2 Prelecture Quiz (True False) The endoplasmic reticulum is the control center of the cell.Cells communicate with each other by means of chemical messenger systems.The glycolytic pathway does not require oxygen to produce cellular energy.Examples of passive movement across the cell membrane include diffusion, osmosis, and active transport.Cells with a similar embryonic origin or function are often organized into larger functional units called tissues.FT
3 Prelecture Quiz__________ tissue is the most abundant tissue type in the body.Three types of __________ tissue exist: skeletal, cardiac, and smooth.__________ literally means “cell eating” and involves the engulfment and subsequent killing or degradation of microorganisms and other particulate matter.The __________ serve as sites of protein synthesis in the cell.Cell metabolism is the process that converts carbohydrates, proteins, and fats into __________, which is the major source of energy for all body cells.ATPConnectivemusclePhagocytosisRibosomes
7 Red Blood Cells Start Out with All the Organelles As they mature, they:Lose their lysosomesProduce hemoglobinHave small Golgi bodiesHave enlarged endoplasmic reticulumWhen they are mature, they:Lose their endoplasmic reticulumLose their mitochondriaHow does this relate to their function?
8 QuestionBy the time a red blood cell (RBC) is mature, it has lost all but which of the following? a. lysosomes b. endoplasmic reticulum c. hemoglobin d. mitochondria
9 AnswerHemoglobinBecause the function of the RBC is to carry oxygen, hemoglobin is an essential component of the cell (each hemoglobin molecule can carry four molecules of oxygen) . Lysosomes, endoplasmic reticulum, and mitochondria all exert some metabolic function in other cells. But, if they remained in the RBC, the oxygen on board would be consumed before reaching its destination.
10 Anaerobic Energy Metabolism— Glycolysis In the cytoplasm, molecules are broken into chunks, 2-carbons eachGlycolysis breaks sugar 2 ATP molecules formedOther pathways break fatty acids or amino acidsBreaking molecules involves removing electronsWhich are handed to electron carriers like NAD and FADH+ follow the electronsAfterwards, they are put back on the 2-carbon chunksForming lactic acid
11 Aerobic Energy Metabolism—Krebs Cycle The 2-Carbon molecules don’t make lactic acid but2-carbon molecules enter the mitochondrion matrix spaceKrebs cycle breaks them down 1 ATP molecule formedCarbon is lost as CO2Energy is extracted from nutrients and used to form ATP from ADPEnergy is released to do cellular work when ATP is broken back down to ADP
12 Krebs Cycle Occurs within Mitochondria Breaking molecules involves removing electronsHanded to electron carriers like NAD and FADH+ follows the electronsMany of these electron carriers are loaded up with electrons by the Krebs cycle
13 QuestionTell whether the following statement is true or false: ATP is produced in the mitochondria.
14 AnswerTrue The Krebs cycle occurs in the mitochondria. Each Krebs cycle produces one molecule of ATP.
15 Diffusion Is Movement of Molecules Passive diffusion: molecules move randomly away from the area where they are most concentratedFacilitated diffusion: molecules diffuse across a membrane by passing through a proteinOsmosis: diffusion of water molecules
16 QuestionYour patient has been given an intravenous solution of water. What will happen to this patient’s red blood cells?They will burst/lyse.They will shrink.They will not be affected by the water solution.
17 AnswerThey will burst/lyse.Osmosis causes movement from “more watery” to “less watery.” Because water is “more watery” than the RBC (it’s water, after all), water moves into the cell, causing it to expand and burst/lyse.
18 Cell CommunicationA messenger molecule attaches to receptor proteins on cell surfaceReceptor proteins cause cell to respond by:Opening ion channels to let ions in or outCausing a second molecule to be released inside the cellTurning on enzymes inside the cellStimulating the transcription of genes in the nucleus
19 The Basics of Cell Firing Cells begin with a negative charge: resting membrane potentialStimulus causes some Na+ channels to openNa+ diffuses in, making the cell more positive
20 The Basics of Cell Firing (cont.) At threshold potential, more Na+ channels openNa+ rushes in, making the cell very positive: depolarizationAction potential: the cell responds (e.g., by contracting)
21 The Basics of Cell Firing (cont.) K+ channels openK+ diffuses out, making the cell negative again: repolarizationNa+/K+ ATPase removes the Na+ from the cell and pumps the K+ back in
23 QuestionTell whether the following statement is true or false: An action potential is the result of K+ movement out of the cell.
24 AnswerFalse An action potential occurs when Na+ moves into the cell, making it more positive on the inside (depolarization). When K+ leaves the cell, it becomes less positive (more negative) until it returns to resting membrane potential (repolarization).
25 Muscle Contraction Na+ enters cell and muscle cell depolarizes Ca2+ releasedfrom sarcoplasmicreticulum into thesarcoplasmCa2+attaches totroponin
26 QuestionWhat happens to the sarcomere when myosin slides across the actin binding sites?It gets longer.It gets shorter.There is no change in length.It releases acetylcholinesterase.
27 AnswerIt gets shorter.When the myosin binds with exposed actin sites (myosin “reaches” forward like your hands do when pulling end-over-end on a rope), the Z lines get pulled closer together, and the muscle cell shortens/contracts.