Early Embryonic Cell Biology Flashcards
Early embryonic cells more resemble _____ cells in their growth patterns.
cancer
_____ means without a specific shape (morphology) or differentiation.
Anaplastic
Early embryonic cells are _____ in appearance.
anaplastic
Early embryonic cells are small and rounded with a large _____-to_____ ratio.
- nuclear
2. cytoplasmic
The large size of the _____ indicates continuing DNA replication.
nucleus
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 _____.
- differentiation
2. pluripotency
As a result of very loose adherence to each other, early embryonic cells _____ within the early embryo.
migrate
Early embryonic cells share _____ with normal differentiated human cells, which is the only shared characteristic at this state.
diploidy
Early embryonic cells perform rapid and continuous cell division with a minimal amount of time spent in the _____ phase.
G (subscript 0)
Early embryonic cells have long _____ that do not shorten with each cell division.
telomeres
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.
commitment
At about day _____ (#) after conception, early embryonic cells each commit to a differentiation pathway and are no longer _____.
- 8
2. pluripotent
Selective gene _____ directs the normal growth and differentiation into specific body tissues and organs.
expression
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.
- 14
- toxins
- commitment
The unborn baby is an _____ from the 3rd week to the eighth week of pregnancy (days _____ through _____).
- embryo
- 15
- 60
The _____ stage is the most dangerous time for external or internal conditions to induce birth defects.
embryonic
The _____ stage is from week _____ (#) of pregnancy through birth.
- fetal
2. 9
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.
embryonic
_____ makes the edges of the palate sticky and is responsible for the palate halves to fuse within only a _____ (#) hour window.
- Apoptosis
2. 24
The hands and feet begin as paddles. The fingers and toes becoming separated is a result of regulated _____.
apoptosis
Although external conditions can influence how well development proceeds, _____ influences determine whether it proceeds.
genetic
_____ is the conversion of diploid germ cells into haploid gametes that are capable of uniting at conception.
Gametogenesis
_____ or _____ cell division is a special type of cell division in which the chromosome number per cell is reduced to half.
- Meiosis
2. meiotic
Meiosis only occurs in _____ cells.
germ
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 _____.
- haploid
2. diploid
At meiosis II, the _____ of each of the 23 chromosomes separate.
chromatids
Meiosis I and meiosis II produces two cells that are _____ for both chromosome number and DNA content.
haploid
_____ are immature male germ cells produced in the seminiferous tubules of the testes in late fetal development.
Spermatogonia
_____ is the conversion of the diploid spermatogonia into mature sperm that does not begin until puberty.
Spermatogenesis
In spermatogenesis, one diploid precursor cell can ultimately result in the formation of _____ (#) haploid sperm.
4
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.
- 1
2. 3
_____ begins at puberty and continues throughout the lifespan in a continuous process.
Spermatogenesis
_____ begins in fetal life and stops when menstruation stops in a cyclical process.
Oogenesis
In ______, completion of meiosis I and meiosis II takes days to weeks.
spermatogenesis
In _____, completion of meiosis I and meiosis II takes years and is not complete until after fertilization.
oogenesis
The primary spermatocyte is _____ with 23 pairs of chromosomes and enters _____ where cell division reduces the chromosome number with multiple stages or steps.
- diploid
2. meiosis I
The _____ phase for meiosis begins shortly after the S phase, and the _____ phase does not really exist for meiosis.
- M
2. G (subscript 2)
List the 4 stages of M phase during meiosis I:
- prophase I
- diakinesis
- metaphase I
- telophase I
During _____, the DNA of the replicated chromosomes continuously condenses.
prophase I
List the 3 stages during prophase I of meiosis I:
- leptotene stage
- zygotene stage
- pachytene stage
- diakinesis
The _____ stage of prophase I of spermatogenesis has the long, thin threads of the chromatids of each chromosome become looser and slightly unwind.
leptotene
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 _____.
- zygotene
2. synapsis
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 _____ _____.
- pachytene
2. crossing over
In the _____ state of prophase I of spermatogenesis, the recombined chromosome pairs now separate, but the chromatids for each chromosome remain connected.
diplotene
During _____ of prophase I of spermatogenesis, the 46 chromosomes are coiled very compactly, the nuclear membrane disperses and they move into the cytoplasm.
diakinesis
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 _____.
metaphase I
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.
anaphase I
In _____, the coiled single chromosomes (with 2 chromatids) in each secondary spermatocyte relax and will enter meiosis II without further DNA synthesis or replication.
telophase I
_____ resembles mitosis and the chromatids segregate independently to produce four spermatids that are haploid for both chromosome number and DNA content.
Meiosis II
Spermatids at the end of meiosis II are genetically correct, but not yet mature _____ capable of fertilizing an ovum.
gametes
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 _____.
epididymis
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 _____.
- 4
- X
- Y
In the _____ stage of oogenesis, the four chromatids per chromosome pair lengthen rather than contract, and the nucleus becomes quite large.
diplotene
The _____ stage of meiosis I is arrested for a prolonged period of time during oogenesis.
prophase I
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.
40,000
Complete separation of the chromosome pairs (not the chromatids like in spermatogenesis) occur during _____.
anaphase I
_____ of the secondary oocyte occurs only if fertilization takes place.
Meiosis II
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.
zona pellucida
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 _____ _____.
corona radiata
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
acrosomal
A _____ is a single diiid cell formed as a result of fertilization that is capable of developing into a multi celled embryo.
zygote
