Lab practical-Biology
What is the cuvette? Why is it important to wipe it clean before reading a sample?
A cuvette is a vessel that holds the sample to be analyzed by the spectrophotometer. When holding the cuvette, it is very important to touch only the top portion of the cuvette. If the bottom portion of the cuvette is touched, use a piece of Kimwipe to wipe them down, as prints and lint can INTERFERE with the readings.
SI for Volume (liquid)
cubic meter or liter m^3 or L
plasmolysis
cytoplasm shrinks and peels away from cell wall
Sudan IV test
detects lipids Positive- reddish color Negative- remains(pink)
Biuret test
detects the presence of proteins(peptide bonds) Positive- violet color Negative- light blue( color of biuret reagent)
What makes a compound light microscope "compound?"
determined by its ocular and the objectives(magnifying lenses)
What factors affect the rate of diffusion of any substance?
diffusion is molecules that move from higher concentration to an area of lower concentration.LEADS TO EQUILLIBERUM 1.Temperature- As temperature increases, the average kinetic energy of particles increases. 2.Density- of diffusing substance. Density is defined as the amount of material that exists in a given volume. 3.Medium- of diffusion. Diffusion also depends upon the medium in which it takes place.
What is an acid and base?
An acid RELEASES H+ into the solution, INCREASING the total H+ concentration A base ABSORBS free H+, DECREASING the total amount if H+ in the solution
SI for Mass is...
gram g
Outliers
greater than 2 or less than 2 -measurements that falls outside of two standard deviations from the mean
Dependent Variable
Variable you observe -the data of the experiment, the portion of the experiment that will be measured or observed.
P10
WHITE micropipette-max 10 microliter top digit can go to 1(10) or 0(less than 10) middle digit is SINGLE units last digit(in RED) is TENTHS(0.1) EX: 4.8uL 0 4 8
spectrophotometer; How did we use it in this lab?
We used the spectrophotometer to measure the effect of pH on lysozymes activity as measured by its ability to lyse bacteria. We determined whether the bacteria are killed by the lysozyme with the spectrophotometer
some differences between plant, animal, protist and bacterial cells?
*Plant and animals cells are different in that plant cells have a cell wall, as well as chloroplasts. * Bacteria and protists do not have a nucleus. *Prokaryotic(bacteria) are smaller, less complex and does not have a membrane-bound structure( no nucleus) *Eukaryotic (plants, animals, fungi, and protists) are larger, more complex and have distinct membrane-bound structure( has nucleus)
TEST for the presence of starch, chloride ion, sulfate ion, glucose, and albumin
*starch test(IKI)- positive will be blue-black *chloride ion test (silver nitrate AGNO3)- positive will be white *sulfate ion(barium chloride BaCl2)- positive will show white *Glucose test(diastix) determine from bottle pos/neg *albumin test(albustix) determine from bottle pos/neg
Kilo (K)=
1,000
1 km=
1,000m
There are three different shapes in bacteria?
1. Cocci- sphere or berry shape 2.Bacilli- rod or pill shape 3.Spirilla- spiral shape or helixes
What is gel electrophoresis? How does it work? What is the role of the buffer in the electrophoresis chamber?
1. Gel electrophoresis is a technique used in molecular biology to separate a variety of types of polar molecules by applying electricity using a gel matrix. 2. sorts molecules by size, due to being run through a gel matrix containing pores, and also separates molecules by charge due to the applied electrical field. 3.The role of a buffer serves to maintain a stable pH and temperature during gel electrophoresis
the procedure to properly bring a specimen into focus
1. Lower stage to the lowest position by turning the course focus knob. 2. Rotate the nosepiece to put the 4X-scanning objective in place.( You start here to give yourself the largest field of view in order to find the object). 3. Position your slide so it is flush with the bottom and left side of the mechanical stage bracket. (The slide should NOT be wedged underneath this bracket, but rather immobilized by it. ) 4. Look through the oculars while raising the stage using the course focus knob until the specimen comes into focus. 5. Use the mechanical stage control knob to move the slide forward, backward, left, and right until you find what you are looking for. Center the object or structure in the field of view. 6. Rotate the nosepiece to put the 10X low power objective in place. 7. Look through the oculars while using the fine focus knob until the specimen is in focus.
List the five steps of the scientific method?
1. Observation-are made when you use your senses to understand the world around you and can be recorded by qualitatively or quantitatively. 2.Question- are used to identify problems in order to investigate data or observations. 3.hypothesis-is an educated guess to further investigate 4.Experiment- is to TEST the hypothesis, not to prove it by doing an experiment 5.Results/conclusion- analysing the data to draw a conclusion based on the acceptance of the hypothesis and results matching the prediction
Proper storage for microscope
1. turn the light source off and unplug cord 2. coil the plug together with the velcro strap attached 3. dial the stage to the lowest position 4.Rotate the scanning objective to the 4x 5. properly transport back to numbered slot
What are the effects of changing tonicity in plant and animal cells?
1.By changing the solute concentration of the environment, the plant cells will respond accordingly. in animal cells a normal cell is isotonic so is changing tonicity will cause either lyse or crenation of the cell
What are the steps in making a proper wet mount? In particular, what are the essential steps required to avoid air bubbles?
1.Place specimen(elodea leaf) and place it on clean slide 2.Add a drop of water to the slide 3.Drop a coverslip at a 45 degree angle over the specimen to make a "sandwich".
What saline % is isotonic to plant and animal cells?
1.Plants prefer a hypotonic environment. The swelling of water will fill the plant cell with water and become turgid(turgor pressure). The internal solute concentration of the plant cell is around 1%. 2.Animal cells prefer an isotonic environment. Animal cells saline % is 1% solute, 99% water.
How can you tell if a gel is running? What are the bubbles made of?
1.The gel is running when it bubbles at the electrodes.(This is a redox reaction) 2.Bubbles are made from forming H2 gas at the anode and O2 gas at the cathode
Milli (m)=
1/1,000 or 0.001
Micro (u)=
1/1,000,000 or 0.000001
Centi (C)=
1/100 or 0.01
1 m=
100cm
1 cm=
10mm
1,000 mm=
1m
1,000,000 um=
1m
What is a theory?
A hypothesis that has been tested and repeatedly supported
compound light micropscope
A. Ocular lenses(10x magnify) B. Rotating Nosepiece(holds and rotates obj lenses) C.Objective lenses(scanning 4x, low 10x, high 40x) D.Mechanical stage control- used to move the slide right-left and up-down E. Mechanical stage- surface that supports the slides F.Condenser- (found underneath the stage) focuses light below on the slide above G.Iris diaphragm lever- adjusts the light hitting the slide.(decrease light to see all clear-translucent, increases contrast naturally) H.Substage light- source of light that illuminates the slide I. Base- bottom of microscope(other hand is placed to properly transport) J.Rheostat(light control)- controls overall light intensity coming into illumination sys. K. Course adjustment knob- (large knob) moves stage up and down, only used with the scanning first .Makes large focus adjustments L.Fine adjustment knob-(smaller knob) makes fine focus on a slide sharper(can be used on any objectives. M.Arm- connection btw head and stage (other hand placed properly for transport) N.Head- holds the oculars(capable of rotating so doesnt have to be moved for another viewer)
What is the difference between accuracy and precision? Lab 1- Measurement
Accuracy can be defined as the degree of closeness to the TRUE VALUE(TARGET) Precision is referred to as the degree of closeness of ALL MEASURED VALUES TO EACHOTHER, which means the measurements is inaccurate
What pH ranges are acids and bases?
Acids 0-7 (basic) Neutral 7 Bases 7-14
P1000
BLUE micropipette- max 1,000 microliter top digit(in RED) can go to 1(1,000) or 0(less than 1,000) middle digit is in HUNDREDS last digit is in TENS EX: 840uL 0 8 4
What kinds of macromolecules are cells composed of? Lab 3- Chemical composition of cells
Carbohydrates, Monosaccharides proteins, amino acids lipids, glycerol and multiple fatty acids nucleic acids, nucleotides
When do we need to stain cells?
Cells are stained to enhance visualization of the cells or certain cellular components under a microscope. EASIER TO VIEW WHEN CONTRASTED Done by adding 1 drop of methylene blue solution at the edge of one side of the coverslip, draw the stain underneath slide by placing a paper towel on opposite side and adding few drops of deionized water. Should be light blue in color if still dark draw out by adding more water.
Which molecules were able to cross the dialysis membrane and which molecules were trapped? Why?
Chloride Ion, Sulfate(small), and Glucose(medium) were able to move across the membrane. Albumin(lrg) and Starch(lrg) are trapped within the membrane. This is due to the molecular size.
What environmental factors can affect an enzyme's function?
Enzyme activity can be affected by changes in temperate, pH, and substrate concentration. Each enzyme has an optimal temperature and pH. Therefore, when the environment conditions change, the enzymes rate of reaction or the ability to catalyze chemical reactions can be compromised.
How do enzymes interact with their substrate? Lab 6-Enzymes
Enzymes are highly selective catalysts, meaning that each enzyme only speeds up specific reaction. The molecule that an enzyme works with is called substrates. The substrates bind to a region on the enzyme called the active site.
What is the difference between Hydrophobic and hydrophilic?
Hydrophobic- is water FEARING, repels water and any other polar molecule (POLAR) Hydrophilic-is water LOVING, capable of mixing with water due to their polarity (NONPOLAR)
What is the difference between ionic and covalent bonding? Lab 2-Basic Principles of Chemistry
Ionic bond-when ions of OPPOSITE charges attract each other Covalent bonds- when electron pairs are SHARED
What is the difference in what pH paper tells us vs. litmus paper?
Litmus paper turns BLUE in( basic )solutions and RED in (acid) solutions. pH paper gives more information about the actual pH of the solution because you can match the color that your pH paper turns with the scale of colors provided with the paper, which corresponds to an ACTUAL pH VALUE
Negative control
No response is expected -attempt to focus on certain variables to see if the desired effects occur with just those variables
What is passive transport? What direction do molecules move when using passive transport? Lab 5- membrane and molecule transport
Passive transport is the cellular process of moving molecules and other substances across membranes. Occurs WITHOUT any additional energy supply by the cell Passive molecules move from [high] to [low]
pick out a positive or negative control for any of the chemical assays?
Positive controls- what you expect to test positive *benedict test- positive control GLUCOSE *IKI test- positive control STARCH *biuret test- positive control ALBUMIN *Sudan IV test- positive control OIL Negative controls- what you always expect to test negative *benedict test-negative control WATER *IKI test- negative control WATER *biuret test- negative test WATER *Sudan IV test- negative control WATER
What is the difference between qualitative and quantitative data? Scientific Method and Experimental Design Activity
Qualitative data is information that is descriptive, and typically harder to analyze.(observations made without numbers) Quantitative data can be measured numerically. (numbers or measurements)
What is the purpose of the blanking solution?
The blanking solution, also known as the "reference solution", is used to calibrate (zero) the measurement.
What does it mean that an enzyme and substrate fit together like a lock and key?
The three-dimensional shape, or structure, of the active is specific to the substrates that bind to it. The relationship between the substrate and active site is analogous to the specific shape a lock has for the particular key that opens it.
P100
YELLOW micropipette-max 100 microliter top digit can go to 1(100) or 0(less than 100) middle digit is in TENS last digit is SINGLE units EX: 55uL 0 5 5
Positive control
a known response is EXPECTED -checks to see if your proposed independent variable will produce the effect you expect.
What are the limits to the scientific method?
a limitation is some reason that would prevent the scientific method from being able to be used 1.measurable(quantifiable) 2.controllable 3.off the natural world
What is the scientific method?
a method of procedure that consists of systematic observation, measurement, and experiment, formulation, testing, and modification of hypotheses.
catabolic reaction
a reaction BREAKS down molecules to smaller molecules(produces energy when products are formed)
anabolic reaction
a reaction BUILDS larger molecules
How does lysozyme work? Where do you find it in living organisms?
an enzyme found in human bodily secretions such as tears, saliva and mucus. . As a key player in the innate immune system of the human body, its mode of action is attacking and breaking apart the carbohydrate structure of the bacterial cell wall.
Replicates/Repeated measures
an experiment must be repeated several times to ensure results are consistently reliable and NOT DUE TO CHANCE -results are usually averaged and need to be further analyzed...
Solvent(water)
and liquid that is capable of DISSOLVING SUBSTANCES
Qualitative data
any NON-numerical information collected from an experiment. *most qualitative data are based on observations and is descriptive in nature
Solutes
any substance that is DISSOLVED in the solvent
What is a control?
can be negative or positive comparing groups for a testing of the desired results. -are devised to test if the results of the experiment would occur w/o impact of the independent variable
What is a buffer?
combination of a weak acid and weak base, maintains stable pH
What is a molecule?
combination of chemical properties of all the atoms it contains.
What is the difference between magnification and resolution? Lab 4- Microscope and cell observation
magnification- refers to the APPARENT SIZE Resolution- refers to the CLARITY of seeing two objects as DISTINCTLY SEPERATE
Polar
means they have charge to them(either full or partial positive and/or negative)
spectrophotometer
measures the amount of light absorbed by a solution -a cloudy solution absorbs more light than a clear solution
SI for length is..
meter m
Microliters
micro=1/1,000,000 1,000,000uL= 1L
identify cellular organelles that are visible in a specimen?
most cellular structures are too small and colorless to be visible using a light microscope however, VISUALIZING NUCLEI IN EUKARYOTIC cells using a light microscope is possible
What is cytoplasmic streaming?
movement of cytoplasm within cells(mostly in plant cells)
Osmosis
movement of water molecules ACROSS the membrane down its concentration gradient
Controlled Variable
must be kept CONSTANT always to make sure the results are from the difference in the independent variable ONLY
Negative cathode
negative charged -attracts the positive anode
isotonic solution
normal cell, equal solute concentration across the membrane and equal H20 across membrane
Sample size
number of samples
Quantitative data
numerical information collected from an experiment or activity. *is measurable and more accurate, however, the accuracy depends on the tools selected and methods used
Independent variable
one factor you are changing -a condition in the experiment that is manipulated by the experimenter
What does pH measure directly?
pH measures the amount of H+ in a solution
What does % error tell us about a data point or a mean?
percent error demonstrates how accurate the data is. -smallest % error is the most accurate(high accuracy) The percentage error is calculated by taking the absolute value of the error; divided by the theoretical value subtracted by the mean value, then multiply by 100. % Error = (Experimental mean value-Theoretical value)/(Theoretical value) x 100%
Positive anode
positive charged
What is a hypothesis - be able to know how to generate one from a given problem
proposing explanations or hypothesis and predict future experimental outcomes. Can be general or specific. Often phrased in the form of an "if/then" statement. Ex: "IF the research hypothesis is correct, THEN a certain outcome is expected. *Predictions help test the hypothesis in number of ways to see if it supports the hypothesis
What is a falsified hypothesis?
provides further information (observations) which helps to formulate a new hypothesis
hypertonic solution
refers to the solution around the cell having a higher concentration of solutes and lower concentration of water than the inside of the cell. The cell loses water and shrinks (crenate).
hypotonic solution
refers to the solution around the cell having a lower concentration of solutes and a higher concentration of water than the inside of the cell. The cell gains water and swells (cell lysis).
Reproducibility
results should be reproduced obtained by others the same way. If not then they are some unforeseen variables
SI for Time is...
second S
molecules according to their size(small to large)
small-chloride ion(Cl-)<sulfate ion (SO4^2-)<glucose(C6H12O6)<albumin(583 amino acids)-Large
What does the mean of a group of data tell us?
tells us an AVERAGE the average value calculated by taking the sum of all values, and dividing by the total number of values. The mean of the group data is calculated to find the "central" value of a set of numbers.
What does the standard deviation of a group of data tell us?
tells us the detection of each measurement from the mean, demonstrating how precise the data is (how close each measurement is to the others.) -Based on PRECISION -the lowest(smallest) is the most precise
Large sample size
the greater the number of samples, the more accurate the results.
calculate rate of travel for a molecule - need to able to measure with a ruler in mm and then divide by total time the gel ran (gives mm/min)
to calculate the rate of travel you must divide the mean (distance traveled mm) by the exact number of minutes you ran the gel. -mm/min measure in cm convert to mm ex, 4.5cm is 45mm
IKI-Iodine test
to detect starch (iodine only interacts with starch) Positive- Blue/black color Negative- Yellow (the color of iodine)
Benedicts test
to detect the presence of reducing sugars Green- low concentration of sugars Yellow- medium level concentration Red/orange- high concentrations Blue/or no color- indicates negative result(no detects)
When would you want to use chemical assays tests?
to quickly determine the presence of certain classes of molecules
Be able to determine total magnification for your compound light microscope
typical ocular has a magnification power of 10(10X) red- 4X(scanning) total mag=40x(larger than original) yellow-10X(low) total mag=100X blue- 40X(high) total mag= 400x
International System of Units(SI)
unit conversions (prefixes) that are based on the power of ten.
tugor pressure
water rushes in, the plasma membrane swells, which increases the pressure of the cytoplasm against the cell wall.
