Genetic Inheritance

1
Genetic Inheritance

• Conception
• The union of sperm and ovum create a zygote
• The zygote contains a complete set of 46
  chromosomes
• The first 22 pairs are called autosomes.
• The 23rd pair are the sex chromosomes.
• DNA
• Genes

2
Genetic Principles

• Genes
• Genotype.
• Phenotype
• Reaction range
• Alleles
• Homozygous Alleles (similar)
• Heterozygous Alleles (different)
• dominant - recessive gene principle
• incomplete dominance (blending)
• codominance (type AB blood)

3
Genetic Inheritance

• Single Gene-Pair Inheritance
• Polygenetic Inheritance
• Genetic Imprinting
• Genes are (chemically marked) in one of the
  parents and have different effects depending on
  which parent carries it.
• Huntington disease manifests earlier if passed on
  by the male
• Asthma / females , Diabetes / males

4
Genetic Inheritance

• Sex Linked Genes or Traits (X-linked inheritance)
• ex hemophilia, red/green color blindness
• Mutations
• A sudden, permanent alteration in DNA
• occurs spontaneously or by environmental hazards
• Chromosomal Abnormalities
• Often the result of the 46 chromosomes not being
  divided equally (too many or too few)
• Down Syndrome

5
Genetics Environment

• Heritability
• The amount of variability in a population on
  some trait dimension that is attributable to
  genetic differences among those individuals

6
Gene-Environment Relationships

• Epigenetic View Heredity ?? Environment
• Passive Gene-Environment Relation
• Evocative Gene-Environment Relation
• Active Gene-Environment Relation
• Shared and Non-shared Experiences

7
Stages of Prenatal Development
8
Germinal Stage (Weeks 1-2)

• The zygote, begins to divide, and travels down
  the fallopian tube.
• The new cells form the blastocyst, which attaches
  itself to the uterine wall
• The blastocyst forms several layers of cells
• The outer cells (trophoblast) form the placenta.

9
Embryonic Stage (weeks 3 8)

• The inner cells of the blastocyst which will
  become the embryo differentiate into three
  layers
• Ectoderm Outermost layer which will become
  skin, hair, nails, the nervous system, and
  sensory receptors
• Mesoderm Middle layer which will develop
  into the circulatory system, bones, muscles,
  excretory and reproductive system
• Endoderm Undermost layer which will develop into
  the digestive and respiratory systems

10
Embryonic Stage (weeks 3 8)

• The formation of organs begins (organogenesis)
• Sexual differentiation takes place around the 7th
  or 8th week
• By the end of the embryonic stage about 95 of
  body parts and systems have begun development.

11
Fetal Stage (Week 9-Birth)

• This period involves the dramatic increase in
  body size and completion of all physical
  structures
• Age of viability approx. week 25

12
Prenatal Growth

• Occurs in three patterns
• Orthogenic
• Cells are all the same and then differentiate
• Cephalocaudal
• Latin for from head to tail.
• Proximodistal
• Latin for from near to far.

13
Influences on Prenatal Development

• Nutrition
• Stress
• Mothers Emotional state
• Mothers Age
• Nearly 50 of pregnancies among women in their
  40s and 50s result in miscarriage.
• Father

14
Influences on Prenatal Development

• Teratogans are any disease, drugs, or other
  environmental agents that can cause damage to a
  developing fetus.
• Effects depend on
• Dose
• Heredity
• Presence of other teratogens
• Age of child
• Sensitive period

15
Postnatal (Postpartum) Depression

• Occurs in 1/10 new mothers
• Effects bonding and initial care of child
• Effects on mother
• May not want child
• Mood lability and other symptoms of depression
• Psychosis
• SI / HI

16
Postnatal (Postpartum) Depression

• Effects on child
• Susceptibility
• Past episode(s) of post partum (30 to 50 chance
  with each subsequent delivery)
• Personal past history of a mood disorder
• Family history of Bipolar disorder (even if not
  personally experienced)