Lab equipment: Tour, terminology, & tips (biochemistry, structural, molecular biology focus) скачать в хорошем качестве

Lab equipment: Tour, terminology, & tips (biochemistry, structural, molecular biology focus)

If you spend lots of time in the lab, it becomes like your second home. But most people have (sadly) never been in a biochemistry lab & our "furniture" & "appliances" may seem foreign, so this post will be a "glossary" of some equipment we use. blog form with full text: http://bit.ly/equippedtoexperiment This glassware is really cool, I swear! Instead of vases and jars, biochemists use Erlenmeyer flasks and Pyrex bottles (in lots of different sizes). Here's a look into our glassware cabinets. Erlenmeyer flasks are a classic go-to “science icon” - they’re wider at the bottom & narrower at the top, which makes them good for swirling liquids & their narrow top helps prevent gas escape (especially if you put in a stopper!) Our normal beakers don't have a skinny top - they’re more like glass tumblers - But they do usually have a lip to help you pour & wide top makes them easier to get in & out of. We use beakers for preparing solutions or temporarily holding them. If we want to store liquids longer-term, we usually put them in Pyrex bottles. These are made of a very strong glass that can withstand the super hot temperatures & pressure of our autoclave (like a dishwasher but much much hotter) Flasks, beakers, & bottles all have measurement lines, but they’re more of “estimates.” If you want accurate measurements you’ll need to go elsewhere & that elsewhere depends on how much you need to measure & how accurate you need to be (does your 50mL really need to be exactly 50mL or is 50.5mL ok? So what are the biochemist’s “measuring cups”? When you want to measure ~50mL - 2L reasonably accurately, the graduated cylinders are your friends. Graduated cylinders are similar to the beakers except they’re skinnier and have more measurement lines (graduations) (being narrower allows these lines to be more spread out). For our purposes, graduated cylinders are usually plenty accurate for these larger volumes (when you have larger volumes, slight measurement error is “diluted out” like a drop in a pool) but there are more accurate types of glassware - volumetric flasks are very accurate, but each is accurate for 1 specific volume - each size has a “fill to” line for that 1 volume. And this fill to line is on the long skinny neck where you get a nice meniscus you can clearly see the bottom of (the meniscus is the smiley shape that liquid takes when it starts crawling up the sides of the container & you want to measure from the bottom of it). They’re more accurate than a graduated cylinder but less multi-functional. We’re mostly concerned about accuracy when measuring smaller volumes and for that, we use pipettes. Getting from tube A to tube B (the Biochemistry Transit System) by transferring liquid from one place to another is probably ~70% of what my lab life entails, so it’s about time we talk about Picking Pipettes A pipette is a piece of lab equipment that you use to draw up and dispense liquid. They come in many sizes and types. The “classic” Pasteur pipette is basically as simple as pipettes get - glass tubes w/a narrowed tip - you attach a rubber bulb to the top & squeeze it to create suction to suck up liquid (people used to do this with their mouth - DON’T!) I don’t use Pasteur pipettes often because you can’t measure with them, but they’re good for adding liquid drop by drop, like when you’re trying to adjust the pH of a solution & have to add drops of acid or base until it settles on the pH you want. We also have plastic transfer pipettes ("eyedroppers”) that are similar to the Pasteur pipettes but they’re plastic and all-in-one (no bulb required) If I want to transfer volumes ranging from ~2mL-25mL, I use serological pipettes. These pipettes have measurement lines so you can move around measured volumes of liquid. You can use rubber bulbs (bigger ones) with serological pipettes, but (thankfully) we have electric “Pipet-Aids” to help. The top button draws up fluid and the bottom button releases it. The Pipet-Aid is powerful, so thankfully these serological pipettes have cotton plugs to prevent you from drawing up liquid too far and damaging the Pipet-Aid. For transferring volumes 1mL or less, we use micropipettes. These are probably our most-used pieces of equipment. They come in multiple volume ranges. When possible, you want to choose a range the volume you want is in the middle of, as that’s where it’s most accurate. We refer to these micropipettes in terms of the largest volume they can transfer - for example, a “P20” is a pipette which can transfer volumes from 2-20µL“P20” is a pipette which can transfer volumes from 2-20µL (a microliter (µL) is 1000X smaller than a mL). To use a micropipette, you push down the top button, place the pipette in liquid then release the button. Then move it to where you want it and push back down to dispense. Once you’re done, you push the ejection lever to eject the tip into a waste container.