Regulator Genes
Modify the instructions even by protein-coding genes
Inheritance Patterns
Dominant-Recessive
Incomplete Dominance
Polygenic Inheritance
Dominant-Recessive
Only one allele affects the child's inheritance
ex: Hair Color
Incomplete Dominance
Both alleles are expressed in the phenotype, resulting in a combined trait
ex: sickle cell anemia
Polygenic Inheritance
Many genes affect the expressed characteristic
X-Linked Inheritance
A pattern of inheritance in which a harmful allele (recessive allele) is carried on the X chromosome
Males are more likely to be affected
ex: hemophilia
Genomic Imprinting
Alleles are imprinted, or chemically marked, so that one pair member (either the mother's or the father's) is activated, regardless of its makeup
less than 1% of genes are subjected to imprinting
The imprint is temporary and may disappear in the next gene
Mutation
A sudden but permanent change in a segment of DNA
Germline Mutation
Takes place in the cells that give rise to Gametes
When an affected individual mates, the defective DNA is passed on to the next generation
Somatic Mutation
Normal body cells mutate
An event that can happen at any time in life
The DNA defect can eventually become widespread enough to cause disease or disability as it appears in every cell derived from the body
Down Syndrome
The most common Chromosomal disorder
Occurs in every 1/700 births
Trisomy 21 (three 21st chromosomes)
Intellectual disability, memory & speech problems, limited vocabulary & slow motor development
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
Prenatal Diagnostic Methods
Medical procedures that permit detection of developmental problems before birth
Gametes
Sex Cells
The Sperm & Ovum
Formed through Meiosis
Autosomes
Any chromosome that is not a sex chromosome
Sex Chromosomes
Female: XX
Male: XY
Y is short and carries very little genetic material
X is a large chromosome
Dizygotic Twins
Fraternal Twins
Resulting from the release and fertilization of two ova
Most common type of multiple offspring
Behavioral Genetics
Field within human development that aims to identify the extent to which genes influence behavior
Nature vs Nurture
Primarily done by comparing persons who share different amounts of their genes
Heritability Estimates
The extent to which individual differences in complex traits are due to genetic factors
Kinship Studies
Studies which compare the characteristics of family members
Most common study looks at identical twins
Gene - Environment Interaction
Due to their genetic makeup, individuals differ in their responsiveness to qualities of the environment
Gene- Environment Correlation
Our genes influence the environments to which we are exposed
Types: Passive, Evocative & Active
Passive Correlation
The child has no control over it
Parents provide environments based on their own heredity (young children)
Evocative Correlation
Children evoke responses that are influenced by the child's heredity, and these responses strengthen the child's original style
Active Correlation
Children actively seek environments that fit with their genetic tendencies
Also known as Niche-Picking
DNA Methylation (Behavioral Epigenetics)
Methyl groups attach to DNA within each cell to select genes necessary for that particular cell's proteins
Tightens DNA around the histone
Inhibits transcription of proteins affecting gene expression
Meaney & Szyf (2004) Experiment 1
Attentive & inattentive rat mothers
Rats from attentive mothers: Genes rarely methylated --> lower stress
Rats from inattentive mothers: Genes highly methylated --> increased stress & anxiety
Meaney & Szyf (2004) Experiment 2
Attentive & inattentive rat mothers
Rat pups switched at birth
Inattentive pups raised by attentive mother: genes rarely methylated --> low stress
Meaney & Szyf (2004)
Examined the genes regulating the production of glucocorticoid receptors, which regulate sensitivity to stress hormones and DNA Methylation
3 Experiments
Meaney & Szyf (2004) Experiment 3
Inattentive mother raises biological pups
Treat damaged pups with Trichostatin A (removes methyl groups)
Epigenetic changes disappear (genes are rarely methylated and lower stress)
Szyf & Meaney (2008)
Compare the brains of people who had committed suicide with the brains of people who had died suddenly
Suicide brains had an excess methylation of genes in the hippocampus
If the suicide victims had been abused as children they had higher methylation
Szyf (2011)
Genome wide analysis of blood samples taken from 40 men born in England in 1958
All men had been either very rich or very poor at some point in life
31% of genes varied significantly based on poverty or wealth
Genes were more than 2x as likely to show met
Zygote
Conception to implantation (2 weeks)
Also called the Germinal period
implantation from 7/9 days to 10/14 days after conception
Blastocyst
A hollow, fluid filled ball
Develops about 4 days after conception
Inner membrane of blastocyst becomes the amnion
Outer membrane, the chorion, becomes the placenta and the umbilical cord
Implantation
Occurs between the 7th and 9th days
The blastocyst burrows deep into the uterine lining
Embryo
Implantation to 8 weeks
Umbilical Cord
2 arteries & 1 vein that connect the placenta to the fetus
1-3 ft long at birth
Amnion/Amniotic Sac
Clear wrap that surrounds the fetus
Filled with amniotic fluid ( 20 oz)
Fluid created from H2O from mother
Constant temperature & buffer from external noise
3 Layers of the Embryonic Disk
Ectoderm (becomes skin & nervous system)
Mesoderm (muscles, bones & circulatory system)
Endoderm (digestive system, lungs, urinary tract & glands)
Monozygotic Twins
Identical twins
one egg is fertilized
Monozygotic Separation after the 4th day
Chorion has already formed for the first twin, so co-twin will share
Higher concordance rate of illness
55-60% of cases
Monozygotic Separation before 4 days
Entirely separate chorions develop for each twin
40% of cases
If separate 8 or more days after conception--> mirror twins
Embryo Development
5-6 Weeks: Develop primitive gonads
7 Weeks: <1 inch long
6-8 weeks: sex organs differentiate (default is female)
Fetus
Week 9 until birth
Lanugo
White, downy hair over the entire body of the fetus
Helps vernix stick to the skin
Age of Viability
between 22 and 26 weeks
Changes in the Fetal Brain
Neurons begin developing in week 3
Neuronal Proliferation between 10th & 18th week
(rapid division of neurons)(vulnerable to teratogens)
Neuronal migration between 13th & 21st weeks (newly formed neurons move to the specialized regions of the brain)
Teratogen
Any environmental agent that causes damage during the prenatal period
The Bloody Show
The mucus plug that sealed the cervix is released
This produces a reddish discharge
Indicates the start of labor
Three Stages of Labor
Stage 1: Dilation & Effacement of the Cervix
Stage 2: Delivery of the Baby
Stage 3: Birth of the Placenta
Stage 1 of Labor
As uterine contractions become more frequent and powerful, they cause the cervix to open (dilate) and thin (efface)
Stage 2 of labor
Typically lasts about 50 minutes for first babies and 20 minutes for later babies
Strong contractions continue and the mother feels the urge to push
Stage 3 of Labor
A few final contraction and pushes separate the placenta from the uterine wall
Takes about 5-10 minutes
Apgar Scale
Used to assess the newborn's physical condition quickly
Made at 1 minute and 5 minutes after birth
A score of 7 or better is good
Natural/ Prepared Childbirth
a group of techniques aimed at reducing pain and medical intervention and making childbirth a rewarding experience
Typically participate in three activities:
Classes, Relaxation & Breathing techniques and Labor Coach
Fetal Monitors
Electronic instruments that track the baby's heart rate during labor
Forceps
Metal clamps placed around the babies head to pull the infant from the birth canal
Use increases the risk of brain damage
Induced Labor
one that is started artificially, usually by breaking the amnion and giving the mother synthetic oxytocin, a hormone that stimulates contractions
23% of American labors are induced
Cesarean Delivery
A surgical birth
The doctor makes an incision in the mother's abdomen and lifts the baby out of the uterus
Breech Position
Baby is turned so that the buttocks or feet would be delivered first
Anoxia
inadequate oxygen supply
can result in Cerebral Palsy
Cerebral Palsy
A variety of impairments in muscle coordination caused by brain damage before, during, or just after birth
Preterm Infants
born several weeks or more before their due date
Small-for-date Infants
below their expected weight considering length of the pregnancy
Sudden Infant Death Syndrome (SIDS)
the unexpected death, usually during the night, of an infant younger than 1 year of age that remains unexplained after thorough investigation
Neonatal Behavioral Assessment Scale
evaluates the baby's reflexes, muscle tone, state changes, responsiveness to physical and social stimuli, and other reactions
Fetal Alcohol Syndrome
involves slow physical growth, facial abnormalities, permanent intellectual impairment, and lasting mental health problems
Rh Factor Incompatibility
An Rh-positive fetus developing within an Rh-negative mother can lead to oxygen deprivation, brain and heart damage, and infant death
Engagement
Baby turns and rotates to get head down
Phenotype
the set of observable characteristics of an individual
Genotype
the complex blend of genetic information that determines our species and influences all our unique characteristics
Protein-coding genes
directly affect our body's characteristics
regulator genes
modify the instructions given by protein-coding genes
Meiosis
Halves the number of chromosomes normally present in body cells
Fraternal (Dizygotic) Twins
the most common type of multiple offspring, resulting from the release and fertilization of two ova
Identical (monozygotic) twins
a zygote that has started to duplicate separates into two clusters of cells that develop into two individuals (same genetic makeup)
Homozygous
If the allele from both parents are alike. Child will display the inherited trait
Heterozygous
If the allele from from both parents are different. Relationships between the allele determine the phenotype
dominant-recessive inheritance
only one allele affects the child's characteristics. it is called dominant; the second allele, which has no effect is called recessive
Carriers
heterozygous individuals who carry the recessive allele but are phenotypically normal
Incomplete dominance
pattern of inheritance in which both alleles are expressed in the phenotype, resulting in a combined training, or one that is intermediate between the two
x-linked inheritance
When a harmful allele is carried on the X chromosome. Males are more likely to be affected because their sex chromosomes do not match.
Genomic imprinting
alleles are imprinted, or chemically marked through regulatory processes within the genome, in such a way that one pair member (either the mother's or the father's) is activated, regardless of its makeup
Polygenic inheritance
many genres affect the characteristic in question
Genetic counseling
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
Prenatal diagnostic methods
medical procedures that permit detection of development problems before birth
behavioral genetics
a field devoted to uncovering the contribution of nature and nurture to those diversity in human traits and abilities
Heritability estimates
measures the extent to which individual differences in complex traits in a specific population are due to genetic factors
gene-environment interaction
because of their genetic makeup, individuals differ in their responsiveness to qualities of the environment
gene-environment correlation
our genes influence the environments to which we are exposed
Niche-picking
tendency to actively choose environments that complement our heredity
Epigenesis
development resulting from ongoing, bidirectional exchanges between heredity and all levels of the environment
methylation
a biochemical process that influences behavior by suppressing gene activity and expression
3 phases of pregnancy
germinal period, embryonic period, fetal period
Amnion
Membrane that encloses the embryo in protective amniotic fluid
yolk sac
produces blood cells until the liver, spleen, and bone marrow are mature enough to take over this function
Chorion
protective membrane which surrounds the amnion
Placenta
permits food and oxygen to reach the developing organism and waste products to be carried away
umbilical cord
a tube containing the blood vessels connecting the fetus and placenta
embryo
implantation to 8 weeks. The most rapid prenatal changes take place, as the groundwork is laid for all body structures and internal organs
Embryonic disk forms three layers of cells:
1) Ectoderm, which will become the nervous system and skin;
2) Mesoderm, from which will develop the muscles, skeleton, circulatory system, and other internal organs;
3) Endoderm, which will become the digestive system, lungs, urinary tract, and glands.
fetus
9th week to end of pregnancy. Longest prenatal period.
Vernix
substance that protects the fetus's skin during development
lanugo
fine downy hair of newborn infant
Corticotrophin-releasing hormone (CRH)
a hormone involved in the stress response. Released by the placenta and causes uterine contraction
False labor or pre labor
Braxton-hicks contractions. Upper part of uterus contractions - brief and unpredictable
Lightening
The movement of the fetus down into the pelvis late in pregnancy.
Bloody show
As the cervix begins to open, the plug of mucus that sealed it during pregnancy is released, producing reddish discharge
dilation and effacement of the cervix
as uterine contractions gradually become more frequent and powerful, they cause the cervix to open (dilate) and thin (efface), forming a clear channel from the uterus into the birth canal, or vagina
Transition
frequency and strength of contractions are at their peak and the cervix opens completely. The climax of stage 1
Crowning
the vaginal opening had stretched around the entire head
Natural or prepared
a group of techniques aimed at reducing pain and medical intervention and making childbirth a rewarding experience
episiotomy
incision that increases the size of the vaginal opening
Analgesics
drugs used to relieve pain, may be given in mild doses during labor to help a mother relax
Anesthetics
stronger type of painkiller that blocks sensation
Epidural analgesia
the most common approach to controlling pain during labor... weakens the uterine contractions
cerebral palsy
a general term for a variety of impairments in muscle coordination caused by brain damage before, during, or just after birth
anoxia
inadequate oxygen supply
Placenta abruptio
premature separation of the placenta from the wall of the uterus
placenta previa
condition caused by implantation of the blastocyst so low in the uterus that the placenta covers the cervical opening
Premature
babies born three weeks or more before the end of a full 38-week pregnancy or who weigh less tan 5 and 1/2 lbs
Preterm infants
born several weeks or more before their due date
Small-for-date infants
below their expected weight considering length of the pregnancy
Infant mortality
the number of deaths of children under 1 year of age per 1,000 live births
Neonatal mortality
the rate of death within the first month of life
sudden infant death syndrome (SIDS)
the unexpected death, usually during the night, of an infant under 1 year of age that remains unexplained after thorough investigation
Neonatal Behavioral Assessment Scale (NBAS)
evaluates the baby's reflexes, muscle tone, state changes, responsiveness to physical and social stimuli, and other reactions
Neonatal Intensive Care Unit Network Neurobehavioral Scale (NNNS)
specially designed for use with newborns at risk for developmental problems because of low birth weight, preterm delivery, prenatal substances exposure, or other conditions