(d)+Active+transport+(Q16-24)

16.What is **active transport**? What is required and where does this occur? It is a kind of transport wherein ions or molecules move against a concentration gradient, which means movement in the direction opposite that of diffusion - or - movement from an area of lower concentration to an area of higher concentration. These are cell membrane processes that require energy. These processes are also (as far as we can tell) mediated by membrane carrier molecule. (Proteins) " Active Transport " "pumps" materials across the membrane against the concentration gradient. I.e. from low concentration to high concentration therefore requires energy. (In humans this process occurs in the small intestine, cells there engulf fat droplets.) Pasted from <[]> media type="file" key="Cell Membrane, Active Transport.flv" width="360" height="270"

 Q 17: Copy the following into your notes. We will cover this in more detail later.

ATP is the small energy carrying molecule that is used within cells of __ALL__ living things. Once the energy is used, it becomes ADP. This is recharged back into ATP inside the mitochondria, during respiration. 

18. Give 2 reasons why cells must use active transport at times, instead of diffusion? · Some substances or molecules are too large to diffused through the cell membrane, so active transport is used to push these substances through · Some ions that need to pass through are charged (like sodium and potassium), and because the hydrophobic tails are also charged, the charged ions wouldn’t be able to pass through. Active transport enables them to pass through the cell membrane · The substances can only diffuse through from a high concentration to a low concentration, so if this is not the case, active transport is used instead.

﻿ <span style="display: block; margin: 0in 0in 0pt 0.5in; mso-list: l0 level1 lfo1; tab-stops: list .5in; text-indent: -0.5in;"><span style="font-family: 'Times New Roman','serif'; font-size: 14pt;">19. Describe the functioning of **protein pumps**. <span style="display: block; margin: 0in 0in 0pt 0.5in; mso-list: l0 level1 lfo1; tab-stops: list .5in; text-indent: -0.5in;"><span style="font-family: 'Times New Roman','serif'; font-size: 14pt;">Protein pumps are used for active transport where proteins diffuse from an area of high concentration to an area of low concentration using energy. For example, the sodium-potassium pump uses ATP to transport sodium ions outside of the membrane and potassium ions back in. <span style="font-family: 'Calibri','sans-serif'; font-size: 11pt; line-height: 115%;">They are also used to transport big and charged molecules and molecules with a concentration against the cells. Below is a link to an animation showing how a sodium-potassium pump works: [] <span style="display: block; margin: 0in 0in 0pt 0.5in; mso-list: l0 level1 lfo1; tab-stops: list .5in; text-indent: -0.5in;"><span style="font-family: 'Times New Roman','serif'; font-size: 14pt;"> <span style="display: block; font-family: 'Times New Roman','serif'; font-size: 14pt;">(20) The Golgi apparatus & endoplasmic reticulum are within the cell away from the plasma membrane. Explain how cells use **vesicles** as an intermediary for materials that they export annotated diagrams!). What is a vesicle? What feature of membranes allows vesicles to form? <span style="display: block; font-family: 'Times New Roman','serif'; font-size: 14pt;">**Vesicles -** tiny, membrane-enclosed sacs that carry cargo within the cell. Vesicles typically transport large molecules that cannot pass through a membrane on their own or by using other transporter molecules. Vesicles gather their large cargo in a process called budding; they move with their cargo through the cell; and then they deliver their cargo by fusing with another membrane-enclosed compartment or with the cell's plasma membrane. <span style="display: block; font-family: 'Times New Roman','serif'; font-size: 14pt;"> <span style="font-family: 'Times New Roman','serif'; font-size: 14pt;">(21) Define **endocytosis** and **exocytosis**. Draw a series of diagrams to describe these processes. <span style="font-family: 'Times New Roman','serif'; font-size: 14pt; line-height: 0px; overflow: hidden;">﻿  <span style="display: block; font-family: 'Times New Roman','serif'; font-size: 14pt;">Q21 <span style="font-family: 'Times New Roman','serif'; font-size: 14pt;">Define **endocytosis** and **exocytosis**. Draw a series of diagrams to describe these processes.
 * <span style="font-family: 'Times New Roman','serif'; font-size: 14pt;">Endocytosis: **<span style="font-family: 'Times New Roman','serif'; font-size: 14pt;">the process by which the cell takes up a substance by surrounding it with membrane.
 * <span style="font-family: 'Times New Roman','serif'; font-size: 14pt;">Exocytosis: **<span style="font-family: 'Times New Roman','serif'; font-size: 14pt;">the reverse of endocytosis: materials are being removed from the cells.

<span style="font-family: 'Times New Roman','serif'; font-size: 14pt;">Endocytosis - is a process in which a substance gains entry into a cell without passing through the cell membrane.

<span style="font-family: 'Times New Roman','serif'; font-size: 14pt;">Exocytosis - Exocytosis is a cellular process where cells eject waste products or chemical transmitters (such as hormones) from the interior of the cell. <span style="font-family: 'Times New Roman','serif'; font-size: 14pt;">Exocytosis is similar in function to ** [|endocytosis] ** but working in the opposite direction.

<span style="display: block; font-family: 'Arial','sans-serif'; font-size: 10pt;"><span style="font-family: 'Arial','sans-serif'; font-size: 10pt;"> video of endocytosis []

<span style="display: block; font-family: 'Times New Roman','serif'; font-size: 14pt;"> Q22 <span style="display: block; font-family: 'Times New Roman'; font-size: 14pt; font-style: normal; font-weight: normal;">Distinguish between pinocytosis & phagocytosis: <span style="display: block; font-family: 'Times New Roman','serif'; font-size: 14pt;"> There are two different types of endocytosis: pinocytosis and phagocytosis. Pinocytosis is when the substance is a fluid and is sometimes called "cell drinking". Phagocytosis is when the substance is solid and is sometimes called "cell eating". Pasted from [] Q23 What is a contractile vacuole? Explain what it does, why, and how it works. A **contractile vacuole** is used to help **protists** (eukaryotic microorganisms that have different modes of nutrition and reproduction) **eliminate excessive** amounts of **liquid** from the cell. This is done through **pumping**, which lessens the "osmotic pressure" (high water potential), thus **preventing the cell from bursting**. This condition, of requiring a contractile vacuole to reduce water pressure, is called "**cytolysis**" or "**osmotic lysis**".

The contractile vacuole is usually found in **freshwater organisms**, such as amoeba. contractile vacuole, regulatory organelle, usually spherical, found in freshwater protozoa and lower metazoans, such as sponges and hydras, that collects excess fluid from the protoplasm and periodically empties it into the surrounding medium. It may also excrete nitrogenous wastes. In amoebas it changes position with the animal’s movement; in most ciliates it follows a definite path through the cell; in the Euglena and other flagellates it remains stationary. The filling and emptying cycle may last from seconds to a minute, depending on the species. Pasted from <[]>  media type="file" key="Paramecium and Osmosis.flv" width="360" height="270"