Transcript Genetics

Unit 2
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So is it Nature that determines who we are, or
Nurture?
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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.
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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
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So which is it?
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BOTH!
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Nature and nurture interact throughout
development.
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Nucleic Acids
◦ DNA
◦ RNA
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Chromosomes
◦ X
◦ Y
◦ Karyotype Chromosomal Maps
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Genotype : What is in the DNA
Phenotype: What is observable as a result of
the genotype
Carrier vs Expressed Genetics
Multifactorial & Polygenic Factors
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Dominant Genes
Recessive Genes
Carrier Patterns
Incomplete Dominance
X-Linked Genes
Y-Linked Genes
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Twin Studies!
◦ Monozygotic
Twins
◦ Dizygotic
Twins
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Down’s Syndrome aka Trisomy 21
◦ Three copies of Chromosom 21 present
◦ Characteristics:
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Thick tongue
Round face
Slanted eyes
Short limbs
Cognitive delays, occasional mental retardation
More prone to dementias and age-related disease
early in life
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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
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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
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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
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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%)
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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
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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
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Age of Viability: 24 weeks of gestation is the
earliest a fetus may possibly be born with a
chance of survival.
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2 Methods of Fetal Development
◦ Cephalo-Caudal development moves Head to Feet
◦ Proximo-Distal development moves from the midline out
to the extremeties
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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
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Fetal Membranes:
◦ Chorion
◦ Amnion
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Maternal Gestation
◦ Counted from the 1st day of the mother’s last
menstrual period
◦ Gestation lasts 40 weeks
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Fetal Gestation
◦ Counted from the date of ovulation/fertilization if
known, or approximate dates based on mother’s
menstrual patterns
◦ Gestation lasts 38 weeks
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Teratogen: Any substance that may negatively
impact the development of a developing fetus
◦ Diseases
 Rubella
 HIV
◦ Medicinal Drugs
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Tetracycline
Anticoagulants
Bromides
Phenobarbital
Hormonal replacements
Antacids
Aspirin
Diet pills
Ect!
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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
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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.
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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
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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