What is the process of the central dogma?
A cell's DNA is stored in the nucleus. This DNA is the blueprint of the cell; it tells the cell how to build all the things that it builds for itself. Sections of DNA are transcribed through RNA polymerase, producing a mRNA (messenger RNA). The mRNA is tr
Why is it important to know the process of the central dogma?
It is important because proteins are the main functional molecules of the cell, and the process of the central dogma explains how they form.
What are the evolutionary advantages to being multicellular (4)?
Multicellular organisms are larger, have a smaller S/V ratio, live longer than unicellular organisms, and can execute many more unique functions at once than a unicellular organism.
What is a ligand?
any molecule that binds specifically to a receptor site of another molecule
What is a receptor?
the site on a molecule at which a ligand binds
Why will a cell without a receptor not respond to a ligand?
If a ligand cannot connect to a receptor, cell signalling cannot occur (i.e. cells cannot receive a signal and enact a response).
What is a morphogen?
numerous signal molecules that control the processes of embryonic development
What is a zygote's role in embryonic development?
The sperm and egg, who each have half the necessary chromosomes to produce a full genome, fuse to form a zygote.
What is a morula's role in embryonic development?
The zygote divides rapidly, producing a ball of 16 cells known as a morula.
What is a blastula's role in embryonic development?
The morula hollows itself out in a process called blastulation, which results in a hollow blastocyst. The blastocyst consists of an inner cell mass, where the organism will develop, and the outer layer.
What is a gastrula's role in embryonic development?
The blastocyst inverts in on itself, with outer cells pushing into the space within the blastocyst, turning it into a gastrula.
What is implantation's role in embryonic development?
After gastrulation, the embryo implants in the uterine wall and undergoes the rest of development inside the mother (in mammals).
What is organogenesis's role in embryonic development?
Organogenesis is the slow process of organ development from newly formed germ layers. It proceeds until birth and afterwards (to a point).
What happens in between the steps of embryonic development? How does convergent extension contribute to the transitions between steps?
Convergent extension is used to reshape the embryo. Convergent extension works by cells rearranging themselves to change the length of a region of the embryo.
Specifically with gastrulation, how does this step organize the embryo? What are the three germ layers called? What tissues result from each of the individual germ layers?
Gastrulation differentiates your endoderm (skin and nerve tissue), mesoderm (muscle, bone marrow, urogenital system), and endoderm (soft tissue organs, interior of digestive tract).
What is the pharyngular stage? Why do biologists think it is so important?
The pharyngular stage is the best example of a point at which development is the same between species (all vertebrae embryos look really similar).
How did scientists characterize the morphogens necessary for development in the Heidelberg genetic screen? Explain what the researchers did to the flies in one sentence, what resulting issues they looked at, and what this change would say about the associ
Researchers in Germany deliberately introduced random mutations to flies and looked for mutations that inhibited development of the outside skin of the baby fly. They identified tons of mutations, and traced each back to its associated region in the genom
How can diffusion lead to the spread of morphogens in the embryo? What are the two methods by which target cells of diffused morphogens can have different responses to the same morphogen?
A lot of morphogens are distributed when they are secreted by cells and diffuse outward from there. The two methods by which target cells of diffused morphogens can have different responses to the same morphogen are differential regulation (having cells r
How does facilitated diffusion work?
A carrier protein is used to help ligand move through membrane to its target receptor.
How does direct cell-cell signaling work?
Direct cell-cell signaling involves a cell sending a signal by directly touching the target cell.
What are the advantages and disadvantages of these two methods of signaling when compared to diffusion?
Facilitated diffusion costs energy, but is much more targeted than normal diffusion. Direct cell-cell signalling is very short-range, but allows for fine targeting of signals.
How do the three different methods of delivering ligands each establish tight patterns?
They use structures called cytonemes, which are hair-like membrane protrusions that reach out to deliver signalling ligands to target cells.
What is a teratoma?
a tumor that contains multiple different kinds of tissue
How did Kiera Echols's teratoma cause her brain to be attacked by her immune system?
Her teratoma contained a significant amount of brain tissue that was triggering her immune system.
What is a stem cell?
a single cell that can replicate itself or differentiate into many cell types
What is multipotency?
Multipotent cells can develop into more than one cell type (but are more limited than totipotent cells).
What does it mean to be totipotent?
have the potential to differentiate into any cell type
What are epigenetics?
regulation of genetic expression by factors other than the DNA
What is a stem cell niche?
The microenvironment around a stem cell that cause it to form a particular tissue
How can chromatin be arranged to either allow or block the transcription of a gene?
Genes are turned "on" or "off" by markers on nearby histones, which designate them to either open chromatin or closed chromatin.
What is "epigenetic silencing"?
Adult stem cells are terminally differentiated, and usually can't produce daughters of a different identity - the genes necessary for these behaviors are "epigenetically silenced".
What is asymmetric division?
stem cells divide so that one daughter cell is a stem cell and the other is not
How can asymmetric division lead to the production of two daughters with different functions?
Stem cells segregate cell fate determinants into only one of the two daughter cells.
How do stem cells use daughter cells to self renew, maintaining their population within a tissue?
One of the two daughter cells is a stem cell, which preserves the stem population.
Explain the hierarchy of epithelial tissues (stem cell -> transit amplifying cell -> adult cell).
Stem cells divide into stem cells and transit-amplifying cells, which divide into adult cells.
Which of these cells (stem cell, transit amplifying cell, adult cell) does the most dividing?
Transit amplifying cells do the most dividing.
Which of these cells (stem cell, transit amplifying cell, adult cell) is capable of self-renewing indefinitely?
Stem cells are capable of self-renewing indefinitely.
What did the Yamanaka lab do to transform normal adult cells into stem cells?
They forced the cells to express 24 different genes simultaneously that were thought to be involved in the stem cell phenotype, then (after achieving the stem cell behaviors they wanted) removed factors from the 24 total factors until they found the remai
What are the four factors the Yamanaka lab used to transform normal adult cells into stem cells? What are these factors generally referred to as?
Sox2, Oct4, Kif4, Myc (induced pluripotent stem cells)
What is cancer?
the aberrant outgrowth of tissue/proliferation of cells
What are the outgrowths cancer produces called?
tumors (ectopic tissue growth make of cancerous cells)
When is cancer at its most dangerous?
during metastasis (when cells from your primary tumor flow through your bloodstream to other organs)
Why is cancer that returns after initial treatment resistant to that treatment?
Tumors evolve like animals do, and surviving cells are those who are most resistant to treatment.
Name at least two ways in which stem cells and cancer cells are similar.
Both have the ability to divide and to produce other cells of the same type.
What three factors do scientists conducting experiments relevant to human biology have to consider?
cost, ethics, scientific value
What is heartburn?
when the gastric juices backflow into the esophagus (medical term: angina)
What are male symptoms of a heart attack?
chest pain, headache, indigestion, dizziness
Why are males the model for heart issues?
menstruation
What are the five symptoms of inflammation?
swelling, redness, heat, pain, and loss of motion
How are "warmth" and "redness" connected (in terms of inflammation)?
increased blood flow; vasodilation
What happens when you scratch an persistent itch (like a mosquito bite)?
Itching is often triggered by histamine, a chemical in the body associated with immune responses, and when you scratch the itch, more histamine is released, causing the itch to continue.
What is a phagocyte?
a white blood cell that engulfs and destroys pathogens by breaking them down (eater cell)
What is atherosclerosis?
hardening of the arteries
What is the medical description of atherosclerosis?
clogged inner lumen of arteries
What happens when you have a clogged artery leading to the heart? The brain?
heart attack; stroke
What are LDLs? Are they good or bad?
LDLs are good, until you have too many of them. Then they can be very bad.
What are HDLs? Are they good or bad?
HDLs are good, pretty much.
How can cholesterol be beneficial?
precursor for steroids, stiffens cell membrane
How do LDLs normally function? What happens when you accumulate too many LDLs?
LDLs typically leave the lumen and pass into the intima, where they are short-term residents. If there are too many LDLs, though, they become long-term residents, and the body attempts to oxidize them.
List three reasons your level of LDLs may increase.
food, genetics, age
List three ways you can fix your LDL levels.
changing lifestyle, changing diet, taking pills
How does inflammation work?
when certain white blood cells (those that usually constitute the first line of defense against infection) invade and become active in a tissue
How do vaccines work?
The vaccine inserts dead or weakened pathogen to produce a primary immune response
Briefly explain Part I of "Inflammation's Many Roles".
An excess of LDL particles build up in the artery wall and are chemically altered (oxidized). These oxidized LDLs then stimulate cells on the interior of the blood vessel to display adhesion molecules, which latch onto monocytes and T-cells in the blood.
Briefly explain Part II of "Inflammation's Many Roles".
In the intima, these monocytes (the snagged cells) mature into phagocytes, able to ingest the oxidized LDLs. The phagocytes and T-cells produce many inflammatory mediators, like cytokines (cell signallers) and factors that promote cell division.
Briefly explain Part III of "Inflammation's Many Roles".
The phagocytes eat the oxidized LDLs, becoming filled with fatty droplets. These frothy-looking, fat-laden phagocytes (called foam cells)and the T-cells make up the fatty streak, the earliest form of atherosclerotic plaque.
Briefly explain Part IV of "Inflammation's Many Roles".
Inflammatory molecules promote plaque growth and formation of a fibrous cap over the lipid core, which develops when the inflammatory molecules prompt smooth muscle cells to migrate to the top of the intima, multiply, and produce a tough, fibrous matrix g
Briefly explain Part V of "Inflammation's Many Roles".
Later, inflammatory substances secreted by foam cells (phagocytes that ate LDLs) can dangerously weaken the cap by eating matrix molecules and damaging smooth muscle cells, which then fail to repair the cap (Basically, the cap is destroyed from the inside