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Lecture 2

Health Sciences 2700A/B Lecture Notes - Lecture 2: Apgar Score, Prenatal Development, Aspirin


Department
Health Sciences
Course Code
HS 2700A/B
Professor
Laura Brunton
Lecture
2

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September 16th- Readings pg 36-57, 61-88
Genetic Environmental Foundations
Genotype-individuals genetic information
Phenotype- an individuals directly observable characteristics
Within every cell (minus red blood cells) is a nucleus containing chromosomes which
store and transmit genetic information. Humans have 23 matching pairs
Genetic Foundation
Chromosomes are rodlike structures within cells that store and transmit genetic
information
DNA chemical substance that makes up chromosomes
A gene is a segment of DNA along the length of chromosomes
Mitosis and Meiosis
Mitosis- process by which DNA duplicates itself. Produces new body cells containing the
same genetic information
Meiosis- process by which gametes (sex cells, sperm/ovum) are formed. Halves the
number of chromosomes normally present. Leads to genetic variability
oAutosomes (none sex chromosomes) 22 of the 23. 23rd pair is sex chromosomes.
Females XX, males XY
Twins
Fraternal (dizygotic) twin – non identical, results from release and fertilization of two ova
Identical (monozygotic) are identical (same DNA), result when a single zygote separates
to form two individuals
Alleles
Two forms of the same gene, one inherited from each parent
oHomozygous-Both alleles are alike
oHeterozygous- alleles differ (carriers)
Occur at the same place on both chromosomes in a pair
Dominant/Recessive Inheritance - only the dominant allele affects the children
phenotypic characteristics. Many serious diseases are product of two recessive alleles
Incomplete Dominance - both alleles are expressed in the phenotype. Possible results
are a combined trait or a trait that is intermediate between the two
X Linked Inheritance - harmful allele is carried on the X chromosome, X-linked
inheritance applies. Males are more likely to be affected because their sex
chromosomes do not match
Genomic Imprinting - chemical marker activates one allele in a pair. Often temporary;
may not occur in all individuals

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Mutation - sudden, permanent change in a segment of DNA. May affect one or two genes
many
Polygenic Inheritance- characteristics influenced by many genes such as intelligence or
personality
Genetic Counseling - process to help couple assess chances of giving birth to a baby
with a heredity disorder and choose the best course of action in view of risks and family
goals. Recommended when couple has trouble bearing children, know genetic problems
are known and women over 35
Chromosomal Abnormality
Down Syndrome is caused by problems with 21st chromosome
Sex chromosomes abnormalities: Caused by problems with X or Y chromosomes. Often
not recognized until adolescence
As women gets older have more difficulty splitting chromosomes
Parental Diagnostic Methods
Amniocentesis
Chronic Villus Sampling
Fetoscopy
Ultrasound
Maternal Blood Analysis
Ultrafast magnetic resonance imaging
Preimplantation genetic diagnosis
Adoption (Trends)
International adoption
Adoption of older children
Adoption of children with known developmental problems
Children typically exhibit some difficulties, but more fare well
Environmental Contexts For Development
Family, SES, Neighbourhoods, towns, cities, cultural context
Family Influences on Development
Direct influences, indirect influence (effects of third parties). Adaptation to changes within
and outside the family
SES- social status (years of education, prestige of one’s job and skill it requires) Economic
Status- Income
SES is linked to timing of marriage and parenthood, family size, values and expectations
for children, parents education and economic security, communication and discipline
styles, investment in children’s cognitive development
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