Mechanics of Hereditary Flashcards
Epigenetics
above genetics, how nature v nurture interact
When does human life begin?
it begins with the union of mother’s ovum (egg cell) and father’s sperm cell.
How often is an egg cell released?
every 28 days
All women’s ova are present at birth (around _____ in number) and only ____ # will mature and be released between puberty & menopause.
maybe a million, 400 mature
How much sperm do males produce per month? per 3-4 days?
billions per month; 200-300 million every 3-4 days; this continues from puberty - death.
_______ is largest cell in body; ______ is one of the smallest.
Ovum; sperm
What are somatic cells?
body cells; contain 23 PAIRS of rod-like structures (chromosomes)
What are sex cells? How do they differ from somatic cells?
ova and sperm; they contain 23 (instead of pairs) chromosomes each
Of the 23 chromosomes in each sex cell, ____ determines the sex of the offspring
one (based on father)
Describe the two types of sperm.
X and Y; X sperm are larger and stronger; Y sperm are smaller, weaker but faster
What do XX and XY represent?
XX = female, XY = male; X chromosome necessary for life (no Y sole disorders)
Define gene.
units of heredity
Define Genotype.
actual genetic make up, all genes inherited from parents, fixed at conception
Define Phenotype.
what you see, manifested characteristics, not fixed - interactions between genotype and environment as a person develops
Each ____ cell of __ chromosomes include roughly ______ genes.
body cell; 46; 20,500
Give examples of inherited genes.
skin pigmentation, eye color, some personality traits (shyness, activity level
Define a dominant gene and give examples.
form of an allele whose chemical instructions are followed; curly hair, normal hair, dark hair, thick lips, cheek dimples, normal hearing/vision/color vision, farsightedness, A/B blood type, Rh positive blood
Define a recessive gene and give examples.
allele whose instructions are ignored in the presence of a dominant allele; straight hair, baldness, blond hair, thin lips, no dimples, some types of deafness, nearsightedness, red-green blindness, O blood type, Rh-negative blood
What happens if a person is a carrier of a single recessive gene for an abnormality?
The person may not know of the abnormality and it will not show up in offspring unless the other mate is also a carrier.
Describe Huntington’s Chorea (disease)
caused by dominant trait; fatal disease that is a progressive degeneration of the nervous system; doesn’t manifest until 30-40/50 years of age
Describe Sickle-Cell Anemia.
recessive trait; carried primarily by African-Americans (10% carry the gene); the blood cell is misshapen so it doesn’t carry oxygen normally
Define Sickle-cell trait.
disorder in which individuals show mild anemia only when they are seriously deprived of oxygen; occurs in individuals who have one dominant allele for normal blood cells and one recessive sickle-cell allele; an example of incomplete dominance
Define incomplete dominance and give an example.
situation in which one allele does not dominate another completely.
Describe PKU.
phenylketonuria; inherited (recessive trait) disorder where liver enzyme needed to process bread, dairy, diet soda and fish is missing; if undetected and the foods are ingested, MR and brain seizures can occur; detected in newborns by blood or urine test
Describe Tay-Sacks.
enzyme disorder where brain is unable to break down some fatty substances; symptoms start at 6 mo; child dies before 3-5 yo; detectable but not preventable.
Describe Downs Syndrome.
two chromosome 21’s are given by mother (Trisomy 21), resulting in 3 chromo. 21’s instead of 2; 1 in 680 births; risk increases with parents age (mother especially); mother in late 20’s = 1/1000 births; late 40’s= 1/50 births
Describe Turner Syndrome.
1 in 2.5K-5K females missing an X chrom (XO); 90% result in miscarriages; survivors underdeveloped secondary sex characteristics, short, problems with spatial relations; treatable with estrogen but infertile
Describe Klinefelters Syndrome.
1 in 500 males presence of extra X (XXY); underdeveloped testicles, some breast development, high pitched voice, little facial hair, tall, passive, below normal intelligence many sterile, treatable with testosterone
Describe XXY Syndrome.
Super males; 1 in 1K male births; taller, lower than avg intelligence, tend to be more aggressive; higher percentage in prison population but majority where jailed due to being caught (less intelligence) instead of aggression
Describe Fragile X syndrome.
X chromo. is abnormally compressed or broken; more common in males; results in MR; no symptoms until puberty (10-15yo) - marked decline in intellectual functioning that worsens with age.
Describe XXX syndrome.
1 in 500-1K female births; normal stature, delayed motor and language development
