Vital Life Sciences

Hadean Eon

(4600 million years ago to 4000 mya) stretches from the formation of the Earth to the formation of the oldest known rocks. This time period is so named because of its harsh conditions, such as intense leftover heat from planetary accretion, the absence of a stable atmosphere, and the frequency of impacts. Key events during the this time period include the Moon's formation (4500 mya), likely due to the impact of a small planet with the young Earth, and liquid water ocean formation (4400 mya).

Archean Eon

(4000 to 2500 mya), the Earth cooled enough for stable continents to form. There is contrasting evidence as to whether a period of increased impact events called the Late Heavy Bombardment (LHB, 4100 to 3900 mya) during the early this period actually occurred. This time period also saw the emergence of life, the first definitive evidence of which comes from stromatolites—fossilized microbial mats that formed in shallow coastal areas.

Proterozoic Eon

(2500 mya to 541 mya) contained the Great Oxidation Event (GOE, 2400 to 2000 mya), during which oxygen levels rose significantly due to oxygenic photosynthesis performed by cyanobacteria. During the late this period, the Earth underwent multiple glaciation events, possibly even resulting in a fully frozen "Snowball Earth." The last period of the this eon was the Ediacaran Period, during which the first known multicellular organisms with specialized tissues—mostly simple, sessile, and flat marine animals—evolved. This time period was followed by the Phanerozoic Eon—the current eon, characterized by the abundance of plant and animal life.

Cambrian Period

(541 mya to 485 mya) is the first period of the Phanerozoic Eon and Paleozoic Era. The key event of the time period was the namesake Explosion, during which almost all modern animal phyla appeared. The namesake Explosion is an example of adaptive radiation, an event by which organisms rapidly evolve and diversify to take advantage of new resources or fill empty ecological niches. The cause of the namesake Explosion is unknown, but could be due to environmental changes or evolutionary breakthroughs such as eyes and/or animals that were exclusively predators. Evidence for the namesake explosion can be found in the Burgess Shale, a fossil deposit in British Columbia. This period also contained the namesake Substrate Revolution, in which the evolution of burrowing animals allowed water and oxygen to penetrate deep into ocean sediments and permanently alter their chemistry.

Ordovician Period

(485 mya to 444 mya) contained the Great namesake Biodiversification Event. Invertebrates flourished, with marine filter-feeders dominating the shallow seas of the period. This period saw the first complex life on land, as plants colonized the continents. The end of this period was marked by the namesake Mass Extinction, the second largest mass extinction in Earth's history, which killed around 85% of marine species. The mass extinction is thought to have been caused by the Late namesake glaciation, which caused sea levels to fall and eliminated many of the shallow seas that housed most organisms of the time.

Silurian Period

(444 mya to 419 mya) was much more stable and warm than the Ordovician. This period saw the expansion of terrestrial life. Vascular plants—which have specialized tissues containing lignin for transporting water and minerals—emerged, as well as terrestrial fungi and three groups of terrestrial arthropods: myriapods (centipedes and millipedes), arachnids (spiders), and hexapods (insects). Jaws and bones evolved for the first time in fish, which were beginning to rapidly diversify.

Devonian Period

(419 mya to 359 mya) is sometimes known as the Age of Fishes, as they came to dominate marine environments. Some fish even moved beyond the ocean; during this period, the ancestors of four-limbed vertebrates, or tetrapods, began to adapt to life on land as the first amphibians. Land plants also underwent an adaptive radiation sometimes known as the namesake Explosion, as evolutionary innovations including the first leaves, roots, and seeds allowed them to rapidly colonize swaths of dry land. These plants may have also indirectly caused the Late namesake Mass Extinction by absorbing huge quantities of atmospheric carbon dioxide, leading to global cooling and marine anoxia (low-oxygen conditions). The extinction primarily affected marine organisms; at least 75% of species went extinct, including almost all of the formerly dominant trilobites.

Carboniferous Period

(359 mya to 299 mya) can be divided into two halves: the Mississippian (359 mya to 331 mya), and the Pennsylvanian (331 mya to 299 mya). This period is named for the abundant coal deposits dated to that time. Receding seas led to the prevalence of lowland swamps, which were filled with lignin-rich trees and numerous ferns. These extensive forests sequestered carbon dioxide, leading to an increase in atmospheric oxygen levels to about 35%, as compared to 21% today. High oxygen levels may have led to gigantism in insects; millipedes grew to over 8 feet long and dragonflies had wingspans of 30 inches. This period is also known as the Age of Amphibians, as tetrapods became the dominant terrestrial animals and began to diversify. The first amniotes appeared, as well as the first reptiles. Landmasses including the southern continent Gondwana and the northern continent Laurasia collided to form the supercontinent Pangaea, which was surrounded by the Panthalassic Ocean.

Permian Period

(299 mya to 252 mya) saw a decline of the swamps of and rainforests that dominated the Carboniferous and an increase in deserts throughout the interior of Pangaea. Amniotes were able to cope with the prevalent dry climates, and two amniotic groups—the synapsids (ancestors of modern mammals) and sauropsids (reptiles)—greatly diversified. The end of the this period was marked by the namesake Mass Extinction (also known as the Great Dying), the largest mass extinction in Earth's history; over 90% of marine species and 70% of terrestrial vertebrate species went extinct. The extinction is thought to have been caused by an eruption of the Siberian Traps, a large igneous province that released massive amounts of lava and noxious gasses. The outgassing of carbon dioxide led to severe global warming, ocean acidification, and anoxia. All large synapsids went extinct, leaving an ecological void.

Triassic Period

(252 mya to 201 mya) was the first period of the Mesozoic Era. A specialized group of reptiles called archosaurs underwent adaptive radiation to fill the voids left by the Permian Mass Extinction. The dominant group of archosaurs was the pseudosuchians, ancestors of modern crocodiles. Another group of archosaurs, the dinosaurs, first appeared, as well as the first true mammals. The climate of the this period was hot and dry, but became humid as Pangaea began to break up near the end of the period. The period ended with the namesake Mass Extinction, which wiped out about 75% of species. Marine invertebrates were hit particularly hard, but large pseudosuchians and amphibians also went extinct, paving the way for the rise of the dinosaurs.

Jurassic Period

(201 mya to 145 mya) was the first to be dominated by dinosaurs. The climate was warm; there were no ice caps and forests stretched to the poles. Many of the most well-known dinosaurs from the this Period are known from the Morrison Formation in Colorado, including Allosaurus, Stegosaurus, Brontosaurus, Diplodocus, and Apatosaurus. Archaeopteryx, a transitional species between dinosaurs and birds, was discovered in the namesake-age Solnhofen Limestone in Germany. The skies were ruled by flying reptiles called pterosaurs, and the oceans were dominated by marine reptiles, including ichthyosaurs and plesiosaurs.

Cretaceous Period

(145 mya to 66 mya) was similar to the Jurassic. The climate was still warm, with numerous shallow inland seas. Dinosaurs continued to dominate, and mammals and birds continued to diversify. Angiosperms, or flowering plants, appeared for the first time and quickly became the dominant group of plants on Earth. North America was split lengthwise by the Western Interior Seaway, which was dominated by marine reptiles called mosasaurs. Some of the most well-known dinosaurs that walked the land included Tyrannosaurus, Velociraptor, and Triceratops. This Period, and the Mesozoic Era, ended with the namesake-Paleogene Mass Extinction. A worldwide layer of iridium dated to 66 mya sparked the Álvarez Hypothesis, which posited that the extinction was caused by a huge impact event. This idea was strongly supported by the discovery of the massive Chicxulub crater on the Yucatán peninsula. 75% of all species went extinct, including all non-avian dinosaurs and large terrestrial animals.

Cenozoic Era

(66 mya to present) is the current era, sometimes known as the Age of Mammals. During the initial Paleogene Period (66 mya to 23 mya), mammals diversified and grew in size to become the dominant land animals, filling the void left by the previous mass extinction. Temperatures were high at the beginning of the period, peaking at the Paleocene-Eocene Thermal Maximum (PETM), but cooled down during the Oligocene epoch as Antarctica froze. During the Neogene Period (23 mya to 2.6 mya), landmasses settled close to their modern positions. The current period is the Quaternary Period (2.6 mya to present). The period's Pleistocene Epoch (2.6 mya to 11,700 ya) was marked by cyclical ice ages. It saw the evolution of megafauna including mammoths, saber-tooth tigers, and giant sloths and armadillos, as well as the first appearance of Homo sapiens. The current epoch is the Holocene epoch, which is characterized by the growth and impacts of the human species.

Mitochondria

This organelle's function can be disrupted by nucleoside reverse transcriptase inhibitors resulting in lipodystrophy and lactic acidosis. This occurs due to the disruption of the beta oxidation and cellular respiration processes that are facilitated by this organelle. That disruption occurs when a drug mistakenly incorporates itself into this organelle's DNA, the existence of which supports the endosymbiotic theory that this organelle may have once lived as an independent organism. What is this organelle with an inner membrane called the "cristae"

Smooth Endoplasmic Reticulum

What specific organelle that lacks ribosomes on its surface serves to detoxify alcohol and synthesize lipids and steroids?

Peroxisome

What organelle that is full of catalase is used to break down a namesake compound with formula H2O2? major metabolic functions include beta-oxidation of very long chain fatty acids to medium chain fatty acids, which in animals, are then shuttled to the mitochondrion.

Strep Throat

What gram positive bacterial infection associated with a sore throat with white patchy exudates that can develop into scarlet fever?

Rhinovirus

What most common virus to infect humans and major cause of the common cold is named for the fact that it mainly impacts the nasal passages and is not named for a large animal?

Pneumonia

One infectious agent that can cause this disease was formerly name P. carinii prior to being renamed P. jirovecii after it was discovered to be a human-specific pathogen. This disease can be sub-classified as hospital-acquired, community-acquired, or viral depending on presentation prior to diagnosis. Atypical organisms, H. influenza, and a namesake streptococcus species are the most common agents that cause what infection that results in lung inflammation?

Glycogen

The liver makes and stores what multi-branched polysaccharide of glucose that stores energy from carbohydrates in the body?

Jaundice

When the liver fails, bilirubin can build up in the blood causing a yellowing of the skin and eyes known by what term?

Cholesterol

A concentration of this bodily molecule can be lowered by inhibiting the PCSK9 enzymes from blocking receptors that remove it from the blood. More common ways of lowering this substance include blocking the NiemannPick cells in the intestines from absorbing it or by blocking the HmG-CoA reductase from synthesizing it in the liver. What is this bodily molecule that aids in membrane fluidity whose good and bad forms are known as HDL and LDL respectively? This type of steroid, which provides structure to the cell membrane, was first isolated from gallstones in a liquid crystal phase.

Vitamin K

What class of fat soluble vitamins, who's synthetic form is known as phytonadione, serve to promote the formation of clotting factors?

Vitamin E

What class of fat soluble vitamins, including tocopherols, are thought to serve an antioxidant function in cell membranes whose deficiency can cause nerve problems

Vitamin C

This vitamin has been co-administered with iron tablets to increase their absorption in iron deficient patients due to its ability to chelate iron in a low pH environment. Excessive intake of this vitamin has been linked to kidney stone formation. Bleeding mucous membranes, spongy gums, and loose teeth can all result from a deficiency of this vitamin due to its role in collagen synthesis. What is this water soluble vitamin also known as ascorbic acid whose deficiency can cause scurvy?

Diabetes

What disease, known as gestational when occurring during pregnancy, has a Type 1 type where no insulin is produced and a Type 2 type that confers insulin resistance?

Arthritis

What disease whose name means joint inflammation comes in a "rheumatoid" variety that is autoimmune and an "osteo" variety that causes crepitus from overuse

Hypertension

This disease can potentially be triggered by inhibition of VEGF and renal artery stenosis is a possible secondary cause of this disease. Dihydropyridine calcium channel blockers, angiotensin receptor blockers, and alpha blockers are all classes of agents used to treat this disease. This disease can be worsened by overuse of anti-inflammatory drugs and excessive salt intake. A sphygmomanometer can be used to monitor what very prevalent cardiovascular risk factor defined as abnormally high blood pressure?

Polio

What virus, that can cause paralysis, has oral and injectable vaccines that were discovered by Albert Sabin and Jonas Salk, respectively

Shingles

What infection that is related to chickenpox is also known as herpes zoster? This infection results in a painful skin rash and is more common in patients over 50.

Pertussis

The vaccine for this illness has been linked to both tetanus and diphtheria and the acellular version of its vaccine was developed to reduce the side effects of vaccination. As of 2012, due to a large number of outbreaks across the United States, the vaccine for preventing this disease is now recommended to all pregnant patients to provide passive immunity to infants. What is this highly contagious bacterial disease that causes a cough so forceful that it may break ribs and makes a distinct sound leading it to be nicknamed "Whooping Cough"?

Intron

Splice site mutations occur when genetic material remains in mRNA from what segments of RNA that do not code for proteins that are normally removed

Plasmid

Mutations can be created in bacteria by inserting DNA into what small circular DNA molecules that are physically separated from their chromosomal DNA

Genetic Drift

Common models that attempt to explain this process include the Moran model, Kimura's neutral model, and the Wright-Fisher model. When this happens naturally, such as due to a natural disaster, it is known as the bottleneck effect and when it occurs due to human decision to form an isolated new population, it is known as the Founder effect. What is this variation in relative allele frequency due to the chance disappearance of particular genes as individuals die or do not reproduce?

Liver

What organ of the human body is damaged in individuals with cirrhosis or hepatitis? This organ converts bilirubin to a more water-soluble form. This organ secretes bile, which can be stored in the nearby gallbladder.

Ribosomes

What organelles are the site of translation and protein synthesis?

Thiamine

The deficiency of what vitamin in the human body leads to a condition known as beriberi? B vitamin. A deficiency of this substance reduces the concentration of alpha-KGDH, causing cerebellar ataxia.

Hippocampus

What portion of the limbic system that is shaped like a seahorse is responsible for storing long-term memories?

Metastasis

What term is applied to the process of a primary source of cancer spreading to a secondary sight somewhere else in the body?

Lymph Nodes

The N category of cancer staging is primarily determined by if the cancer has reached what bean shaped immune system structures that can become swollen when infected?

Breast Cancer

The monoclonal antibody trastuzumab can be used to manage the HER2 positive type of this cancer and genetic screening for risk to develop this type of cancer involves screening for the BRCA1 and BRCA2 gene mutations. Management of this cancer may also involve the use of hormonal therapy like aromatase inhibitors of selective estrogen receptor modulators if the cancer is ER and PR positive. What is this type of cancer that in non-invasive circumstances may be managed with a mastectomy

Serotonin

What neurotransmitter that binds to 5-HT receptors is the primary target of SSRI antidepressants because of its role in regulating mood and appetite

Histamine

What neurotransmitter increases stomach acid secretion when binding to its class 2 receptors and regulates allergic reactions when binding to its class 1 receptors?

Dopamine

This hormone was initially administered to critically ill patients with impaired renal function before the benefit was proven to be negligible. Blockage of this hormone's receptors can lead to unopposed acetylcholine activity causing dystonia. This hormone is the precursor to norepinephrine. This hormone is depleted from the substantia nigra in patients with Parkinson's disease. What is this hormone that regulates reward seeking behaviors and binds to "D" receptors?

RNA polymerase

Transcription is performed by what enzyme, which opens the DNA double helix and produces a strand of RNA matching it. The product of this enzyme undergoes polyadenylation and splicing. For 10 points, name this enzyme that synthesizes RNA from a DNA template.

mRNA

If the gene being transcribed encodes a protein, the RNA produced will be what kind of RNA?

Splicing

One form of this process, which does not use a transesterification reaction like the more common forms of this process, occurs almost exclusively in tRNA. This process removes a section of RNA which usually begins with a GU sequence and ends with an AG sequence. This process is catalyzed by a large protein complex, which comes in "major" and "minor" types and is composed of smaller proteins known as snRNPs ["snurps"]. Identify this process in which introns are removed from RNA sequences and exons are joined together.

HIV

What retroviral STD that invades the body's helper T-cells is classified as AIDS when the helper T-cell count drops below 200?

Herpes

What incurable STD, which has a similar strain that causes cold sores, causes painful genital lesions when emotional or physical stress re-activates the virus? For 10 points, name this virus family including the Epstein-Barr virus and the chicken pox-causing Varicella zoster, whose types 1 and 2, or "simplex," cause cold sores and their namesake STD.

Gonorrhea

In 1256, Louis IX issued a decree that banished all people who had been inflicted with this disease. When diagnosing this sexually transmitted disease, observing Gram negative double ball-shaped bacteria on a stain of pus in a male is diagnostic. Treatment of this disease is usually a single injection of ceftriaxone and anytime this disease is suspected the patient should also receive treatment for Chlamydia as co-infection is so common. What is this sexually transmitted disease nicknamed "the clap"

Methionine

What amino acid, one of only two that contains sulfur, is coded for by only a single AUG codon and is used to mark where protein synthesis is to start

Cysteine

What amino acid, the only other amino acid to contain sulfur, forms disulfide bonds via its thiol side chains that are broken by perm solution when perming hair?

Tyrosine

Kinases that transfer phosphate from ATP to a protein named for this amino acid have become prime targets for anti-cancer drugs due to their role in unregulated cell growth when they become stuck in the "on" position. Patients suffering from phenylketonuria cannot convert phenylalanine to this amino acid leading to insufficient levels. This amino acid is the direct precursor to L-DOPA, which is later converted to key neurotransmitters like dopamine and norepinephrine. What is this non-essential amino acid symbolized "Y"?

Auxin

What plant hormone drives gravitropism and phototropism to promote cell elongation and root formation?

Ethylene

What plant hormone whose production is stimulated by auxin is responsible for promoting fruit ripening and stem thickening?

Abscisic Acid

This hormone inhibits production of a-amylase to inhibit seed germination and promotes synthesis of storage proteins. This hormone promotes stomata closure leading some to refer to this hormone as "dormin" as it promotes seed dormancy. Frederick Addicott discovered this hormone which can promote the ripening of fruit. Identify this plant hormone that was initially named due to the fact that it was believed this hormone was responsible for promoting the shedding of leaves in the winter or "abscission"?

Circadian Rhythm

Sleep cycle is included in what set of endogenous biological oscillations of approximately 24 hours that can become out of sync when traveling across time zones?

Apnea

Many overweight patients are impacted by the obstructive type of what temporary cessation of breathing that typically afflicts people while they are sleeping

Melatonin

Ramelteon and tasimelteon are two supplements that selectively bind receptors of this hormone, the latter of which was approved for use in blind people due to the inability of their retinas to cue the brain to the time of day, thus disrupting their circadian rhythm. Wearing blue blocking goggles before bedtime may decrease loss of this hormone as certain wavelengths of light will reduce its production. Supplements of this hormone can be taken to help reduce jet lag. What is this hormone secreted by the pineal gland that regulates wakefulness and can also be supplemented to treat insomnia?

Knee

Between ten percent and thirty percent of humans have a fabella, a small extra bone embedded in the tendons of this joint. The better-known bone located at this joint, which almost all humans have, is the patella

Fingers

Poly·dac·tyly is a usually-benign mutation in which a person is born with more than the usual number of these body parts.

Teeth

The most common kind of additional instances of these structures is known as a mesiodens. Parts of these structures are covered by cementum, and these structures are separated into two parts by the cemento·enamel junction. Humans have two sets of these structures, and the second set contains four more of these things than the first set, which fall out and are replaced. These structures can be covered in a biofilm known as plaque.

Golgi body

This organelle named for an Italian biologist is responsible for sorting and packaging proteins for transport to the rest of the cell

Dodo

This species of large flightless bird native to Mauritius went extinct less than a hundred years after the arrival of Dutch sailors on the island; its extinction in 1662 was the first time that a species was recognized to have been made extinct by humans

Passenger pigeon

This bird species went extinct in 1901 because of habitat destruction and overhunting; at one point, they were so numerous that their migrations could darken the sky.

Cancer

A specific variety of these cells can be transmitted between Tasmanian devils. The HeLa cell line is derived from cells of this type taken from Henrietta Lacks without her consent. Cells of this type are able to outlive their Hayflick limit because of a specific enzyme. Cells of this type typically express a higher number of oncogenes than normal. Cells of this type can spread to other locations via the blood or lymph via a process known as metastasis. Name this type of cell, the uncontrolled multiplication of which is responsible for diseases such as melanoma and lymphoma, and which forms tumors.

Valves

The heart contains mitral and tricuspid examples of these structures, which allow blood to flow in only one direction.

EKG

This medical technique measures electrical signals produced by the heart. Its output includes P, QRS, and T regions

Aspirin

It's not a cytochrome, but the presence of this compound allows for the conversion of arachidonic acid to lipoxin, a type of SPM. This compound prevents the production of prostaglandins by inhibiting the cyclooxygenase COX-2. When ingested by children, this derivative of salicylic acid can cause mitochondrial damage in Reye's syndrome. This drug, a type of NSAID, is taken during heart attacks. Name this drug that is manufactured by Bayer, which treats inflammation, fever, and pain.

Phosphorus

Arsenic poisoning is caused by arsenic's chemical similarity to this element, allowing it to replace this element in compounds such as ATP, which causes cells to be unable to store energy

Hydrogen peroxide

The metal cadmium is highly toxic because its ions cause cells to generate this compound with formula H2O2 which damages cells

Mercury

A spill of a few drops of a compound containing this element and two CH3 groups was absorbed through researcher Karen Wetterhahn's latex gloves, causing her death ten months later. Minamata disease, an often-fatal neurological condition, is caused by exposure to a methyl compound of this element. The presence of this element in the compound thimerosal has led to false claims that vaccines will cause poisoning of this element. Poisoning of this element can be caused by ingestion of certain fish high in it, in particular tuna. Identify this metallic element which is liquid at room temperature.

Antibodies

These Y-shaped proteins have a structure called a "paratope" which binds to a specific chemical on the surface of a specific antigen. They are used by the immune system.

Glucagon

This protein hormone increases blood glucose levels by promoting gluconeogenesis, giving it an opposite effect to insulin.

Collagen

This protein contains an abnormally high amount of the non-pro·teino·genic amino acid hy·droxy·proline. The most common amino acids which make up this protein are proline and glycine. This protein has a triple helix structure, and several triple helices bind together to form fibrils, which bind together to form fibers. When this protein is hydrolyzed, the result is gelatin. This protein is the most abundant protein in mammals because of its ubiquity in connective tissue. Name this protein which makes up, among other things, ligaments, bone, tendons, and cartilage.

: E. coli

These Gram-negative bacteria have been used in studies of recombinant DNA. These bacteria, some strains of which can cause serious food poisoning in humans, are the most-used prokaryotic model organisms Richard Lenski has been studying the evolution of populations of this organism since 1988. The O157:H7 strain of this bacterium produces Shiga toxin.

Fruit flies

A well-known mutation in the Hox gene in these organisms causes additional legs to grow in place of their antennae. These insects, which have only four chromosomes, are commonly used for genetic research

Mouse

Gregor Mendel switched to using pea plants after conducting genetic experiments on these animals' colorings because his superior asked him to stop breeding "smelly animals." C. C. Little developed the DBA, or "dilute, brown, and non-Agouti," strain of these animals. Jackson Laboratory in Maine produces almost three million of these animals per year, including so-called "knockout" examples of these animals with individual genes removed. These animals were the second mammals to have their genome sequenced, after humans. Identify these rodents commonly used for laboratory experiments. the first mammal to have its genome sequenced.

Bubonic plague

This disease, caused by the pathogen Yersinia pestis, is named for the large painful and swollen lymph nodes that its sufferers often acquire in their groin, neck, and armpits. This disease and a similar "pneumonic" type caused a 2017 outbreak in Madagascar.

Dysentery

This non-cholera disease causes diarrhea through an infection of the intestines, which can cause death through dehydration. It can be caused by amoebas or by the Shigella bacteria.

Tuberculosis

Robert Koch received the Nobel Prize in Medicine for isolating this disease's causative agent. This disease is caused by bacteria of the genus Mycobacterium. Most people infected with this disease are asymptomatic for a long time before the infection becomes "active." This disease can be diagnosed with a chest X-ray and sputum cultures. Sufferers of this disease were often kept in sanatoria, and an alternative name for this lung infection was derived from its causing weight loss and wasting. Identify this infection of the lungs also known as consumption.

Vitamin A

Golden rice was created to provide one of the precursors of this vitamin in diets lacking it, because a deficiency of this vitamin, especially in childhood, can lead to blindness. fat-soluble vitamin which can besynthesized from beta carotene.

Muscles

Actin, along with myosin, are two molecules important to the structure of the sarcomere, which is responsible for contracting these body structures

Cytoskeleton

Actin also makes up microfilaments, which along with microtubules and intermediate filaments make up this cell structure responsible for giving the cell its shape.

Flagellum

A part of these structures called an axoneme consisting of nine fused pairs of microtubules is present in these structures in eukaryotes. In bacteria, these structures have a hook joined by a junction to a filament. These structures use a bending motion in eukaryotes but a rotary motion in prokaryotes. These structures are present in sperm cells and allow them to move towards the egg. Identify these cellular structures which consist of long protrusions and allow cells to move independently

Smooth and Rough

There are two different types of endoplasmic reticulum, which are distinguished by, and named for, the presence or absence of ribosomes on their surfaces. Name both

Phospholipids

The smooth ER synthesizes, among other things, these molecules present in cell membranes. These molecules have two hydrophobic "tails" and a hydrophilic "head." Many vesicle membranes are composed of these amphiphilic molecules that also form a "bilayer" in the cell membrane.

Calcium

A special type of ER present in muscle tissue, the sarcoplasmic reticulum, is used to synthesize and release this ion. It's not potassium, but an "exchanger" named for sodium and this ion is found in the endoplasmic reticulum and the mitochondria. Parathyroid hormone increases the concentration of this ion in the bloodstream, and hyperparathyroidism can therefore result in osteoporosis by removing too much of this ion from where it is stored. Identify this ion whose phosphate and sulfate are the primary components of bone.

Reverse transcriptase

This enzyme, found in a number of viruses, generates DNA from an RNA template, an action for which it is named. This enzyme performs the opposite process as RNA polymerase

Retrovirus

The HIV virus is a member of this class of viruses which integrate their genome into the genome of host cells by using reverse transcriptase. Howard Temin and David Baltimore discovered an enzyme central to these entities that produce complementary DNA. One of these entities binds to CD4 to attack Helper T cells.

Telomerase

In vertebrates, this enzyme creates the DNA sequence TTAGGG. This enzyme is a special class of reverse transcriptase which carries its own RNA sequence. This enzyme's function is instead performed by retrotransposons in Drosophila. The activation of this enzyme occurs in almost all human cancers because this enzyme permits cells to divide rapidly without losing genetic information. This enzyme restores material which is typically lost during DNA replication. Identify this enzyme which restores the tips of chromosomes.

Tryptophan

This amino acid, contrary to popular belief, isn't any more common in turkey than other poultry. This amino acid has also been claimed to cause post-Thanksgiving drowsiness because it is a precursor for melatonin

W

This letter is used to represent tryptophan in the one-letter amino acid code. This letter is used in IUPAC notation to represent a nucleotide which can be either A or T. The element whose symbol is this letter is used similarly to molybdenum, which it is located below, by some prokaryotes. This letter is the abbreviation for a unit equal to a joule per second. Identify this letter which is the chemical symbol for tungsten, as well as the first letter in the SI unit of power.

Thylakoid

The light-dependent reactions of photosynthesis take place at the membrane of this subunit of the chloroplast.

two membranes

Like mitochondria, chloroplasts have this quality, which means that they possess an intermembrane space.

Red

It's not green, but the light-harvesting pigment phycoerythrin absorbs all but this color of light, which results in the existence of algae of this color. The Japanese product nori is produced from a member of the class of algae named for this color, which also includes agarophytes, which produce agar. Toxic algal blooms caused by Karenia bravis take on this color, causing such blooms to be known as this type of tide. Hemoglobin is found in a class of cells named for this color.

DNA

Pauling proposed a triple helix structure for this molecule. Watson and Crick won a Nobel Prize for their discovery of this molecule's structure

Enzymes

The existence of a class of these molecules, which include a "hammerhead" type, is used as evidence for the RNA world hypothesis. A constant denoted K-sub-m characterizes the kinetics of these molecules that are modeled by the Michaelis-Menten equation. HindIII and EcoRI are among the "restriction" types of them that cut DNA at specific sites. Pauling discovered that these molecules stabilize the transition state, allowing the activation energy of reactions to decrease. Name these proteins that catalyze biochemical reactions.

Primary succession

This form of succession occurs in areas that were previously lifeless, and pioneer plants comprise a stage within it.

Fires

Secondary succession can follow one of these destructive events, which can be naturally caused by lightning or volcanic eruptions.