Hereditary v. Environment Flashcards
Every cell in the body has how many pair and how many total chromosomes (except sex/germcells)
23 pairs of chromosomes - 46 altogether.
autosomes
22 pairs of matching chromosomes, all but sex chromosomes
Genes
the blueprints/instructions for the development of the individual from one generation to the next. Genes tell the cells what to do.
Genetic instructions are established at conception and development is a gradual unfolding of genetic potential.
DNA
Each gene consists of arrangements of molecules called ( ).
The arrangement is the genetic code.
Each gene is made up of ( ), which specifies precisely what kinds of chemical substances will be created by each cell. (BLOOD CELLS, BONE CELLS, NERVE CELLS)
Chromosomes
they are arranged in pairs within every body cells and contain the genes - 20,000 to 100,000 genes. Chromosomes store and transmit genetic information.
Genetic Inheritance
Two forms of each gene occur at the same place on the autosomes, one inherited from the mother and one from the father. Each different form of the gene is the allele. [genetic inheritance is extremely complex]
Allele:
A pair of genes, found on corresponding chromosomes that affect the same trait.
For example: The ability to curl your tongue!
Every person receives a pair of alleles for a given characteristic, one from each biological parent.
When both alleles are the same, the person is homozygous.
all of the pairs of alleles constitute the person’s genotype (individual biochemical make-up).
“On the 22 pairs of autosomes, every gene normally is paired and thus exists as two alleles. The sex chromosomes, however, are slightly different.”
meiosis
is the process by which reproductive cells (ova and sperm)—called gametes—are formed: This process results in cells that contain 23 chromosomes—one half of each pair.
It halves the number of chromosomes so each gamete contains 23.
the chromosomes duplicate themselves as the cell divides, producing two new cells.
After the first division the cells divide again, but they do not duplicate themselves as they did on the first cell division. When the second division is complete there are four cells, each with 23 chromosomes, or half the number found in the original ce
phenotype
the displayed characteristic or trait
zygote
after fertilization, the the genetic material of two individuals “fuses” and is translated into this new entity
New cells are created by this new entity through mitosis.
mitosis.
This is a copying process that replicates the genetic material of the zygote.
All cells of the individual are duplicated this way (except sperm and ova) ‑‑ this begins a few hours after conception.
46 chromosomes move to the middle of the zygote where they produce exact copies of themselves (92 chromosomes).
These chromosomes separate into two identical sets which migrate to opposite sides of the cell (46). The cell divides ‑ the new cell’s chromosomes are identical to those in the original cell.
identical genetic information is maintained in the body cells over the life of the organism.
Mendel
studied mechanisms of transmission ‑ basically, a single pair of genes determines a particular inherited characteristic
Genotype
The genetic make-up of an individual.
Polygenic Inheritance “COMBINATION OF GENES”
Many traits do not result from the alleles of a single gene pair, but from a combination of many gene pairs. This is why phenotypes differ markedly from those of either parent
Are defects normally carried on recessive or dominant gene?
Certain physical defects are carried on the recessive gene – PKU, Sickle Cell (genetic defects generally not carried on dominant gene – people don’t live long enough to pass them on).
Identical Twin:
Monozygotic. They develop from a single fertilized egg that splits into two genetically identical replicas, each of which becomes a person.
fertilized egg divides in half before meiosis
Dizygotic/fraternal twin:
Two eggs are fertilized
Sickle Cell Anemia (recessive disorder)
Occurs most often in children of African decent. Genetic disorder affecting red blood cells. A red blood cell is usually shaped like a disc, but in sickle cell anemia a change in a recessive gene modifies its shape to a hook-shaped “sickle” These cells die quickly, resulting in anemia and early death of the individual because of their failure to carry oxygen to the body’s cells. About 1 in 400 African American babies is affected. One in 10 is a carrier. One in 20 Latinos is a carrier.
PKU Phenylketonuria
one of the most frequently occurring recessive disorders. It’s a metabolic disorder. Infants born with two recessive alleles lack an enzyme that converts one of the basic amino acids that make up proteins (phenyalinine) into a by-product essential for body functioning. Without this enzyme, phenylalanine quickly builds up to toxic levels that damage the central nervous system. By 1 year, PKU infants are permanently retarded. Diet w/o phenyalinine makes a difference.
J. Chromosomal Abnormalities
Occur during the process of meiosis.
Down Syndrome – When the twenty-first pair of chromosomes fail to separate during meiosis.
So they have an extra chromosome
Down Syndrome
Down Syndrome – Most commonly, it results from the failure of the 21st pair of chromosomes to separate during meiosis. The new individual inherits three of these chromosomes. Caused by the presence of an extra chromosome – individual has 47 altogether. We’re not sure why it happens, but it appears that the health of the sperm or ovum are involved. Women between the ages of 18 and 38 are less likely to give birth to a child with Down syndrome. Appears in approximately one in 700 live births. African American children are rarely born with Down Syndrome.
An individual with Down Syndrome has a round face, a flattened skull, an extra fold of skin over the eyelids, a protruding tongue, speech problems, short limbs and retardation of motor and mental abilities.
Down syndrome children develop more favorably when their parents take extra steps to encourage them to become interested in their surroundings. Benefit from preschool intervention.
X-linked Inheritance
Occurs when a recessive allele is carried on the X chromosome. Red-green color blindness is one example of an X-linked recessive trait. Baldness.
The genes carried by the 23rd chromosome result in sex-linked characteristics. Males (XY) are more susceptible to genetic defects, carried on the X chromosome, which is recessive. Defective genes on the X chromosome.
Sex-linked inheritance:
the 23rd chromosome pair determines sex-linked inheritance. Because the X chromosome contains many more genes than the Y chromosome, males are much more likely than females to display recessive traits.
If a normally recessive allele appears on the male’s X chromosome, there often is no allele on the Y chromosome to offset it. The recessive trait will be expressed as the individual’s phenotype.
In contrast, in females the recessive trait will be expressed only if it occurs on both X chromosomes.
Genetic counseling
Communication process designed to help a couple to assess the likelihood of giving birth to a baby with a hereditary disorder and to choose the best course of action.
Gene Therapy
cures for genetic disorders that involve altering the molecular structure of DNA – re-inserting genetically altered cells into the person. Not too successful so far.
Prenatal diagnosis
Some problems can be treated before birth!
Amniocentesis: Prenatal diagnosis
A prenatal medical procedure in which a sample of amniotic fluid is withdrawn by syringe and tested to discover it the fetus is suffering from any chromosomal or metabolic disorders. Amniocentesis is performed between the 12th and 16th weeks of pregnancy.
Ultrasound sonography: Prenatal diagnosis
a prenatal medical procedure in which high-frequency sound waves are directed into the pregnant woman’s abdomen. The echo from the sounds is transformed into a visual representation of the fetus’s inner structures. Can detect certain disorders. Ultrasound sonography is often used in conjunction with amniocentesis to determine the precise location of the fetus in the mother’s abdomen.
Chorionic villus sampling : Prenatal diagnosis
– A prenatal medical procedure in which a small sample of the placenta is removed at some point between 8th and 11th weeks of pregnancy. Look at the cells from the chorionic villi.
Maternal blood analysis – AFO : Prenatal diagnosis
A prenatal diagnostic technique that is used to assess blood alphaprotein level which is associated with neural tube defects.
Environmental Influences on Human Development
Emphasizes such processes as imitation of models, such as parents, teachers, peers and TV.
Adoption
Availability of healthy babies has declined. People adopting from foreign countries. Taking children who are older or with developmental problems.
Adopted children have more emotional and learning problems than the general population.
Environmental contexts for development
Normative events: Age, biological growth, maturation
Non-normative events
Can occur at any time and impact a person’s life – accident, illness, death of family member, winning the lottery.
History-normative events:
are the historical events, such as wars, depressions, epidemics, and widespread technological advances, that affect large numbers of individuals in a given society at about the same time.
Page(s): 59, Understanding Human Development by Grace J. Craig and Wendy L. Dunn, Pearson Education NOOK Study (Emily Moran, eam88487@marymount.edu). This material is protected by copyright.
