Chapter 6: Genetic and Developmental Disorder

Question 1

the human DNA is organized into how many chromosomes, composed of how many pairs?

Answer 1

total of 46 chromosomes, composed of 23 pairs from each (mother and father)

Question 2

how many pairs of chromosomes are autosomal?

Answer 2

22 pairs are autosomal

Question 3

which pair of chromosomes is defined as the sex chromosomes?

Answer 3

the 23rd pair are the sex chromosomes (X and Y) which helps decide either male (XY) or female (XX)

Question 4

what are the four groups of genetic disorders?

Answer 4

chromosomal abnormalities, mendelian single-gene disorders, non-mendelian single-gene disorders, and polygenic/ multifactorial disorder

Question 5

chromosomal abnormalities generally result from?

Answer 5

an abnormal amount of chromosomes and alterations to the structure of one or more chromosomes

Question 6

what does aneuploidy refer to?

Answer 6

an abnormal number of chromosomes either less than or greater than 46 chromosomes

Question 7

what is an example of autosomal aneuploidy and why?

Answer 7

Down syndrome (trisomy 21) which means there is an extra copy of chromosome 21. This is because autosomal aneuploidy generally happens due to nondisjunction which is the failure of pairs to separate properly during 1st of 2nd meiotic division

Question 8

trisomy 18 and trisomy 13 are examples of which aneuploidy, and what is another name for each?

Answer 8

examples of autosomal aneuploidy 
trisomy 18 ( Edwards syndrome)
trisomy 13 (patau syndrome)

Question 9

what are two examples of a sex chromosome aneuploidy?

Answer 9

klinefelter syndrome and turner syndrome

Question 10

what are the difference in abnormal chromosome structure between meiosis and mitosis?

Answer 10

abnormal chromosome structure results from breakage and loss of rearrangement of chromosome pieces during meiosis or mitosis. meiosis is due to crossing over error where chromosome portions are lost, attached to the wrong chromosome or not attached correctly. mitosis is where there are opportunities for chromosomal breakage and rearrangement

Question 11

true or false: the long arm is labeled the q arm, and the short arm is labeled the p arm.

Answer 11

true

Question 12

what is cri du chat syndrome?

Answer 12

the deletion of part of the short arm (p arm) of chromosome 5

Question 13

the location of the defective gene is found where, and the mode of transmission is defined as?

Answer 13

the location= autosomal or sex chromosomes

mode of transmission= dominant or recessive

Question 14

Marfan syndrome is an example of an autosomal dominance disorder, falling under which type of tissue disorder?

Answer 14

connective tissue disorder

Question 15

what are some clinical manifestations for Marfan syndrome?

Answer 15

patients typically present with tall, slender bodies, long/thin arms, fingers, and the aorta tends to be weaker

Question 16

Marfan syndrome is traced to which mutation, and low levels of this cause..?

Answer 16

fibrillin 1 gene on chromosome 15

low levels of fibrillin leads to weakened connective tissue

Question 17

what does Huntington disease affect?

Answer 17

neurologic function

Question 18

an abnormal amount of this protein is produced in Huntington disease that causes nerve degeneration?

Answer 18

Huntington protein

Question 19

what are some examples of autosomal recessive disorders?

Answer 19

albinism, phenylketonuria (PKU), and cystic fibrosis

Question 20

true or false: do males always express the disease for a sex-linked (X-linked) disorder?

Answer 20

true; males always express the disease because they only have one X chromosome

Question 21

what classifies polygenic traits, and what are some examples of these traits?

Answer 21

polygenic traits develop in response to more than one gene, and some examples are height, weight, and intelligence

Question 22

true or false: multifactorial traits do follow clear cut modes but tend to “run in families”

Answer 22

false

Question 23

what do teratogenic agents do?

Answer 23

interfere with cell proliferation, migration, or differentiation

Question 24

what are some examples of teratogenic agents?

Answer 24

chemical and drugs: thalidomide
alcohol
infectious agents: viruses, rubella, toxoplasmosis, others, rubella, cytomegalovirus, herpes (TORCH)
radiation

Question 25

between which weeks, is the embryo most susceptible to teratogenesis?

Answer 25

between the 3rd and 9th week ( especially week 4 & 5 when organs develop)