregnancy
Behavioral and environmental risks
Healthcare risks
Evolving concepts of risks
(See Table 3-2)
Post-mature Babies:
Too Late, Too Large
2 weeks or more overdue
– Blood supply from placenta may become
insufficient
– Blood supply to brain may be decreased, leading
to the potential of brain damage
– Labor becomes riskier for larger fetus to pass
through birth canal
Cesarean Delivery
Baby is surgically removed from uterus
Occur most frequently when fetal stress appears
More prevalent in older mothers
Related to position in birth canal: breech (teeth
first) transverse (cross wire)
True or False?
Cesareans are effective medical
interventions?
Mortality and Stillbirth: The
Tragedy of Premature Death
• Stillbirth
• Resources:
– March of Dimes
– National Stillbirth Society
– MISS Foundation
Race and Infant Mortality
Review and Apply
REVIEW
____ joins the sperm and ovum to start the journey of
prenatal development. Some couples, however, need
medical help to conceive. Among the alternative
routes to conception are ____ ____ and ____ ____
____ (IVF).
The prenatal period consists of three stages: ____,
____, and ____.
Review and Apply
REVIEW
The ____ environment significantly influences the
development of the baby. The diet, age, prenatal
support, and illnesses of mothers can affect their
babies’ ____ and ____.
Mothers’ use of ____, ____, ____, and ____ can
adversely affect the health and development of the
unborn child. Fathers’ and others’ behaviors (e.g.,
smoking) can also affect the health of the unborn
child.
Review and Apply
REVIEW
Stages
In the ____ stage of labor, contractions increase in frequency,
duration, and intensity until the baby’s head is able to pass
through the cervix.
In the ____ stage, the baby moves through the cervix and birth
canal and leaves the mother’s body.
In the ____ stage, the umbilical cord and placenta emerge.
Immediately after birth, birthing attendants usually
examine the neonate using a measurement system
such as the ____ scale.
Review and Apply
REVIEW
Many birthing options are available to parents today.
They may weigh the advantages and disadvantages
of ____ ____ during birth.
They may choose alternatives to traditional hospital
birthing, including the ____ method, the use of a
____ ____, and the use of a ____.
Review and Apply
REVIEW
Largely because of ____ ____ ____, preterm infants
may have substantial difficulties after birth and later
in life.
Very-low-birth weight infants are in special danger
because of the ____ of their organ systems.
Review and Apply
REVIEW
Preterm and low-birth weight deliveries can be caused
by ____, ____, and pregnancy-related factors in the
mother.
____ (and, because of its relationship with income,
____) is also an important factor.
Review and Apply
REVIEW
____ ____ are performed with post mature babies or
when the fetus is in distress, in the wrong position,
or unable to progress through the birth canal.
Infant ____ ____ can be affected by the availability of
inexpensive health care and good education
programs for mothers-to-be.
Review and Apply
APPLY
It has been found that a mother’s diet is a crucial part
of the development of the fetus. What sorts of
environmental and social factors affect
development?
Studies show that “crack babies” who are now entering
school have significantly difficulty dealing with
multiple stimuli and forming close attachments. How
might both genetics and environmental influences
have combined to produce these results?