CHLD DVLP 02

Chapter 2 Child Development Textbook

Heredity

the biological transmission of traits and characteristics from one generation to another by means of genes

Genetics

The field within science of biology that studies heredity

Chromosomes

Rod-shaped structures that are composed of genes and found within the nuclei of cells

How many chromosomes does a normal human cell contain?

23 pairs (46 chromosomes)

Genes

The basic unit of heredity, composed of deoxyribonucleic acid (DNA)

Polygenic traits

traits that result from many different genes

zygote

a new cell formed from the union of a sperm and an ovum, aka a fertilized egg

Mitosis

The form of cell division where each chromosome splits lengthwise to double in number. Half of each chromosome combines with chemicals to retake its original form and then moves to the new cell.

mutations

a sudden variation in a heritable characteristic, usually caused by an accident that affects the composition of genes

meiosis

the form of cell division where each pair of chromosomes splits and one member of each pair moves to the new cell. As a result each new cell has 23 chromosomes.

Autosomes

a member of a pair of chromosomes (within the exception of sex chromosomes)

sex chromosomes

A chromosome in the shape of a Y (male) or an X (female) that determines the sex of the child

monozygotic (MZ) twins

Twins that derive from a single zygote that has split into two; identical twins. Each MZ twin carries the same genetic code.

dizygotic (DZ) twins

Twins that derive from two zygote; fraternal twins

what are 2 reasons twinning rates have been increasing in developing countries?

increasing age of mothers

use of assisted reproductive technologies

ovulation

the release of an ovum from the ovary

allele

a member of a pair of genes

homozygous

having two identical alleles (HH, hh)

Heterozygous

having two different alleles (Hh)

dominant traits

a trait that is expressed

recessive traits

a trait that is not expressed when the gene or genes involved have been paired with dominant genes. Recessive traits are transmitted to future generations and expressed if they are paired with other recessive genes.

carriers

a person who carries and transmits characteristics but that does not exhibit them

multifactorial problems

problems that stem from the interaction of heredity and environmental factors

down syndrome

a chromosomal abnormality characterized by intellectual disability and caused by an extra chromosome in the 21st pair

sex-linked chromosomal abnormalities

abnormalities that are transmitted from generation to generation, carried by a sex chromosome, usually an x sex chromosome.

Klinefelter syndrome

A chromosomal disorder found among males that is caused by an extra x sex chromosome and is characterized by

-primary and secondary sex characteristics don’t develop properly

-enlarged breasts (gynecomastia)

-mild intellectual disability

-infertility

testosterone

a male sex hormone produced mainly by the testes

Turner syndrome

A chromosomal disorder found among females that is caused by having a single X chromosome and is characterized by

-infertility

-poorly developed ovaries

-produce little estrogen

-shorter than average

-dont develop breasts or mensturate

triple x syndrome

a chromosomal abnormality where a female has three x chromosomes and is characterized by

-lower than average language skills

-poor short term memory

-increased incidence of infertility

estrogen

a female sex hormone mainly produced in the ovaries

Phenylketonuria (PKU)

a genetic abnormality where phenylalanine builds up and causes intellectual disability

Huntington Disease

a fatal genetic neurological disorder whose onset is in middle age characterized by uncontrollable muscle movements and loss of intellectual functioning

Sickle-cell Anemia

A genetic disorder that decreases the bloods capacity to carry oxygen

in vitro

performed or occuring in a culture dish, test tube, or elsewhere outside the mother

Tay-Sachs Disease

A fatal genetic neurological disorder in which nerve cells in the brain and spinal cord are progressively destroyed

Cystric Fibrosis

a fatal genetic disorder in which mucus obstructs the lungs and pancreas

hemophilia

a genetic disorder where blood does not clot properly

sex linked genetic abnormalities

abnormalities that result from genes located on the X sex chromosomes

muscular dystrophy

a chronic disease characterized by a progressive wasting away of the muscles

genetic counseling

advice concerning the probabilities that a couples children

alpha-fetoprotein (AFP) assay

a blood test that assesses the mothers blood level of alpha-fetoprotein, a substance that is linked to fetal neural tube defects

ultrasound

sound waves too high in pitch to be sensed by the human ear.

sonogram

a procedure for using ultrasonic sound waves to create a picture of an embryo or a fetus

Amniocentesis

a procedure for drawing out and examining fetal cells sloughed off into the amniotic fluid to determine whether various disorders are present

spina bifida

a neural tube defect that causes abnormalities of the brain and spine

chorionic villus sampling (CVS)

a method for the prenatal detection of genetic abnormalities that samples the membrane enveloping the amniotic sac and the fetus

reaction range

the variability in the expression of inherited traits as they are influenced by environmental factors

genotypes

the genetic form, or constitution, of a person as determined by heredity

phenotype

the actual form, or constitution of a person as determined by heredity and environmental factors. (expression of the genotype)

canalization

the tendency of growth rates to return to genetically determined patterns after undergoing environmentally induced changes

passive genetic-environmental correlation

the correlation between the genetic endowment parents give their children and the environments in which they place their children

evocative genetic-environmental correlation

the correlation between the child’s genetic endowment and the responses the child elicits from other people

active genetic-environmental correlation

the correlation between a childs genetic endowment and the choices the child makes about which environments they will seek

niche-picking

choosing environmental conditions that foster ones genetically transmitted abilities and interests

epigenesis

the view that development reflects continual and bidirectional exchanges between ones genotype and ones environmental conditions

autism spectrum disorder

a developmental disorder characterized by failure to relate to others, communication problems, intolerance of change, and ritualistic behavior

conception

the union of a sperm cell and an ovum that occurs when the chromosomes of each of these cells combine to form 23 new pairs

fallopian tube

a tube through which the ova travel from an ovary to the uterus

endometrium

the inner lining of the uterus

spontaneous abortion

unplanned, accidental abortion, also called miscarriage

fertility problems found in men:

-low sperm count

-deformed sperm

-poor ability of the sperm to swim to the ovum

-infectious diseases such as STI’s

-chronic diseases, such as diabetes

-injury of the testes

-an ‘autoimmune’ response, in which the man’s body attacks his own sperm as foreign agents

fertility problems in women:

-irregular ovulation or failure to ovulate

-declining hormone levels of estrogen and progesterone that occur with aging

-inflammation of the tissue that is sloughed off during mensuration (endometriosis)

-obstructions or malfunctions of the reproductive tract, which are often caused by infections or diseases involving the reproductive tract

pelvic inflammatory disease (PID)

an infection of the abdominal region that may have various causes and may impair fertility

endometriosis

inflammation of endometrial tissue that is sloughed off into the abdominal cavity rather than out of the body during mensuration. The condition is characterized by abdominal pain and sometimes infertility.

artificial insemination

injection of sperm into the uterus to fertilize an ovum

in vitro fertilization (IVF)

fertilization of an ovum in a laboratory dish

Donor IVF

the transfer of a donors ovum, fertilized in a laboratory dish, to the uterus of another woman.

embryonic transplant

the transfer of an embryo from the uterus of one woman to that of another

surrogate mothers

a woman who is artificially inseminated and carries to term a child who is given to another woman, typically the spouse of the sperm donor.