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Thomas Hunt Morgan completed breeding experiments with _____-___ ___

drosophila
fruit fly

1

reasons for studying drosophila
-easy to ___
-generation time- ____
-produce ____ of offspring
-easy ____ characteristics
-only __ chromosomes to look at

keep
10-15 days
100s
physical
8

2

Morgan observed that of 4 pairs of homologous chromosomes: there are how many different pairs in male and female

one

3

in females
-pair was ___
-longer was called ____

same
X

4

makes
-pairs were ___
-___ and ___ shaped
-referred to as ___

different
short, hook
Y

5

Morgan correctly hypothesized that the X and Y were ___ chromosomes

sex

6

all the other chromosomes are called

autosomes

7

traits determined by alleles on the sex chromosomes

sex-linked traits

8

an example of a sex-linked trait

fruit fly eye color

9

what is the wild type

the 'normal' phenotype

10

group of genes located on one chromosome

linkage groups

11

number of linkage groups equals the number of

chromosome pairs

12

some unexpected results in linkage groups

come genes appeared to be separated

13

in Morgan's results of linkage groups he saw that so,e of the offspring were ___/___ and others were ___/___

gray short
black long

14

who was Alfred sturtevant

one or Morgan's students

15

Alfred used crossing-over data to construct the first ____

chromosome map

16

what are chromosome maps created by

comparing the frequency of cross-over for three or more characteristics

17

in map units the percentage of crossover is proportional to the distance between...

genes on a chromosome

18

1% of cross-over is equal to...

one map unit

19

change in DNA at the genes or in the chromosomes themselves

mutation

20

mutation of the sex cells, passed to the next generation

germ cell mutation

21

mutation of body cells, passed to the daughter cells

somatic cell mutation

22

chromosome mutation often occur during

cell division

23

chromosome mutation occur from...
-changes in ____ structure
-___ of entire chromosome

chromosome
loss

24

most chromosome mutations are

harmful

25

mutation that doesn't allow the organism to develop beyond the zygote

lethal mutation

26

environmental factors that damage DNA

mutagens

27

what are these examples of
carcinogens, biological, pathogens(viruses), UV and other forms of radiation, chemical mutagens, etc.

mutagens

28

4 ways mutations occur

deletion
inversion
translocation
nondisjunction

29

what is deletion

piece of chromosome breaks off and is lost