Cell Cycle Flashcards
MITOSIS
-is a process of cell division resulting in _ genetically (equivalent or not?) daughter cells.
2
Equivalent
All body cells divide by ____
mitosis
the germ cells divide by _____ to produce ____
meiosis
gametes.
The period between 2 cycles of mitosis is called the _____ which covers the __,___,and___phases of cell cycle
interphase
G1, S, & G2
-the cell spends most of its life in the ___ phase of the interphase to make ___and ____
G1
organelles and proteins
During the ___ phase,the ‘_____’ phase, DNA is replicated from ___pairs to ____ pairs
S
Synthesis
23
46
During the G2phase, DNA has been replicated and the chromosome number is _n from the S phase so it just prepares for mitosis and makes _____ and Shii
4
mictotubules
In the interphase, chromosomes are (visible or not visible?) by light microscopy because_______
Not visible
chromatin diffuses throughout the nucleus
Mitosis ends with 2 identical cells (2n)
T/F
T
Prophase of mitosis
- Each chromosome is made of two genetically identical ____, joined by a ____.
- During Dna replication , genetic material is (loosely or tightly?) packed as ____.
chromatids
centromere
Tightly
chromatin
However, during mitosisDNA needs to be more tightly packed to allow for easier separation in telophase.
T/F
F
Anaphase
At the start of prophase of mitosis, chromatin begins condensing into chromosomes.
T/F
T
At the prophase of mitosis,
mitotic spindles begin to form.
T/F
T
Mitotic spindles are structures made from _____ that aid in the organisation and arrangement of ______.
-The spindles attach to an organelle known as the _______.
microtubules
chromosomes
centrosome
Each cell in mitosis has one centrosome
T/F
F
2
during prophase of mitosis, the centrosomes begin to move in opposite directions.
T/F
T
Prometaphase of mitosis
-In this stage the chromosomes are still condensing into their compact state.
T/F
F
They’ve finished
In prometaphase of mitosis ,The nuclear envelope begins to breakdown, allowingspindle fibres to attach to the chromosomes at a site called the ______
-The sister chromatids are attached to ____ that originate from the opposite _____, linking the two together.
kinetochore
spindles
centrosome
kinetochore is an area of the_____ found on each sister chromatid
centromere
kinetochore microtubules invade_____ and attach to_____
-polar microtubules push against each other , moving ____ apart
nuclear space; kinetochores
centrosome
Metaphase of mitosis
-At this stage, the chromosomes align upon a theoretical line known as the ______.
metaphase plate
In Metaphase of mitosis , The centrosomes have finished moving and are located at opposite ends of the cell.
T/F
T
In metaphase of mitosis
At this stage, the cell will check that all the chromosomes are aligned along the metaphase plate, with their kinetochores correctly attached.
T/F
At this stage, the cell will check that all the chromosomes are aligned along the metaphase plate, with their kinetochores correctly attached.
- This helps to ensure sister chromatids are split evenly between the two daughter cells.
- An error in chromosomal alignment or spindle attachment will result in the cell halting further progress until the problem is fixed.
Anaphase
- During this stage, sister chromatids are pulled to opposite ends of the cell.
- The spindle fibres contract, breaking the chromatids at the centromere and moving them to opposite poles of the cell.
- Spindle fibres not attached to chromatids will elongate the cell to prepare it for division.
Telophase
- In this phase the cell has elongated and is nearly finished dividing.
- Cell-like features begin to reappear such as reformation of two nuclei (one for each cell).
- The chromosomes decondense and the mitotic spindles fibres are broken down
Cytokinesis
- is the division of the cytoplasm to form two new cells.
- This stage actually begins between anaphase and telophase, however doesn’t finish until after telophase.
- To separate the two cells, a ring of protein (actin ring) pinches the cytoplasm along a crease known as a cleavage furrow.
- This splits the cytoplasm equally between the two cells.
An error in chromosomal alignment or spindle attachment will result in the cell undergoing further progress while the problem is fixed.
T/F
F
Progress is halted till error is fixed
Anaphase of mitosis
- During this stage,______ are pulled to opposite ends of the cell.
- The spindle fibres (contract or relax?) , breaking the _____ at the ______ and moving them to opposite poles of the cell.
sister chromatids
Contract
chromatids
centromere
In anaphase of mitosis
Spindle fibres not attached to chromatids will ____ the cell to prepare it for____.
elongate
division
Telophase of mitosis
- In this phase the cell has elongated and is nearly finished dividing.
- Cell-like features begin to reappear such as reformation of two nuclei (one for each cell).
- The chromosomes _____ and the mitotic spindles fibres are ______
decondense
broken down
Cytokinesis of mitosis
- is the division of the cytoplasm to form two new cells.
- This stage actually begins between ____and____, however doesn’t finish until after_____.
- To separate the two cells, a ring of protein (____ ring) pinches the cytoplasm along a crease known as a _____
- This splits the cytoplasm equally between the two cells.
anaphase and telophase
telophase
actin
cleavage furrow.
MEIOSIS
- Special type of cell division resulting in _ genetically (equivalent or not?) daughter cells
- each containing ____ the number of chromosomes of the parent cell.
4
Not
half
Germ cells (eggs & sperm) are produced by ____.
meiosis
Meiosis produces cells with half chromosomes = ____(sperm & egg -____)
-Fertilization(sperm + egg)=____ chromosomes
23
haploid
46
Prophase I of meiosis 1
- Chromosomes ___
- SYNAPSIS - ____PAIR together =_____
- CROSSOVER -exchange occurs at a____.
- 5 substages :____,______,_____,_____,____
condense
homologs
tetrad
chiasma
Leptotene Zygotene Pachytene Diplotene Diakinesis
Leptotene: individual chromosomes, each consisting of two replicated sister chromatids , become “ ______ “ to form ____ strands within the_____
Zygotene: In this stage the homologous chromosomes become much more ____ and _____(a process called _____)
individualized ; visible; nucleus.
closely and stably paired
synapsis
Pachytene: In this stage ____ recombination, including chromosomal crossover (crossing over), is _____
homologous
completed
In Diplotene, homologous chromosomes separate from one another totally
T/F
F
Only a little
Diplotene:the homologous chromosomes of each bivalent remain tightly bound at _____, the regions where _____ occurred.
Diakenesis: first point in meiosis where the ____ parts of the tetrads are actually____. Resembles _____ of mitosis
chiasmata
crossing-over
four; visible; prometaphase
Metaphase I of meosis 1
- chromosomes align at ____
- Maternal and paternal versions of (different or the same chromosome?) (____ chromosomes) align along the equator of the cell.
- A process called _____occurs
equator
The same
homologous
independentassortment
Independent assortment of genes is when maternal and paternal chromosomes line up predictably and align themselves on either side of the equator.
T/F
F
It’s random
Anaphase I of meiosis 1
- chromosomes migrate toward _____
- Here, each of the _____ get pulled towards opposite poles of the cell as the spindle fibres retract.
- This equally divides the DNA between the two cells which will be formed.
poles
homologous chromosomes
Telophase I
- chromosome at poles -cell domains separate.
- the nuclear envelope ____ and spindle fibres______.
reforms
disappear
In cytokinesis I, the cytoplasm and cell divides resulting in two cells that are technically ____ – there is___ chromosome and ____ chromatids for each chromosome (2c, n).
haploid
one
two
STILL ON MEIOSIS
- After the 1stdivision, the chromosome number in each daughter cell becomes _n.
- The process of the 2nddivision is the same as in mitosis except that there is no ____ during the_____.
- As a result, the produced cell is a _____ (_n).
2
DNA replication
interphase
haploid; 1
meiosis 2 is Similar to mitosis[but without ___ phase].
-it Separates ____ of one ____ of the ____ pair just as is in mitosis.
An S
chromatids
homolog
homologous
In human oocyte, MI is completed during b4 ovulation.
T/F
F
It’s completed shortly before
Once secondary oocyte shows _____, ovulation occurs.
spindle
In oocyte,M2 is completed @ _____
fertilization.
Gametogenesis is the _____ formation by _____
- Spermatogenesis is ____ formation (1N)
- Oogenesis is ____ formation (1N)
Gamete
Meiosis
Sperm
Egg
Spermatogenesis
-The approximate __-day cycle of the spermatogenesis can be subdivided into __ phases that last different lengths of time
74
4
Mitosis of the spermatogonia takes ____ days and reaches the point of _______
Meiosis 1 of spermatogenesis takes ____ days and reaches the point of _______
Meiosis 2 of spermatogenesis takes ____ days and reaches the point of _______
Spermiogenesis takes ____ days and reaches the point of _______
20; primary spermatocyte
28; secondary soermatocyte
Few hours ; engendering the spermatids
21-24 days ; competed sperm cells
Spermatozoon
- Capacitation:
- these are physiological changes that spermatozoa must undergo in order to______
have the ability to penetrate and fertilize an egg.
Capacitation of spermatozoon is The final step in the maturation of mammalian spermatozoa and is required to render them competent to fertilize an oocyte
T/F
F
It’s the penultimate step
Ovum
-secondary oocyte arrested at ___phase in the ______ division
meta
second meiotic
Process of fertilization
- Sperm bind to sperm-receptor called ‘_____’ to induce _____ reaction
- then ____ reaction occurs : degrade ____, alteration of ____ to create a ____ for further sperm penetration
- once this is happening, The second meiotic division of the secondary oocyte is (slowly or rapidly?) completed and the ____ body is released, leaving a haploid female nucleus
ZP-3
Acrosome
Zona
ZP-3; zona
barrier
Rapidly
second polar
Acrosome reaction is the release of _______
acrosomal enzyme
Cortical granules of an ovum are _____and____organelles (found within oocytes and are most associated with _____ prevention after the event of ______
regulatory and secretory
polyspermy
fertilization
perivitelline space is the space between the ____ and the _____ of an oocyte or fertilized ovum.
zona pellucida
cell membrane
Process of fertilization
- fusion of the membrane of ____ and _____
- nucleus of ____ penetrate into ovum
- formation of ____
- fusion of ____
- takes about ___hrs
sperm and ovum
sperm
pronuclei
pronuclei
24
Conditions of fertilization
- Normal ovum
- Normal sperm
- ____numbers
- Certain time __-__h
- ____ reproductive tract
sufficient
12-24
Free
Consequences of fertilization
- Completion of ___ division
- Restores ____ number of chromosomes
- Variation of human species
- Sex determination
- Metabolic activation of oocyte
- Initiation of _____
M2
diploid
clevage
