BIO140 Quiz Ch. 10
What happens during The G2 Checkpoint?
- Bars entry into the mitotic phase if certain conditions are not met. - The most important role of the G2 checkpoint is to ensure that all of the chromosomes have been replicated and that the replicated DNA is not damaged. - If the checkpoint mechanisms detect problems with the DNA, the cell cycle is halted and the cell attempts to either complete DNA replication or repair the damaged DNA.
What happens during metaphase? (3)
- Centrosomes begin pulling the chromosomes towards opposite ends of the cell. - Chromosomes to align in middle of cell on the metaphase plate - Metaphase checkpoint
What happens during the G1 Checkpoint? (5)
- Determines whether all conditions are favorable for cell division to proceed. - The cell irreversibly commits to the cell division process. - Cell size and protein reserves are assessed - External influences, such as growth factors, play a large role in carrying the cell past the G1 checkpoint. - There is a check for genomic DNA damage
To achieve the outcome of cloned offspring, what 2 steps are essential?
- Genomic DNA must be replicated and then allocated into the daughter cells - Cytoplasmic contents must also be divided to give both new cells the machinery to sustain life.
What happens during prometaphase? (4)
- Mitotic spindle continues to develop - Chromosomes become more condensed and discrete. - A kinetochore in the centromeric region of each sister chromatid - Mitotic spindle microtubules from opposite poles attach to each sister chromatid at the kinetochore
What happens during prophase? (4)
- Nuclear envelope dissociates into small vesicles - (Golgi apparatus & ER) fragment and disperse toward the periphery of the cell. - Nucleolus disappears. - Centrosomes begin to move to opposite poles of the cell.
What happens during/define the M checkpoint (4)
- Occurs near the end of the metaphase stage of karyokinesis. - Also known as the spindle checkpoint - Determines whether all the sister chromatids are correctly attached to the spindle microtubules. - the cycle will not proceed until the kinetochores of each pair of sister chromatids are firmly anchored to at least two spindle fibers arising from opposite poles of the cell.
What happens during telophase? (5)
- Prophase and prometaphase are reversed. - Nuclear membranes re-form around each set of chromatids at the poles of the cell - Nucleoli reappear - Spindle microtubules depolymerize. - Chromosomes unwind back into the expanded chromatin that is present during interphase.
The levels of _______________ fluctuate throughout the cell cycle in a predictable pattern. Also note the sharp decline of cyclin levels following _________________, as cyclin is degraded by cytoplasmic enzymes
- the four cyclin proteins - each checkpoint (the transition between phases of the cell cycle) See PPT 2 Slide 38
What happens during anaphase? (3)
-Replicated chromosomes are split by dissolving cohesion protein - Microtubules shorten - Change in chromatid shape (V-shape or Y-shape) as they are pulled back to opposite poles of the cell
The cytoplasm is usually divided during the mitotic phase, resulting in what?
2 daughter cells.
The human body has ____________ cells. Radioisotope studies show that _______ of the atoms in your body today will not be there in 1 years time. The body is constantly engaged in ______________.
60-100 trillion 98% turning over its cells
Blood type: It is possible to have two copies of the same gene sequence on both homologous chromosomes, with one on each (for example, ______________), or two different sequences, such as _______.
AA, BB, or OO AB
What is the G0 phase?
An inactive phase occurring when the cell exists the cell when cells are not actively preparing to divide.
In what phase of the cell is chromatin more prominent? In what phase of the cell can you see chromosomes?
Anaphase Prophase
What happens during cytokinesis (the physical splitting of 2 daughter cells) in animal cells as opposed to in plant cells?
Animal Cells: A ring of actin filaments forms at the metaphase plate. A cleavage furrow separated the daughter cells Plant Cells: Golgi vesicles coalesce at the former metaphase plate, forming a phragmoplast. A cell plate separated the daughter cells
_________________ often spreads through a bacterial colony through plasmid exchange.
Antibiotic resistance
Mature _____________ & _____________ stay in G0 permanently.
Cardiac cells & nerve cells
What is it called when crowding of cells may inhibit cell division?
Contact inhibition
Length of cell cycle varies by what 2 things? The length of the cell cycle is rapid in ________________, takes around 2-5 days for _________________, and a llife time for differentiated __________________
Developmental phase and cell type embryonic development epithelial cells cardiac and nerve cells
In the active, dephosphorylated state, Rb binds to proteins called transcription factors, most commonly, ______. Transcription factors "turn on" specific genes, allowing the production of proteins encoded by that gene.
E2F
The first stage of interphase is called the _______________. What happens during this phase?
G1 phase (first gap) Little change is visible from a microscopic aspect. However, the cell is quite active at the biochemical level. It is accumulating the building blocks of chromosomal DNA and the associated proteins. And accumulating sufficient energy reserves to complete the task of replicating each chromosome in the nucleus.
What are the 3 stages of interphase?
G1 phase (first gap) S Phase (Synthesis of DNA) G2 Phase (Second Gap)
In rapidly dividing human cells with a 24-hour cell cycle: G1 phase lasts ___________ S phase lasts ___________ G2 phase lasts ____________ M phase lasts ___________
G1 phase lasts ~9 hours S phase lasts ~10 hours G2 phase lasts ~4 1/2 hours M phase lasts ~1/2 hour.
The third phase of interphase is called _________________. What happens during this phase?
G2 Phase (Second Gap) The cell replenishes its energy stores and synthesizes proteins necessary for chromosome manipulation. Some cell organelles are duplicated The cytoskeleton is dismantled to provide resources for the mitotic phase. There may be additional cell growth during G2.
__________ are the functional units of chromosomes and determine specific characteristics by coding for specific proteins.
Genes
Matched pairs of chromosomes in a diploid organism are called "_________________" chromosomes The pairs are the same length and have specific nucleotide segments called _________ in exactly the same location, or locus.
Homologous genes
___________________ of cyclin proteins are triggered by both external and internal signals. After the cell moves to the next stage of the cell cycle, the cyclins that were active in the previous stage are ____________.
Increases in the concentration degraded
What is assessed at the G1 checkpoint? What is assessed at the G2 checkpoint? What is assessed at the M checkpoint?
Integrity of the DNA Proper chromosome duplication Attachment of each kinetochore to a spindle fiber See PPT2 Slide 31
In binary fission of prokaryotes, the process of cell division is simplified. ______________ is unnecessary because there is no nucleus and thus no need to direct one copy of the multiple chromosomes into each daughter cell.
Karyokinesis
What guarantees that kinetochores are properly attached to the mitotic spindle and that the chromosomes are aligned along the metaphase plate?
Metaphase checkpoint
During prophase, _________ will form the mitotic spindle extend between the centrosomes, pushing them farther apart as the microtubule fibers lengthen.
Microtubules
What have been identified in more than ½ of all human tumor cells?
Mutated p53 genes
To prevent defective cells from continuing to divide, there are 3 internal checkpoints. These checkpoints occur when?
Near the end of G1 At the G2/M transition During Metaphase
_______________ are smaller loops of DNA that are not essential for normal growth found in some prokaryotes. Bacteria can exchange these with other bacteria.
Plasmids
What are the stages of karyokinesis or mitosis?
Prophase, Prometaphase, Metaphase, Anaphase, Telophase, and Cytokinesis Study PPT 1 Slide 20
What happens to chromosomes during karyokinesis?
Prophase: Chromosomes condense and become visible Prometaphase: Chromosomes continue to condense Metaphase: Chromosomes are lined up at the metaphase plate. Each sister chromatid is attached to a spindle fiber originating from opposite poles Anaphase: Sister Chromatids now called chromosomes are pulled towards opposite poles Telophase: Chromosomes arrive at opposite poles and begin to decondense
What are genes that code for the positive cell cycle regulators?
Proto-oncogenes
What are the best known tumor suppressor genes?
Rb, p53, and p21
What is a common tumor suppressor protein in many cells? It halts the cell cycle and releases its hold in response to cell growth.
Retinoblastoma protein (Rb)
The second phase of interphase is called _________________. What happens during this phase?
S Phase (Synthesis of DNA) DNA replication proceeds and results in the formation of identical pairs of DNA molecules—sister chromatids—that are firmly attached to the centromeric region. The centrosome is duplicated during the S phase. The two centrosomes will give rise to the mitotic spindle, the apparatus that orchestrates the movement of chromosomes during mitosis. At the center of each animal cell, the centrosomes of animal cells are associated with a pair of rod-like objects, the centrioles, which are at right angles to each other. Centrioles help organize cell division. Centrioles are not present in the centrosomes of other eukaryotic species, such as plants and most fungi.
What is a multistep process during which the duplicated chromosomes are aligned, separated, and move into two new, identical daughter cells? The first portion of the mitotic phase is called _____________, or nuclear division. The second portion of the mitotic phase, called ______________, is the physical separation of the cytoplasmic components into the two daughter cells.
The Mitotic Phase karyokinesis cytokinesis http://openstaxcollege.org/l/Cell_cycle_mito
__________ are the variations of those characteristics. For example, hair color is a characteristic with these that are blonde, brown, or black.
Traits
The 23rd pair of chromosomes will either be _____ for female or ____ for male.
XX XY
A human, as well as every sexually reproducing organism, begins life as what?
a fertilized egg (embryo) or zygote
In bacterial cells, the genome consists of what?
a single, circular DNA chromosome
Prokaryotes, including bacteria and archaea, have _______________ located in a central region called the ___________.
a single, circular chromosome nucleoid
Over and over, small uncorrected errors are passed from the parent cell to the daughter cells and amplified. Eventually, the pace of the cell cycle speeds up as the effectiveness of the control and repair mechanisms decreases.Uncontrolled growth of the mutated cells outpaces the growth of normal cells in the area, and _____________ can result.
a tumor ("-oma")
Inherited abnormalities of tumor suppressor genes have been found in some family cancer syndromes. They cause certain types of cancer to run in families. Most tumor suppressor gene mutations are ________, not ___________.
acquired, inherited
Regulator molecules may act individually, or they can influence the activity or production of other regulatory proteins. The failure of a single regulator may have __________________ on the cell cycle, especially if more than one mechanism controls the same event. Conversely, the effect of a deficient or non-functioning regulator can be _________________ to the cell if multiple processes are affected.
almost no effect wide-ranging and possibly fatal
Genes can become oncogenes if they are mutated and cause the cell to become cancerous. An oncogene is any gene that, when altered, leads to what?
an increase in the rate of cell cycle progression
Prokaryotes, such as bacteria, propagate by _____________
binary fission
To become fully activated, a Cdk must _____________ and then be phosphorylated by _______________.
bind to a cyclin protein another kinase
When Rb is bound to E2F, production of proteins necessary for the G1/S transition is __________. As the cell increases in size, Rb is slowly phosphorylated until it becomes inactivated. Rb releases E2F, which can now turn on the gene that produces the transition protein, and this particular block is removed.
blocked
The occasional failure of regulation can have life-threatening consequences such as what?
cancer
A cell with an abnormal p53 protein cannot repair damaged DNA and thus cannot signal apoptosis. Cells with abnormal p53 can become ______________.
cancerous
All _____________ start when a gene mutation gives rise to a faulty protein that plays a key role in cell reproduction.
cancers
The ____________ is an orderly sequence of events that describes the stages of a cell's life from the division of a single parent cell to the production of two new daughter cells.
cell cycle
The nucleosomes are coiled into a 30-nm __________.
chromatin fiber
A method of staining called _________________ employs fluorescent dyes that highlight chromosomes in different colors.
chromosome painting
When a cell undergoes mitosis, the chromosomes do what?
condense even further http://openstaxcollege.org/l/Packaged_DN
There is a direct correlation between ________________ and the _________________
cyclin accumulation three major cell cycle checkpoints
What are the two groups of proteins that are responsible for the progress of the cell through the various checkpoints?
cyclins and cyclin-dependent kinases (Cdks)
An external event such as _____________ may serve as a trigger for regulation of the cell cycle
death of a nearby cell
Each copy of a homologous pair of chromosomes originates from a ___________________ The variation of individuals within a species is due to the specific combination of the genes inherited from both parents. Even a slightly altered sequence of nucleotides within a gene can result in an _____________.
different parent alternative trait
Human body (somatic) cells are ___________ and have 46 chromosomes or 23 pairs of chromosomes.
diploid (2n)
The original single cell is the ancestor of what? All multicellular organisms use __________ for growth and the maintenance and repair of cells and tissues.
every other cell in the body cell division
A ______________ results if changes to the DNA nucleotide sequence occur within a coding
gene mutation
A checkpoint is a place in the cell cycle where the progression of the cell to the next stage can be _____________ until conditions are favorable
halted
Human eggs and sperm (gametes, or sex cells) are designated 1n, or ___________, and contain 23 chromosomes
haploid
Daughter cells should be an ______________ of the parent cell
identical copy
Timing of the cell cycle is controlled by what?
internal and external events
The cell undergoes normal growth processes while also preparing for cell division. Throughout ___________, nuclear DNA remains in a semi-condensed chromatin configuration
interphase
During _____________, the cell grows and the nuclear DNA is duplicated. During ______________, the duplicated chromosomes are segregated and distributed into daughter nuclei.
interphase the mitotic phase
The cell cycle consists of what 2 phases?
interphase and the mitotic phase
The chromosomes in a somatic cell are viewed within the nucleus, removed from a cell in mitosis and spread out on a slide, and artificially arranged according to length. An arrangement like this is called a ________________
karyotype
A _________________ may inhibit cell division resulting in dwarfism. An _________________ can result in giantism
lack of human growth hormone (HGH) over-production of HGH
The role of normal p53 is to ___________________ (hypoxia is a condition of reduced oxygen supply). If damage is detected, p53 ________________. If repairs are unsuccessful, p53 signals _________________.
monitor DNA and the supply of oxygen triggers repair mechanisms apoptosis (programmed cell death)
Minor variations of traits, such as blood type, eye color, and handedness, contribute to the ________________ found within a species. However, if the entire DNA sequence from any pair of human homologous chromosomes is compared, the difference is less than __________.
natural variation 1%
Each species of eukaryotes has a characteristic number of chromosomes in the ____________ of its cells. The letter n is used to represent what?
nuclei a single set of chromosomes
Double-stranded DNA wraps around histone proteins to form __________ that have the appearance of "beads on a string."
nucleosomes Study PPT 1 Slide 13
A variety of fibrous proteins are used to ________________. These fibrous proteins also ensure that each chromosome in a non-dividing cell occupies a particular area of the nucleus that does not overlap with that of any other chromosome
pack the chromatin
Cyclin-dependent kinases (Cdks) Protein kinases that, when fully activated, can _______________ and thus activate other proteins that advance the cell cycle past a checkpoint.
phosphorylate
2 groups of intracellular molecules that regulate the cell cycle. Either promote progress of the cell to the next phase (________________) or halt the cycle (____________________). For the cell to move past each of the checkpoints, all ____________ regulators must be "turned on," and all ____________ regulators must be "turned off."
positive regulation negative regulation positive, negative
Single-celled organisms use cell division as their method of what?
reproduction
What are the three possible gene sequences that exist on the human chromosome that code for blood type?
sequence A, sequence B, and sequence O.
In eukaryotes, the genome consists of what?
several double-stranded linear DNA molecules.
The sex chromosomes, X and Y, are the _____________ to the rule of homologous chromosome uniformity: Other than a small amount of homology that is necessary to accurately produce gametes, the genes found on the X and Y chromosomes are different
single exception
During prophase, The ________________ begin to coil more tightly with the aid of condensin proteins and become visible under a light microscope.
sister chromatids
Another factor initiating cell division is when the cell size increases to the point that it become inefficient due to what?
surface-to-volume ratio
One of the critical processes monitored is ________________. A small percentage of replication errors (mutations) will occur.
the proper replication of DNA during the S phase
Cell division is ____________ Trillions of cell divisions subsequently occur in a controlled manner to produce what?
tightly regulated a complex, multicellular human.
Molecules that prevent the full activation of Cdks are called Cdk inhibitors. The block placed on Cdks by inhibitor molecules will not be removed until what?
until the specific event that the inhibitor monitors is completed
Because all diploid human cells have two copies of the chromosome that determines blood type, the blood type (the trait) is determined by what?
which two versions of the marker gene are inherited