Transcript Genetics
Unit 2
So is it Nature that determines who we are, or
Nurture?
Nature: This side states that we have a range
of abilities, traits, and limitations that are
inherited genetically from the parents at the
time of conception that cannot be changed.
Nurture: This side states that we have a
variety of environmental influences that
impact us, starting at conception!
◦ Examples:
Mother’s health during pregnancy
Chemicals encountered in the environment
Psychological/Sociological experiences
So which is it?
BOTH!
Nature and nurture interact throughout
development.
Nucleic Acids
◦ DNA
◦ RNA
Chromosomes
◦ X
◦ Y
◦ Karyotype Chromosomal Maps
Genotype : What is in the DNA
Phenotype: What is observable as a result of
the genotype
Carrier vs Expressed Genetics
Multifactorial & Polygenic Factors
Dominant Genes
Recessive Genes
Carrier Patterns
Incomplete Dominance
X-Linked Genes
Y-Linked Genes
Twin Studies!
◦ Monozygotic
Twins
◦ Dizygotic
Twins
Down’s Syndrome aka Trisomy 21
◦ Three copies of Chromosom 21 present
◦ Characteristics:
Thick tongue
Round face
Slanted eyes
Short limbs
Cognitive delays, occasional mental retardation
More prone to dementias and age-related disease
early in life
Phenylketonuria aka PKU
◦ Metabolic disorder leading to inability to digest
proteins
◦ 1/5,000 US births
◦ Recessive linked
◦ Dietary treatment available
◦ Can be detected prenatally and through standard
newborn testing
Huntington’s Disease
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Dominant linked
Symptoms begin around age 35
Manifests as mental illness and extreme aggression
Typically ends in suicide
Can be screened for in genetic testing
Kleinfelter Syndrome: XXY Chromosomal
Pattern
◦ Seemingly male appearance with an absence of
secondary sex characteristics typically present at
puberty
◦ Learning disabilities, language deficits, and anger
issues are common
Fragile X Syndrome: Part of the X is thinly
attached and prone to breaking
◦ One gene mutation replicates over 200 times
(normal range is 30)
◦ Enlargement of the head and ears are typically
present
◦ Males may have enlarged scrotum and testicle
◦ May lead normal lives (20%)
◦ Mild retardation (30%)
◦ Severe retardation (47%)
Turner’s Syndrome: XO Genetic mutation,
only one chromosome present
◦ Learning disabilities (particularly
math/science/logical reasoning)
◦ Flat affect and difficulty recognizing emotions
◦ Short stature
◦ Secondary sex characteristics and puberty changes
do not develop
◦ “Webbed” neck sometimes present
3 Periods of Pregnancy
◦ Germinal Stage: ~ Day 1 – day 14
Lasts from Fertilization to Implantation
◦ Embryonic Stage: ~ Week 3 – Week 8
Lasts from Implantation through the development of
all major organs
The placenta is formed during this phase
◦ Fetal Stage: ~ Week 9 to Birth
Lasts from the completion of all major organs through
the labor and delivery process
Age of Viability: 24 weeks of gestation is the
earliest a fetus may possibly be born with a
chance of survival.
2 Methods of Fetal Development
◦ Cephalo-Caudal development moves Head to Feet
◦ Proximo-Distal development moves from the midline out
to the extremeties
3 Embryonic Tissue Layers
◦ Ectoderm: Outermost layer
Forms the Skin and Neural Tissue
◦ Mesoderm: Middle layer
Forms Muscles and Bones
◦ Endoderm: Inner Layer
Forms Organs
Fetal Membranes:
◦ Chorion
◦ Amnion
Maternal Gestation
◦ Counted from the 1st day of the mother’s last
menstrual period
◦ Gestation lasts 40 weeks
Fetal Gestation
◦ Counted from the date of ovulation/fertilization if
known, or approximate dates based on mother’s
menstrual patterns
◦ Gestation lasts 38 weeks
Teratogen: Any substance that may negatively
impact the development of a developing fetus
◦ Diseases
Rubella
HIV
◦ Medicinal Drugs
Tetracycline
Anticoagulants
Bromides
Phenobarbital
Hormonal replacements
Antacids
Aspirin
Diet pills
Ect!
Teratogen: Any substance that may negatively
impact the development of a developing fetus
◦ Recreational Drugs
◦ Psychoactive Drugs
◦ Alcohol Use
Fetal Alcohol Syndrome: Facial abnormalities, delayed
growth and cognitive development, behavioral and
learning disorders, etc.
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Tobacco Use
Low Birth Weight
Maternal Nutrition
Anoxia: Brain damage due to a lack of oxygen
Birth is a positive-feedback mechanism!
◦ The pressure of baby’s head against the cervix
causes the brain to release Oxytocin.
◦ Oxytocin causes the uterus to contract, pushing
baby’s head against the cervix.
◦ The increase in pressure causes additional oxytocin
to be released, which leads to more frequent and
stronger contractions, and the cycle continues until
baby is born.
3 Stages of Labor:
◦ 1st Stage: Dilation of the Cervix to 10 Centemeters
◦ 2nd Stage: Movement of the fetus’s head into the
birth canal
◦ 3rd Stage: Movement of the fetus through the birth
canal and expulsion of the afterbirth
Neonate: Term used to describe babies under
1 month of age
Apgar Scale: A 1-10 scale used at 1 minute of
age and 5 minutes of age to asses…
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Heart rate
Breathing
Muscle tone
Color
Reflex Reactions