PSY 330 Exam 1

Intellectual Disability (ID)

Significant limitations in intellectual functioning AND adaptive behavior, originating before age 22.

Two main areas required for an ID diagnosis

Impact on intellectual functioning and adaptive behavior.

Adaptive behavior

The everyday social and practical skills needed to function independently.

What does AAIDD say about people with ID/DD?

They have both strengths and limitations, and appropriate personalized supports can improve functioning.

3 major areas of adaptive functioning

Conceptual, social, and practical skills.

Developmental disability (DD)

A severe, chronic disability caused by a mental and/or physical impairment that begins before age 22 and is expected to continue indefinitely.

Examples of major life areas that DD can substantially limit

Self-care, language, learning, mobility, self-direction, independent living, and economic self-sufficiency.

Important assumption when evaluating limitations

Limitations should be considered in the context of the person's age, culture, and typical community environment.

What happens when appropriate supports are provided over time?

Functioning and quality of life can generally improve.

DNA

Deoxyribonucleic acid; the molecule containing genetic instructions.

Four DNA bases

Adenine (A), thymine (T), cytosine (C), and guanine (G).

DNA bases pair that together

A pairs with T; C pairs with G.

How many chromosomes does a typical human have?

46 chromosomes arranged in 23 pairs.

How many autosomes does a typical human have?

44 autosomes.

Sex chromosomes

The 23rd chromosome pair; typically XX or XY.

Chromosome

A structure made of DNA that contains many genes.

Gene

A section of DNA that provides instructions for producing a particular protein

Allele

An alternative form of a gene.

Genotype

A person's genetic makeup.

Phenotype

The observable characteristics or traits produced by genes and environment

Homozygous

Having two identical alleles for a gene.

Heterozygous

Having two different alleles for a gene.

Dominant

An allele expressed when at least one copy is present.

Recessive

A trait generally expressed when two recessive copies are present.

Karyotype

An organized picture/display of a person's chromosomes.

What can a karyotype show?

Chromosome number, sex chromosome pattern, and large chromosomal abnormalities.

Trisomy

Having three copies of a chromosome instead of two.

Monosomy

Having only one copy of a chromosome instead of two.

Nondisjunction

Failure of chromosomes to separate properly during cell division.

What can meiotic nondisjunction cause?

Trisomy or monosomy.

Mosaicism

Having two or more genetically different cell lines within the same person.

What causes mosaicism?

A genetic error occurring after fertilization during mitotic cell division.

Translocation

A chromosome segment becomes attached to another chromosome.

Mutation

A change in DNA.

Point mutation

A change in a single DNA base.

Deletion mutation

Loss of a section of DNA.

Repeat expansion

When a DNA sequence is repeated more times than normal.

What can a mutation do to a protein?

It can produce a poorly functioning protein, reduce the amount of protein, or prevent the protein from being produced.

Mitosis

Cell division used primarily for growth, development, and maintenance.

Meiosis

Cell division that produces reproductive cells/gametes.

Recombination

The exchange of genetic material during meiosis.

Transcription

DNA is copied into messenger RNA (mRNA).

Transcription occurs

In the nucleus.

What happens to mRNA after transcription?

It leaves the nucleus and travels to the cytoplasm.

Translation

The ribosome reads mRNA and builds a chain of amino acids to make a protein.

Translation occurs

At the ribosome in the cytoplasm.

Basic sequence of gene expression

DNA → transcription → mRNA → translation → protein.

If one DNA strand is A-G-T-C-G, what is the complementary strand?

T-C-A-G-C.

A gene ultimately provide instructions for

Producing a particular protein.

What does the "C" in a gene location code such as C4q36 mean?

Chromosome 4.

The "p" in a chromosome location

The short arm of the chromosome.

The "q" in a chromosome location

The long arm of the chromosome.

p or q represent

The approximate location/band on the chromosome.

C4q36 means

Chromosome 4, long arm (q), at approximately band/location 36.

Centromere

Between the p and q arms of a chromosome.

Two major prenatal developmental stages

Embryonic stage and fetal stage.

When is the embryonic stage?

Approximately weeks 0–8.

When is the fetal stage?

Approximately week 9 through birth.

Proliferation

Cells rapidly increase in number through mitosis.

Differentiation

Cells become specialized for specific functions.

Migration

Cells move to their proper locations in the developing body/brain

Apoptosis

Programmed cell death that removes unnecessary cells.

Synaptogenesis

The formation of connections between neurons.

Myelination

The development of myelin around nerve fibers, which helps speed neural signaling.

Fertilization

Sperm and egg combine to form a zygote.

Morula

An early ball of dividing cells after fertilization.

Blastocyst

A developing structure containing an inner cell mass/embryoblast and trophoblast that will contribute to the placenta.

Implantation

The blastocyst attaches to the uterine wall.

Gastrulation

The process that forms the three germ layers.

Three germ layers

Ectoderm, mesoderm, and endoderm.

Ectoderm develops into

Skin and nervous system.

Mesoderm develops into

Muscles, bones, and blood vessels.

Endoderm develops into

Many internal organ systems.

Neural fold fusion

The neural folds come together to form the neural tube.

The neural tube develops into

The brain and spinal cord.

Correct basic order of early development

Fertilization → morula → blastocyst → implantation → gastrulation → neural development → fetal development → birth.

If a major developmental problem occurs before or very early in pregnancy

It is more likely to result in miscarriage

"all-or-none" idea in very early development

A very early severe insult may cause pregnancy loss; if the embryo survives, development may continue but potentially with major differences.

If a developmental disruption occurs during the embryonic stage

It is more likely to cause structural abnormalities/malformations

If a developmental disruption occurs later during the fetal stage

The person may appear physically typical but develop functional problems such as epilepsy or cerebral palsy.

General pattern of timing of prenatal insults

Early = miscarriage; embryonic = structural abnormalities; later fetal = functional problems

Brain cell proliferation occurs

Primarily during the early-to-middle prenatal period.

Disruption of proliferation causes

Microcephaly due to reduced brain growth.

Microcephaly

A condition in which the head/brain is significantly smaller than expected.

Neuronal migration

The movement of developing brain cells to their appropriate locations.

Abnormal neuronal migration may cause

Abnormal brain development and conditions such as epilepsy.

Synaptogenesis

Formation of connections between neurons.

Pruning

Removal of unnecessary neural connections to make brain networks more efficient.

X inactivation

The process in which one X chromosome in female cells becomes largely inactive.

X inactivation occurs

To balance gene expression between individuals with different numbers of X chromosomes

Mosaicism related to X inactivation

Different cells may have different X chromosomes active, creating genetically different cell populations.

Common example of X-inactivation mosaicism

Calico/tortoiseshell cats.

Difference between screening and diagnostic testing

Screening estimates risk; diagnostic testing is used to determine whether a condition is actually present.

What are screening tests generally like?

Less invasive, less expensive, earlier, and probabilistic.

What are diagnostic tests generally like?

More invasive, more expensive, usually later, and much more definitive.

What does sensitivity measure?

How well a test correctly identifies people who have the condition.

What does specificity measure?

How well a test correctly identifies people who do not have the condition.

What is a false positive?

A test says a person has a condition when they do not.