genetics and prenatal development

Genetics and Prenatal Development

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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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