Lecture 27

Question 1

chromosome

Answer 1

the vehicle by which traits are passed on

Question 2

Drosophila

Answer 2

species of fly Morgan used to test/study genetics; had red and white eyes, but Morgan first noticed only males had white eyes leading him to question where traits are carried on the chromosomes

Question 3

Thomas Morgan

Answer 3

1910; experimented with fruit flies;

Question 4

segregation

Answer 4

some offspring exhibit one trait (yellow seeds) some exhibit another (black seeds)

Question 5

test cross

Answer 5

crossing homozygous recessive with all possibilites of what the other parent would be, barring homozygous recessive

Question 6

Meiosis

Answer 6

animals and plants reproduce sexually; this is how their gametes are formed

Question 7

Fertilization

Answer 7

male and female gametes unite to form a zygote

Question 8

Zygote

Answer 8

fertilized egg, will become whole organism

Question 9

sperm

Answer 9

male gamete(23 chromosomes in humans)

Question 10

egg

Answer 10

female gamete (23 chromosomes in humans)

Question 11

Sex chromosomes

Answer 11

XX makes female, XY makes male

Question 12

Sex-linked traits

Answer 12

allele for white eyes resides only on X chromosome

Question 13

Red-green colorblindness

Answer 13

found on the X chromosome

Question 14

Hemophelia

Answer 14

found on X chromosome; blood does not clot

Question 15

dosage compensation

Answer 15

one of X chromosomes in females is deactivated so cells don’t produce twice as much of the proteins encoded by genes on the X chromosomes. Ensures equal levels of expression from sex chromosomes despite differing number of sex chromosomes in males and females

Question 16

anaphase II

Answer 16

when microtubules shorten, centromeres split

Question 17

sister chromatids

Answer 17

pulles to opposite poles which allows daughters to have complete sets of chromsomes

Question 18

nondisjunction

Answer 18

failure of sister chromatids to separate properly

Question 19

aneuploidy

Answer 19

gain or loss of a chromosome

Question 20

autosomes

Answer 20

all chromosomes except sex chromsomes

Question 21

Trisomy

Answer 21

gain of an extra chromosome; product of aneupolidy

Question 22

J. Langdon Down

Answer 22

described Down’s syndrome in 1866

Question 23

Down syndryome

Answer 23

trisomy in chromosome 21; child survives, but has developmental defects;