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What makes water special?
Living systems depend on properties of water that result from its polarity and hydrogen bonding. The hydrogen bonds between water molecules result in cohesion, adhesion, and surface tension.
What makes carbon special?
Carbon is used to build biological molecules such as carbohydrates, proteins, lipids, and nucleic acids. Carbon is used in storage compounds and cell formation in all organisms.
What makes nitrogen and phosphorous special?
Nitrogen is used to build proteins and nucleic acids. Phosphorus is used to build nucleic acids and certain lipids.
What does the structure of nucleic acids look like?
In nucleic acids, biological information is encoded in sequences of nucleotide monomers. Each nucleotide has structural components: a five-carbon sugar (deoxyribose or ribose), a phosphate, and a nitrogen base (adenine, thymine, guanine, cytosine, or uracil). DNA and RNA differ in structure and function.
What determines the structure of a protein?
In proteins, the specific order of amino acids in a polypeptide (primary structure) determines the overall shape of the protein.
What determines the properties and functions of complex carbohydrates?
Complex carbohydrates comprise sugar monomers whose structures determine the properties and functions of the molecules.
Are phospholipids fully non-polar?
No, phospholipids contain polar regions that interact with other polar molecules, such as water, and nonpolar regions that are often hydrophobic.
What happens during DNA and RNA synthesis?
During DNA and RNA synthesis, nucleotides are added to the 3’ end of the growing strand, resulting in the formation of a covalent bond between nucleotides.
What determines the primary structure of a protein?
Proteins have a primary structure determined by the sequence order of their constituent amino acids.
What determines the secondary structure of a protein?
Secondary structures arise through local folding of the amino acid chain into elements such as alpha-helices and beta-sheets.
Can carbohydrate polymers only be branched?
Carbohydrate polymers may be linear or branched.
What are the components of DNA and RNA?
Both DNA and RNA have three components—sugar, a phosphate group, and a nitrogenous base
What do ribosomes do?
Ribosomes comprise ribosomal RNA (rRNA) and protein. Ribosomes synthesize protein according to mRNA sequence.
What does the fact that all living creatures have ribosomes imply?
Ribosomes are found in all forms of life, reflecting the common ancestry of all known life.
What does the rough endoplasmic reticulum do?
Rough ER compartmentalizes the cell.
What does smooth endoplasmic reticulum do?
Smooth ER functions include detoxification and lipid synthesis.
What does the golgi complex do?
Functions of the Golgi include the correct folding and chemical modification of newly synthesized proteins and packaging for protein trafficking. (The golgi also synthesizes specific phospholipids and the packages of specific enzymes for lysosomes, peroxisomes, and secretory vesicles)
What does the mitochondria do?
Mitochondrial double membrane provides compartments for different metabolic reactions. The mitochondria is the site of cellular respiration, producing ATP through glycolysis (done outside of it), the Kreb cycle, the ETC, and finally, ATP synthase.
What do lysosomes do?
Lysosomes contain hydrolytic enzymes, which are important in intracellular digestion, the recycling of a cell’s organic materials, and programmed cell death (apoptosis).
What are vacuoles?
A vacuole is a membrane-bound sac that plays many and differing roles. In plants, a specialized large vacuole serves multiple functions.
What do vacuoles do?
Vacuoles have many roles, including storage and release of macromolecules and cellular waste products. In plants, it aids in retention of water for turgor pressure.
What’s in a chloroplast?
Within the chloroplast are thylakoids and the stroma.
How are the thylakoids organized?
The thylakoids are organized in stacks called grana.
What happens in the grana?
The light-dependent reactions of photosynthesis occur in the grana.
What is the stroma?
The stroma is the fluid within the inner chloroplast membrane and outside of the thylakoid.
What happens in the stroma?
The carbon fixation (Calvin-Benson cycle) reactions of photosynthesis occur in the stroma.
Why does cell size matter?
The surface area of the plasma membrane must be large enough to adequately exchange materials.
What is passive transport?
Passive transport is the net movement of molecules from high concentration to low concentration without the direct input of metabolic energy
What is active transport?
Active transport requires the direct input of energy to move molecules from regions of low concentration to regions of high concentration.
What happens in exocytosis?
In exocytosis, internal vesicles fuse with the plasma membrane and secrete large macromolecules out of the cell.
What happens in endocytosis?
In endocytosis, the cell takes in macromolecules and particulate matter by forming new vesicles derived from the plasma membrane.
Can charged ions move into the cell thought passive transport?
Charged ions, including Na+ and K+, require channel proteins to move through the membrane.
What is water potential?
The ability of water molecules to flow freely inside a given environment or system.
How is water potential calculated?
Ψ = Ψp + Ψs where s equals iCRT (s = solute potential)
What is the endosymbiosis theory?
Symbiogenesis is the leading evolutionary theory of the origin of eukaryotic cells from prokaryotic organisms.
What do enzymes do?
Enzymes act as biological catalysts, facilitating chemical reactions within cells and lowering the activation energy.
What can mess with enzymes?
Environmental temperatures and pH outside the optimal range for a given enzyme will cause changes to its structure, altering the efficiency with which it catalyzes reactions.
Do higher temperatures always mess up enzymes’ ability to do their thing?
No, higher environmental temperatures can increase the speed of movement of molecules in a solution, increasing the frequency of collisions between enzymes and substrates and therefore increasing the rate of reaction.
What is the second law of thermodynamics which life cannot violate?
Energy input must exceed energy loss to maintain order and to power cellular processes.
Cellular processes that release energy may be coupled with cellular processes that require energy.
Loss of order or energy flow results in death.
What was responsible for the creation of an oxygenated atmosphere?
Scientific evidence supports the claim that prokaryotic photosynthesis was responsible for the production of an oxygenated atmosphere.
What happens when electrons are transferred between molecules in a sequence of reactions?
When electrons are transferred between molecules in a sequence of reactions as they pass through the ETC, an electrochemical gradient of protons (hydrogen ions) is established across the internal membrane.
What happens to the hydrogen ions within the proton gradient?
They are involved in the synthesis of ATP from ADP and inorganic phosphate via ATP synthase
What does fermentation do?
Fermentation allows glycolysis to proceed in the absence of oxygen and produces organic molecules, including alcohol and lactic acid, as waste products.
What benefit comes from more variation in the number and types of molecules within cells?
Variation in the number and types of molecules within cells provides organisms a greater ability to survive and/or reproduce in different environments.
What can signal transduction pathways do?
Many signal transduction pathways include protein modification and phosphorylation cascades.
What are ligands?
Ligands are chemical messengers that can be recognized by receptor proteins in target cells.
What do signaling cascades do?
Signaling cascades relay signals from receptors to cell targets, often amplifying the incoming signals, resulting in the appropriate responses by the cell, which could include cell growth, secretion of molecules, or gene expression.
What happens after the ligand binds?
After the ligand binds, the intracellular domain of a receptor protein changes shape initiating transduction of the signal.
What are second messengers?
Second messengers (such as cyclic AMP) are molecules that relay and amplify the intracellular signal.
What else does signal transduction do?
Signal transduction may result in changes in gene expression and cell function, which may alter phenotype or result in programmed cell death (apoptosis).
How does a change in the structure of any signaling molecule affect the activity of the signaling pathway?
Mutations in any domain of the receptor protein or in any component of the signaling pathway may affect the downstream components by altering the subsequent transduction of the signal.
What are negative feedback mechanisms?
Negative feedback mechanisms maintain homeostasis for a particular condition by regulating physiological processes. If a system is perturbed, negative feedback mechanisms return the system back to its target set point.
What are positive feedback mechanisms?
Positive feedback mechanisms amplify responses and processes in biological organisms. The variable initiating the response is moved farther away from the initial set point.
What are the stages of the cell cycle?
The cell cycle consists of sequential stages of interphase (G1, S, G2), mitosis, and cytokinesis.
What does mitosis do?
Mitosis plays a role in growth, tissue repair, and asexual reproduction.
Mitosis alternates with interphase in the cell cycle.
Mitosis occurs in a sequential series of steps (prophase, metaphase, anaphase, telophase).
What are cyclins?
Cyclins are proteins associated with the cycle of cell division which are thought to initiate certain processes of mitosis.
What are kinases?
Kinases are a type of enzyme that adds chemicals called phosphates to other molecules, such as sugars or proteins
What role do cyclins and cyclin-dependent kinases play in the cell cycle?
Interactions between cyclins and cyclin-dependent kinases control the cell cycle.
What does meiosis do?
Meiosis results in daughter cells with half the number of chromosomes of the parent cell.
Meiosis involves two rounds of a sequential series of steps (meiosis I and meiosis II).
When does crossing over happen?
During meiosis I, homologous chromatids exchange genetic material through “crossing over” (aka recombination), which increases genetic diversity among the resultant gametes.
How do how shared, conserved, fundamental processes and features support the concept of common ancestry for all organisms?
DNA and RNA are carriers of genetic information.
Ribosomes are found in all forms of life.
Major features of the genetic code are shared by all modern living systems.
Core metabolic pathways are conserved across all currently recognized domains.
What does Mendel’s law of segregation say?
Mendel’s law of segregation and independent assortment can only be applied to genes that are on different chromosomes.
What are two deviations from Mendel’s model of the inheritance of traits?
Genes that are adjacent and close to one another on the same chromosome may appear to be genetically linked; the probability that genetically linked genes will segregate as a unit can be used to calculate the map distance between them.
Many traits are the product of multiple genes and/or physiological processes acting in combination; these traits therefore do not segregate in Mendelian patterns.
What are plasmids?
Plasmids are small extra-chromosomal, double-stranded, circular DNA molecules. Prokaryotes and eukaryotes can contain these plasmids.
What are purines?
Purines; Guanine and Adenine have a double ring structure.
What are pyrimidines?
Pyrimidines; Cytosine, Thymine, and Uracil have a single ring structure.
What does helicase do?
Helicase unwinds the DNA strands during DNA replication.
What does DNA polymerase do?
DNA polymerase synthesizes new strands of DNA continuously on the leading strand and discontinuously on the lagging strand.
What does ligase do?
Ligase joins the fragments on the lagging strand.
What does RNA polymerase do?
The enzyme RNA polymerase synthesizes mRNA molecules in the 5’ to 3’ direction by reading the template DNA strand in the 3’ to 5’ direction.
What are codons?
Codons encode for specific amino acids, which can be deduced by using a genetic code chart. Many amino acids are encoded by more than one codon.
What is fitness?
Evolutionary fitness is measured by reproductive success.
p + q = 1
p2 + 2pq + q2 = 1
p = dominant allele frequency q = recessive allele frequency
p2 = dominant genotype (pp) frequency q2 = recessive genotype frequency
What is allopatric speciation?
In allopatric speciation, groups from an ancestral population evolve into separate species due to a period of geographical separation.
What is sympatric speciation?
In sympatric speciation, groups from the same ancestral population evolve into separate species without any geographical separation.
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