Early Embryonic Cell Biology

Question 1

Early embryonic cells more resemble _____ cells in their growth patterns.

Answer 1

cancer

Question 2

_____ means without a specific shape (morphology) or differentiation.

Answer 2

Anaplastic

Question 3

Early embryonic cells are _____ in appearance.

Answer 3

anaplastic

Question 4

Early embryonic cells are small and rounded with a large _____-to_____ ratio.

Answer 4

1. nuclear

2. cytoplasmic

Question 5

The large size of the _____ indicates continuing DNA replication.

Answer 5

nucleus

Question 6

Up to day 8 in humans, early embryonic cells do not perform any specific ______ functions and have unlimited potential for differentiation, a feature known as _____.

Answer 6

1. differentiation

2. pluripotency

Question 7

As a result of very loose adherence to each other, early embryonic cells _____ within the early embryo.

Answer 7

migrate

Question 8

Early embryonic cells share _____ with normal differentiated human cells, which is the only shared characteristic at this state.

Answer 8

diploidy

Question 9

Early embryonic cells perform rapid and continuous cell division with a minimal amount of time spent in the _____ phase.

Answer 9

G (subscript 0)

Question 10

Early embryonic cells have long _____ that do not shorten with each cell division.

Answer 10

telomeres

Question 11

The change that occurs in early embryonic cells to become differentiated is known as _____ and involves adjusting the activity of the promitotic oncogenes and the genes that regulate differentiation.

Answer 11

commitment

Question 12

At about day _____ (#) after conception, early embryonic cells each commit to a differentiation pathway and are no longer _____.

Answer 12

1. 8

2. pluripotent

Question 13

Selective gene _____ directs the normal growth and differentiation into specific body tissues and organs.

Answer 13

expression

Question 14

Just after conception and for the next _____ days, the cells have not yet started to differentiate within this early embryo into specific organs or tissues. Very few drugs affect the embryo at this stage unless the mother is harmed. However, _____ and infectious organisms an damage the early embryo, but most miscarriages at this state are callused by genetic issues that disrupt _____ and differentiation.

Answer 14

1. 14
2. toxins
3. commitment

Question 15

The unborn baby is an _____ from the 3rd week to the eighth week of pregnancy (days _____ through _____).

Answer 15

1. embryo
2. 15
3. 60

Question 16

The _____ stage is the most dangerous time for external or internal conditions to induce birth defects.

Answer 16

embryonic

Question 17

The _____ stage is from week _____ (#) of pregnancy through birth.

Answer 17

1. fetal

2. 9

Question 18

The _____ stage is when most of the important organs are beginning to differentiate and form, and is when some, such as the heart, begin to function.

Answer 18

embryonic

Question 19

_____ makes the edges of the palate sticky and is responsible for the palate halves to fuse within only a _____ (#) hour window.

Answer 19

1. Apoptosis

2. 24

Question 20

The hands and feet begin as paddles. The fingers and toes becoming separated is a result of regulated _____.

Answer 20

apoptosis

Question 21

Although external conditions can influence how well development proceeds, _____ influences determine whether it proceeds.

Answer 21

genetic

Question 22

_____ is the conversion of diploid germ cells into haploid gametes that are capable of uniting at conception.

Answer 22

Gametogenesis

Question 23

_____ or _____ cell division is a special type of cell division in which the chromosome number per cell is reduced to half.

Answer 23

1. Meiosis

2. meiotic

Question 24

Meiosis only occurs in _____ cells.

Answer 24

germ

Question 25

The two cells resulting from meiosis I are _____ for chromosome number, but because each chromosome at this point still have two chromatids that have not separated, the DNA content is still _____.

Answer 25

1. haploid

2. diploid

Question 26

At meiosis II, the _____ of each of the 23 chromosomes separate.

Answer 26

chromatids

Question 27

Meiosis I and meiosis II produces two cells that are _____ for both chromosome number and DNA content.

Answer 27

haploid

Question 28

_____ are immature male germ cells produced in the seminiferous tubules of the testes in late fetal development.

Answer 28

Spermatogonia

Question 29

_____ is the conversion of the diploid spermatogonia into mature sperm that does not begin until puberty.

Answer 29

Spermatogenesis

Question 30

In spermatogenesis, one diploid precursor cell can ultimately result in the formation of _____ (#) haploid sperm.

Answer 30

4

Question 31

In oogenesis, one diploid precursor cell can result in the formation of _____ (#) haploid ova/ovum capable of being fertilized and up to _____ (#) haploid polar bodies.

Answer 31

1. 1

2. 3

Question 32

_____ begins at puberty and continues throughout the lifespan in a continuous process.

Answer 32

Spermatogenesis

Question 33

_____ begins in fetal life and stops when menstruation stops in a cyclical process.

Answer 33

Oogenesis

Question 34

In ______, completion of meiosis I and meiosis II takes days to weeks.

Answer 34

spermatogenesis

Question 35

In _____, completion of meiosis I and meiosis II takes years and is not complete until after fertilization.

Answer 35

oogenesis

Question 36

The primary spermatocyte is _____ with 23 pairs of chromosomes and enters _____ where cell division reduces the chromosome number with multiple stages or steps.

Answer 36

1. diploid

2. meiosis I

Question 37

The _____ phase for meiosis begins shortly after the S phase, and the _____ phase does not really exist for meiosis.

Answer 37

1. M

2. G (subscript 2)

Question 38

List the 4 stages of M phase during meiosis I:

Answer 38

1. prophase I
2. diakinesis
3. metaphase I
4. telophase I

Question 39

During _____, the DNA of the replicated chromosomes continuously condenses.

Answer 39

prophase I

Question 40

List the 3 stages during prophase I of meiosis I:

Answer 40

1. leptotene stage
2. zygotene stage
3. pachytene stage
4. diakinesis

Question 41

The _____ stage of prophase I of spermatogenesis has the long, thin threads of the chromatids of each chromosome become looser and slightly unwind.

Answer 41

leptotene

Question 42

The _____ stage of prophase I of spermatogenesis is where chromosome movement occurs lining the four chromatids up next to and even on top of each other along their axis in a process called _____.

Answer 42

1. zygotene

2. synapsis

Question 43

In the _____ stage of prophase I of spermatogenesis, the chromatids line up length wise and exchange genetic material from both maternal and paternal genes with a shuffling of genetic material through breaks and rearrangements in an exchange called _____ _____.

Answer 43

1. pachytene

2. crossing over

Question 44

In the _____ state of prophase I of spermatogenesis, the recombined chromosome pairs now separate, but the chromatids for each chromosome remain connected.

Answer 44

diplotene

Question 45

During _____ of prophase I of spermatogenesis, the 46 chromosomes are coiled very compactly, the nuclear membrane disperses and they move into the cytoplasm.

Answer 45

diakinesis

Question 46

The homologous chromosome pairs move to the center of the spindle area of each cell where spindle fibers form and attach to each chromosome during _____.

Answer 46

metaphase I

Question 47

Complete separate of the chromosome pairs (not the chromatids) occurs during _____, resulting in two secondary spermatocytes that are now haploid for chromosome number and diploid for DNA content.

Answer 47

anaphase I

Question 48

In _____, the coiled single chromosomes (with 2 chromatids) in each secondary spermatocyte relax and will enter meiosis II without further DNA synthesis or replication.

Answer 48

telophase I

Question 49

_____ resembles mitosis and the chromatids segregate independently to produce four spermatids that are haploid for both chromosome number and DNA content.

Answer 49

Meiosis II

Question 50

Spermatids at the end of meiosis II are genetically correct, but not yet mature _____ capable of fertilizing an ovum.

Answer 50

gametes

Question 51

To mature over about a 2 month period, spermatids lose most of their cytoplasm, condensing the nucleus, develop a functional tail (flagellum), acquire the acrosomal material and cap, and are stored in the tubular environment just outside the testes called the _____.

Answer 51

epididymis

Question 52

The final result o normal, complete spermatogenesis from one spermatogonium is the generation of ____ (#) haploid spermatocytes, with two having 22 autosomes and one _____, and two having 22 autosomes and one _____.

Answer 52

1. 4
2. X
3. Y

Question 53

In the _____ stage of oogenesis, the four chromatids per chromosome pair lengthen rather than contract, and the nucleus becomes quite large.

Answer 53

diplotene

Question 54

The _____ stage of meiosis I is arrested for a prolonged period of time during oogenesis.

Answer 54

prophase I

Question 55

By birth, most female infants have about a million primary oocytes trapped in meiosis I in both ovaries, and no further proliferation of these cells occur until puberty. At puberty, only about _____ (#) oocytes remain from regression and degeneration.

Answer 55

40,000

Question 56

Complete separation of the chromosome pairs (not the chromatids like in spermatogenesis) occur during _____.

Answer 56

anaphase I

Question 57

_____ of the secondary oocyte occurs only if fertilization takes place.

Answer 57

Meiosis II

Question 58

The mature ovum has a plasma membrane that is surrounded by a thicker membrane , the _____ _____, and a layer of follicle cells within a “shell” that also contains a gelatinous fluid.

Answer 58

zona pellucida

Question 59

At ovulation, this entire mature ovum and its shell are released from the ovary. The shell separates from the ovum, although some follicular cells remain, surrounding the ovum like a halo known as the _____ _____.

Answer 59

corona radiata

Question 60

The _____ area of the sperm head contains enzymes that allow the corona radiata to be penetrated and then this area falls off of the sperm

Answer 60

acrosomal

Question 61

A _____ is a single diiid cell formed as a result of fertilization that is capable of developing into a multi celled embryo.

Answer 61

zygote