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DAY 2

Unit 3Inheritance and Molecular

Genetics

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Inheritance of traits

• 46 chromosomes• Organization– Nucleotides (ACTG)– Gene– Chromosome

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Genes

Dominant v. RecessiveAllelesHomozygous v. Heterozygous for a traitGenotype v. Phenotype

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Mendel Revisited

Punnett Squares

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Tay Sachs

deadly disease of the nervous system passed down through families.

body lacks hexosaminidase A, a protein that helps break down a chemical found in nerve tissue called gangliosides

defective gene on chromosome 15

Symptoms usually appear when the child is 3 to 6 months old. The disease tends to get worse very quickly, and the child usually dies by age 4 or 5.

Symptoms include: delayed mental and social skills

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Albinism

defect of melanin production that results in little or no color (pigment) in the skin, hair, and eyes.

The defects may be passed down through families.

most severe form of albinism is called oculocutaneous albinism. People with this type of albinism have white or pink hair, skin, and iris color, as well as vision problems.

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PKU

Phenylketonuria (PKU) is a rare condition in which a baby is born without the ability to properly break down an amino acid called phenylalanine.

Phenylalanine an essential amino acidSymptoms include: Delayed mental and social

skills, Head size significantly below normal, Hyperactivity, Jerking movements of the arms or legs, Mental retardation

Treatment: strict diet to limit Phenylalanine intake

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Huntington

inherited disease that causes the progressive breakdown (degeneration) of nerve cells in the brain.

autosomal dominant disorderimpact on a person's functional abilities and

usually results in movement, thinking (cognitive) and psychiatric disorders.

develop signs and symptoms in their 40s or 50s, but the onset of disease may be earlier or later in life

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Huntington Disease continued

Symptoms include: Motor: Slow, uncoordinated fine movements Slow

or abnormal eye movements Impaired gait, posture and balance Difficulty with the physical production of speech,

Cognitive: Difficulty planning, organizing and prioritizing tasks, Lack of impulse control that can result in outbursts, acting without thinking and sexual promiscuity, Slowness in processing thoughts or "finding" words,

Psychiatric: Social withdrawal Insomnia or excessive sleeping Fatigue, tiredness and loss of energy Feelings of worthlessness or guilt

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Down Syndrome

genetic disorder that causes lifelong developmental delays (mental, physical and social) and other problems.

Continuum of severityTrisomy 21 (gamete

production problem)

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Alzheimer’s (familial)

Familial Alzheimer's disease is an uncommon form of Alzheimer's disease that usually strikes earlier in life, defined as before the age of 65 (usually between 50 and 65 years of age, but can be as early as 15)

autosomal dominantaccounts for approximately half the cases of

early-onset Alzheimer's disease. Familial AD requires the patient to have at least

one first degree relative with a history of AD