Chapter 2 - Biological and Environmental Foundations Flashcards Preview

PSYC 3351 Topics in Child Development > Chapter 2 - Biological and Environmental Foundations > Flashcards

Flashcards in Chapter 2 - Biological and Environmental Foundations Deck (100):

Characteristics of your phenotype, such as your height, are determined by a combination of your ____________ and your ____________

genotype and your environment


Phenotype vs. Genotype

Phenotype – the directly observable characteristics Genotype - the complex blend of genetic information that influences our unique characteristics


Deoxyribonucleic acid (DNA)

long, double-stranded molecules that make up chromosomes


The ‘rungs’ on the (DNA) ladder are made up of …

The ‘rungs’ on this ladder are made up of four bases Adenine (A) Thymine (T) Guanine (G) Cytosine (C) The pairings are always A-T and C-G



A segment of a DNA molecule that contains hereditary instructions Genes can be of different lengths, varying from maybe 100 to thousands of base pairs It’s been estimated that we have 20,000 to 25,000 genes • We share between 98% and 99% of these with the chimpanzee • You share about 99.1% of your genes with the person sitting next to you



The process of cell duplication, in which each new cell receives an exact copy of the original chromosomes This is how body cells reproduce



human sperm and ova, which contain half as many chromosomes as regular body cells


Meiosis And the steps

the process of cell division through which gametes are formed and in which the number of chromosomes in each cell is halved Steps 1. Chromosomes each duplicate and then pair up with one another 2. Crossing over takes place between the two innermost pair members 3. The pairs of chromosomes separate to form two cells, each with 23 duplicated chromosomes 4. The duplicated chromosomes separate to form gametes each with 23 single chromosomes This results in 4 sperm or 1 ovum



When gametes unite at conception



The area surrounding the cell nucleus, where the genes send instructions for an assortment of proteins


Crossing over during meiosis

When chromosomes next to each other break at one or more points along their length and exchange segments, so that genes from one are replaced by genes from the other. This increases genetic diversity.



the 22 matching chromosome pairs in each human cell they are numbered from longest to shortest


Sex chromosomes

The 23rd pair of chromosomes, which determines the sex of the child In females, we see XX; in males, we see XY The X chromosome is significantly larger than the Y, and carries more genetic material


Fraternal, or dizygotic, twins

Twins resulting from the release and fertilization of two ova. They are genetically no more alike than ordinary siblings


Maternal factors linked to fraternal twinning

Ethnicity Family history of twinning Age (rise with age peaking at 35-39) Nutrition (more often with tall and/or normal to overweight) Number of births (more likely with each additional birth) Fertility drugs and in-vitro fertilization Climate


Identical, or monozygotic, twins

Twins that result when a zygote, during the early stages of cell duplication, divides in two. They have the same genetic makeup


Multiple birth children are often …

born early, and are thus often less healthy and slower to develop in the early years than are single birth children



Each of two forms of a gene located at the same place on the autosomes A pair can be homozygous or heterozygous


Dominant-recessive inheritance

a pattern of inheritance in which, under heterozygous conditions, the influence of only one allele is apparent The allele that is apparent in heterozygous conditions is referred to as dominant The one that is apparent only in the homozygous condition is referred to as recessive


Recessive carrier

A heterozygous individual is a carrier for the recessive trait


Phenylketonuria or PKU

One of the most frequent occurring recessive disorders. It effects how the body breaks down proteins in many foods. By year one infants with PKU are permanently restarted if not treated. If treated they still show some issues with certain cognitive skills but they will have an average intelligence and life span.


Modifier genes

Genes that can enhance or dilute the effects of other genes Thus, even if two siblings inherit a given gene from their parents, they may display the trait to different extents


It’s ______ for serious diseases to be due to _______ alleles

It’s rare for serious diseases to be due to dominant alleles


Huntington Disease

An example of the rare dominant disorders. It is a condition where the nervous system degenerates. It occurs because the symptoms do not occurs to the age of 35 or later.


Incomplete dominance

a pattern of inheritance in which both alleles are expressed in the phenotype, resulting in a combined trait, or one that is intermediate between the two An example here is sickle cell anemia Individuals who are heterozygous show symptoms under conditions of oxygen deprivation, such as during intense exercise or at high altitudes


x-linked inheritance

When a harmful allele is carried on the x chromosome Males are more likely to be affected because they don’t have another x chromosome to have an allele that could be dominant and counter act it.



A disorder that is x-linked in its inheritance Blood fails to clot normaly.


Genomic imprinting (aka genetic imprinting)

A pattern of inheritance in which alleles are imprinted, or chemically marked, in such a way that one pair member is activated, regardless of its makeup This is often temporary; the imprinting may be erased in the next generation, and doesn’t seem to occur in everyone Examples include an increased likelihood of inheriting diabetes from one’s father and an increased likelihood of inheriting asthma or hay fever from one’s mother


Prader-Willi syndrome

A disorder with symptoms of mental retardation and severe obesity Genomic imprinting is involved


Mutation Germline mutation Somatic mutation

A sudden but permanent change in a segment of DNA Some mutations affect single genes, while others affect multiple genes One well-known cause of mutations is ionizing radiation exposure in either parent Germline mutation takes place in the cells that will produce gametes Somatic mutation takes place in body cells and can occur any time in life


Polygenic inheritance

A pattern of inheritance in which many genes affect the characteristic in question Traits that vary from one individual to another as a matter of degree, rather than type or category, are generally polygenic Height, weight, skin tone, intelligence, personality traits, all seem to be polygenic in nature


Chromosomal Abnormalities

Chromosomal abnormalities represent a major cause of serious developmental problems Most of the time, this results from mistakes during meiosis Many autosomal abnormalities result in miscarriage Abnormalities of the sex chromosomes are comparatively more likely to result in live birth. Often, these abnormalities are not even apparent until adolescence


Down syndrome or trisomy 21

Is the most common chromosomal disorder Characteristics of individuals with Down syndrome include: • Flattened face • Protruding tongue • Almond-shaped eyes • An unusual crease running across the palm of the hand • Eye cataracts • Hearing loss • Heart and intestinal defects • Short, stocky build • Mental retardation • Speech difficulties • Limited vocabulary • Slow motor development Infants with Down syndrome often have breathing and feeding difficulties They smile less readily, show poorer eye contact, and are less persistent in exploring objects This makes them particularly challenging to care for, but an enriched environment can be extremely important in influencing their outcomes If they survive past 40 they often develop symptoms of Alzheimer’s


Myths about individuals with sex chromosome disorders

Males with XYY syndrome and not necessarily more aggressive or antisocial Most with sex chromosome differences do not suffer from mental retardation Intellectual problems are usually very specific


Turner syndrome

Occurs when an ovum is fertilized by a sperm with no sex chromosome, or (less likely) when a sperm with an X chromosome fertilizes an ovum with no sex chromosome This will usually result in a spontaneous abortion, but not always A baby with Turner syndrome is female in appearance, but the ovaries have already begun to disappear by birth, and don’t produce the hormones necessary for the sex differentiation process to continue Women with Turner syndrome don’t develop breasts or menstruate unless given hormone therapy Women with Turner syndrome are typically short, with an unusual neck and chest structure They demonstrate deficiencies in spatial skills, mathematics, attention, and social interaction


Klinefelter’s syndrome

Occurs when a male inherits an extra X chromosome Normal male appearance until puberty, when secondary sex characteristics develop Often somewhat timid and unassertive in their interpersonal interactions Testosterone injections, beginning at puberty, have been found to help development in some cases


Supermale syndrome

Occurs when the sperm provides two Y chromosomes Males produced when this occurs have large body builds and masculine personality characteristics They may exhibit poor frustration tolerance, an increased risk for learning difficulties, and poor physical coordination


Fragile-X syndrome

Abnormality of the X chromosome caused by a defective gene and associated with mild to severe mental retardation Most common cause of mental retardation Note that most females with this disorder display only mild cognitive impairments, if any


Triple X or “superfemale” syndrome (XXX)

Female, normal in appearance, produce children with the usual number of sex chromosomes, below average in intelligence, particularly verbal reasoning


Genetic counseling

a communication process designed to help couples assess their chances of giving birth to a baby with a hereditary disorder and choose the best course of action in view of risks and family goals Often sought by people who have had difficulties bearing children, who are outside the ‘ideal’ childbearing age range, or who have a family history of genetic problems


Prenatal diagnostic methods

Medical procedures that permit detection of developmental problems before birth • Ultrasound imaging • Amniocentesis • Chorionic villus sampling • Endoscopic Fetoscopy • Test-Tube Screening


Ultrasound imaging

The level of detail in this image permits an assessment of fetal age It allows for identification of the sex of the fetus by 16 to 20 weeks It can determine whether there is more than one fetus Many potential problems aren’t detectable with ultrasounds Among the problems it can detect are • Abnormal head growth • Defects of the heart, bladder, and kidneys • Some chromosomal anomalies • Neural tube defects Ultrasound imaging can help guide medical personnel during diagnostic procedures that require collection of amniotic fluid



A procedure for collecting cells that lie in the amniotic fluid surrounding the fetus. A needle is passed through the mother’s abdominal wall into the amniotic sac to gather discarded fetal cells. These cells can be examined for chromosomal and genetic defects If an infant has abnormally high levels of alpha-feto protein, this can be detected via amniocentesis This may indicate certain types of damage to the brain, the central nervous system, or the liver and kidneys Chromosomal analysis of fetal cells can also detect many other disorders, including • Down syndrome • Achondroplasia • Cystic fibrosis • Duchenne muscular dystrophy • Sickle-cell anemia • Tay-Sachs


Chorionic villus sampling

Amniocentesis can’t usually be done until after the 14th week, and it takes 2 weeks more to obtain the results CVS can be conducted by 9-11 weeks, and the results are available in a few days Risk of miscarriage slightly higher with CVS


Endoscopic Fetoscopy

This is a relatively new procedure in which a fibre-optic endoscope is inserted into the uterus either through the abdomen or the cervix The endoscope allows the health care provider to visualize the fetus, obtain fetal tissue samples, or even perform fetal surgery Some abnormalities that can be treated by endoscopic fetoscopy include congenital diaphragmatic hernia and urinary tract obstruction Diagnosing and treating these defects prenatally can prevent serious complications that can arise during and following birth


Test-Tube Screening

This involves screening embryos in the test tube before they are implanted in the mother’s uterus Ova are collected from the mother and then fertilized in a petri dish through in vitro fertilization One cell is removed from each embryo at the 8-cell stage From this cell, the sex of the embryo can be determined, and the DNA of the cell can be checked for suspected anomalies


Prenatal Medical Therapy

Medical therapy would include treatments such as Providing extra vitamins to the mother when enzyme deficiencies are discovered in the blood of the fetus Drug treatment of pregnant women with HIV to reduce the risk of their babies becoming infected Injecting the umbilical cord of a fetus with a hereditary immune deficiency with immune cells from the thymus and liver of aborted fetuses, so that the cells would multiply in the baby after birth


Prenatal Surgery

One example of a successful fetal surgery was a case in which a small valve was inserted in the back of the head of a fetus who was accumulating fluid on the brain This permitted the excess fluid to drain, and the child appeared normal by 16 months of age Among conditions for which fetal surgery is an option are Blockage of the urinary tract Congenital diaphragmatic hernia Spina bifida Other neural tube defects


Genetic Engineering

This involves procedures that allow defective genes to be identified and replaced with synthetic genes To date, applications of gene therapy have been limited Applications of fetal gene therapy have been even more limited—most cases of gene therapy have occurred in childhood or even adulthood Applications have also thus far been limited to the body cells In germ-line therapy, characteristics of the germ cells are altered, which would affect not only the treated individual, but also the genes that are passed on to the individual’s offspring Proteomics – modify gene-specified proteins involved in disease Treatments for single-gene defects are in the future but not as far as ones that are multi-gene.


The Alternative of Adoption

Lack of fertility, lack of a partner, and high risk of genetic disorders are all reasons why some people decide to adopt Ethnic and religious backgrounds are often matched between adoptive and birth parents, and age is often matched as well Because there are more people who want to adopt than there are babies up for adoptions in North America and Western Europe, people often adopt from other countries, adopt older children, or adopt children who have developmental problem Adopted children and adolescents tend to have more learning and emotional difficulties than do other children, particularly if they were adopted at later ages In some cases, there may be genetic problems that contributed to the birth mother’s inability to care for the child If the child was adopted at a later age, early environment may contribute to parents The lower similarity between parent and child in adoptive homes may threaten family harmony Adoptees often fare much better than birth siblings raised by their birth parents or agemates who have been institutionalized Most do seem to be well-adjusted in adulthood By adolescence, adoptees have often become curious about their biological roots, which can cause some uncertainty in their lives Most do not search for their birth parents until at least early adulthood


Pros and Cons of Reproductive Technologies

1 in 6 couples find out that they are infernal Pros - It is the only way for some to have a baby do to age, infertility, lack of partner, health risks of carrying a baby - Can guarantee a daughter for people with x-linked disorders - Just as securely attached as “naturally conceived” children - Well adjusted Cons - Birth defects - Multiple births (low birth weight) - Surrogate motherhood may cause conflict or family disruptions for the surrogate mothers kids - Ethical concerns about what constitutes human life - Ethical concerns about old perent who are at a high risk of dieing before their kids are no longer dependent - Ethical concerns about selective breeding “designer babies”


Donor insemination

the injection of sperm of an anonymous man in to a woman – in is 70-80% successful.


In-vitro fertilization

a woman is given hormones that stimulate the ripening of several ova. These are removed surgically and placed in a dish of nutrients which the sperm is added. Once the ovum is fertilized and begins to duplicate it is injected in the woman.


Surrogate motherhood

When In-vitro fertilization is used to impregnate a woman who is not the mother


The Family

Typically the first and longest-lasting influence on a child’s development Relationships here form our models for what other relationships will be like Influences within a family can be direct or indirect Influences are generally bidrectional



Mutually supporting each other’s parenting behaviors


Socioeconomic status (SES)

A measure of a family’s social position and economic well-being that combines three related variables: 1. years of education, 2. the prestige of and skill required by one’s job, 3. and income


High Socioeconomic Status and Family Functioning

Higher SES is often associated with having fewer children, and having them at a later age place more value on curiosity, happiness, self-direction, and cognitive and social maturity Higher-SES parents • Talk to and stimulate their children more • Grant their children more freedom to explore • Use more warmth, explanation, and verbal praise • Set higher developmental goals • Give fewer commands • Give less criticism • Give less physical punishment Higher-SES parents are usually more educated, and are often accustomed to thinking about abstract, subjective ideas Higher SES is associated with • Enhanced cognitive and language development • Reduced incidence of emotional and behavioural problems • Better school performance, and higher levels of education


Low Socioeconomic Status and Family Functioning

Lower-SES often associated with having more children, and having them at a younger age Lower-SES parents place more value on obedience, politeness, neatness, and cleanliness, Lower-SES parents are often in jobs where obeying authority is paramount Lower-SES parents often experience more financial stress


Danger of Affluence

Many high-SES youths do have high risk of alcohol and drug use • Unlike low-SES youths, affluent adolescents show a correlation between substance use and anxiety and depression scores, suggesting self-medicating • This seems to be related to the fact that many high-SES parents work a lot of hours, spend less time with their children, and make high demands for achievement • Development proceeds better if parents show that they place more value on their children’s character than on their accomplishments • Eating dinner with family is vitally important


Worldwide education of girls

Over the past century education went from a just few boys to most children Schooling is vita for all children, but educating girls has en especially large impact on the welfare of families, societies, and future generations. The benefits of girls education accrue in two ways 1. Through enhanced verbal skills, reading, writing, and communication 2. Through empowerment Results of education - More likely to seek health services and benefit from public health info - Preventative health behaviors - Family planning - More equitable male-female relationships - Better parenting - More educated children



About 12% of Canadians live in poverty This rate increases to about 18% for children, 60% for Canadian Aboriginal children, and nearly 50% for single mothers with preschool children Children in poverty are more likely than other children to experience - Lifelong poor physical health - Persistent deficits in cognitive development and academic achievement - High school dropout - Mental illness - Antisocial behaviour The financial stress can lead parents to be depressed, irritable, and distracted In turn, they become less warm and sensitive, and may show hostility Single-parent homes and dangerous neighbourhoods can exacerbate the problems If the family is homeless, children may not go to school and are likely to suffer from developmental delays and serious emotional stress



The type of neighbourhood in which a child grows up has an impact on development In poverty-stricken areas Families move often, and thus don’t form close ties with neighbours Parks and playgrounds are in disarray There’s a lack of community centres with organized activities Family violence, child abuse and neglect, problem behaviour, and antisocial activity are especially high In one study, low-SES families were randomly assigned vouchers that allowed them to live in affluent neighbourhoods The children in these families showed better physical and mental health, and higher school achievement than did children of similar SES families who remained in low-SES neighbourhoods Ironically, the impact of neighbourhood resources is lower for children in high-SES families, whose parents are better able to transport them to more distant facilities


Influences of social support for parents within the neighbourhood

- Increased parental self-worth - Parental access to valuable information and services - Child-rearing controls and role models - Direct assistance with child rearing These are often absent in low-SES neighbourhoods and households


In low-SES neighbourhoods, children’s outcomes can be improved by

In-school and after-school programmes that provide art, music, sports, scouting, or other enrichment activities Neighbourhood organizations like religious youth groups and special-interest clubs


In neighbourhoods where there are strong family ties to the community, we see

- Frequent contact with friends and relatives - Regular church, synagogue, or mosque attendance - Community centres - Reduced family stress - Fewer adjustment problems



By high school graduation, the average child has spent about 14,000 hours in school, so we know schools have much opportunity to impact development Schools differ from one another in terms of • Student body size • Number of children per class • Space available for work and play • How teachers view students (active or passive?) • Cooperative v. competitive atmosphere • Integration of students of differing abilities, SES, ethnicity • Safety of classrooms, hallways, and school yards We see better achievement in children whose parents are involved in school activities and attend parent-teacher conferences This is often more common among high-SES parents It’s also more common in small towns, where most citizens know each other



A group of people with beliefs and customs that differ from those of the larger culture Although the dominant North American culture is very nuclear family based, many ethnic minority groups have cooperative family structures The additional support provided by an extended-family household can sometimes protect families from some of the effects of living in poverty


The make-up of households, as well as the effects of public policies, is partially determined by whether people live in an _______________ or a _______________

The make-up of households, as well as the effects of public policies, is partially determined by whether people live in an individualistic society or a collectivist society


Public policies

laws and government programs designed to improve current conditions Examples include government-funded health care and low-cost housing Although Canada tends to exceed the US in many public policies, we lag behind many other developed countries


Why Canada lags behind many other developed countries on public policies that relate to children?

Cultural values of self-reliance and privacy discourage government intervention Good social programmes are expensive Children’s needs aren’t always considered, since children aren’t voters and are rarely protestors Collectivist societies often fare better in terms of public policy


Two reasons why public policies protecting children are important

1. Children do represent a culture’s future, and are thus a rather wise investment 2. Humanitarian grounds


The United Nations consider children to have the right to…

The United Nations consider children to have the right to the highest attainable standard of health; an adequate standard of living; free and compulsory education; a happy, understanding, and loving family life; protection from all forms of abuse and neglect; freedom of thought, conscience, and religion, subject to appropriate parental guidance and national law


Behavioural genetics

a field devoted to uncovering the contributions of nature and nurture to the diversity of human traits and abilities


Polygenic traits

Traits that are due to many genes


Understanding the Relationship Between Heredity and Environment

We are a long way from understanding all of the genetic factors that influence our traits, or how they interact with environmental factors


Heritability estimate

A statistic that measures the extent to which individual differences in complex traits in a specific population are due to genetic factors Note that heritability estimates are looking at differences among individuals, not similarities Note that a heritability estimate is specific to the population for which is was calculated


Kinship studies

Kinship studies are often used to try and determine heritability of a trait Different kinship studies, even when they examine the same characteristic, often give very different results The most accepted consensus is a heritability estimate of about .5 for intelligence and between .4 to .5 for various personality measures


Concordance rate

the percentage of instances in which both members of a twin pair show a trait when it is present in one pair member, used to study the contribution of heredity to emotional and behaviour disorders Note that concordance rates can be calculated for other pairs; twin rates are just often more telling Often, concordance rates for identical twins are compared to those for fraternal twins, who presumably share the same amount of environmental influence, but have less genetic similarity


Range of reaction

each person’s unique, genetically determined response to a range of environmental conditions



the tendency of heredity to restrict the development of some characteristics to just one or a few outcomes Think about some traits that seem to develop similarly across individuals, in a broad variety of environmental contexts


Genetic-environmental correlation

the idea that heredity influences the environments to which individuals are exposed These can be: Passive, because the people who give us our genes are usually the people who create our environments Evocative, because our inherited tendencies affect how others behave toward us Active, because as we grow older and are able to select our environments, we select those that suit our inherited tendencies



a type of genetic-environmental correlation in which individuals actively choose environments that complement their heredity This may be part of the reason why identical twins actually often become more alike over time, while other siblings often become less alike


The Relationship Between genetics and environment

It’s notable that the environment also affects genetic expression There is a gene on the X chromosome known to predispose both animals and humans to aggression However, in boys with this gene, increased aggression is seen only if there has been a history of abuse Studies indicate that we can decrease expression of ‘negative’ genes by taking away the environmental influences that often accompany them—for instance, by removing the evocative genetic-environment correlations for children who are predisposed towards aggression The relationship between genetics and environment is clearly a bidirectional one; genes affect behaviour and experiences, and stimulation influences gene activity



development of the individual resulting from ongoing, bidirectional exchanges between heredity and all levels of the environment For instance, think of how an infant’s nutrition affects brain growth and energy, how this affects exploration and social interactions, how those affect pruning, how that affects the potential for future cognitive development, which affects exploration, etc…


hemophilia is a well-known example of

X-linked inheritance


Huntington disease is the product of

a dominant allele


Mara has Turner syndrome. She is likely to have trouble with

drawing pictures, telling right from left, and noticing changes in facial expressions.


What fraction of couples who try to conceive discover that they are infertile



In many African societies, newly married couples

move in with members of their extended family.


Which of the following describes an active genetic-environmental correlation?

Once old enough, children seek out environments that fit with their genetic tendencies.


Dominant Recessive Mode of Inheridence



Examples of Domminent Resesive Diseases



Examples of Dominent Resesive Diseases



Examples of Dominent Resesive Traits



Maturnal Factors Linked To Twinning



Sex Cell Creation



Sex Chromosome Disorders



X Linked Disorders



X Liked Inherdince