Bio Do Not Fail This One!! Chp 15

Front 1

After Mendel, biologists developed the chromosomal theory of inheritance, explain this theory

Back 1

genes have specific loci(positions) along chromosomes and it is the chromosomes that undergo segregation and indpendent assortment

Front 2

genes have specific loci along chromosomes and it is the chromosomes that undergo segregation and indpendent assortment

Back 2

chromosmal theory of inheritance

Front 3

how are chromosomes and mendel's factors relate to each other?

Back 3

chromosomes and genes are both present in pairs in diploid cells
homologous chromsomes separate and alleles segregate during meiosis
Fertilization restores the apired condition for both chromosomes and genes

Front 4

who was the first to associate a specific gene with a specific chromosome in the early 20th C?

Back 4

Thomans hunt morgan

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Thomas Hunt Morgan:

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was the first to associate a specific gene with a specific chromosome in the early 20thC

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normal character phenotype?

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wild type

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alternative traits from the wild type are called

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mutant phenotypes

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what did Morgan discover?

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gene with white-eyed mutation is only on the X chromsoome for fruit flies.

Front 9

Genes on sex chromsomes are called

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sex-linked genes

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chromsomes other than sex chromosomes are called

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autosomes

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genes found together on an autosome are called

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linked genenes

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sex-linked genes:

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genes on sex chromosomes are called

Front 13

autosomes:

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chromosomes other than sex chromsomes

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linked genes

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genes foudn together on an autosome

Front 15

production of offpsring with new combinations of traits inherited from two parents is. .

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gentic recombination

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results of crosses with linked genes deviate from those expected according to. . . .

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independent assortment

Front 17

what two things produce genetic recombinants?

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independent assortment of chromosomes and crossing over

Front 18

Genetic recombination can result from indepndent assormtnet of genes located on

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nonhomologous chromsomes

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genetic recombination can result from crossing over of genes located on

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homologous chromsomes

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parental phenotypes

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phenotypes that match the original parents

Front 21

phenotypes that match the original parents

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parental phenotypes

Front 22

A cross between an F1 plant and a homozygous recessive plant produces how many different phenotypes?

Back 22

4

Front 23

A cross between an F1 plant and a homozygous recessive plant produces what phenotypes?

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2 parental phenotypes and 2 recombinant phenotypes

Front 24

50 % frequency of recombination is observed for any two genes located on. . .

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nonhomolougs chromosomes

Front 25

In unlinked genes genes tend to move in what way during meiosis?

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random orientation of homologous chromsomes at metaphase 1 of meiosis

Front 26

the orientation of the tetrad between character and trait for an unlinked gene is that they. .

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have no influence on the other. the shape of a plant has no influence on the color of it

Front 27

Linked genes move how in meiosis?

Back 27

they move together through meiosis and fertilization

Front 28

In unlinked genes we would expect how many different combinations of alleles?

Back 28

4

Front 29

In linked genes we would expect hwo many different combinations of alleles?

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2

Front 30

If most of the offprsing had parental phenotypes we would expect what?

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linkage between genes

Front 31

If you know there is linkage between genes then that suggests what about the offspring genes?

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that there is linkage between genes

Front 32

If genes are completely linked what would the Pheno ratio be?

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1:1:0:0

Front 33

how many and what are the sex chromosomes in humans and mammals

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2, X and Y

Front 34

An individual who inherits two X Chromosomes usually becomes

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a female

Front 35

An individual who inherits one X and one Y usually becomes

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a male

Front 36

Y and X chromosomes behave as what kind of chromosomes during meiosis?

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homologous chromsomes in meiosis

Front 37

Y and X chromosomes are only partially . . .

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homologous and rarely undergo crossing over

Front 38

when do signs of embroy's sex appear?

Back 38

two months

Front 39

SRY gene. .

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sex determining region of the Y chromosome.

Front 40

In individuals with the SRY gene what happens?

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embroyonic gonads are modified into testes

Front 41

What is one hypothesis about how the Y chromosome came about?

Back 41

Z and Y were originally a pair of identical autosomes (same size carrying the same genetic mateiral) Then 300 million years ago a chance mutation suddenly occured on the Y, mutating the SOX3 gene to the SRY gene, It is at this point that the Y chromsome took on the sex determinnig role for maleness. The X retained the numutated SOX3 gene and sex chromsomes emerged

Front 42

in individuals lacking the SRY gene what happens?

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embroyonic gonads turn into ovaries

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hemizygous means. . .

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only one type of chromosomes like how males only carry one X chromsome

Front 44

Duchenne muscular dystrophy

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sex linked human disorder. Affects 1 on 3500 males born in U.S. they rarely live past their early 20s. This disorder is due to the absense of an X-linked gene for a muscle protein called dystrophin.

Front 45

dystrophin

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muscle protein that links the yctoskeleton of a musle fiber to the extracellular matrix.

Front 46

Hemophillia

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sex linked disorder, recessive trait defined by the absense of oen ore more clotting factors. These proteins numrallyh slow and then stop bleeding but with hemophillacs they have prolonged bleeding due to lack of clotting.

Front 47

Although female mamals inherit two X chromsomes. .

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only one is active

Front 48

Do males and females have the same effective dose of genes on the X chromsome?

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yes because females have one inactive X chromsome

Front 49

During female development, one X chromsome per cell condenses into a compact objected called a

Back 49

barr body

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Barr body

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when one X chromosome in each female cell condenses into a compact object

Front 51

Explain how only one female X chromsome is active

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during female development one X chromsome per cell condenses into a compact object called a barr body, this compaction inactivates most of it's genes.

Front 52

Who discovered that the selection of which X crhomsome to form the Barr body is random and independent?

Back 52

Mary Lyon

Front 53

Mary Lyon. .

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British gentiticist, discovered that the selection of which X chromosome that forms into a Barr body is random and independent

Front 54

"Females consist of a mosaic of cells" means. .

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that one female X gene comes from the father (paternal X) and one X gene comes from the mother (maternal X)

Front 55

What determines the inactive X for all decendent cells?

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the Barr body formation

Front 56

occurs when problems with the meiotic spindle cause errors in the chromsome structure or number of chromsomes each daughter cell receives

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nondisjuction

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nondisjuction

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errors in the chromsome structure or number of chromosomes each daughter cell receives

Front 58

if tetrad chromsomes do not eparate properly during meiosis I what may occur?

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nondisjuction

Front 59

when one daughter cell ends up with all four chromatids of the two homolgues at the end of meiosis I and the other daughter cell has no chromsomes for that homologue then what may occur?

Back 59

nondisjuction

Front 60

if sister chromatids failt o separate during meiosis II what may occur?

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nondisjuction

Front 61

when some gametes receive two of the same type of chromsome and another gamete receives no copy then what happened?

Back 61

nondisjuction

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aneuploidy

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offspring that result from fertilization of a normal gamete with one after nondisjuction. This offspring will have an abnormal chromosome number

Front 63

offspring that result from fertilization of a normal gamete with one after nondisjunction will have an abnormal chromsome number

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aneuploidy

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trisomic cells

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have three copies of aparticular chromsome type and have 2N + 1 total chromosomes

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have three copies of a particular chromsome type and have a 2N + 1 total chromomes

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trisomic cells

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monosomic cells

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have only one copy of a particular chromome type and have 2N - 1 chromsomes

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have only one copy of a particular chromosome type and have 2N - 1 chromsomes

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monosomic cells

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If the organism survives after having only one copy of a particular chromosome type then it will usually lead . . .

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to a distinct phenotype

Front 69

Organisms with more than two complete sets of chromosomes have undergone. .

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polypoidy

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polypoidy

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organisms with more than two complete sets of chromsomes have undergone this

Front 71

what is relatively common among plants and much less common among animals?

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polypoidy

Front 72

what are more nearly normal in phenotype than aneupolids?

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polypoids

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polyploids are more nearlly normaly normal in phenotype than

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aneuploids

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Break of a chromosome can lead to four types of changes in chromsome structure

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deletion
duplication
inversion
translocation

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deletion

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occurs whena chromsome fragment lacking a centromere is lost during cell dvision

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occurs when a chromsome fragment lacking a centromere is lost during cell division

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deletion

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duplication

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occurs when a fragment becomes attached as an extra segment to a sister chromatid

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occurs when a fragment becomes attached as an extra segment to a sister chromatid

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duplication

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inversion

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occurs when a chromosomal fragment joins a nonhomologous chromsome

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occurs when a chromosomal fragment joins a nonhomlogous chromsome

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inversion

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Down syndrome

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aneuploid condition, due to three copies of chromsome 21. affects about one in 700 children born in U.S. Most cases of down syndrome result from nondisjuction during gamete production in one parent
frequency of down syndrome increases with the age of the woman bc the probably of trisomies of other chromsomes also increases with amternal age

Front 82

Klinefelter's syndrome

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XXY male, occurs once in ever 2000 live births. have male sex organs but are sterile, may have some feminine characteristics and have diminished mental capacity but may appear normal. Exhibit Barr bodies

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jacob's syndrome

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males with an extra Y chromsome, 1 out of 1000 births tend to somewhat taller than average and maybe have soemwhat reduced intelligence but many appear and act normally

Front 84

trisomy X

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triple X syndrome, which occurs once in every 2000 live births produces females that appear normal but they are usually sterile. show two Barr bodies

Front 85

Monosomy X or Turner's syndrome (X0)

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1 in every 5000 births, produces usually phneotypically normal but infertile females.

Front 86

cri du chat

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cry of the cat, results from a specific deletion in chromsome 5, mentally retarded and have a small head with unusual facial features and cry like that of a distressed cat.

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chronic myelogenus leukemia (CML)

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fragment of chromsome 22 switches places with a small fragment from the tip of chromsome 9.

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Gragile X syndrome

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second most common cause of mental retardation, more common in males, more common if the abnormal chromsome is inherited from the father. In the fragile X gene on the X chrosmome, the CGG nucleotide triplet is repeated about 3o times in the normal alelle. In the mutant allele the triplet is repated hundred to thousands of times created the fragile site on the chromsome

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most common cause of mental retardation

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down syndrome

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second most common cause of mental retardation

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fragile x syndrome

Front 91

traits of the genes found in mitochondria depends only upon the . . .

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maternal parent

Front 92

In animals, the zygote cytoplasm comes only from the

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egg. No sperm mitochondria are present.