Bio Lab Exam 1

What are the 4 parts of the microscope?

1. fine adjustment
2. coarse adjustment
3. objective lenses
4. ocular

bigger notch

coarse adjustment

smaller notch

fine adjustment

objective lenses

oculars

what is it and what is it used for?

* stage micrometer
* 1 space = 10 micrometers (μm)
* used to convert pixels to micrometers

define total magnification

ocular magnification x objective magnification (multiply objective lens magnification by 10)

define working distance

* space between objective lens and slide
* the greater the magnification the less working distance

field of view

* amount of space that can be seen
* the greater the magnification the smaller field of view

what to do when finished with microscope

* turn off
* rotate to 4x objective

what is the software used with microscope?

LAS EZ

independent variable

variable you manipulate in experiment (changes)

dependent variable

variable you measure to see if there was an effect

potentially confounding variables

factors that are kept constant b/c they may change results

null hypothesis

“there is no effect of independent variable on dependent variable”

Ex: there is no effect of music on studying habits

alternative hypothesis

“independent will have blank affect on dependent variable”

controlled experiment

changing one factor and observing its affect on another while keeping all other factors constant

how to calculate size of cell given scale + length of cell in pixels or # of spaces of stage micrometer

scale = line distance / known distance

what is scale when determining cell size?

pixels/unit

what is line distance when determining cell size?

size measured of cell in pixels

what is known distance when determining cell size?

\# of spaces x 10 μm

what is the size difference between prokaryotic and eukaryotic cells

eukaryote is 6.642 times bigger than the prokaryote

explain paper chromatography

* isolates pigment molecules from leaves of plant
* uses properties of molecules to separate the 4 pigment molecules
* carotenes
* xanthophylls
* chlorophyll a
* chlorophyll b
* uses non-polar solvent to dissolve non-polar pigments
* the higher it travels up the paper, the more polar/non polar it is (depends on the solvent)

what would happen if water was used as solvent in paper chromatography?

Pigments would not dissolve and remain at the origin because water is polar

what would happen if pigment line is submerged in solvent in paper chromatography?

pigments will dissolve in solvent (leaves green liquid in jar)

how to calculate Rf value?

distance of pigment from origin / distance of solvent from origin

what does Rf value tell you about solubility?

Greater = more soluble

smaller = less soluble

what does Rf value tell you about polarity?

* if solvent is polar, the higher it is the more polar it is
* if solvent is non-polar, the higher it is the more non-polar it is

how does color of pigment relate to absorbance spectrum in chromatography?

* colors with no peaks are the colors reflected (we see the reflected color)

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What is purpose of setting the scale in imageJ?

To convert pixels into micrometers so that we can measure cells at any magnification.

what pipettes are used with green pump?

* 5mL
* 10mL

what pipettes are used with blue pump?

2 mL

How to use 2 mL pipette?

* draw liquid up to 0 mL mark
* dispense to # needed

5 Steps to extract DNA from strawberries?

1. mash strawberry
2. add DNA extraction buffer
3. Filter
4. Meat tenderizer
5. alcohol

Purpose of mashing strawberry step

replicate breaking cell/disturbing membrane

purpose of adding DNA extraction buffer step

soap: breaks down cell membrane

salt: stabilizes DNA molecules and removes proteins bound to DNA

purpose of filter step

remove large cellular debris (cell membrane/organelles)

purpose of meat tenderizer step?

releases DNA by breaking down histone proteins with digestive enzymes

purpose of alcohol step?

DNA is not soluble in alcohol and will be able to be picked up.

How to determine purity of DNA sample from A260/A280 ratio?

* pure DNA sample has ratio of 1.8
* lower ratio = protein impurities

describe structure of nucleotide and its 3 main components

* monomer of nucleic acids (like DNA/RNA)
* contains 3 bases: nitrogenous, sugar, phosphate group

describe nitrogenous base

* 5 types: adenine, guanine, cytosine, thymine, uracil
* contains genetic information

describe sugar base

* pentose (5 carbon) sugar
* backbone of nucleotide
* deoxyribose/ribose

describe phosphate group

* attached to sugar molecule
* 4 phosphate 1 oxygen
* negative charge stabilizes structure of nucleic acid

what type of bond connects components of a nucleotide

2 covalent bonds:

* glycosdic
* phosphodiester

covalent bond stronger than hydrogen bonds

what type of bond connects complementary bases?

hydrogen bonds, weaker than covalent bonds

identify complementary base pairs

A-T : two hydrogen bonds

C-G : three hydrogen bonds

what part of the DNA molecule interacts with the cellular environment and whether that part is hydrophobic or hydrophilic

sugar-phosphate backbone, which is hydrophilic

how to tell that the two strands of a DNA molecule are anti-parellel?

They run in opposite directions

* you can look at the orientation of the sugar molecules in the backbone. This creates a repeating pattern of a sugar-phosphate backbone with a free @@**5' phosphate group**@@ at one end and a free **3' hydroxyl group** at the other end.

what does red represent on dna molecule

oxygen atoms

what does yellow represent on dna molecule

phosphorus atoms

what does gray represent on dna molecule

carbon atoms

what does blue represent on dna molecule

nitrogen

what does white represent on dna molecule

hydrogen

what does grey and red central ring represent

sugar (gray + red), base (central ring)