Lec 12-1

Question 1

Constraints of human genetic studies

Answer 1

1. Controlled matings are not possible
   Cannot do a test cross
2. Humans have long-generation times (~20 years)
   Fruit Fly generation time is 2 weeks!
3. Human family size too small to evaluate progeny ratios
   (like 9:3:3:1 ratio - dihybrid cross)

Question 2

Pedigree

Answer 2

Pictorial representation of a family history, essentially a family tree outlining inheritance of characteristics

Question 3

Pedigree is used to

Answer 3

Track traits

Make predictions about which members had what genotype

Question 4

Diamond in a pedigree means

Answer 4

Sex is unknown

Question 5

Obligate carrier

Answer 5

Carries the gene but does not have the trait (Shape with a dot in it)

Question 6

Proband

Answer 6

Original family member to be affected (designated with a P)

Question 7

Modes of inheritance

Answer 7

Autosomal
Sex linked

Dominant
Recessive

Question 8

If a pedigree shows a equal number of male/female with a trait

Answer 8

Cannot be sex linked

Must be autosomal

Question 9

If a pedigree does not skip generations

Answer 9

Must be dominant

Question 10

Familial Hypercholesterolemia

Answer 10

Autosomal dominant trait

Defect in cholesterol transport leads to greatly elevated cholesterol

Cholesterol transported in low-density lipoproteins (LDLs)

Disease makes LDL receptors deffective

Question 11

Familial Hypercholesterolemia

Consequences

Heterozygous

Answer 11

Blood LDL levels are twice the normal levels

Heart attacks by 35

Question 12

Familial Hypercholesterolemia

Consequences

Homozygous

Answer 12

Blood LDL levels are 6 times normal

Heart attacks by 2-20 years of age

Question 13

Autosomal recessive on a pedigree

Answer 13

Equally for both sexes and skips generation

Offspring likely to have heterozygous parents

Question 14

Consanguinity

Answer 14

Mating between two closely related people

Indicated by 2 lines

Question 15

x-linked recessive in a pedigree

Answer 15

More frequent in males

Father does not pass down to son

Affected males are born to unaffected mothers who have the trait

Question 16

Obligate carriers

Answer 16

When mother carries a trait but it is not shown

Question 17

Hemophilia A

Answer 17

X-linked recessive

Absence of protein needed for blood to clot

Individuals bleed excessively, small cuts are life threatening

Question 18

X-linked dominant

Answer 18

Appear in males and females equally

At least one parents of each affected child must also be affected

Fathers do not pass down to son only daughters

Heterozygous women pass it to half daughters and half sons

Question 19

Hypophosphatemia

Answer 19

X-linked dominant

Bone deformities

Stiff spines and joints

Bowled legs

Mild growth deficiencies

Question 20

Hypophosphatemia

Cause

Answer 20

Defective transport of phosphate in cells of kidney

Question 21

Y-linked traits

Answer 21

Neither dominant or recessive as only one Y chromosome, so acts like a dominant

Father will always pass on to son