Chapter 15 Flashcards Preview

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Flashcards in Chapter 15 Deck (47):
1

chromosome theory of inheritance

-mendelian genes have specific loci (positions) on chromosomes
-chromosomes undergo segregation and independent assortment

2

who had the first solid evidence associating a specific gene with a specific chromosome

thomas hunt morgan
--experimented with fruit flies provided convincing evidence that chromosomes are the location of mendel's heritable factors

3

morgan noted wild type which is really...

normal phenotypes that were common in the fly populations

4

traits alternative to the wild type/ normal phenotypes are called

mutant phenotypes

5

what did morgan's experiment deal with and how did he figure out it had to do with chromosomes?

Correlating Behavior of a Gene’s Alleles
with Behavior of a Chromosome Pair
• In one experiment, Morgan mated male flies with white eyes (mutant) with female flies with red eyes (wild type)
– The F1 generation all had red eyes
– The F2 generation showed the 3:1 red:white eye ratio, but only males had white eyes
• Morgan determined that the white-eyed mutant allele must be located on the X chromosome
• Morgan’s finding supported the chromosome
theory of inheritance
---sex linked genes

6

are x and y chromosomes homologous?

technically yes but only the ends of y chromosome have regions that are homologous to regions of the x chromosome

7

true or false:
eggs can have either x or y and sperm can have either x or y

FALSE;
eggs are only x and sperm can be x or y

8

sex linked gene

a gene that is located on either sex chromosome

9

_ chromosome have genes for many characters unrelated to sex, whereas the _ chromosome mainly encodes genes related to sex determination

-x
-y

10

for a recessive x-linked trait to be expressed in a girl what has to happen?
-what about a boy?

-a girl needs two recessive x chromosomes
-a boy only needs one

11

True or false: x-linked recessive disorders are much more common in males than in females

true

12

what are some disorders caused by recessive alleles on the x chromosome in humans

-colorblindness
-duchenne muscular dystrophy
-hemophilia

13

what is the Barr body

when one of the x chromosome in mammalian females condenses and does not work anymore.
*

14

if a female is heterozygous for a particular gene located on the x chromosome she will be a _____ for that character

mosaic- a picture or pattern produced by arranging together small colored pieces of hard material, such as stone, tile, or glass.

15

linked genes

genes located on the same chromosome that tend to be inherited together

16

who crossed flies with different traits to see how linkage affects inheritance

thomas hunt morgan

17

wild type is recognized with....

wild type is normal
it is recognized with a plus +

18

what would be the ratio if genes are located on different chromosomes?

1:1:1:1

19

what would be the ratio if genes are linked

1:1:0:0

20

dihybrid cross would have what ratio?

9:3:3:1

21

genetic recombination

the production of offspring with combinations of traits differing from either parent

22

parental types

offspring with a phenotype matching one of the parental phenotypes

23

recombinant types or recombinants

offspring with nonparental phenotypes (new combinations of traits)

24

crossing over was discovered by who?

thomas hunt morgan

25

genetic map

an ordered list of the genetic loci along a particular chromosome

26

the farther apart two genes are, the _____ the probability that a crossover will occur

higher

27

linkage map

genetic map of chromosome based on recombination frequencies

28

map units

represents a 1% recombination frequency
-indicate relative distance and order, not precise locations

29

cytogenetic maps

indicate the positions of genes with respect to chromosomal features

30

nondisjunction

pairs of homologous chromosomes do not separate normally during meiosis
-as a result one gamete receives two of the same type of chromosome, and another recieves no copy

31

aneuploidy

results from the fertilization of gametes in which nondisjunction occured
-offspring with this condition have an abnormal number of a particular chromosome

32

monosomic

zygote has only one copy of a particular chromosome

33

trisomic

zygote has three copies of a particular chromosome

34

polyploidy

condition in which an organism has more than two complete sets of chromosomes

35

triploidy

three sets of chromosomes

36

tetraploidy

four sets of chromosomes

37

polyploidy is common in ___, not _____

plants, animals

38

deletion

removes a chromosomal segment and that removed segment usually goes into another DNA

39

duplication

repeats a segment within the DNA

40

inversion

reverses orientation of a segment within a chromosome

41

translocation

moves a segment from one chromosome to another

42

an aneuploid condition that results from three copies of chromosome 21

down syndrome

43

an extra chromosome in a male, producing XXY individuals
OR;
XYY (male but still fertile)

Klinefelter

44

produces X0 females who are sterile ...only known monosomy

monosomy x called Turner Syndrome

45

results from a specific deletion in chromosome 5, a child born with this syndrome is mentally retarded and has a catlike cry, usually die early in life

Syndrome Cri du Chat

46

genomic imprinting

the silencing of certain genes that are "stamped" with an imprint during gamete production.
If the allele inherited from the father is imprinted, it is thereby silenced, and only the allele from the mother is expressed.

47

extranuclear genes

found in organelles in cytoplasm...Mitochondria, chloroplasts, and other plant plastids carry small circular DNA moleculess....extranuclear genes are inherited maternally because zygotes cytoplasm comes from the egg ...mostly in plants