CHAPTER FOUR: CHROMOSOME THEORY OF INHERITANCE

most human somatic cells contain a total of ________ chromosomes.

46

the chromosome theory of inheritance states that ...

chromosomes are the carriers of genes

the germ line refers to

all the embryonic cells in an animal

centrioles

a minute cylindrical organelle near the nucleus in animal cells, occurring in pairs and involved in the development of spindle fibers in cell division.

centrosomes

microtubule-organizing centers that help to form and organize the mitotic spindle during mitosis

select all the events that occur during prophase of mitosis,

- the nucleolus becomes less visible

- the centrosomes move apart

- the centrosomes are replicated

- the chromatin condenses into more compact structures

- the chromosomes are separate

- the nucleolus becomes less visible

- the centrosomes move apart

- the chromatin condenses into more compact structures

what phase of the cycle does centrosome replication

S phase

a member of the heterogametic sex can...

make two different types of gametes

during which phases of the cell cycle does a chromosome consists of two chromatids

G2 of interphase, prophase & metaphase

astral microtubules

extend from the centrosome toward the cell's periphery

polar microtubules

originate at centrosomes and interdigitate near the cell's equator

kinetochore microtubules

extend between a centrosome and the kinetochore of a chromatid

what event occurs during anaphase of mitosis?

sister chromatids separate from each other and head to opposite poles

what event occurs during metaphase of mitosis?

The chromosomes align along the metaphase plate of the cell.

where do chromosomes line up during mitosis

metaphase plate

if the orginal diploid mother cell had eight chromosomes, a cell in telophase of mitosis would have _______ nuclei, each with _______ chromosomes

2; 8

cleavage furrow

the first sign of cytokinesis during cell division in an animal cell; a shallow groove in the cell surface near the old metaphase plate

an animal cell with two or more nuclei is called a(n).....

syncytium

syncytium

an animal cell containing more than one nucleus

when a cell evaluates the results of previous steps, this is called a(n)

checkpoint

events that occur in telophase

- nuclear membrane reforms to produce two separate nuclei

- chromosomes reach their respective poles and decondense

- nucleolus or nucleoli become visible

events of telophase I of meiosis

- homologs have reached their respective poles

- the nuclear membrane reforms in many species

interkensis

the interphase between meiosis I and meiosis II

what is the starting material of meiosis II in humans?

23 sets of sister chromatids

what is the starting material of meiosis I in humans?

23 pairs of homologous chromosomes

if the chromosomes decondense during the preceding interphase, they recondense during __________ II of meiosis

prophase

the number of chromosomes in a cell in metaphase II is how many times the number of chromosomes in a cell from the same species in mitotic metaphase?

half

the connections between centromeres of sister chromatids are broken during....

anaphase II of meiosis

during _________ II, membranes from around daughter nuclei, resulting in four haploid gametes after cytokinesis takes place

telophase

a daughter cell produced from a cell containing 8 chromosomes at the start of meiosis II will have how many chromosomes at the end of meiosis II

8

when homologs of a chromosome pair do not segregate during meiosis I is called

non-disjunction

aspects of meiosis that contribute to genetic diversity in a population

independent assortment & crossing-over

main difference between mitosis and meiosis

mitosis produces two diploid daughter cells, while meiosis produces four haploid daughter cells

consider an organism that has four pairs of chromosomes (2n=8). At the end of meiosis I, each cell would have _______ chromosomes and ______ chromatids

4;8

consider an organism that has 3 pairs of chromosomes (2n=6). At the end of meiosis I, each cell would have _______ chromosomes and ______ chromatids

3;6

in metaphase II, the two _________ __________ of most chromosomes are no longer strictly identical because of crossing over during meiosis I

sister chromatids

because daughter cells undergoing meiosis II have the same number of chromosomes as the parental cell at the beginning of the division, meiosis II is known as a(n) __________ division

equational

chromosomes inherited from each parent that match in size, shape, and banding are called

homologous

synapsis is the process by which

homologous chromosomes recognize each other and begin to align themselves in prophase I

events that occur during prometaphase

- the nuclear envelope completely breaks down

- chromosomes attach to the microtubules through the kinetochore

kinetochore function

to aid in chromosome sorting during mitosis

during which phase do pairs of sister chromatids become attached to kinetochore microtubules which emanate from opposite poles of the cell

prometaphase

each centrosome of an animal cell contains a pair of _________ at right angles to each other

centrioles

T/F: centrosomes and centrioles are found only in plant cells

false; (they are found only in animal cells)

during prophase of mitosis, chromosomes _________ into discrete structure. furthermore, the two _____ separate moving towards the poles and the mitotic _____ begins to form

condense; centrosomes; spindle

chromosomes that differ in size and composition between males and females are called

sex chromosomes

in eukaryotes, diploid cells can divide by a process called ________

meiosis

what are the phases of interphase

G1 phase, S phase, G2 phase

which is the inheritance pattern for a trait that is more likely to occur in females and which is seen in every generations

x-linked dominant

the two main types of chromosomes that a human cell contains are...

sex chromosomes and autosomes

T/F: each species has a particular chromosome composition

true

a medical procedure in which a sample of amniotic fluid is taken from a pregnant woman to determine the karyotype of an unborn baby

amniocentesis

aminocentesis is a procedure for....

obtaining fetal cells in a sample from the fluid surrounding the fetus

in order to perform a cell-free fetal DNA analysis, a medical specialist.....

draws blood from the mother

the structures within all living cells that contain the genetic material are called...

chromosomes

a person who has somatic cells with two Barr bodies could have which of the following genotypes?

- XXX

- XXY

- XO

- XYY

- XXXY

XXX & XXXY

Barr bodies

inactivated X chromosomes found only in females

pseudoautosomal regions (PAR)

regions containing about 30 genes that are found on both the X and Y chromosomes in humans. The presence of PARs allows the X and Y chromosomes to pair with each other during the first meiotic division.

which genes on the X chromosome are able to escape the effects of X chromosome inactivation in female mammalian cells?

pseudoautosomal regions (PAR) genes

Y-linked traits would pass from an affected father to all of his ________, and no _________ would be affected

sons, females

male birds often have more ornate and colorful feathering patterns than female birds. this is an example of.....

sexual dimorphism

sexual dimorphism

distinct difference in size or appearance between the sexes of an animal in addition to difference between the sexual organs themselves.

which inheritance pattern is shown for a trait occurring in one sex but not in the opposite sex?

sex-limited inheritance

sex-influenced traits

an autosomal trait exhibits different experssion due to the influence in the presence of male or female sex hormones

male pattern baldness is an example of what kind of trait?

sex-influenced

a person with complete androgen insensitivity syndrome is externally ________ but chromosomally _______

female; male

a male with Klinefelter syndrome (XXY) would have how many barr bodies in his somatic cells?

one

a phenomenon involving animals of the same species, but of opposite sexes, that have different physical features is called

the sexual dimorphism phenomenon

cells that are destined to undergo meiosis and produce gametes are called

germ cells

people with klinefelter syndrome are usually

tall, thin, male & sterile

the kind of nuclear division followed by cell division that results in two daughter cells containing the same number and type of chromsomes as the original parent cell is called

mitosis

the five stages of prophase I:

leptotene

zygotene

pachytene

diplotene

diakinesis

what are all the genes found in the male-specific region of the Y chromosome

- three male fertility genes

- eight essential genes shared with the X chromosome

- SRY gene

to prove that the SRY gene determine maleness, scientists placed the SRY gene

on an autosome in an XX mouse

a true statement about the X-O system of sex determination seen in insects is...

the male has one sex chromosome (the X) and is designated XO, whereas the female has a pair (two Xs)

in the Z-W system of sex determination, the males are represented as _______, whereas the females are represented as ______

ZZ; ZW

in certain lizards and alligators, sex is determined by

the environmental temperature

a ZZ butterfly is

a male

where is the SRY gene located on the Y chromosome

MSY (male specific region)

when scientists added an SRY transgene to the genome of XX mice, the mice

were phenotypically male

the part of the nucleus that is important for the manufacture of ribosomes is the....

nucleolus

eukaryotic cells that are destined to divide progress through G1, S, G2 & M phases, which are collectively known as the...

cell cycle

Reasons behinds Walter Sutton's Chromosome of Inheritance Theory

- both chromosomes and alleles of unrelated genes assort independently

- in all cells derived from a fertilized egg, half of the chromosomes and genes have maternal origin, and half have paternal origin

- every cell has two copies of each chromosome, and there are two copies of each kind of gene

- during meiosis, homologous chromosomes and alternative alleles of a gene pair then separate to different gametes

- the chromosome complement, like Mendel's genes, appears unchanged as it is transmitted from parents to offspring through generations

- at fertilization, an egg's set of chromosomes unites with a randomly encountered sperm's set of chromosomes

law of independent assortment

the law that states that genes separate independently of one another in meiosis

the random arrangement of homologs along the metaphase plate in meiosis I is consistent with Mendel's law of __________ ________

independent assortment

the behavior of chromosomes during meiosis explains Mendel's law of segregation. Specifically, a gamete contains only one copy of each type of chromosome because of...

the homologs segregate during meiosis I and the sister chromatids separate during meiosis II

what scientist carried out experiments that confirmed the chromosome theory of inheritance

thomas hunt morgan

when thomas hunt morgan crossed the red-eyed F1 generation fruit flies with each other, the F2 generation included both red-eyed and white-eyed individuals. interestingly, all the white-eyed flies were male. what did these results indicate?

the eye color gene was on the X chromosome

crisscross inheritance

an inheritance pattern in which males inherit a trait from their mothers, while daughters inherit the trait from their fathers

when male flies inherit their eye color from their mother, and female flies inherit their eye color from their fathers, this is an example of ________ inheritance

crisscross

genes that are physically located on the X chromosome are called _______ genes

X-linked

hemizygous

the genotype for genes present in only one copy in an otherwise diploid organism (such as X-linked genes in male)

color blindness is inherited with an X-linked recessive allele. which term best describes the genotype for a color-blind male?

hemizygous

which zygotes can be formed from fertilization of an egg that is the abnormal product of nondisjunction of the sex chromosomes.

- XO

- XXY

- OY

- XX

- XY

- XXX

- XO

- XXY

- OY

- XXX

bridges observed that in a cross between white-eyed females and red-eyed males, the majority of the progeny were red-eyed females and white-eyed males. However, a very small number of males had red eyes, and female has white eyes. bridges proposed this was due to ______ in meiosis

nondisjunction

spermatogenesis takes place in the

testes

the ______ of a eukaryote is the organelle that contains most of the genetic material found in the cell

nucleus

chromosomes are best defined as

the structures within living cells that contain the genetic material

mitosis results in

two daughter cells containing the same number and type of chromosomes as the original parent cell

in humans, a diploid cell contains two sets of chromosomes, for a total of ____ chromosomes. in contrast, a gamete (sperm or egg cell) contains only a single set, consisting of ___ chromosomes

46; 23