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they are not made of cells. To make new viruses, they have to invade and hijack the reproductive mechanism of a living cell; only then can they obtain the materials they need to reproduce.) Some organisms consist of a single cell and others are multicellular. Cells are classified as prokaryotic or eukaryotic. Prokaryo... |
of living things are shown. From a single organelle to the entire biosphere, living organisms are parts of a highly structured hierarchy. (credit “organelles”: modification of work by Umberto Salvagnin; credit “cells”: modification of work by Bruce Wetzel, Harry Schaefer/ National Cancer Institute; credit “tissues”: m... |
http://cnx.org/content/col12078/1.6 Chapter 1 | The Study of Life 29 Carl Woese and the Phylogenetic Tree In the past, biologists grouped living organisms into five kingdoms: animals, plants, fungi, protists, and bacteria. The organizational scheme was based mainly on physical features, as opposed to physiology, bioch... |
a fish be classified? Why? a. Archaea, because fish are multicellular. b. Eukarya, because fish are multicellular. c. Archaea, because fish are single-celled. d. Eukarya because fish are single-celled. This OpenStax book is available for free at http://cnx.org/content/col12078/1.6 Chapter 1 | The Study of Life 31 Phyl... |
Chapter 1 | The Study of Life 33 Forensic science is the application of science to answer questions related to the law. Biologists as well as chemists and biochemists can be forensic scientists. Forensic scientists provide scientific evidence for use in courts, and their job involves examining trace materials associat... |
a genetically-modified food—demonstrates the way biology is active in and important to our everyday world. This OpenStax book is available for free at http://cnx.org/content/col12078/1.6 Chapter 1 | The Study of Life KEY TERMS 35 abstract opening section of a scientific paper that summarizes the research and conclusio... |
molecules such as DNA, RNA, and proteins molecule chemical structure consisting of at least two atoms held together by one or more chemical bonds natural science field of science that is related to the physical world and its phenomena and processes neurobiology study of the biology of the nervous system organ collecti... |
of basic science is to expand knowledge without any expectation of shortterm practical application of that knowledge. The primary goal of applied research, however, is to solve practical problems. Two types of logical reasoning are used in science. Inductive reasoning uses particular results to produce general scienti... |
calculating surface area of rectangular ground, functioning of planetary orbitals, formation of metamorphic rocks, galaxy formation and evolution c. plant responses to external stimuli, functioning of planetary orbitals, formation of metamorphic rocks, galaxy formation and evolution d. plant responses to external stim... |
. If the car doesn’t start the problem might be in the battery. 2. Car doesn’t start. 3. After changing the battery. Car starts working. 4. The car should start after charging the battery or changing the battery. 5. The car doesn’t start because the battery is dead. 6. The car doesn’t start even after charging the batt... |
, elephant, water molecule, planet Earth, tropical rainforest, hydrogen atom, wolf pack, liver. a. hydrogen atom, water molecule, skin cell, liver, elephant, wolf pack, tropical rainforest, planet Earth b. hydrogen atom, skin cell, water molecule, liver, elephant, wolf pack, tropical rainforest, planet Earth c. hydroge... |
scientist Jacques Monod famously said, “Anything found to be true of E. coli must also be true of elephants.” How is this statement based on the notion that living organisms share a common ancestor? 40 Chapter 1 | The Study of Life a. E. coli is a eukaryote and share similarities with line of evidence that has led to ... |
functions. All biological processes follow the laws of physics and chemistry. Therefore, in order to understand how biological systems work, it is important to understand the underlying physics and chemistry. For example, the flow of blood within the circulatory system follows the laws of physics regulating the modes ... |
forms of an element that have different numbers of neutrons while retaining the same number of protons; many isotopes, such as carbon-14, are radioactive. The information presented and examples highlighted in this section support concepts and Learning Objectives outlined in Big Idea 2 of the AP® Biology Curriculum Fra... |
for calcium. Other elements’ chemical symbols derive from their Latin names; for example, the symbol for sodium is Na, referring to natrium, the Latin word for sodium. The four elements common to all living organisms are oxygen (O), carbon (C), hydrogen (H), and nitrogen (N). In the nonliving world, elements are found... |
with electrons in orbitals surrounding the nucleus. Protons and neutrons have approximately the same mass, about 1.67 × 10-24 grams. Scientists arbitrarily define this amount of mass as one atomic mass unit (amu) or one Dalton, as shown in Table 2.2. Although similar in mass, protons and neutrons 44 Chapter 2 | The Ch... |
illustrated in this figure. Note that the small contribution of mass from electrons is disregarded in calculating the mass number. This approximation of mass can be used to easily calculate how many neutrons an element has by simply subtracting the number of protons from the mass number. Since an element’s isotopes wi... |
. 46 Chapter 2 | The Chemical Foundation of Life Carbon Dating Carbon is normally present in the atmosphere in the form of gaseous compounds like carbon dioxide and methane. Carbon-14 (14C) is a naturally occurring radioisotope that is created in the atmosphere from atmospheric 14N (nitrogen) by the addition of a neutr... |
ratio of 14 C to 12 C in a living elephant compare to the 14 C to 12 C ratio found in the mammoth? a. The ratio would be the same in the elephant and the mammoth. b. The ratio would be lower in the elephant than the mammoth. c. The ratio would be higher in the elephant than the mammoth. d. The ratio would depend on th... |
mass appears below it. The periodic table groups elements according to chemical properties. The differences in chemical reactivity between the elements are based on the number and spatial distribution of an atom’s electrons. Atoms that chemically react and bond to each other form molecules. Molecules are simply two or... |
of the outermost energy level determine the energetic stability of the atom and its tendency to form chemical bonds with other atoms to form molecules. Under standard conditions, atoms fill the inner shells first, often resulting in a variable number of electrons in the outermost shell. The innermost shell has a maxim... |
elements of group 14 need to lose 4 electrons and elements of group 17 need to lose 1 electron. Understanding that the organization of the periodic table is based on the total number of protons (and electrons) helps us know how electrons are distributed among the shells. The periodic table is arranged in columns and r... |
called its orbital. Recall that the Bohr model depicts an atom’s electron shell configuration. Within each electron shell are subshells, and each subshell has a specified number of orbitals containing electrons. While it is impossible to calculate exactly where an electron is located, scientists know that it is most p... |
two electrons. This is designated as 1s2, referring to the two electrons of helium in the 1s orbital. On the periodic table Figure 2.5, hydrogen and helium are the only two elements in the first row (period); this is because they only have electrons in their first shell, the 1s orbital. Hydrogen and helium are the onl... |
r model would have one electron ring, and a Bohr model would not show the sub-shells of first ring c. A Bohr model would have 2 electron rings, and a Bohr model would not show the sub-shell of second ring d. A Bohr model would have one electron ring, and a Bohr model would not give information about number of electron ... |
hydrogen atoms bonded to two oxygen atoms (H2O2). The reactant hydrogen peroxide is broken down into water, containing one oxygen atom bound to two hydrogen atoms (H2O), and oxygen, which consists of two bonded oxygen atoms (O2). In the equation below, the reaction includes two hydrogen peroxide molecules and two wate... |
content/col12078/1.6 Chapter 2 | The Chemical Foundation of Life 55 hydrogen ions. HCO− + H+ — H2 CO3 In biological reactions, however, equilibrium is rarely obtained because the concentrations of the reactants or products or both are constantly changing, often with a product of one reaction being a reactant for anothe... |
this example, sodium will donate its one electron to empty its shell, and chlorine will accept that electron to fill its shell. Both ions now satisfy the octet rule and have complete outermost shells. Because the number of electrons is no longer equal to the number of protons, each is now an ion and has a +1 (sodium c... |
for living systems to break apart this nitrogen in order to use it as constituents of proteins and DNA. The formation of water molecules provides an example of covalent bonding. The hydrogen and oxygen atoms that combine to form water molecules are bound together by covalent bonds, as shown in Figure 2.9. The electron... |
way of stating this is that the probability of finding a shared electron near an oxygen nucleus is more likely than finding it near a hydrogen nucleus. Either way, the atom’s relative electronegativity contributes to the development of partial charges whenever one element is significantly more electronegative than the... |
two types of bonds, life as we know it would not exist. Hydrogen bonds provide many of the critical, lifesustaining properties of water and also stabilize the structures of proteins and DNA, the building block of cells. When polar covalent bonds containing hydrogen form, the hydrogen in that bond has a slightly positi... |
using human subjects to make sure the drug is not harmful and effectively treats the condition it aims to treat. This process often takes several years and requires the participation of physicians and scientists, in addition to chemists, to complete testing and gain approval. An example of a drug that was originally d... |
hydrogen bonds? a. Covalent bonds are stronger than hydrogen bonds. b. There are many more disulfide bonds than hydrogen bonds. c. Covalent bonds are stronger than disulfide bonds. d. Covalent bonds are less elastic than hydrogen bonds. 2.2 | Water In this section, you will investigate the following questions: • How d... |
and the examples highlighted in this section support concepts and Learning Objectives outlined in Big Idea 2 of the AP® Biology Curriculum. The Learning Objectives listed in the Curriculum Framework provide a transparent foundation for the AP® Biology course, an inquiry-based laboratory experience, instructional activ... |
charge to a water molecule, the polarity of water creates a slightly positive charge on hydrogen and a slightly negative charge on oxygen, contributing to water’s properties of attraction. Water’s charges are generated because oxygen is more electronegative than hydrogen, making it more likely that a shared electron w... |
On the other hand, when the temperature of water is reduced and water freezes, the water molecules form a crystalline structure maintained by hydrogen bonding (there is not enough energy to break the hydrogen bonds) that makes ice less dense than liquid water, a phenomenon not seen in the solidification of other liqui... |
. Red and white balls represent oxygen and hydrogen respectively, tightly packed arrangement of molecules results in a low density of ice c. Red and white balls represent hydrogen and oxygen, respectively, loose arrangement of molecules results in low density of ice d. Red and white balls represent oxygen and hydrogen,... |
. Eventually, as water reaches its boiling point of 100° Celsius (212° Fahrenheit), the heat is able to break the hydrogen bonds between the water molecules, and the kinetic energy (motion) between the water molecules allows them to escape from the liquid as a gas. Even when below its boiling point, water’s individual ... |
a dome-like shape above the rim of the glass. This water can stay above the glass because of the property of cohesion. In cohesion, water molecules are attracted to each other (because of hydrogen bonding), keeping the molecules together at the liquid-gas (water-air) interface, although there is no more room in the gl... |
and adhesive forces are important for the transport of water from the roots to the leaves in plants. These forces create a “pull” on the water column. This pull results from the tendency of water molecules being evaporated on the surface of the plant to stay connected to water molecules below them, and so they are pul... |
un-ionized water molecules, forming hydronium ions (H30+). Still, by convention, scientists refer to hydrogen ions and their concentration as if they were free in this state in liquid water. The concentration of hydrogen ions dissociating from pure water is 1 × 10-7 moles H+ ions per liter of water. Moles (mol) are a ... |
organisms adapted to this saline environment are able to thrive in it. The pH scale is, as previously mentioned, an inverse logarithm and ranges from 0 to 14 (Figure 2.20). Anything below 7.0 (ranging from 0.0 to 6.9) is acidic, and anything above 7.0 (from 7.1 to 14.0) is alkaline. Extremes in pH in either direction ... |
. Maintaining a constant blood pH is critical to a person’s –), and well-being. The buffer maintaining the pH of human blood involves carbonic acid (H2CO3), bicarbonate ion (HCO3 carbon dioxide (CO2). When bicarbonate ions combine with free hydrogen ions and become carbonic acid, hydrogen ions are removed, moderating p... |
damage living organisms, such as this forest in the Czech Republic. Limestone is a naturally occurring mineral rich in calcium carbonate ( CaCO3 to form carbonate (CO3 rain, an environment rich in limestone or an environment poor in limestone? 2 − ), a weak base that acts as a buffer. Which would you expect to be more... |
of the seven Science Practices. Big Idea 2 Enduring Understanding 2.A Biological systems utilize free energy and molecular building blocks to grow, to reproduce, and to maintain dynamic homeostasis. Growth, reproduction and maintenance of living systems require free energy and matter. Essential Knowledge 2.A.3 Organis... |
atoms reside in three dimensions, is determined by the shape of its electron orbitals. The carbons and the four hydrogen atoms form a shape known as a tetrahedron, with four triangular faces; for this reason, methane is described as having tetrahedral geometry. 70 Chapter 2 | The Chemical Foundation of Life Figure 2.2... |
on either side are locked in place. Hydrocarbon Rings So far, the hydrocarbons we have discussed have been aliphatic hydrocarbons, which consist of linear chains of carbon atoms. Another type of hydrocarbon, aromatic hydrocarbons, consists of closed rings of carbon atoms. Ring structures are found in hydrocarbons, som... |
on the same side of the double bond, this is the cis configuration; if they are on opposite sides of the double bond, it is a trans configuration. In the trans configuration, the carbons form a more or less linear structure, whereas the carbons in the cis configuration make a bend (change in direction) of the carbon b... |
ic acid) and a trans (eliadic acid) fatty acid. Notice the bend in the molecule caused by the cis configuration. Enantiomers Enantiomers are molecules that share the same chemical structure and chemical bonds but differ in the three-dimensional placement of atoms so that they are mirror images. As shown in Figure 2.28,... |
. This carboxyl group ionizes to release hydrogen ions (H+) from the COOH group resulting in the negatively charged COOgroup; this contributes to the hydrophilic nature of whatever molecule it is found on. Other functional groups, such as the carbonyl group, have a partially negatively charged oxygen atom that may form... |
covalent bond heat of vaporization of water high amount of energy required for liquid water to turn into water vapor hydrocarbon molecule that consists only of carbon and hydrogen hydrogen bond weak bond between slightly positively charged hydrogen atoms and slightly negatively charged atoms in other molecules hydroph... |
an atom; has a mass of one amu and a charge of +1 radioisotope isotope that emits radiation composed of subatomic particles to form more stable elements reactant molecule found on the left side of a chemical equation reversible chemical reaction chemical reaction that functions bi-directionally, where products may tur... |
for the overall temperature to remain stable, although energy is added to the system. Water also exhibits a high heat of vaporization, which is key to how organisms cool themselves by the evaporation of sweat. Water’s cohesive forces allow for the property of surface tension, whereas its adhesive properties are seen a... |
is false? a. Electrons are unequally shared in polar covalent bonds. b. Electrons are equally shared in nonpolar covalent bonds. c. Hydrogen bonds are weak bonds based on electrostatic forces. d. Ionic bonds are generally stronger than covalent bonds. Based on the information provided, which of the following statement... |
. To be enantiomers, a molecule must have at least three different atoms or groups connected to a central carbon d. To be enantiomers, a molecule must have at least four different atoms or groups connected to a central carbon 10. What happens to the pH of a solution when acids are added? 16. Which of the following is n... |
. Why are hydrogen bonds and van der Waals interactions necessary for cells? a. Hydrogen bonds and van der Waals interactions form weak associations between molecules, providing the necessary shape and structure of DNA and proteins to function in the body. b. Hydrogen bonds and van der Waals interactions form strong as... |
density of water as a solid versus a liquid allows ice to float, forming an insulating surface layer for aquatic life. Second, the high specific heat capacity of water insulates aquatic life or bodily fluids from temperature changes. Third, the low heat of vaporization of water allows animals to cool themselves by swe... |
? Which macromolecules contain carboxyl? a. Carboxyl groups release H+, making its parent molecule hydrophilic. It is found amino acids and fatty acids. b. Carboxyl groups absorb H+ ion, making its parent molecule hydrophilic. It is found in phospholipids and triglycerides. c. Carboxyl groups release OH−, making its pa... |
Water moving up from the roots of plants to the leaves as a result of capillary action is because of adhesion. Heat of vaporization is the amount of energy required to convert liquid into gas. This property helps humans maintain homeostasis of body temperature by evaporation. c. Cohesion is the attraction between the ... |
” D. In your own words, summarize the argument that Macallum is using to justify this claim. 32. Approximately half the energy that flows through the Earth’s biosphere is captured by phytoplankton, photosynthetic microscopic organisms in the surface waters of the oceans. Scientists think the growth of phytoplankton in ... |
ater follows from the central organizing principle of biology: the theory of evolution. B. The elements in the table above all occur in aqueous solution as ions. The net charges on the inside and outside of a cell are both zero. A very large difference in the concentrations of ions, though, results in stresses that the... |
the effect of enrichment on phytoplankton productivity. Figure 2.32 The graphs (Anbar and Knoll, Science, 297, 2002) show models of concentrations of two trace elements, iron (Fe) and molybdenum (Mo), in ocean waters. The model describes the change over time of these elements from early Earth (>1.85 billion years ago,... |
this section, you will explore the following questions: • How are complex macromolecule polymers synthesized from monomers? • What is the difference between dehydration (or condensation) and hydrolysis reactions? Connection for AP® Courses Living organisms need food to survive as it contains critical nutrients in the ... |
able to evaluate scientific questions based on hypotheses about the origin of life on Earth. Dehydration Synthesis As you’ve learned, biological macromolecules are large molecules, necessary for life, that are built from smaller organic molecules. There are four major classes of biological macromolecules (carbohydrate... |
gains a hydroxyl molecule (OH–) from a split water molecule. Figure 3.3 In the hydrolysis reaction shown here, the disaccharide maltose is broken down to form two glucose monomers with the addition of a water molecule. Note that this reaction is the reverse of the synthesis reaction shown in Figure 3.2. Dehydration an... |
. Steam from the “ocean” combined with methane, ammonia, and hydrogen gases from the early Earth’s atmosphere and was exposed to electrical sparks to act as lightning. As the gas mixture cooled and condensed, it was found to contain organic compounds, such as amino acids and nucleotides. According to the abiogenesis th... |
The Learning Objectives listed in the Curriculum Framework provide a transparent foundation for the AP® Biology course, an inquiry-based laboratory experience, instructional activities, and AP® Exam questions. A Learning Objective merges required content with one or more of the seven Science Practices. Big Idea 4 Endu... |
grains, fruits, and vegetables are all natural sources of carbohydrates. Carbohydrates provide energy to the body, particularly through glucose, a simple sugar that is a component of starch and an ingredient in many staple foods. Carbohydrates also have other important functions in humans, animals, and plants. Carbohy... |
and that energy is used to help make adenosine triphosphate (ATP). Plants synthesize glucose using carbon dioxide and water, and glucose in turn is used for energy requirements for the plant. Excess glucose is often stored as starch that is catabolized (the breakdown of larger molecules by cells) by humans and other a... |
sugar, it is said to be in the alpha (α) position, and if it is above the plane, it is said to be in the beta (β) position. 96 Chapter 3 | Biological Macromolecules Figure 3.7 Five and six carbon monosaccharides exist in equilibrium between linear and ring forms. When the ring forms, the side chain it closes on is loc... |
include maltose (grain sugar), lactose (milk sugar), and sucrose (table sugar). Polysaccharides A long chain of monosaccharides linked by glycosidic bonds is known as a polysaccharide (poly- = “many”). The chain may be branched or unbranched, and it may contain different types of monosaccharides. The molecular weight ... |
, the glucose chains have a helical structure. Glycogen (not shown) is similar in structure to amylopectin but more highly branched. Glycogen is the storage form of glucose in humans and other vertebrates and is made up of monomers of glucose. Glycogen is the animal equivalent of starch and is a highly branched molecul... |
oskeleton, which protects their internal body parts (as seen in the bee in Figure 3.12). This exoskeleton is made of the biological macromolecule chitin, which is a polysaccharide-containing nitrogen. It is made of repeating units of N-acetyl-β-d-glucosamine, a modified sugar. Chitin is also a major component of fungal... |
contain soluble and insoluble elements; the insoluble part is known as fiber, which is mostly cellulose. Fiber has many uses; it promotes regular bowel movement by adding bulk, and it regulates the rate of consumption of blood glucose. Fiber also helps to remove excess cholesterol from the body: fiber binds to the cho... |
, which is easily digested by humans. How are cows and other ruminants able to digest cellulose? 3.3 | Lipids In this section, you will explore the following questions: • What are the four major types of lipids? • What are functions of fats in living organisms? • What is the difference between saturated and unsaturated... |
are classified as lipids based on their hydrophobic properties. Cholesterol is a type of steroid in animal cells’ plasma membrane. Cholesterol is also the precursor of steroid hormones such as testosterone. Information presented and the examples highlighted in the section, support concepts outlined in Big Idea 4 of th... |
Oils Lipids include a diverse group of compounds that are largely nonpolar in nature. This is because they are hydrocarbons that include mostly nonpolar carbon–carbon or carbon–hydrogen bonds. Non-polar molecules are hydrophobic (“water fearing”), or insoluble in water. Lipids perform many different functions in a cel... |
acid, is derived from the palm tree. Arachidic acid is derived from Arachis hypogea, the scientific name for groundnuts or peanuts. Fatty acids may be saturated or unsaturated. In a fatty acid chain, if there are only single bonds between neighboring carbons in the hydrocarbon chain, the fatty acid is said to be satur... |
fatty acids from packing tightly, keeping them liquid at room temperature (Figure 3.17). Olive oil, corn oil, canola oil, and cod liver oil are examples of unsaturated fats. Unsaturated fats help to lower blood cholesterol levels whereas saturated fats contribute to plaque formation in the arteries. This OpenStax book... |
, a curved shape. For clarity, the carbons are not shown. Each singly bonded carbon has two hydrogens associated with it, also not shown. The farthest carbon away from the carboxyl group is numbered as the omega (ω) carbon, and if the double bond is between the third and fourth carbon from that end, it is known as an o... |
ol or sphingosine backbone. Instead of three fatty acids attached as in triglycerides, however, there are two fatty acids forming diacylglycerol, and the third carbon of the glycerol backbone is occupied by a modified phosphate group (Figure 3.20). A phosphate group alone attached to a diaglycerol does not qualify as a... |
, and the hydrophobic “tails” are on the inside where they are protected from the surrounding water. Figure 3.22 Steroids Unlike the phospholipids and fats discussed earlier, steroids have a fused ring structure. Although they do not resemble the other lipids, they are grouped with them because they are also hydrophobi... |
(-COOH), and a variable group. (Think of how many protein “words” can be made with 20 amino acid “letters”). Each amino acid is linked to its neighbor by a peptide bond formed by a dehydration reaction. A long chain of amino acids is known as a polypeptide. Proteins serve many functions in cells. They act as enzymes t... |
is able to explain the connection between the sequence and the subcomponents of a biological polymer and its properties. Essential Knowledge 4.A.1 The subcomponents of biological molecules and their sequence determine the properties of that molecule. Science Practice 1.3 The student can refine representations and mode... |
ates are called anabolic enzymes, and enzymes that affect the rate of reaction are called catalytic enzymes. It should be noted that all enzymes increase the rate of reaction and, therefore, are considered to be organic catalysts. An example of an enzyme is salivary amylase, which hydrolyzes its substrate amylose, a co... |
group (Figure 3.24). Figure 3.24 Amino acids have a central asymmetric carbon to which an amino group, a carboxyl group, a hydrogen atom, and a side chain (R group) are attached. The name "amino acid" is derived from the fact that they contain both amino group and carboxyl-acid-group in their basic structure. As menti... |
. For example, valine is known by the letter V or the three-letter symbol val. Just as some fatty acids are essential to a diet, some amino acids are necessary as well. They are known as essential amino acids, and in humans they include isoleucine, leucine, and cysteine. Essential 116 Chapter 3 | Biological Macromolecu... |
production. b. Protein is stored in the liver and muscles to supply energy for future use. c. Protein is required for tissue formation and constitutes hormones and enzymes. d. Proteins are required for the absorption of all fat soluble vitamins. This OpenStax book is available for free at http://cnx.org/content/col120... |
be unable to bind to the substrate. To understand how the protein gets its final shape or conformation, we need to understand the four levels of protein structure: primary, secondary, tertiary, and quaternary. Primary Structure The unique sequence of amino acids in a polypeptide chain is its primary structure. For exa... |
acids are encoded by three nucleotides each, and the mutation is caused by a single base change (point mutation), 1 in 1800 bases. Figure 3.28 The beta chain of hemoglobin is 147 residues in length, yet a single amino acid substitution leads to sickle cell anemia. In normal hemoglobin, the amino acid at position seven... |
R groups are attached to the carbons and extend above and below the folds of the pleat. The pleated segments align parallel or antiparallel to each other, and hydrogen bonds form between the partially positive nitrogen atom in the amino group and the partially negative oxygen atom in the carbonyl group of the peptide ... |
together. Silk (a fibrous protein), however, has a β-pleated sheet structure that is the result of hydrogen bonding between different chains. The four levels of protein structure (primary, secondary, tertiary, and quaternary) are illustrated in Figure 3.32. This OpenStax book is available for free at http://cnx.org/co... |
attention to the protein they eat? a. Plant proteins contain all of the essential as well as non-essential amino acids. b. It is more difficult to obtain all essential amino acids from single plant sources. c. Plant proteins contain only non-essential amino acids. d. Plants proteins do not have all of the non-essentia... |
that is passed from parent to offspring via cell division. DNA has a double-helical structure with the two strands running in opposite directions (antiparallel), connected by hydrogen bonds and complementary to each other. In DNA, purines pair with pyrimidines: adenine pairs with thymine (A-T), and cytosine pairs with... |
of biological molecules and their sequence determine the properties of that molecule. Science Practice Learning Objective 7.1 The student can connect phenomena and models across spatial and temporal scales. 4.1 The student is able to explain the connection between the sequence and the subcomponents of a biological pol... |
the cellular activities by turning the genes “on” or “off.” The other type of nucleic acid, RNA, is mostly involved in protein synthesis. The DNA molecules never leave the nucleus but instead use an intermediary to communicate with the rest of the cell. This intermediary is the messenger RNA (mRNA). Other types of RNA... |
: adenine (A), guanine (G) cytosine (C), and thymine (T). Adenine and guanine are classified as purines. The primary structure of a purine is two carbon-nitrogen rings. Cytosine, thymine, and uracil are classified as pyrimidines which have a single carbon-nitrogen ring as their primary structure (Figure 3.33). Each of ... |
and in many nucleic acid interactions.) Figure 3.34 Native DNA is an antiparallel double helix. The phosphate backbone (indicated by the curvy lines) is on the outside, and the bases are on the inside. Each base from one strand interacts via hydrogen bonding with a base from the opposing strand. (credit: Jerome Walker... |
G, and C), and the phosphate group. There are four major types of RNA: messenger RNA (mRNA), ribosomal RNA (rRNA), transfer RNA (tRNA), and microRNA (miRNA). The first, mRNA, carries the message from DNA, which controls all of the cellular activities in a cell. If a cell requires a certain protein to be synthesized, t... |
Double helix Usually single-stranded Sugar Deoxyribose Ribose Pyrimidines Cytosine, thymine Cytosine, uracil Purines Adenine, guanine Adenine, guanine Table 3.2 Even though the RNA is single stranded, most RNA types show extensive intramolecular base pairing between complementary sequences, creating a predictable thre... |
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