genetics and prenatal development 2. genetic basics building blocks of life chromosomes dna genes...
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Genetics and Prenatal Development
2
Genetic BasicsBuilding Blocks of Life Chromosomes DNA Genes Genomes
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Genetic BasicsExpression of Traits Genotype-The totality of an individual’s genes Phenotype-Actual Characteristics
This is what is seen or observed and can include a wide range of things
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Genetic BasicsExpression of Traits Dominant Genes-Expressed characteristics Recessive Genes-Not expressed, although it is
a part of the genotype (genetic background) Allele-Alternate form of a gene Dominant-Recessive Inheritance
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Genetic BasicsExpression of Traits
Incomplete Dominance Phenotype influenced
primarily but not exclusively by the dominant gene
Polygenic Inheritance Interaction of multiple
genes
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Genetic BasicsThe Sex Chromosomes
The 23rd chromosomes pair determine male or female
Males more vulnerable to X-linked recessive disorders
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Genetic BasicsGenes and Environment Behavior Genetics
Estimating influence of genes and environment on development
Utilize twins to understand importance of genetics and tease out environment effects
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Genetic BasicsGenes and Environment Heritability
An estimate of the extent to which genes are responsible for differences among persons within a specific population
Concordance Rates Percentage that indicates degree of similarity in
phenotype among pairs of family members
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The Human ExperienceConception and Prenatal Development
The Beginning of LifeConception
For conception to occur there must be a released ovum and a sperm.
Ovulation releases the ovum, and if sperm available, fertilization can occur.
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The Germinal PeriodFirst 2 Weeks of Life
During the travel from the fallopian tube to the uterus cell division is taking place Blastocyst Trophoblast Embryonic disk
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The Embryonic PeriodWeek 3-Week 8
Key Developments Embryonic Layers
Ectoderm Mesoderm Endoderm
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The Embryonic PeriodWeek 3-Week 8
Key organs and structures are forming including Heartbeat Eyes, nose and mouth Bone development Arm and leg buds Digestive system
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The Fetal PeriodWeek 9-Birth The longest period of prenatal development
Heartbeat can be heard Movement can be felt Responds to sounds Main impediment to viability is lung development
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Prenatal CareTraditional Cultures and Beliefs Prenatal beliefs are impacted by generational
wisdom of the time These beliefs can include
Avoiding wine Specific types of meat Certain types of hot, cold food Witches Strong foods
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Prenatal CareScience Driven Prenatal Care Some current science-driven prenatal
methods are derived from traditional cultures which includes massages
Current care can vary by ethnicity and SES Developing world less likely to receive
prenatal care Current focus on diet, exercise, and
teratogens
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Prenatal CareDiet Two key vitamins are iodine and iron Iodine deficiency tends to be a bigger issue in
developing countries Iron is necessary for a healthy pregnancy
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Prenatal CareExercise Continued physical activity is encouraged
during pregnancy Aerobic exercise encourages good
cardiovascular health and positively benefits the fetus
A Non-aerobic exercise called Kegel exercises are also encouraged
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Prenatal CareTeratogens Teratogens are environmental and bodily
conditions that could be harmful They can include tobacco, alcohol,
prescription medications and other drugs The physical environment could also be a
teratogen due to malnutrition or exposure to hazardous chemicals
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Safety sign. Source: http://www.compliancesigns.com
Pregnancy Problems
Chromosomal Disorders Chromosomal disorders can occur because of
an issue during meiosis This may cause too many or too few chromosomes
in the cells of the zygote Two types of chromosomal disorders are:
Sex chromosome disorders Disorder on the 21st chromosome (Down
Syndrome)
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Sex Chromosome Disorders Sex chromosomal disorder can result from
extra X, an extra Y, or only an X and no second chromosome Common consequences of sex chromosome
disorders include: Cognitive Deficit Abnormality in reproductive system at puberty
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Down SyndromeTrisomy 21 Identifiable by physical characteristics Cognitive Deficits
Speech problems Mental retardation
Social development varies Lower life expectancy
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Parental Age and Chromosomal Disorder Chromosomal disorders tend to NOT be
passed from parent to child Relationship between maternal age and
chromosomal disorders There may be a relationship between a
father’s age and chromosomal disorders but it isn’t as clear
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TeratogensTiming of Teratogens Teratogens can impact the developing fetus
and embryo at any time There does appear to be a critical period of
prenatal development centered in the embryonic period
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