Unit 7 Lesson 6: Gene Expression Flashcards
Body cells all reproduce by the process of
mitosis
How do cells replicate
That means that when your cells replicate, they do so by making identical copies of all their genetic material.
A parent cell becomes
two identical daughter cells
Every cell in your body contains exactly the same genetic information, so how do cells differ
but your cells differ in appearance and function. Your blood cells, for instance, look nothing like your skin cells.
What is the state of cells right after mitosis
Just after mitosis, all replicated cells are the same and share the same function.
. The increase in number of cells by replication is called
proliferation
When cells become more specialized, that is known as
differentiation, or differential gene expression.
differential gene expression
the process by which different genes in a cell activate during specialization
After mitosis, a cell that is not specialized will undergo what to gcome more specialzied
gene expression
gene expression
the process in which instructions in DNA are used to produce a protein or other functional product
In molecular biology, the cell cycle is the sequence of events that happen during
cell replication and division.
In molecular biology, the cell cycle is the sequence of events that happen during cell replication and division. Describe it. Mitosis, Gap , gap 1. When id synthsis ready to begin
Mitosis (M) in a parent cell results in two genetically identical daughter cells. This is followed by a gap ( G1
) that gives the cell time to rest from replication and grow in preparation for another cycle. When growth is complete, the cell passes the G1
checkpoint, which assures it has reached the correct size to begin synthesis
What is sythesis
Synthesis (S), the period in which the cell’s genetic information is copied within its nucleus, begins. Another gap ( G2
) follows, and then mitosis. As mitosis starts, the cell is said to have cycled. This may continue until the cell reaches senescence and loses its ability to replicate.
In G0
, the cell leaves the cycle. Why might this happen
This can sometimes happen in order to give a cell a rest period before replication restarts. Cells may also leave the cycle permanently to serve a particular function.
terminal differentiation
cells that exit the cell cycle to provide a particular function and can no longer divide
what kind of cells are stem cells
Stem cells are undifferentiated cells.
What are stem cells able to do
They are able to proliferate and can also give rise to more specialized kinds of cells.
A stem cell’s ability to differentiate into certain kinds of specialized cells depends on its
type
What may happen when a celll differentiates
When a cell differentiates, it may change in size, shape, and function. Cells change these aspects through gene expression.
Think of DNA as your cells’ college course catalog. Elaborate
Every cell will take some courses from the catalog, but very few cells have the ability or need to take all of them. A cell’s function is determined by the portion of DNA that it reads. By turning on or off the parts of the DNA script that are read, stem cells give rise to cells of various functions. On the college campus, all students belong to the college, but they do not all do the same things. Cellular differentiation works in a similar fashion.
Totipotent cells
Totipotent cells are the first cells to arise in a developing embryo. They are only present at the beginning of an organism’s development. Think of totipotent cells as students who have just been accepted at a college. The students have not declared a major and can take any course they want. At this college, they aren’t limited to living in the dorms. Totipotent cells are able to differentiate into any cell type the growing embryo needs and may also become extraembryonic (outside of the embryo) placental cells. These cells aid in the development of the embryo and provide functions such as waste removal and providing nutrition.
Pluripotent cells
Pluripotent cells are the second type of stem cell to develop in an embryo. Sometimes they are simply called embryonic stem cells. Pluripotent cells are precursors to the tissues that will be formed in a growing embryo. These cells are like students living in the dorms, but they haven’t decided on a major. They might still become anything. A pluripotent cell can differentiate into any cell type within the body but cannot become extraembryonic. This means that these cells cannot fully support the development of the embryo on its own.
Multipotent cells
Multipotent cells make up most adult stem cells. Think of them as being like students who have declared their majors, but they can still take many different classes within their fields. A multipotent stem cell can become many different types of specialized cells within a tissue or organ, such as lymphocytes, epithelial cells, or blood cells. In some parts of the body, such as the intestinal tract, multipotent stem cells divide regularly to repair aged or damaged tissues.
Oligopotent cells
Oligopotent cells are a class of multipotent stem cells that can become many different types of specialized cell within a tissue or organ, but their ability to differentiate is limited by location. Within the bone marrow, for instance, hematopoietic stem cells differentiate into the different kinds of blood cells, while nonhematopoietic become tissues.
oligopotent cells direct meaning
type of multipotent cells that can differentiate into many types of specialized cells but are limited by location
A cell’s specific developmental program for specialization is called its
cell fate
When does cell fate happen
Cell fate happens when a cell differentiates into a specialized type of cell, such as a liver or muscle cell.
what is a expressed gene
A gene segment that is activated to determine a cell’s fate is called an expressed gene
What causes a gene to become expressed?
Various environmental factors affect the type of gene expression that occurs.
How does temperature affect corrdicles
Temperature, for example, at which crocodile and turtle eggs are incubated determines which sex the embryo becomes.
Other environmental factors that have been shown to influence gene expression include:
- pH of the environment
- infection
- nutrition
- light
- oxygen level
First step of gene expression transcripation. describe
Transcription – The first step of gene expression occurs within the nucleus. The DNA helix unwinds, and parts of it are transcribed (read) to produce strands of RNA (ribonucleic acid). The new RNA strands contain all the information that the cell will use in differentiation. Though RNA is an exact copy of a DNA section, not all the DNA from a section is always needed for gene expression. After the RNA forms, it goes through a process to remove unneeded (non-coding) DNA and to connect the sections of DNA that will code its differentiation. This process is called splicing. The spliced RNA, ready to control the type of cell differentiation, is called mRNA (messenger RNA). These strands of mRNA then travel out of the nucleus into the cytoplasm.
Second step of gene expression translation. describe
Translation – The second step of gene expression usually occurs in the cytoplasm. An mRNA molecule attaches to a ribosome. The ribosomes then make chains of amino acids by translating the information (types and arrangement of molecules) carried by the mRNA. The chains of amino acids are then combined into long strands to form proteins.
Thrid step of gene expression folding. describe
Folding – The final step of gene expression is folding of the proteins into complex ribbons and strands. This step is important because without folding the proteins would not be useful in the body. It is the folded proteins that the ribosomes make that determine a cell’s function.
Can a cell replicate during differentiation
A cell may be able to replicate itself during differentiation—the process by which less specialized cells become more specialized.
What is the role of some differentiated cells
Some differentiated cells repair and maintain body functions.
Can all differetinared cells replicate and can all cel profilferate often
Not all differentiated cells are able to replicate, however, and some cannot proliferate often.
What does it mena when a cell is in a state of senescence
When a cell is unable to replicate any longer, it is in a state of senescence. In senescence, cellular reproduction stops.
When do cells proliferate
Different kinds of cells have different time periods during which they can proliferate.
Diufference in senescence in cells
Some cells become senescent almost immediately upon differentiation. Others may proliferate for long periods before senescence sets in.
When cells stop proliferating, they are considered to
have left the cell cycle.
What does terminal differentiation
A cell that is no longer able to replicate has undergone terminal differentiation.
What are examples of body parts that are terminall differentiation
Heart and neural cells are examples of cells that have undergone terminal differentiation.
Describe cell activity during the G1 phase and how it relates to mitosis and differentiation.
During the G1 phase, the cell rests from replication while it grows. G1 happens after mitosis but before differentiation. A cell that remains in the cell cycle will continue on to sequencing, and subsequently back to mitosis, while a cell that exits the cycle to begin the G0 phase may then differentiate.
Bone marrow cells are considered oligopotent cells and can be transplanted to treat certain types of cancer. Why might bone marrow cells be especially useful for treating certain types of cancer as well as other blood and immune system diseases? Why do you think bone marrow cells might be considered more useful than pluripotent cells?
Hematopoietic cells that can differentiate into any kind of blood cell can more easily replace a diseased blood supply. Nonhematopoietic cells can repair different sorts of damage and allow healthy new growth. Because oligopotent bone marrow cells can become only certain kinds of differentiated cells, they may be more useful than pluripotent cells in which inducing differentiation might leave more chance of error.
What is formed during gene expression?
Different types of proteins are formed to initiate gene expression. The type of specialized cells that are produced depends on the type of protein that activates them.
In tereating cell damage why doesnt neural stem cells work
Treating cell damage is one of the trickiest parts of medicine. If cell damage causes hearing loss, doctors have traditionally found that loss to be incurable. Neural stem cells hold some promise of helping with cochlear repair, but inducing them to differentiate is difficult and continues to be tested to develop a safe and effective transplant process.
How might scienstist use ginkgo biloba to help with cell damage
ginkgo biloba, an extract made from the ginkgo tree, to stimulate new growth of cochlear neural stem cells in mice. The ginkgo biloba leaf contains several unique compounds such as an organic compound called ginkgolide.
Ginkgolide A shows
promise as a treatment for inflammation.
Ginkgolide B is a component in
migraine remedies and is also used to treat disease relating to the brain and its blood vessels.
Ginkgolide C has been shown to im
improve blood flow. Ginkgolide C also is known to protect blood cells from damage.
