Description : Cells must constantly manage metabolic pathways, and this is often done by balancing specific biochemical reactions within a pathway. For example, the metabolic product of one pathway may block the formation ... the pathway to prevent a buildup of that specific product. What is this process called?
Last Answer : Feedback inhibition
Description : Metabolism is carried out by a large class of proteins that decrease the activation energy required for chemical reactions inside a cell. Therefore they only facilitate reactions that would naturally occur at a much slower rate. What is the name of these proteins that speed up biochemical reactions?
Last Answer : Enzymes
Description : What are enzymes? (a) saccharides that catalyze chemical reactions (b) unsaturated fats that catalyze chemical reactions (c) DNA molecules that catalyze chemical reactions (d) proteins that catalyze chemical reactions
Last Answer : proteins that catalyze chemical reactions
Description : Name the three metabolic processes used to produce energy in a eukaryotic cell when oxygen is present.
Last Answer : Glycolysis, Citric Acid Cycle, Oxidative Phosphorylation. Or glycolysis and respiration, but the question specifies three processes.
Description : The site of enzymes directing the metabolic oxidation (respiration), ATP synthesis and considered as power house of cell are (A) Lysosomes (B) Microsomes (C) Mitochondria (D) Golgi apparatus
Last Answer : (C) Mitochondria
Description : Which one of the following statements is not characteristic of allosteric enzymes? (A) They frequently catalyze a committed step early in a metabolic pathway (B) They are often composed of subunits (C) They follow Michaelis-Menten kinetics (D) They frequently show cooperativity for substrate binding
Last Answer : Answer : C
Description : Typically proteins do not work in their simple amino acid chain structure but instead fold and form shapes that help in their function. Which of the structures is described as being in alpha helices and beta sheets?
Last Answer : Secondary Protein Structure
Description : Describe how proteins that are synthesized in the endoplasmic reticulum (ER) are transported to their final destination.
Last Answer : Proteins that are synthesized in the ER have a signal sequence that directs them to their target destination. Soluble proteins are carried inside the lumen of vesicles. Cargo-bearing vesicles ... lysosomes or plasma membrane. Vesicles that have released their cargo return via the reverse direction.
Description : How does facilitated diffusion present similarities with enzymatic chemical reactions ?
Last Answer : One of the main examples of facilitated transport is the entrance of glucose from the blood into cells. Glucose from blood binds to specific permeases (hexose-transporting permeases) present in the ... job is concluded the permease is not consumed and can perform successive other transports.
Description : Instead of using energy from oxidative reactions immediately, cells store some of this energy for later use. Name two of these small, energy-rich molecules used to store energy.
Last Answer : ATP and NADH
Description : Which of the following is not true regarding enzymes? (A) They catalyze only a particular type of reaction (B) They remain active even after separation from the source (C) They are destroyed ... They are irreversibly destroyed at high temperature (E) Their activity depends on the pH of the solution
Description : How do the rough endoplasmic reticulum and the Golgi apparatus act in the production and releasing of proteins ?
Last Answer : The rough endoplasmic reticulum has in its outer membrane numerous ribosomes, structures where translation of messenger RNA and protein synthesis occur. These proteins are stored in the rough endoplasmic reticulum ... exocytosis) in the right place and its content is liberated outside the cell.
Description : Without saturation of transport proteins and under same concentration gradient how can the speed of simple diffusion be compared to the speed of facilitated diffusion ?
Last Answer : The action of facilitator proteins in facilitated diffusion makes this type of diffusion faster than simple diffusion under equal concentration gradients of the moved substance.
Description : In many types of cancer, proteins that are crucial regulators of the cell cycle are often mutated and cannot function correctly. This leads to the evasion of apoptosis and to the loss of control of cell ... protein named p53. What is the normal function of p53 that is lost when it is mutated?
Last Answer : Normally, p53 senses DNA damage and acts as a transcription factor for checkpoint control genes.
Description : In order to function, CDKs must interact with members of a separate family of proteins named the cyclins. Do individual cyclins remain associated with the same CDKs throughout the entire cell cycle?
Last Answer : No. Separate cyclins interact with specific CDKs only during defined periods of the cell cycle.
Description : Multiple checkpoints in the eukaryotic cell cycle ensure that division occurs only after sufficient growth and faithful DNA replication, and only when favorable conditions exist. Of the many proteins involved in ... CDKs) are among the most important. How do CDKs function to control the cell cycle?
Last Answer : CDKs phosphorylate various protein substrates that are required for cell cycle progression. Some of the important substrate proteins that CDKs phosphorylate include condensin proteins, which are essential ... which form a stabilizing network under the nuclear membrane that assembles during mitosis.
Description : What are heterotrimeric G proteins?
Last Answer : G proteins with three different subunits, designated as alpha, beta, and gamma. Alpha and gamma subunits attach to the plasma membranes via lipid anchors. In the absence of a signal, the entire GDP ... alpha subunit is replaced by GTP, and the GTP-bound alpha subunit and beta-gamma dimer dissociate.
Description : What are G proteins?
Last Answer : G proteins are proteins that can bind guanosine triphosphate (GTP) and guanosine diphosphate (GDP). G-proteins function as switches; GTP-bound G-proteins are active whereas GDP-bound G-proteins are inactive.
Description : True or False: The vast majority of mitochondrial proteins are synthesized from genetic information encoded in the mitochondrial genome.
Last Answer : False. Most mitochondrial proteins are synthesized from nuclear genes and then transported into the mitochondria through the presence of a signal sequence.
Description : Name the organelle that contains high levels of hydrolases and is responsible for digestion of proteins, sugars, nucleic acids and lipids.
Last Answer : Lysosomes
Description : What is the function of proteins like microtubules and actin filaments?
Last Answer : Give structure to cells.
Description : What types of proteins are involved in the packaging and condensing of DNA into tightly wound nucleosome structures of a chromosome?
Last Answer : Histone
Description : A cell that is missing lysosomes would have difficulty doing what? (A) Digesting food (B) Storing energy (C) Packaging proteins (D) Moving cytoplasm
Last Answer : (A) Digesting food
Description : Biochemically the ribosome consists of _______________ and some 50 structural . (A) mRNA, Carbohydrates (B) tRNA, lipids (C) mRNA, Proteins (D) rRNA, Proteins
Last Answer : (D) rRNA, Proteins
Description : How enzymes speed up catalyze reactions?
Last Answer : Feel Free to Answer
Description : Proteinous substances which catalyze biochemical reactions are known as (A) Activators (B) Catalysts (C) Enzymes (D) Hormones
Description : The electron transport chain within the inner mitochondrial membrane creates a gradient of ____________ across the inner membrane which is utilized to drive the activity of ATP synthase and the generation of ATP.
Last Answer : Hydrogen (H+ ions) or protons
Description : Hormone receptors that stimulate cAMP production (A) are part of a complex of two proteins that transform the external signal into internal cAMP production (B) are proteins distinct and separate from those ... binding of the hormone (D) are not very specific and bind a number of different hormones
Last Answer : Answer : B
Description : Tissues are constructed from many distinct cell types that perform different functions in response to signals from each other and the extracellular matrix. During tissue development and tissue regeneration, ... that stem cells undergo when they are required to generate a particular type of cell?
Last Answer : Asymmetric cell division. After asymmetric division, each of the two resulting daughter cells has a unique life course. For example, one daughter cell may differentiate into a specific cell type ( ... cell), whereas the other daughter cell may remain a stem cell with unlimited proliferative ability.
Description : How does the sodium-potassium pump present in the cell membrane work ?
Last Answer : What is the importance of this protein for the cell? The sodium-potassium pump is the transport protein that maintains the concentration gradient of these ions between the intra and the ... maintain the cellular metabolism. Cell Membrane Review - Image Diversity: sodium-potassium pump
Description : How do RTKs differ from other cell surface receptors?
Last Answer : RTKs are receptors that contain intrinsic enzyme (tyrosine kinase) activity.
Description : Why do ion channels contribute to faster cellular responses than other signaling mechanisms, such as GPCR-mediated signaling?
Last Answer : Ion channels generate electrical signals, which signals travel much more rapidly than chemical signals that depend on the process of molecular diffusion. An electrical signal can traverse the entire length of a nerve cell within milliseconds.
Description : Chromatin has two different regions, euchromatin and heterochromatin. One of these regions is highly condensed and considered an inactive region whereas the other is less condensed so it is more ... for transcription. Which of these regions would contain genes that are being transcribed often?
Last Answer : Euchromatin. Euchromatin is less condensly packaged allowing for easier access by transcription factors and polymerases. Heterochromatin is a region of condensed packaging and considered an inactive region.
Description : Concerning permeability what type of membrane is the cell membrane ?
Last Answer : The cell membrane is a selectively permeable membrane, i.e., it allows the passage of water and some selected solutes. Cell Membrane Review - Image Diversity: cell membrane
Description : Which type of cell came first in evolution the eukaryotic cell or the prokaryotic cell ?
Last Answer : This is an interesting problem of biological evolution. The most accepted hypothesis asserts that the more simple cell, the prokaryotic cell, appeared early in evolution than the more ... from the mutualist ecological interaction between aerobic prokaryotes and primitive anaerobic eukaryotes.
Description : RNA molecules can be broken up into three classes-which type of RNA molecule is translated into a protein sequence?
Last Answer : Messenger RNA (mRNA). mRNAs are the RNA transcripts that contain protein coding sequences which are translated into protein.
Description : How are solutions classified according to their comparative tonicity ?
Last Answer : Comparatively to other a solution can be hypotonic (or hyposmotic), isotonic (or isosmotic) or hypertonic (or hyperosmotic). When a solution is less concentrated than other the adjective hypotonic ... the adjective isotonic. So this classification makes sense only for comparison of solutions.
Description : Concerning their permeability how are membranes classified ?
Last Answer : Membranes can be classified as impermeable, permeable, semipermeable or selectively permeable. An impermeable membrane is that through which no substance can pass. Semipermeable membranes are those that let only ... the passage of solvent let only some specific solutes to pass blocking others.
Description : List three common second messengers and the enzyme responsible for their production:
Last Answer : - cAMP - synthesized from ATP by adenylate cyclase - diacylglycerol (DAG) and inositol 1,4,5-triphosphate (IP3)- produced by the phospholipase C - Ca2+ - released from intracellular stores (the second messenger IP3 is a common trigger for Ca2+ release).
Description : Cytoskeletal elements are responsible for giving cells their shape and provide a basis for cell movement, migration, and cell division. Name the three major classes of cytoskeletal elements in eukaryotic cells.
Last Answer : Microtubules (composed of tubulin); actin filaments (made up of actin); intermediate filaments
Description : Isolation of cellular components to determine their chemical composition is called (A) Cell differentiation (B) Chromatography (C) Cell fractionation (D) All of these
Last Answer : (C) Cell fractionation
Description : Adjacent plant cells are “cemented” together by (A) Their primary walls (B) Their secondary walls (C) A middle lamella (D) Plasmodesmata
Last Answer : (C) A middle lamella
Description : Can two normal individuals of the same species with sexual reproduction have identical genomes and identical karyotypes ? How the human karyotype is usually represented?
Last Answer : Except for clones (individuals created from nucleus transplantation, like the Dolly sheep) and monozygotic twins, it is very improbable the genomes of two individuals of the same species and generated by sexual ... normal karyotype is represented by the formula 44+XX for women and 44+XY for men.
Description : What is the difference between the concepts of karyotype and genome ?
Last Answer : Genome is the set of DNA molecules that characterizes each living being or each species. The concept then includes the specific nucleotide sequence of the DNA molecules of each individual or species. ... of each chromosome or pair of homologous. Cell Nucleus Review - Image Diversity: karyotype
Description : What are homologous chromosomes ?
Last Answer : Which are the human cells that do not have homologous chromosomes? Chromosomes contain genes (genetic information in the form of nucleotide sequences) that command the protein synthesis thus ... chromosomes are the gametes since during meiosis the homologous chromosomes are separated.
Description : What are the primary and the secondary constrictions of a chromosome ?
Last Answer : What is the other name given to the secondary constriction? Primary constriction is the narrower region of a condensed chromosome where the centromere, the structure that unites identical chromatids, is located. ... can be one or more in chromosome) is called nucleolus organizer region (NOR).
Description : How the chromosome region where the centromere is located is called ?
Last Answer : How are chromosomes classified in relation to the position of their centromere? The chromosome region where the centromere is located is called primary constriction. In microscopic view ... constriction the chromosomes are classified as telocentric, acrocentric, submetacentric or metacentric.
Description : What is the structure that maintains identical chromatids bound ?
Last Answer : The structure that maintains identical chromatids bound is the centromere. Cell Nucleus Review - Image Diversity: centromere
Description : How are the concepts of chromosome ?
Last Answer : chromatin and chromatids related? In which phase of the cell cycle does DNA duplicate? Chromatin is a set of filamentous DNA molecules dispersed in the karyoplasm forming euchromatin and heterochromatin ... chromosomes (and not only one). Cell Nucleus Review - Image Diversity: chromatids
Description : In the phase when the cell is not dividing ?
Last Answer : interphase) is there activity within the cell nucleus? In the interphase there is intense metabolic activity in the cell nucleus: DNA is duplicating, euchromatin is being transcript and RNA is produced.