Vol 115

I've never been good at note taking.
Maybe because I'm not sure if what "I" believe is important is actually important to the instructor who creates the exams.
I mean, it takes me 3-4 hours to read ONE chapter of a textbook and take notes.
And my notes can go on for days.
Example: The image above is the textbook I use for my Child Development Psychology class.
Of the 30 or so pages for chapter 3, I've only taken notes for the first 15 pages and already have 4 typed pages of notes.
See for yourself.




Chapter 3

Genes are only one part of a complex developmental system
Period of development prior to birth - prenatal period
Development involves differentiation - process by which parts of an organism progressively take on specialized forms and functions.
Development involves repeated reorganization and qualitative change
New structures and capacities emerge in an orderly way from those that existed before
Through childhood and adolescences, human development is orderly, cumulative, and directional

GENETIC PROCESSES

Genetic instructions are stored in chromosomes, which are located in the nucleus. Chromosomes are composed of long molecules of DNA (deoxyribonucleic acid) , twisted double helix.
Structures allows them to unzip down the middle and give exact copies of themselves.
Gene is simply a segment of DNA that contains the code for producing a particular protein.
Human genome, complete DNA sequence, contained 30K-40K genes.
Life begins with one cell (fertilized egg) that contains one set 46 chromosomes
Cells that make up the body, not including sperm or egg cells, are somatic cells
Somatic cells are formed during mitosis :
Mitosis is the process of cell division where the parent cells are duplicated to form daughter cells.
During the process of meiosis, the number of chromosomes from the egg and sperm cells are reduced to 23.
DNA is a germ cell (cells from which egg and sperm cells are produced).Germ cells duplicate itself, resulting in double stranded chromosomes.
First division: Mitosis, cell divides, resulting in each of the two cells receiving 23 double stranded chromosomes.
Second division: Meiosis, cells divide yielding 4 new cells, each with a single set of 23 chromosomes.
In males, all four cells become mature sperm.
In females, only one becomes a mature egg.
Gametes, mature reproductive cells, have half of the normal number of chromosomes.
Meiosis also involves crossing over (exchange of corresponding segments of genetic material between homologous chromosomes during meiosis) and random assortment (shuffling of chromosomes from the mother and father that occurs during meiosis when homologues separate in preparation for cell division).
Development is a result between interplay between genes and environment.
Human gender begins at the moment of conception
The sex chromosomes, number 23, determines gender. XX = female. XY = male
A critical period is a limited time when some parts of a developing organism is susceptible to influences that can bring about specific and permanent changes
Sexual differentiation begins in the seventh week. In the first six weeks, the primitive gonad (sex gland) tissues look the same in both X and Y chromosomes.
In presences of SRY (sex determing region of Y chromosome) testes are form. If no SRY gene is present, ovaries form.
After sex organ is formed, development is shaped by hormones (chemicals produced in the body that regulate the physiological processes)
Once testes are partially formed, the secret male sex hormones (androgens)
Form penis
Presence or absences of androgens is the key to physical gender development
Alleles are alternate forms of particular genes.
Genotype: genetic makeup
Phenotype: physical traits
Homozygous: identical alleles
Heterozygous: two different alleles
Sex-linked traits: Recessive genetic traits that are carried on the X chromosome and are commonly expressed only in males
Example: Red-green blindness and hemophilia
Polygenic: influenced by multiple genes
Examples: Height, weight, skin color, and intelligence
Few traits are directly determined by genes acting alone.
Genes always act within a context that influences how they are expressed.

CONCEPTION

Conception depends on appropiate timing of a chain of events
Ovum: egg cell
When ovum is ready for fertilization, ovulation (release of an ovum into one of the fallopian tubes, the passage that leads to the uterus) occurs.
Journey down fallopian tubes takes several days
If ovum is not fertilized within first 24 hours, it disintegrates upon reaching the uterus.
The union between a sperm and an ovum results in a zygote
Sometimes a woman’s ovaries will release more than one ovum at a time.
If two ova are fertilized by two different sperm, the result is dizgotic (two zygote) twins: faternal twins
Twins are no more similar genetically than any other two siblings
When a single fertilized egg splits into two separate unit, monozygotic (one zygote) twins are formed and are genetically identical.

PRENATAL DEVELOPMENT

Prenatal period - conception to birth is approximately 38 weeks
Three major periods:

Germinal period: tiny, self-contained cluster of cells becomes implanted in the lining of the mother’s uterus, and cell differentiation begins

Conception - 2weeks

The hallow, ball-like structure into which a zygote develops in the first week of conception is called the blastocyst

Embryoblast: a groups of cells at one end of the blastocyst that develops into the embryo

The rest of the blastocyst that forms into the embryo’s life-supporting system is the trophoblast

Placenta: mass of tissue that supplies oxygen and nutrients to the embryo and carries away waste (starts developing during week 2)
Umbilical cord: cord containing blood vessels that connects the embryo with the placenta (attaches during week 3)

Amniotic sac: fluid-filled sac that surrounds and protects the embryo and the fetus

Implantation of the zygote into the lining of the uterus

Embryonic period: major organs and body parts develop, organism particularly susceptible to damage from harmful environment

Weeks 3-8

Once zygote is implanted it is called an embryo (developing organism during weeks 3-8)

Rapid cell division and differentiation.

Embrynoic cell differentiation:

Endoderm cells develop inyo internal organs suck as the stomach, liver, lungs

Mesoderm cells become muscles, bone, and blood

Ectoderm cells will form the central nervous system, sensory organs, and skin

Organogenesis: formation of organs and other major body parts

Embryonic induction: chemical interaction between cells of different tissues that triggers developmental changes in the embryo

Development process from the head downward (cephalocaudal development)

Development process from the center of the body outward to the extremities (proximodistal development)

Child is most vulnerable to developmental errors

See page 96 about prenatal brain development

Fetal period: Increases in size and becomes a moving, sleeping, waking being

Weeks 9 - Birth
Fetus: developing organism during weeks 9-38 of prenatal development
Major body parts grow rapidly and become refined in structure
By week 10, nervous system is mature enough so that the fetus will flex its entire trunk if any part of its body is touched
By week 12. moves arms, legs, swallows and breathes
By week 18, responses become specific to touched area
Develops a regular sleep-wake cycle

MOTHER’S EXPERIENCE

Trimesters: three-month periods that correspond to changes in the mother’s experience of pregnancy

PROBLEMS IN PRENATAL DEVELOPMENT

Congenital defect/birth defect: Abnormality that is present at birth
Single-gene disorders are called Mendelian disorders, disorders produced by inheritance of a single gene.
Most result of inheriting a recessive allele from each parent
Example: Sickle-cell anemia (painful and potentially fatal blood disorder)
Tay-Sachs disease (steady deterioration of nervous system leading to death before age 2)
Chromosomal abnormalities occur when errors in meiosis produce sperm or egg cells with extra, missing, or damaged chromosomes.
Over 90 are miscarried
Sex chromosome abnormalities occurs when a baby receives an abnormal number of sex chromosomes