Chapter 2 Child Development and Dynamic Process Essay Question : ———-Only use the source from the website and book I provide. I will provide two reso
Chapter 2 Child Development and Dynamic Process Essay Question : ———-Only use the source from the website and book I provide. I will provide two resources once accepted. Please follow this thoroughly and in-text cite.
We have discussed the importance of culture as a significant influence on a childs development alongside biological components. Consider the quotation: from the earliest hours of life, cultural conceptions of what children are and what the future holds for them influence the way parents interpret their childrens behavior and shape their experience.
Explain this quotation in the context of what you have learned in this module (10pts)
Use key terms from course resources as part of your explanation. Be sure to explain the nature(heredity)/nurture(environment) relationship and the role of parents/caregivers in shaping the lives of their children.
Then, give an example of how culture can shape how a child develops (10pts).
You may use an example from your own experience or what you have observed in others, but you MUST explain them in detail for full credit.
This explanation should include the specific cultural influence AND resulting consequences of that influence. Chapter 2: Conception, Heredity, & Prenatal
Development
Chapter Objectives
After this chapter, you should be able to:
1. Evaluate roles of nature and nurture in development.
2. Define genes and chromosomes.
3. Differentiate mitosis and meiosis.
4. Explain dominant and recessive patterns on inheritance.
5. List common genetic disorders and chromosomal abnormalities.
6. Describe changes that occur within each of the three periods of prenatal development.
7. Recognize the risks to prenatal development posed by exposure to teratogens.
8. Evaluate different types of prenatal assessment.
Introduction
In this chapter, we will begin by examining some of the ways in which heredity helps to shape
the way we are. We will look at what happens genetically during conception, and describe
some known genetic and chromosomal disorders. Next we will consider what happens during
prenatal development, including the impact of teratogens. We will also discuss the impact that
both the mother and father have on the developing fetus.1
Heredity
Nature and Nurture
Most scholars agree that there is a constant interplay between nature (heredity) and nurture
(the environment). It is difficult to isolate the root of any single characteristic as a result solely
of nature or nurture, and most scholars believe that even determining the extent to which
nature or nurture impacts a human feature is difficult to answer. In fact, almost all human
features are polygenic (a result of many genes) and multifactorial (a result of many factors,
both genetic and environmental). Its as if ones genetic make-up sets up a range of
possibilities, which may or may not be realized depending upon ones environmental
experiences. For instance, a person might be genetically predisposed to develop diabetes, but
the persons lifestyle may determine whether or not they actually develop the disease.
This bidirectional interplay between nature and nurture is the epigenetic framework, which
suggests that the environment can affect the expression of genes just as genetic predispositions
1
Lifespan Development: A Psychological Perspective (page 34) by Martha Lally and Suzanne Valentine-French is
licensed under CC BY-NC-SA 3.0
39 | C h i l d G r o w t h a n d D e v e l o p m e n t
can impact a persons potentials. And environmental circumstances can trigger symptoms of a
genetic disorder.2
Environment Correlations
Environment Correlations refer to the processes by which genetic factors contribute to
variations in the environment (Plomin, DeFries, Knopik, & Neiderhiser, 2013). There are three
types of genotype-environment correlations:
Passive genotype-environment correlation occurs when children passively inherit the genes
and the environments their family provides. Certain behavioral characteristics, such as being
athletically inclined, may run in families. The children have inherited both the genes that would
enable success at these activities, and given the environmental encouragement to engage in
these actions.
Figure 2.1 Two skiers.3
Evocative genotype-environment correlation refers to how the social environment reacts to
individuals based on their inherited characteristics. For example, whether one has a more
outgoing or shy temperament will affect how he or she is treated by others.
Active genotype-environment correlation occurs when individuals seek out environments that
support their genetic tendencies. This is also referred to as niche picking. For example, children
who are musically inclined seek out music instruction and opportunities that facilitate their
natural musical ability.
Conversely, Genotype-Environment Interactions involve genetic susceptibility to the
environment. Adoption studies provide evidence for genotype-environment interactions. For
example, the Early Growth and Development Study (Leve, Neiderhiser, Scaramella, & Reiss,
2
Lifespan Development – Module 3: Prenatal Development by Lumen Learning references Psyc 200 Lifespan
Psychology by Laura Overstreet, licensed under CC BY 4.0
3
Image by Alexey Ruban on Unsplash
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2010) followed 360 adopted children and their adopted and biological parents in a longitudinal
study. Results have shown that children whose biological parents exhibited psychopathology,
exhibited significantly fewer behavior problems when their adoptive parents used more
structured parenting than unstructured. Additionally, elevated psychopathology in adoptive
parents increased the risk for the childrens development of behavior problems, but only when
the biological parents psychopathology was high. Consequently, the results show how
environmental effects on behavior differ based on the genotype, especially stressful
environments on genetically at-risk children.4
Genes and Chromosomes
Now, lets look more closely at just nature. Nature refers to the contribution of genetics to
ones development. The basic building block of the nature perspective is the gene. Genes are
recipes for making proteins, while proteins influence the structure and functions of cells. Genes
are located on the chromosomes and there are an estimated 20,500 genes for humans,
according to the Human Genome Project (NIH, 2015).
Figure 2.2 DNAs location in the cell.5
Normal human cells contain 46 chromosomes (or 23 pairs; one from each parent) in the nucleus
of the cells. After conception, most cells of the body are created by a process called mitosis.
Mitosis is defined as the cells nucleus making an exact copy of all the chromosomes and
splitting into two new cells.
However, the cells used in sexual reproduction, called the gametes (sperm or ova), are formed
in a process called meiosis. In meiosis, the gametes chromosomes duplicate, and then divide
twice resulting in four cells containing only half the genetic material of the original gamete.
Thus, each sperm and egg possesses only 23 chromosomes and combine to produce the normal
46.
4
Lifespan Development: A Psychological Perspective (page 40) by Martha Lally and Suzanne Valentine-French is
licensed under CC BY-NC-SA 3.0
5
Image by Radio89 is licensed under CC BY-SA 3.0 (original image has been modified)
41 | C h i l d G r o w t h a n d D e v e l o p m e n t
Table 2.1 – Mitosis & Meiosis6
Type of Cell
Division
Mitosis
Explanation
All cells, except those used in
sexual reproduction, are
created by mitosis
Steps
Step 1. Chromosomes make a duplicate copy
Step 2. Two identical cells are created
Step 1. Exchange of gene between the
chromosomes (crossing over)
Meiosis
Cells used in sexual
reproduction are created by
meiosis
Step 2. Chromosomes make a duplicate
Step 3. First cell division
Step 4. Second cell division
Figure 2.3 Mitosis and Meiosis.7
Given the amount of genes present and the unpredictability of the meiosis process, the
likelihood of having offspring that are genetically identical (and not twins) is one in trillions
(Gould & Keeton, 1997).
6
Lifespan Development: A Psychological Perspective (page 34) by Martha Lally and Suzanne Valentine-French is
licensed under CC BY-NC-SA 3.0 (content modified: image made into table)
7
Image by Community College Consortium for Bioscience Credentials is licensed under CC BY 3.0
42 | C h i l d G r o w t h a n d D e v e l o p m e n t
Of the 23 pairs of chromosomes created at conception, 22 pairs are similar in length. These are
called autosomes. The remaining pair, or sex chromosomes, may differ in length. If a child
receives the combination of XY, the child will be genetically male. If the child receives the
combination XX, the child will be genetically female.8
Here is an image (called a karyogram) of what the 23 pairs of chromosomes look like. Notice the
differences between the sex chromosomes in female (XX) and male (XY).
Figure 2.4 The 23 pairs of chromosomes.9
Genotypes and Phenotypes & Patterns on Inheritance
The word genotype refers to the sum total of all the genes a person inherits. The word
phenotype refers to the features that are actually expressed. Look in the mirror. What do you
see, your genotype or your phenotype? What determines whether or not genes are expressed?
Because genes are inherited in pairs on the chromosomes, we may receive either the same
version of a gene from our mother and father, that is, be homozygous for that characteristic
the gene influences. If we receive a different version of the gene from each parent, that is
referred to as heterozygous.
In the homozygous situation we will display that characteristic. It is in the heterozygous
condition that it becomes clear that not all genes are created equal. Some genes are dominant,
meaning they express themselves in the phenotype even when paired with a different version
of the gene, while their silent partner is called recessive. Recessive genes express themselves
only when paired with a similar version gene. Geneticists refer to different versions of a gene as
alleles. Some dominant traits include having facial dimples, curly hair, normal vision, and dark
hair. Some recessive traits include red hair, being nearsighted, and straight hair.
8
Lifespan Development: A Psychological Perspective (page 34-35) by Martha Lally and Suzanne Valentine-French is
licensed under CC BY-NC-SA 3.0
9
Image by Nami-ja is in the public domain
43 | C h i l d G r o w t h a n d D e v e l o p m e n t
Most characteristics are not the result of a single gene; they are polygenic, meaning they are
the result of several genes. In addition, the dominant and recessive patterns described above
are usually not that simple either. Sometimes the dominant gene does not completely suppress
the recessive gene; this is called incomplete dominance.10
Genetic Disorders
Most of the known genetic disorders are dominant gene-linked; however, the vast majority of
dominant gene linked disorders are not serious or debilitating. For example, the majority of
those with Tourette’s Syndrome suffer only minor tics from time to time and can easily control
their symptoms. When dominant-gene linked diseases are serious, they do not tend to become
symptomatic until later in life. Huntington’s Disease is a dominant gene linked disorder that
affects the nervous system and is fatal, but does not appear until midlife.
Recessive gene disorders, such as cystic fibrosis and sickle-cell anemia, are less common but
may actually claim more lives because they are less likely to be detected as people are unaware
that they are carriers of the disease.
Some genetic disorders are sex-linked; the defective gene is found on the X-chromosome.
Males have only one X chromosome so are at greater risk for sex-linked disorders due to a
recessive gene such as hemophilia, color-blindness, and baldness. For females to be affected by
recessive genetic defects, they need to inherit the recessive gene on both X-chromosomes. But
if the defective gene is dominant, females are equally at risk.
Here are tables of some genetic disorders:
Recessive Disorders (Homozygous): The individual inherits a gene change from both parents. If
the gene is inherited from just one parent, the person is a carrier and does not have the
condition.
Table 2.2 – Recessive Disorders (Homozygous)11
Disorder
Sickle Cell Disease
(SCD)
Description
A condition in which the red blood cells in the
body are shaped like a sickle (like the letter C)
and affect the ability of the blood to transport
oxygen.
10
Cases per Birth
1 in 500 Black births
1 in 36,000 Hispanic
births
Lifespan Development: A Psychological Perspective (page 35) by Martha Lally and Suzanne Valentine-French is
licensed under CC BY-NC-SA 3.0
11
Lifespan Development: A Psychological Perspective (pages 36-37) by Martha Lally and Suzanne Valentine-French
is licensed under CC BY-NC-SA 3.0
44 | C h i l d G r o w t h a n d D e v e l o p m e n t
Disorder
Description
A condition that affects breathing and
digestion due to thick mucus building up in the
body, especially the lungs and digestive
system. In CF, the mucus is thicker than normal
and sticky.
Cases per Birth
1 in 3500
1 in 10,000
Phenylketonuria
(PKU)
A metabolic disorder in which the individual
cannot metabolize phenylalanine, an amino
acid. Left untreated, intellectual deficits occur.
PKU is easily detected and is treated with a
special diet.
Tay Sachs Disease
Caused by an enzyme deficiency resulting in
the accumulation of lipids in the nerves cells of
the brain. This accumulation results in
progressive damage to the cells and a decrease
in cognitive and physical development. Death
typically occurs by age five.
1 in 4000
1 in 30 American
Jews is a carrier
1 in 20 French
Canadians is a
carrier
Albinism
When the individual lacks melanin and
processes little to no pigment in the skin, hair,
and eyes. Vision problems can also occur.
Fewer than 20,000
US cases per year
Cystic Fibrosis (CF)
Autosomal Dominant Disorders (Heterozygous): In order to have the disorder, the individual
only needs to inherit the gene change from one parent.
Table 2.3 – Autosomal Dominant Disorders (Heterozygous)12
Disorder
Huntingtons
Disease
Tourette Syndrome
Description
A condition that affects the individuals
nervous system. Nerve cells become damaged,
causing various parts of the brain to
deteriorate. The disease affects movement,
behavior and cognition. It is fatal, and occurs at
midlife.
A tic disorder which results in uncontrollable
motor and vocal tics as well as body jerking
12
Cases per Birth
1 in 10,000
1 in 250
Lifespan Development: A Psychological Perspective (pages 36-37) by Martha Lally and Suzanne Valentine-French
is licensed under CC BY-NC-SA 3.0
45 | C h i l d G r o w t h a n d D e v e l o p m e n t
Disorder
Achondroplasia
Description
The most common form of disproportionate
short stature. The individual has abnormal
bone growth resulting in short stature,
disproportionately short arms and legs, short
fingers, a large head, and specific facial
features.
Cases per Birth
1 in 15,000-40,000
Sex-Linked Disorders: When the X chromosome carries the mutated gene, the disorder is
referred to as an X-linked disorder. Males are more affected than females because they possess
only one X chromosome without an additional X chromosome to counter the harmful gene.
Table 2.4 – Sex-Linked Disorders13
Disorder
Fragile X Syndrome
Hemophilia
Duchenne Muscular
Dystrophy
Description
Occurs when the body cannot make enough of
a protein it needs for the brain to grow and
problems with learning and behavior can
occur. Fragile X syndrome is caused from an
abnormality in the X chromosome, which then
breaks. If a female has a fragile X, her second X
chromosome usually is healthy, but males with
fragile X dont have a second healthy X
chromosome. This is why symptoms of Fragile
X usually are more serious in males.
Occurs when there are problems in blood
clotting causing both internal and external
bleeding.
A weakening of the muscles resulting in an
inability to move, wasting away, and possible
death.
Cases per Birth
1 in 4000 males
1 in 8000 females
1 in 10,000 males
1 in 3500 males
Chromosomal Abnormalities: A chromosomal abnormality occurs when a child inherits too
many or two few chromosomes. The most common cause of chromosomal abnormalities is the
age of the mother. As the mother ages, the ovum is more likely to suffer abnormalities due to
longer term exposure to environmental factors. Consequently, some gametes do not divide
evenly when they are forming. Therefore, some cells have more than 46 chromosomes. In fact,
13
Lifespan Development: A Psychological Perspective (pages 36-37) by Martha Lally and Suzanne Valentine-French
is licensed under CC BY-NC-SA 3.0
46 | C h i l d G r o w t h a n d D e v e l o p m e n t
it is believed that close to half of all zygotes have an odd number of chromosomes. Most of
these zygotes fail to develop and are spontaneously aborted by the mothers body.14
Here is a table of some autosomal chromosomal disorders:
Autosomal Chromosome Disorders: The individual inherits too many or two few chromosomes.
Table 2.5 – Autosomal Chromosomal Disorders15
Disorder
Description
Down
Syndrome/Trisomy
21
Caused by an extra chromosome 21 and includes a combination of
birth defects. Affected individuals have some degree of intellectual
disability, characteristic facial features, often heart defects, and other
health problems. The severity varies greatly among affected
individuals.
Trisomy 9
Mosaicism
Caused by having an extra chromosome 9 in some cells. The severity
of effects relates to the proportion of cells with extra chromosomes.
The effects include fetal growth restriction resulting in low birth
weight and multiple anomalies, including facial, cardiac,
musculoskeletal, genital, kidney, and respiratory abnormalities.
Trisomy 13
Caused by an extra chromosome 13. Affected individuals have
multiple birth defects and generally die in the first weeks or months of
life.
Trisomy 18
Caused by an extra chromosome 18 and the affected individual also
has multiple birth defects and early death.
14
Lifespan Development: A Psychological Perspective (page 38) by Martha Lally and Suzanne Valentine-French is
licensed under CC BY-NC-SA 3.0
15
Trisomy 9 Mosaicism Diagnosed In Utero by Hironori Takahashi, Satoshi Hayashi, Yumiko Miura, Keiko
Tsukamoto, Rika Kosaki, Yushi Itoh, and Haruhiko Sago is licensed under CC BY 3.0; Lifespan Development: A
Psychological Perspective (page 39) by Martha Lally and Suzanne Valentine-French is licensed under CC BY-NC-SA
3.0
47 | C h i l d G r o w t h a n d D e v e l o p m e n t
Figure 2.5 – Infant boy with Trisomy 9 Mosaicism.16
Figure 2.6 – Girl with XXX Syndrome.17
When the abnormality is on 23rd pair, the result is a sex-linked chromosomal abnormality. This
happens when a person has less than or more than two sex chromosomes.18
Here is a table of some sex-linked chromosomal disorders:
Table 2.6 – Sex-Linked Chromosomal Disorders19
Disorder
Description
Turner Syndrome
(XO)
Caused when all or part of one of the X chromosomes is lost before or
soon after conception due to a random event. The resulting zygote
has an XO composition. Turner Syndrome affects cognitive functioning
and sexual maturation in girls. Infertility and a short stature may be
noted.
Klinefelter
Syndrome (XXY)
Caused when an extra X chromosome is present in the cells of a male
due to a random event. The Y chromosome stimulates the growth of
male genitalia, but the additional X chromosome inhibits this
development. The male can have some breast development,
infertility, and low levels of testosterone.
16
Image by Ashley Onken used with permission
Image is in the public domain
18
Lifespan Development: A Psychological Perspective (page 38) by Martha Lally and Suzanne Valentine-French is
licensed under CC BY-NC-SA 3.0
19
XYY Syndrome by Wikipedia is licensed under CC BY-SA 3.0; Triple X Syndrome by Wikipedia is licensed under CC
BY-SA 3.0; Lifespan Development: A Psychological Perspective (page 39) by Martha Lally and Suzanne ValentineFrench is licensed under CC BY-NC-SA 3.0
17
48 | C h i l d G r o w t h a n d D e v e l o p m e n t
Disorder
Description
XYY Syndrome
Caused when an extra Y chromosome is present in the cells of a male.
There are few symptoms. They may include being taller than average,
acne, and an increased risk of learning problems. The person is
generally otherwise normal, including normal fertility.
Triple X Syndrome
(XXX)
Caused when an extra X chromosome is present in the cells of a
female. It may result in being taller than average, learning difficulties,
decreased muscle tone, seizures, and kidney problems.
Prenatal Development
Now we turn our attention to prenatal development which is divided into three periods: The
germinal period, the embryonic period, and the fetal period. The following is an overview of
some of the changes that take place during each period.
The Germinal …
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