Anatomy and Physiology - The Cell

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Study GuideAnatomy and PhysiologyThe Cell1.Quiz: The Cell and Its Membrane1. QuestionThe fluid matrix inside the cell is called __________.Answer Choices• nucleoplasm• endoplasm• cytosolCorrect AnswercytosolWhy This Is CorrectCytosolis the jelly-like fluid inside the cell where organelles are found and many chemical reactionsoccur.(Nucleoplasmis the fluid inside the nucleus.)2. QuestionThe cytosol consists of all the following except __________.Answer Choices• organelles• water• cell membrane

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Study GuideCorrect Answercell membraneWhy This Is CorrectThecell membranesurrounds the cell, so it isnot part of the cytosol.Cytosol contains mostlywater, dissolved substances, and is the fluid that surroundsorganellesinside the cell.3. QuestionThere is water on the inside and outside of a cell. The inside water and outside water are separatedby a cell membrane that is composed of two layers of phospholipids. Due to the hydrophobic nature ofthe fatty acids in the cell membrane, which of the following best describes the position of the fattyacids within the membrane?Answer Choices• facing toward each other• facing away from each other• facing toward each other while others face away from each otherCorrect Answerfacing toward each otherWhy This Is CorrectFatty acid tails arehydrophobic (water-fearing), so they turn inward away from water.They facetoward each otherin the middle of the membrane, while the hydrophilic heads faceoutward.4. QuestionThe cell membrane is composed of numerous proteins, some of which allow for passage of materialin and out of the cell. Which of the following proteins allow large molecules to pass through passively?

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Study GuideAnswer Choices• receptor• channel• transmembrane transporter proteinCorrect AnswerchannelWhy This Is CorrectChannel proteinsallow certain substances to pass through the membranepassively(facilitateddiffusion), meaningno ATP is required.5. QuestionWhich of the following proteins have a carbohydrate molecule associated with it?Answer Choices• channel• adhesion• recognitionCorrect AnswerrecognitionWhy This Is CorrectRecognition proteinsoften have carbohydrate chains attached (formingglycoproteins) that act likeID tagsfor cell identification.

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Study Guide6. QuestionSince the liver cells detoxify drugs, they most likely have an abundance of __________.Answer Choices• smooth endoplasmic reticulum• nuclei• lysosomesCorrect Answersmooth endoplasmic reticulumWhy This Is CorrectThesmooth endoplasmic reticulum (SER)is responsible fordetoxifying drugs and harmfulsubstances, especially in liver cells.7. QuestionSince the cells of the cortex of the adrenal gland produce steroid hormones, they most likely have anabundance of __________.Answer Choices• mitochondria• nuclei• smooth endoplasmic reticulumCorrect Answersmooth endoplasmic reticulumWhy This Is CorrectThesmooth endoplasmic reticulumis important for makinglipids and steroid hormones, sosteroid-producing cells have a lot of SER.

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Study Guide8. QuestionSince muscle cells make and utilize an abundance of ATP (energy) for muscle activity, each musclecell most likely has numerous __________.Answer Choices• peroxisomes• lysosomes• mitochondriaCorrect AnswermitochondriaWhy This Is CorrectMitochondriaare the “powerhouses” of the cell whereATP is produced, so active muscle cellscontain many mitochondria.9. QuestionDuring metabolism, hydrogen peroxide is produced as a byproduct. Hydrogen peroxide can lead tothe formation of toxic products. In order to prevent this, the cells break hydrogen peroxide down toform water and oxygen. Which of the following cell organelles has this function?Answer Choices• lysosomes• smooth endoplasmic reticulum• peroxisomesCorrect Answerperoxisomes

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Study GuideWhy This Is CorrectPeroxisomescontain enzymes (like catalase) that break downhydrogen peroxide (HO)intowater (HO)andoxygen (O)to protect the cell.2.Cell JunctionsNormally, theplasma membranesof neighboring cells arenot touching directly.Instead, there is usually a small space filled withextracellular fluidbetween them.This fluid is important because it helps materials move:nutrientsfrom the bloodstream to cellswastesfrom cells back to the bloodstreamHowever, in some tissues, cells need to staystrongly connectedorcommunicate quickly. In thosecases, the cell membranes join together to form special connections calledcell junctions.Figure 1. The three types of cell junctions.

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Study Guide2.1The 3 Types of Cell Junctions1) Desmosomes (Strong “Spot Welds”)Desmosomesare strongprotein attachmentsbetween adjacent cells.Inside the plasma membrane, a desmosome has:adisk-shaped structureprotein fibersthat extend into the cytoplasmMain job:hold cells together tightlyDesmosomes work likespot welds, which makes tissues strongerespecially tissues thatexperience a lot of pulling, stretching, or pressure.Examples of where desmosomes are common:skinheart muscle2) Tight Junctions (Leak-Proof Seams)Tight junctionsare liketightly stitched seamsbetween cells.A tight junction:completely surrounds each cell (like a seal)blocks materials from slippingbetweencellsSo, substances cannot pass through the spaces between cells.Why is this important?In some organs, the body needs materials to passthrough the cell, not between cells. Tightjunctions force that controlled movement.Where tight junctions are found:cells lining thedigestive tractThis helps regulate what enters the bloodstream from digestion.

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Study Guide3) Gap Junctions (Communication Tunnels)Gap junctionsare tinytunnelsbetween neighboring cells.They are made of protein structures called:connexonsConnexons allow only:ionssmall moleculesWhat do gap junctions do?Gap junctions allow cells to:communicate by exchanging materialssend electrical signals quickly (electrical impulses)Key TakeawaysDesmosomes=Durable “spot welds” (strong hold)Tight junctions=Tight seal (no leaks between cells)Gap junctions=Gaps for communication (small tunnels)3.Quiz: Cell Junctions1. QuestionMany cells in our body have a certain degree of space between them. Generally, there is water orfibrous products within that space; however, some cells don't have a space between them and aretightly bound to each other. Which of the following cell junctions is designed in such a manner tocreate a “tube” connecting one cell to the other such as in cardiomyocytes?Answer Choices• gap junctions• tight junctions• desmosomes

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Study GuideCorrect Answergap junctionsWhy This Is CorrectGap junctionsform tiny channels (“tubes”) that connect the cytoplasm of one cell to another, allowingions and small molecules to pass through.This is especially important incardiomyocytes (heart muscle cells)so electrical signals can travelquickly for coordinated contractions.2. QuestionWhich of the following types of junctions have protein that extends from one cell to another, thus“attaching” one cell to the other such as in the cells of the stratum spinosum?Answer Choices• gap junctions• tight junctions• desmosomesCorrect AnswerdesmosomesWhy This Is CorrectDesmosomesare strong “spot weld” junctions that use proteins toanchor cells together, providingstrength and resistance to pulling forces.They are common in areas with mechanical stress, like thestratum spinosum of the skin.

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Study Guide4.Movement of SubstancesTo understand how substances move in and out of cells, you need to know a few key ideas first.These ideas show up again and again in biology and anatomy.4.1Key Ideas You Must Know First1) Movement often happens across a semi-permeable membraneMany substances move across asemi-permeable membrane, such as theplasma membrane.Semi-permeablemeans:some substances can pass throughothers cannotSo the membrane acts like a “selective filter.”2) We may be talking about solute or solventWhen we describe movement in body fluids, we usually mean either:Water→ thesolventDissolved particles(like salt or sugar) → thesolute3) Movement depends on the concentration gradientSubstances can move:Down the concentration gradientfromhigher concentration → lower concentrationUp (against) the concentration gradientfromlower concentration → higher concentration4) Tonicity describes solute concentration differencesSolute concentration can vary between two regions. Compared to another area, a solution can be:
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