Bio Cell Division, Cell Cycle Regulation, and Cell Differentiation


Terms in this set (...)

What is the 'limbo' period in which cells are not dividing called
The interphase
What is a chromatin
The coupled groups of DNA stuck in the nucleus
What is a nuclear envolpe
The surrounding area of a chromatin that during the prophase step disntegrates
Microtubules are for what
Microtubules give a cell structure and support
What is the first step of cell division
The prophase step where chromatin start condensing to the point that they become chromosomes split in two pairs that are connected each called chromatid . Each chromosome has a sister pair with the same DNA. The conjunction point of each chromosome is called a centrome.
What happens next in the prophase
Next the centrosomes start widening the cell in by pushing its borders. When this is happening the centrosomes are leaving microtubules connecting to each other side.
What is the next phase of mitosis
The metaphase which is the longest phase of cell division. During the metaphase the chromosomes start to connect with the microtubules at their centromeres. This step takes so long because small motor proteins are pushing each chromosome to match with the microtubules.
Describe the chromosomes formed during the phophase
The chromosomes formed have sister pairs connected with something called a centrome. These chromosomes are called sister chromatides.
What is the metaphase of mitosis
During the metaphase the centromers of the duplicated chromosomes line up in the middle of the cell and spindle fibers come to connect the chromosomes to either side of the cell.
What happens after the metaphase
The anaphase starts with the motor proteins pushing each chromosome pair into their separate chromosomes (as 2 were connected before each with 2 chromatids).
What phase happens after the splitting of each chromosome pair
The telophase where the two separated piles of chromosomes form back into their respective cells with the new organelles becoming chromatin again. The chromatin (who are on separate sides of the cell mass) split down the middle in what is called cytokinesis
What are the parts of the interphase
The G1, S, G2, and M stages
What happens in the G1 stage
The G1 stage is when a normal cell will grow until it reaches the point that life is no longer sustainable if it grows any further. At this point most cells will start the processes before mitosis and cytokineses. Other cells will stay at their maximum size (nerve, brain) and go into the G0 stage.
What happens in the S stage
During the S (synthesis) stage all DNA is replicated for the new cell. This replicated DNA is still in a loose chromatin state.
What happens in the G2 stage
During the G2 stage organelles, as well as molecules required for cell division, are replicated.
What is the M stage
The M stage is the name applied to cytokineses and mitosis
What is cytokinesis
Cytokineses is the stage of cell division when the cytoplasm is reproduced, however the specifics of this process is different for plants and animals.
What happens in cytokineses in animals cells
In animal cytokineses the plasma membrane is drawn in until it is pinched into two equal parts with their own organelles and nucleus.
What happens in plant cytokinesis
With the cell wall of plants being rigid pinching the cell is impossible. Instead organelles and two nuclesus are moved to either side of the cell and a cell plate forms between them.
What's cell differentiation?
The process where un-specialized cells become specialized.
What mass of cells do all organisms start as?
An embryo
What are three specializations for plant cells?
Root cells, Stem cells (actual stems), and leave cells
What is the purpose for specializing cells?
To allow cells to perform specific tasks.
What kind of organisms need differentiated cells?
Multicelluar organisms.
In some organisms how are the roles of most cells figured out?
By a cell's location during devolpment.
What is differentiation like in mammals?
The function of cells are determined by varying factors and at a certain point during the differentiation of cells these cells can no long differentiate.
What are stem cells?
Stem cells are un-specialized cells that differentiate into normal cells.
What are the first few cell division's offspring called and why are they special?
These cells are called totipotent and can form into any kind of specialized cell.
What happens after a few day of cell divisions in a human embryo?
A human embryo develops into a blastocyst, or a hollow ball of cells with the inside being called the inner cell mass.
What is the significance to the inner cell mass cells?
These cells are pluripotent, which means that they are capable of developing into most, but not all of specialized cells.
What are the two kinds of stem cells?
There are embryonic and adult stem cells.
Describe embryonic stem cells.
Embryonic stem cells come from the inner mass of the early embryo and are pluripotent. Embryonic stem cells have been proven to be able to grow into most cell types.
Describe adult stem cells.
Adult stem cells are multipotent and can grow into some cell types (less than pluripotent) and typically produce only cell types from the area it was obtained from.
What are some benefits of stem cell research?
Stem cells can allow for the use of undifferentiated cells to repair or replace damaged cells and tissues, which can cure diseases and health issues currently deadly; including heart attack, stroke, and spinal cord injury.
What are the ethical issues with stem cell research?
Most modern techniques for harvesting, or gathering, embryonic stem cells cause the destruction of the embryo (fetus).
What regulates the cell cycle?
Regulatory proteins found both inside and outside the cell.
How do these regulatory proteins work in say skin cells?
Skin cells have regulatory proteins turning on and off with the need for new cells. For example when an injury occurs these proteins are used to stimulate cell growth to heal the injury.
How is the healing of cells proportionate to the age of an organisms and amount of time an organism has been healed?
The older an organism is the longer a wound takes to heal. With a healing wound no matter the age of the organism the longer a wound has been healing the slower it will end up healing.
What are kinases?
Kinases are enzymes that transfer the phosphate group of ATP to a specialized molecule.
What are cyclins used for primarily and when are they necessary in cell division.
Cyclins are proteins that phosphorylate kinases allowing them to transfer the phosphate group. Cyclins are necessary for all parts of cell division.
When are kinases active and how does the increase in cyclins affect the activity of these kinases enzymes?
Kinases are active only when bonded to specific cyclin and the increase of said cyclins increase the activity of the kinases enzymes.
What is the other goal of mitotic cyclins?
Cyclins also have to activate enzymes that break down specific proteins used during mitosis like spindle fibers.
What are some examples of the enzymes that break down unnecessary proteins from cell division?
Ubiquitin; a peptide that marks unnecessary proteins to be broken down.
Proteosomes that break down proteins that are marked by ubiquitin.
What are the two major kinds of regulatory proteins?
Internal regulators that respond to events inside a cell and allow for the cell cycle to proceed only once certain processes have happened.

External regulators that respond to events outside the cell and speed up or slow down the cell cycle.
What is an example of an external regulator?
Growth factors are external regulators that stimulate growth and cell division and are most important during embryonic development and wound healing.
What is apoptosis and what role does it play in organism development (example).
Apoptosis is programmed cell death that place a role in the structure of tissues and organisms. An example is the webbing on the foot in a mouse that is killed during tissue development.
How do cancer cells kill someone with them?
Cancer cells divide uncontrollably and take valuable resources from healthy cells kill a cancer cells host.
What are the two pathways that inhibit cancer growth and what happens when they both fail?
Proto-oncogenes that promote cell division and tumor suppressors that inhibit cell division. With both of these off cancer cells form.
Why would these pathways fail?
Mutations in proto-oncogenes can cause them to change to oncogenes, or cancer genes.
What is a mass of uncontrollably dividing cells called?
A mass of said cells is called a tumor.
What are the kinds of tumors?
Benign or noncancerous and malignant or cancerous.
What is the spread of cancer cells called?
What causes the mutations that lead to cancer?
Sources found in our environment known as carcinogens like smoking, radiation, defective genes, and viral infections.
What are checkpoint controls?
Checkpoint controls are proteins that detect the mutation and halt the cell cycle such as p53. Damaged p53 genes are common in cancer cells.
What are the possible treatments for cancer?
Some localized tumors can be removed by surgery, others can be targeted with radiation, and chemotherapy is the use of compounds that kill or slow the growth of cancer cells along with other kinds of cells.