UNIT 3.2: CELL CYCLE + CONTROLS OF CELL CYCLE Flashcards
Identify if euchromatin or heterochromatin:
Transcriptionally active
Euchromatin
Identify if euchromatin or heterochromatin:
DNA is loosely packed
Euchromatin
Identify if euchromatin or heterochromatin:
Actively present in prokaryotic and eukaryotic gene
Euchromatin
Identify if euchromatin or heterochromatin:
Genetically active
Euchromatin
Identify if euchromatin or heterochromatin:
Present at inner side of the nucleus
Euchromatin
Identify if euchromatin or heterochromatin:
Stained lighter
Euchromatin
Identify if euchromatin or heterochromatin:
Early replicative
Euchromatin
Identify if euchromatin or heterochromatin:
Aren’t sticky
Euchromatin
Identify if euchromatin or heterochromatin:
Allow gene to form a protein
Euchromatin
Identify if euchromatin or heterochromatin:
Low genetic density
Euchromatin
Identify if euchromatin or heterochromatin:
Consist 2-3% part of the genome
Euchromatin
Identify if euchromatin or heterochromatin:
Transcriptionally inactive
Heterochromatin
Identify if euchromatin or heterochromatin:
DNA is highly packed
Heterochromatin
Identify if euchromatin or heterochromatin:
Only present in eukaryotic genome
Heterochromatin
Identify if euchromatin or heterochromatin:
Genetically inactive
Heterochromatin
Identify if euchromatin or heterochromatin:
Present at nucleus perpiphery
Heterochromatin
Identify if euchromatin or heterochromatin:
Stained dark
Heterochromatin
Identify if euchromatin or heterochromatin:
Later replicative
Heterochromatin
Identify if euchromatin or heterochromatin:
Usually sticky
Heterochromatin
Identify if euchromatin or heterochromatin:
Regulates genetic integrity, and control gene expression
Heterochromatin
Identify if euchromatin or heterochromatin:
High genetic density
Heterochromatin
Identify if euchromatin or heterochromatin:
Consist 97% to 98% part of the genome
Heterochromatin
Identify the phase of interphase:
Each of the 46 chromosomes is duplicated by the cell
S Phase
Identify the phase of interphase:
Cellular contents, excluding the chromosomes are duplicated
G1 phase
Identify the phase of interphase:
The cell “double checks” the duplicated chromosomes for error, making any needed repairs
G2 phase
Checkpoints of the cell division is discovered by ___ in ___
Leland Hartwell and Ted Weinert
1988
Internal quality control mechanisms represented by biochemical pathways that control transition between cell-cycle stages
Checkpoints
Monitor and modulate the progression of cells in response to intracellular or environmental signals
Checkpoints
Defined as the failure to arrest the cell cycle before or at mitosis, resulting in aberrant chromosome segregation
Mitotic catastrophe
Caused by malfunction of cell cycle checkpoints and may lead to cell death and tumor cell development
Mitotic catastrophe
G1 phase lasts for ___
9 to 12 hours
Identify the phase of interphase:
Usually the longest and most variable phase of the cell cycle, and it begins at the end of M phase
G1 phase
Identify the phase of interphase:
The cell gathers nutrients and synthesizes RNA and proteins necessary for DNA synthesis and chromosome replication
G1 phase
Identify the phase of interphase:
Doubles/increases the volume of the cell
G1 phase
Monitors the integrity of newly replicated DNA
G1 DNA checkpoint
Sensitive to the size of the cell, the state of the cell’s physiologic processes, and its interactions with extracellular matrix
Restriction checkpoint
The restriction checkpoint is mediated by interactions between ___ and a family of ___ with ___
pRb
E2F
target promoters
Identify the phase of interphase:
DNA is replicated
S phase
S phase lasts for ___
7.5 to 10 hours
Identify the phase of interphase:
Chromosome replication is initiated at many different sites along the chromosomal DNA replicon
S phase
Checkpoint during the S phase
S DNA-damage checkpoint
G2 phase lasts for ___
3.5 to 4.5 hours
Identify the phase of interphase:
The cell prepares for cell division and examines its replicated DNA in preparation for cell division
G2 phase
Identify the phase of interphase:
Period of cell growth and reorganization of cytoplasmic organelles before entering the mitotic cycle
G2 phase
Checkpoints during the G2 phase
G2 DNA-damage checkpoint
Unreplicated-DNA checkpoint
M phase lasts for ___
about 1 hour
Division of the nucleus
Karyokinesis
Division of the cell
Cytokinesis
Checkpoints during the mitosis
Spindle-assembly checkpoint
Chromosome-segregation checkpoint
Resting phase
G0 phase
The activation of G0 phase may occur in what instances?
- normal wound healing
- repopulation of seminiferous epithelium after intense acute exposure of the testis to X-irradiation
- regeneration of an organ, such as the liver, after removal of a major portion
Reversibly growth-arrested cells that can regrow
Quiescent cells
Cells that cannot be induced to proliferate by means of growth factor stimulation of transduction of cellular oncogenes
Terminally differentiated cells
Identify the differentiation potential:
Zygote
Totipotent
Identify the differentiation potential:
Embryonic stem cells
Induced stem cells
Pluripotent
Identify the differentiation potential:
Amniotic fluid stem cells
Mesenchymal stem cells
Hematopoietic stem cells
Amniotic epithelial cells
Broadly multipotent/multipotent
Identify the differentiation potential:
Mesenchymal stem cells
Hematopoietic stem cells
Epithelial stem cells
Neural stem cells
Multipotent
Identify the differentiation potential:
Myeloid, lymphoid, osteogenic, cardiomyocyte, endothelial, hepatocyte, renal, neural, glial progenitor cells
Oligopotent/unipotent
Identify the differentiation potential:
Lymphocytes, erythrocytes, osteocytes, muscle cells, endothelial cells, hepatocytes, podocytes, neurons, astrocytes, oligodendrocytes
Terminally differentiated
A part of the ear derived from the mother
Otic capsule
Identify the phase of mitosis:
Replicated chromosomes condense and become visible
Prophase
Identify the phase of mitosis:
Sister chromatids are held together by the ring of proteins
Prophase
Ring of proteins that hold the sister chromatids during the prophase
Cohesins and centromere
Identify the phase of mitosis:
The nuclear envelope begins to disintegrate into small transport vesicles and resembles the sER
Prometaphase (late prophase)
Identify the phase of mitosis:
The nucleolus, which may still be present in some cells, also completely disappears
Prometaphase (late prophase)
A highly specialized protein complex called a ___ appears on each chromatid opposite to the centromere during the ___
Kinetochore
Prometaphase (late prophase)
Identify the phase of mitosis:
Begins as the mitotic spindle becomes organized around the MTOCs located at the opposite poles of the cell
Metaphase
MTOC means ___
Microtubule-organizing centers
Three types of tubules that organize during the metaphase
Astral microtubules
Polar microtubules
Kinetochore microtubules
___ and their associated motor proteins direct the movement of the chromosomes to a plane in the middle of the cell
Kinetochore microtubules
Motor proteins associated to the kinetochore microtubule
Dynein and kinesin
Motor protein associated to the kinetochore microtubule that move to the (-) end
Dynein
The center of the cell is the ___ (+/-) end
(-)
Motor protein associated to the kinetochore microtubule that moves to the (+) end
Kinesin
Identify the phase of mitosis:
Begins at the initial separation of sister chromatids
Anaphase
Responsible for anaphase
Cohesins
Microtubule-associated molecular motors (dyneins and kinesins)
The polymers that compose the mitotic spindle that has a vital role in mitosis
Microtubule
Identify the phase of mitosis:
Marked by the reconstitution of a nuclear envelope around the chromosomes at each pole
Telophase
Identify the phase of mitosis:
Chromosomes uncoil and become indistinct except at regions that will remain condensed in the interphase nucleus
Telophase
Identify the phase of mitosis:
Nucleoli reappear, and the cytoplasm divides to form two daughter cells
Telophase
An important protein during the telophase that consists of a very thin array of actin filaments
Contractile Ring
Responsible for the splitting of the cells during the telophase
Actomyosin ring (myosin II)
Where actomyosin ring is found
Cleavage furrow
The cell division that happens in germ cells
Meiosis
T/F: Cytoplasmic events during meiosis are the same in both sexes
F
T/F: Nuclear events during meiosis is different from male and female
F
During the ___ that precedes meiosis, DNA is replicated forming sister chromatids joined together by the centromere
S phase
During meiosis, the DNA content becomes ___, but chromosome number remains ___
4d
2n
T/F: after meiosis I, another interphase will happen to prepare the cell for meiosis II
F
Chromosome number is reduced from diploid to haploid
Reductional division (meiosis I)
The amount of DNA is reduced from 4d to 2d
Reductional division (meiosis I)
No DNA replication
Meiosis II
The number of chromosomes remains at 1n, although the amount of DNA represented by the number of chromatids is reduced to 1d
Meiosis II
Five stages of Prophase I
Leptotene
Zygotene
Pachytene
Diplotene
Diakinesis
Identify the phase in meiosis:
An extended phase in which pairing of homologous chromosomes, synapsis, and recombination of genetic material on homologous chromosomes is observed
Prophase I
Close association of homologous chromosomes
Synapsis
Identify the phase of prophase I:
Characterized by the condensation of chromatin and by the appearance of chromosomes
Leptotene
Means “thin ribbon”
Leptotene
Identify the phase of prophase I:
Sister chromatids also condense and become connected with each other by meiosis-specific cohesion complexes
Leptotene
Identify the phase of prophase I:
Pairing of homologous chromosomes of maternal and paternal origin is initiated
Leptotene
Identify the phase of prophase I:
Synapsis begins and continues throughout pachytene
Zygotene
Identify the phase of prophase I:
Formation of a synaptonemal complex
Zygotene
Identify the phase of prophase I:
Synapsis is complete
Pachytene
Identify the phase of prophase I:
“thick” stage
Pachytene
Identify the phase of prophase I:
Crossing over occurs early in this phase and involves transposition of DNA strands between two different chromosomes
Pachytene
Identify the phase of prophase I:
Early in this stage, the synaptonemal complex dissolved, and the chromosomes condense further
Diplotene
Identify the phase of prophase I:
Homologous chromosomes begin to separate from each other and appear to be connected by newly formed junctions between chromosomes
Diplotene
The junction between chromosomes during diplotene
Chiasmata
Identify the phase of prophase I:
Sister chromatids still remain closely associated with each other
Diplotene
Identify the phase of prophase I:
Homologous chromosomes condense and shorten to reach their maximum thickness
Diakinesis
Identify the phase of prophase I:
Nucleolus disappears
Diakinesis
The nucleolus disappears during diakinesis in preparation for ___
Further division
Identify the phase of prophase I:
Nuclear envelope disintegrates
Diakinesis
Identify the phase in meiosis:
Paired chromosomes are aligned at the equatorial plate with one member on either side
Metaphase I
Homologous chromosomes are still held together by chiasmata
Metaphase I
Identify the phase in meiosis:
Once the nuclear envelope has broken down, the spindle microtubules begin to interact with the chromosomes through the multilayered protein structure which is usually positioned near the centromere
Metaphase I
Identify the phase in meiosis:
The centromeres do not splite
Anaphase I and Telophase I
Identify the phase in meiosis:
The sister chromatids, held together by cohesin complexes and by the centromere, remain together
Anaphase I and Telophase I
Identify the phase in meiosis:
A maternal or paternal member of each homologous pair, now containing exchanged segments, moves to each pole
Anaphase I and Telophase I
Identify the phase in meiosis:
Genetic diversity
Anaphase I and Telophase I
Inactivated X chromosomes seen in female somatic cells present adjacent to the nuclear membrane
Barr body
Small, well-defined body which stains intensely with nuclear dyes
Barr body
Present in a large proportion of nuclei of female origin and absent in male nuclei
Barr body
The average size of a Barr body is estimated as ___
0.7 x 1.2 um
In Klinefelter’s syndrome, the number of Barr bodies in male is ___, and in female is ___
1
2
In a normal male, the number of Barr bodies is ___, while in female ___
0
1
pRb means ___
Retinoblastoma protein
Promotes the formation of Cdk inhibitor
p53
Scans DNA for any damage
p53
A powerful tumor suppressor gene
p53
Another suppressor gene aside from p53
pRb
Responsible for S DNA-damage checkpoint
Polymerase
___ oncogenes and ___ tumor suppressor gene lead to cancer
high
low
Tumor suppressor genes are also called ___
“gatekeepers”
“caretakers”
Code for proteins involved in regulating cell growth and differentiation
Proto-oncogenes
Code for proteins that help slow down cellular growth/promote apoptosis
Tumor suppressor genes
A small protein that induces the cell to begin cell division
Mitogen
A naturally occurring substance that is capable of stimulating the cell proliferation, wound healing, and cellular differentiation
Growth factor
Trigger the rate of cell division by removing intracellular molecular breaks that restrain the cell cycle progression in G1 in the cell cycle
Mitogen
Promote and increase in cell mass by triggering the synthesis and inhibiting the degradation of macromolecules
Growth factor
Mitogen mainly act upon the ___ phase
G1
Growth factor mainly act upon phase’s transition such as ___
G0 to G1
G1 to S
Identify the growth factor:
Mitogenic for vascular smooth muscle, fibroblasts
Platelet-derived growth factor
Identify the growth factor:
Mitogenic for most epithelial tissues, fibroblasts, endothelial cells
Epidermal growth factor
Identify the growth factor:
Mesenchymal and neural tissue mitogen
Fibroblast growth factor
Identify the growth factor:
Inhibits replication of most cells in vitro, including keratinocytes, endothelial cells, lymphocytes, and macrophages; may inhibit or stimulate fibroblasts
Transforming growth factor-beta
Identify the growth factor:
Mitogenic for endothelial cells, but not keratinocytes, smoot muscles, or fibroblast
Vascular endothelial growth factor
Caused by mutations in the ATM gene
A-T
Gene which encodes a protein of ATM protein
Ataxia Telangiectasia Mutated gene
Protein responsible for the coordination of cellular signaling pathways in response to DNA double strand breaks, oxidative stress and other genotoxic stress
Ataxia Telangiectasia Mutated protein
Identify the CDK for Cyclin D
CDK 4/6
Identify the CDK for Cyclin E
CDK 2
Identify the CDK for Cyclin A (S phase)
CDK 2
Identify the CDK for Cyclin A (G2 phase)
CDK 1
Identify the CDK for Cyclin B (M phase)
CDK 1
Occurs toward the end of growth phase I
Cell growth checkpoint
Checks whether the cell is big enough and has made the proper proteins for the synthesis phase
Cell growth checkpoint
If the cell is not ready yet, it goes through a ___ until it is ready to divide
Resting period (G0)
Occurs during the synthesis phase (S)
DNA synthesis checkpoint
Checks whether DNA has been replicated correctly
DNA synthesis checkpoint
Occurs during the mitosis phase
Mitosis checkpoint
Checks whether mitosis is complete
Mitosis checkpoint
An enzyme which prevents the sister chromatids to divide
Securin
