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Questions and Answers
What are the main classes of cell-surface receptors mentioned?
G protein-coupled receptors, ion-channel receptors, receptors linked to cytosolic tyrosine kinases, receptors with intrinsic catalytic activity
Which molecules are mentioned as examples of small lipophilic molecules in the content?
Cellular metabolism, function, or development can be modulated by intracellular pathways triggered by binding of extracellular signaling molecules.
True
______ coordinate the formation of multicomponent signaling complexes.
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Match the following signaling molecules with their modulation in response to binding of ligand to cell-surface receptors:
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What class of receptors do growth factors such as EGF, FGF, and NGF bind to?
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Cell signaling pathways can regulate cell survival and apoptosis.
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What changes occur in the target cell during intracellular signal-transduction pathways?
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Cell signaling involves the synthesis, release, transport, detection, initiation, and removal of __________.
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Match the signaling molecule with its category:
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What is biochemistry defined as?
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What are some important bio-molecules found in the cell?
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All organisms use the same type of molecules, including carbohydrates, proteins, lipids, and nucleic acids.
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Cells are the fundamental structural and functional units of living creatures. New cells arise from previously existing __________.
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What are the common components of each cell?
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What are the two types of cells based on their structure?
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What is the function of the Endoplasmic Reticulum?
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Match the organelles with their functions:
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Study Notes
Introduction to Biochemistry
- Biochemistry is the science of the chemical basis of life.
- It studies the chemical constituents of living cells and the reactions and processes they undergo.
- Biochemistry covers large areas of cell biology, molecular biology, and molecular genetics.
Principles of Biochemistry
- Cells are highly organized and require a constant source of energy to maintain their ordered state.
- Living processes contain thousands of chemical reactions, which require precise integration and regulation to maintain life.
- Certain important reactions are found in almost all organisms.
- All organisms use the same type of molecules, such as carbohydrates, proteins, lipids, and nucleic acids.
- The instruction for reproduction, growth, and development for each organism is encoded in their DNA.
Importance of Biochemistry
- Knowledge of biochemistry is essential to all life sciences, including physiology, immunology, pharmacology, and pathology.
- Biochemistry impacts medicine, illuminating many areas of medicine and effectively treating diseases.
Biochemistry and Medicine
- The two major concerns of workers in the health sciences are understanding and maintaining health, and understanding and effectively treating diseases.
- Biochemistry has a significant impact on both of these concerns, with advances in biochemical knowledge illuminating many areas of medicine.
Biochemical Processes for Life
- The maintenance of health requires optimal dietary intake of certain chemicals, such as vitamins, amino acids, fatty acids, minerals, and water.
- Biochemical processes are essential for preventing diseases, such as atherosclerosis and cancer.
Causes of Diseases with a Biochemical Basis
- Many diseases are manifestations of abnormalities in genes, proteins, chemical reactions, or biochemical processes.
- Electrolyte imbalance, defective nutrient ingestion or absorption, hormonal imbalances, toxic chemicals or biologic agents, and DNA-based genetic disorders are some causes of diseases.
The Human Genome Project
- The sequence of the entire human genome was completed in 2003.
- The project revealed previously unknown genes and their products, providing new insights into procedures for identifying disease-related genes.
- Understanding human health and disease continues to be made by mutating the genomes of model organisms, such as yeast and eukaryotes, to provide clues to curing human diseases.
Cells and Their Components
- Cells are membrane-bound compartments filled with chemicals.
- They are the fundamental structural and functional units of living creatures.
- Cells have four common components: plasma membrane, region containing DNA, cytoplasm, and biochemical molecules and pathways.
Cell Membrane and Its Components
- The cell membrane is a thin barrier (8nm thick) that separates the living cell from its nonliving surroundings.
- It is selectively permeable, allowing some substances to cross more easily than others.
- The cell membrane is made up of phospholipids, proteins, and other macromolecules.
- Phospholipids are composed of fatty acid tails and phosphate group heads.
Organelles
- Nucleus: a double membrane surrounding the chromosomes and the nucleolus, with pores allowing specific communication with the cytoplasm.
- Mitochondrion: surrounded by a double membrane with series of folds called cristae, functioning in energy production through metabolism.
- Endoplasmic reticulum (ER): a network of interconnected membranes forming channels within the cell, with two types: rough ER and smooth ER.
- Golgi apparatus: a series of stacked membranes, receiving proteins from the ER and extruding them in the direction of the cell membrane.
- Lysosomes: formed when pieces of the Golgi apparatus are pinched off as a sac containing lysozymes.
- Peroxisomes: contain oxidative enzymes that form and degrade hydrogen peroxide.
- Cytoskeleton: provides strength and structure to the cell, and provides fundamental mechanistic components needed for movement.
Cell Signaling
- Cell-to-cell communication is essential for multicellular organisms and is also important for many unicellular organisms.
- Cells must communicate to coordinate their activities, and biologists have discovered some universal mechanisms of cellular regulation, involving the same small set of cell-signaling mechanisms.
- Signal-transduction pathway: the process by which a signal on a cell's surface is converted into a specific response.
Cell Signaling Pathways
- Regulate cell cycle, proliferation, and differentiation.
- Involved in cytoskeleton, migration, and membrane traffic.
- Play a role in transcription, development, and body plan.
Importance of Cell Signaling in Medicine
- Cell signaling is central to modern medicine, with implications for cancer, diabetes, Alzheimer's disease, and many other diseases.
General Principles of Cell Signaling
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Cell communication occurs at various distances.
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Numerous signaling molecules and receptors, but limited signaling pathways.
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Ligand-receptor interactions are specific.
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Formation of signaling complex.
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Some intracellular signaling proteins function as molecular switches.### Cell Signaling
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Cells respond to extracellular signals through specific receptors, enabling them to respond to corresponding signal molecules produced by other cells.
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Multiple signals work together to regulate cell behavior, with some signals required for survival and others for division or differentiation.
Receptor Complex
- The hormone-receptor complex enters the nucleus and binds to specific genes, stimulating the transcription of the gene into mRNA.
- The mRNA is then translated into a specific protein in the cytoplasm.
Responses to Cell Signaling
Biochemical Responses
- Gene expression is altered at the level of transcription, RNA processing, or translation.
- Enzyme activities are altered.
- Protein-protein interactions are induced or inhibited.
- The localization of certain proteins and other molecules is altered.
Physiological Responses
- The cell divides or stops dividing.
- The cell differentiates.
- The cell commits suicide or kills something.
- The cell moves somewhere or stops moving.
- The cell alters its metabolism.
- The cell passes on the signal.
Types of Signals
- Membrane-anchored and secreted proteins and peptides.
- Small lipophilic molecules (e.g., steroid hormones, thyroxine).
- Small hydrophilic molecules derived from amino acids (e.g., catecholamines).
- Gases.
- Signals can act at short range, long range, or both.
Cell-Surface Receptors
- Four main classes: G protein-coupled receptors, ion-channel receptors, receptors linked to cytosolic tyrosine kinases, and receptors with intrinsic catalytic activity.
Intracellular Signaling Pathways
- Binding of extracellular signaling molecules to cell-surface receptors triggers intracellular pathways that ultimately modulate cellular metabolism, function, or development.
- The level of second messengers (e.g., Ca2+, cAMP, IP3) is modulated in response to binding of ligand to cell-surface receptors.
- These intracellular signaling molecules regulate the activities of enzymes and nonenzymatic proteins.
Conserved Proteins
- GTPase switch proteins (trimeric G proteins and monomeric Ras-like proteins).
- Protein kinases.
- Adapter proteins, which coordinate the formation of multicomponent signaling complexes.
Regulatory Networks
- Extracellular signals are often integrated into complex regulatory networks, where the synthesis, release, and degradation of hormones are precisely regulated.
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Description
Learn the basics of biochemistry, including the chemical constituents of living cells, reactions, and processes. Explore the principles of biochemistry, cell organization, and energy requirements.
