Final Flashcards
_____ are hereditary units, each consisting of a sequence of DNA that occupies a specific location, or ______, on a chromosome and determines a particular characteristic in an organism.
Genes, locus
Genes occur in alternate forms called ______, which differ in their base sequences and result in alternative expressions of genetic traits that can be dominant or recessive.
alleles
Other reasons for differences in base sequences include DNA ________ resulting from environmental agents (ex: UV light, toxic chemicals) and deletions and other errors that occur during DNA ________.
mutations, replication
Variation in DNA sequences between individuals can be determined with the help of _________ ________.
restriction enzymes
What’s another name for a restriction enzyme?
Restriction endonuclease
Restriction enzymes are molecules that attach to double stranded-DNA at particular _________ sites, resulting in ________ of both DNA strands at or near those sites.
recognition, cutting/cleavage
How do restriction enzymes work?
They attach to double stranded-DNA at particular recognition sites, resulting in cutting/cleavage of both DNA strands at/near those sites.
Recognition sites are very specific sequences of nucleotide bases, usually _ to _ base pairs in length.
4 to 8
Recognition sites are frequently symmetrical, i.e. both DNA strands in the site have the same base sequence when read in a _’ to _’ direction.
5’ to 3’
Restriction enzymes are produced by many species of bacteria, mainly for the purpose of…?
For the purpose of cutting viral DNA that invades them
A _____ is a section of DNA that codes for a particular trait.
gene
Differences in DNA sequences between individuals can be visualized by using _________ __________.
restriction enzymes
Restriction enzymes are molecules produced by ______ that attach to DNA at particular “recognition sites” and cut the DNA
bacteria
Exonucleases – cut nucleic acids on the ____.
Endonucleases – cut nucleic acids within __________ _____
ends, polynucleotide chain
The restriction enzyme ______ binds to the sequence GAATTC.
EcoRI
EcoRI cuts unevenly, leaving overhangs (“______ ____”), which are useful in some laboratory applications
“sticky ends”
________ or ________ during replication can also create or eliminate recognition sites.
Mutations or deletions
Gel Electrophoresis is a technique used to separate molecules based on ______ & ____
charge & size
Gel Electrophoresis uses an _______ ______ applied to a gel ______.
electrical current, gel matrix
Gel Electrophoresis is used to separate ___, ___, and _______.
DNA, RNA, protein
The micropipette (P20) can dispense between \_\_ - \_\_ microliters The micropipette (P200) can dispense between \_\_ - \_\_\_ microliters
2-20
20-200
Electrophoresis is a separatory technique which utilizes an _______ ______ to separate biological molecules so that they may be identified, isolated, or further characterized.
electric field
The most common application is to separate _______ ______ or _______ molecules of different sizes.
Nucleic acids, protein
The DNA and RNA will migrate toward the ________ pole of an electric field.
postive (+)
Electrophoresis is commonly used to separate molecules based entirely or almost-entirely on their _____.
size
Which END of the gel box should DNA samples be loaded at?
The negative end so that they migrate toward the positive end.
How do different-sized DNA fragments migrate in an agarose gel?
Larger molecules will experience greater friction and move less effectively than smaller molecules
Smaller molecules will experience less friction and will move further down the gel than larger molecules
The use of _______ gels as a way to apply ______ has revolutionized electrophoresis of biological molecules and is termed gel electrophoresis.
porous gels, friction
The two most common types of gel are made of _______ and __________.
agarose and polyacrylamide
Agarose gel is used for ___ and ___.
DNA and RNA
Polyacrylamide is used for _______ and ________ ______.
protein and nucleic acids
The higher the concentration of agarose gel, the ______ the pores are within the gel.
smaller
The lower the concentration of agarose gel, the _______ the pores are within the gel.
larger
The size of an unknown DNA fragment may be estimated by comparison to a standard that is run on the same gel. The standard, also called a “_______,” is a sample of DNA containing several differently-sized fragments of known length.
marker
So how is a standard (‘marker’) used?
It is used to estimate the size of DNA fragments in base pairs
The DNA samples from the crime scene and the two suspects will be loaded and run on an agarose gel stained with ________ _______.
ethidium bromide (EtBr)
DNA migrates from _______ to ______ in electrophoresis.
cathode (+) to anode (-)
What is ethidium bromide?
An intercalating agent that binds to DNA and allows it to be visible under UV light
Prepare to cast a 50 ml 0.8% gel by calculating how much agarose you need.
0.8% (w/v) = __ g/100 ml or __g/50 ml
0.8, 0.4
What carries the electrical current?
The buffer
High agarose = ______ pores
Low agarose = ______ pores
Range: __% - __%
small
large
0.5-2.0 %
How much agarose needs to be added to 50ml to make a 1% gel?
1% = 1g/100ml = 0.5g/50ml → need 0.5g
How much agarose needs to be added to 100ml to make a 2% gel?
2% = 2 x 1g/100ml → need 2g
Observe banding patterns on a U.V light box called the __ ___________.
UV transilluminator
What are enzymes?
Biological catalysts that speed up reactions in various ways by directly binding the molecules (in contrast to heat)
Enzymes bind directly to a _________ molecule.
substrate
Enzymes are not _____ __, but __________.
not used up, but recycled
What two things do enzymes do?
1) lower activation energy
2) increase rate of reaction
The ________ binds to the enzyme’s ______ site.
substrate, active
What was the ENZYME in exercise 8: enzyme catalysis?
Polyphenoloxidase
Polyphenoloxidase is responsible for the production of ________ and other ________.
melanin, pigments
What was the SUBSTRATE in exercise 8: enzyme catalysis?
Catechol
In this lab exercise, what was oxidized?
Catechol
What were the two PRODUCTS in exercise 8: enzyme catalysis?
O-Quinone and H20
Which compound undergoes secondary reactions to produce colored products?
O-quinone
What are two factors that can affect the rate of an enzyme-catalyzed reaction?
1) The concentration of the enzyme
2) The temperature of the solution
Catechol contains two alcohol groups and is oxidized to _________
O-quinone
What was the reaction in exercise 8?
Catechol + 1/2 O2 —-(polyphenoloxidase)—> O-quinone + H20
Who was the reducing agent?
Who was the oxidizing agent?
The reducing agent is catechol
The oxidizing agent is 1/2 O2
Why was the enzyme kept on ice throughout the exercise?
Enzymes catalzyes a reaction, so that the rate will be quicker. The ice was to slow down the reaction rate.
Also, enzymes are proteins and can denature at certain temperatures.
In this exercise,you will purify polyphenoloxidase from ______ and assess its activity under several different temperatures.
potatoes
Why is the absorbance measured in this exercise?
The absorbance was measured because the rate of the polyphenoloxidase reaction can be seen by the increase of color per minute, which is why the absorbance readings were taken at 30 second intervals.
How would you calculate the initial rate of reaction based on a graph of absorbance vs. time?
To find the initial rate, draw a straight line through the first couple of data points, selecting those that lie in a straight line.
The initial rate is the slope of the line (Y2-Y1)/(X2-X1).
How does enzyme concentration affect the reaction rate?
The more enzyme present, the faster the reaction rate, as long as there is enough substrate.
How do higher and lower temperatures affect the reaction rate?
Higher temperatures and adding heat will speed up the reaction rate until proteins begin to denature.
Lower températures will slow down a reaction rate.
What about boiling or freezing the enzyme prior to the reaction?
Keeping the enzymes on ice before the reaction will slow the rate, though the reaction will still progress.
Boiling the enzyme will cause it to be denatured, and since they were denatured, they are nonfunctional.
What is the equation for aerobic cellular respiration?
C6H12O6 + 6O2 —-> 6CO2 + 6 H20 + ATP
What is the equation for alcohol fermentation?
C6H12O6 —–> 2C2H5OH + 2CO2 + ATP
Monosaccharides, like _______ and _______ are metabolic fuels.
glucose and fructose
Monosaccharides are stored as disaccharides (________) and polysaccharides such as ______.
sucrose, starch
Cellular respiration breaks down food into __________ which serve as ________ ______.
monosaccharides, metabolic fuels
How was alcohol fermentation measured in the lab?
Alcohol fermentation was measured by the amount of CO2 gas present in a fermentation tube, milliliters.
Glycolysis is an ________ process that takes place in the _______.
anaerobic, cytosol
What is the final electron acceptor in the ETC?
What is the product?
Oxygen
H20
In the cellular respiration exercise…
What was being reduced?
What was being oxidized?
DPIP was reduced
Succinate was oxidized
DPIP is ____ in its oxidized state but turns _____ in its reduced state.
blue, clear/colorless
Succinate was oxidized into ________.
fumarate
In the cellular respiration exercise…
Who was the oxidizing agent?
Who was the reducing agent?
The oxidizing agent was DPIP
The reducing agent was succinate
What is the role of DPIP in the enzyme-catalyzed conversion of succinate to fumarate?
DPIP is the oxidizing agent
Why is the oxidation of succinate to fumarate a critical step in the citric acid cycle?
It’s how energy is transferred and it’s required to make the citric acid cycle continue
What is the equation for photosynthesis?
6CO2 + 6H20 + light energy —–> C6H12O6 + 6O2
Name the organisms whose photosynthetic cells you have viewed in this course. (Ex 3 and 9)
Elodea, cyanobacteria, Euglena
The molecules responsible for capturing solar energy are called ________.
pigments
In plants, these pigments are within the _________.
chloroplasts
You will first prepare an extract of pigments from fresh _______.
spinach
The pigments will be extracted with ________, an organic solvent.
acetone
You will then separate the pigments using ______ __________.
paper chromatography
To do this, you will apply the pigment extract to a cylinder of chromatographic paper. You will then place the cylinder in a jar with the organic solvents _______ _____ and _______. The solvents will move up the paper and carry the pigments along.
petroleum ether and acetone
Polar molecules dissolve/are attracted to _____ molecules.
polar
The solvent, composed of _______ ______ and _______ is polar/non-polar?
non-polar
What is chromatography paper made out of?
Cellulose
Chromatography paper is polar/non-polar?
polar
The most non polar substance will dissolve most effectively in the non-polar substance, and the most polar substance will stick to the polar chromatography paper and will move the ______.
slowest
In the second part of the lab, you will carry your investigation a step further by plotting the _________ _______ of leaf pigments separated by paper chromatography.
absorption spectrum
The absorption spectrum is the absorption pattern for a particular pigment, showing relative absorbance at different _________ of light.
wavelengths
Which photosynthetic pigment traveled the fastest and why?
Beta carotene, least polar, least amount of oxygens
Which photosynthetic pigment traveled the slowest and why?
Chlorophyll b, most polar, most amount of oxygens
Rank the photosynthetic pigments in order of fastest to slowest
Beta carotene
Xanthophyll
Chlorophyll a
Chlorophyll b
Why were the absorption spectra of the leaf pigments measured?
The absorption spectra of the lead pigments measured because each pigment absorbs and transmits at different wavelengths.
What can be inferred about the wavelengths showing the greatest light absorbance?
It can be inferred that the wavelengths showing the greatest light absorbance are the most helpful for photosynthesis
Why does a substance appear to be a certain color?
A substance appears to be a certain color because that is the wavelength at which light is not absorbed by the pigment.
A leaf appears green because it does not absorb any green light.
What sub-organelle in the chloroplast is responsible for photosynthesis?
Thylakoid
What is the leading edge of a solvent called?
Is the solvent polar or non-polar?
A front
The solvent is non-polar
Cells spend most of their time in _______.
interphase
Mitosis occurs in eukaryotic _______ cells.
somatic
Mitosis involves:
- Division of the ______.
- _________ (division of cytoplasm and organelles, occurs after mitosis).
- Results in ___ daughter cells
nucleus
Cytokinesis
two
Prophase:
Chromosomes become visible in the ______, centrosomes begin to move away from each other, _______ spindle begins to form.
nucleus, mitotic
Prometaphase:
_______ envelope fragments, _________ condense more, each chromatid now has a kinetochore, microtubules attach to kinetochores.
Nuclear, chromosomes
Metaphase:
Centrosomes at opposite poles, __________ line up along metaphase plate, kinetochores of sister chromatids attached to microtubules coming from opposite poles
chromosomes
Anaphase:
Shortest stage, begins with _______ of cohesin proteins, allowing sister chromatids to part and move to opposite ends of the cell, cell _______.
cleaving/cutting, elongates
Telophase:
____ daughter nuclei form in the cell, _______ envelope develops from parent cell’s nuclear envelope and other parts of endomembrane system, chromosomes become less condensed
Two, nuclear
Viewing Cells of ______ Root Tips
Onion
How do you calculate the length of time spent in each phase of the cell cycle?
(# of cells in a particular stage)/(total # of cells counted) X 100
Meiosis occurs in _____ cells of sexually reproducing organisms
germ
Meiosis results in _____ daughter cells (sperm or egg)
four
Typical number of chromosomes is called the \_\_\_\_\_\_ number (Ex. 46 in human cells)
The halved number is called the \_\_\_\_\_\_ number (Ex. 23 in human cells)
diploid
haploid
Meiosis II —-> ______ chromatids separate
sister
Where does crossing over occur in meiosis?
Prophase I
_______ _______ is often used to demonstrate crossing over because the arrangement of colored ascospores within an ascus reflect meiotic divisions in which crossing over did or did not occur
Sordaria fimicola
How do you calculate recombination frequency?
(#recombinant asci/ #recombinant asci + #nonrecombinant asci) x 100
How do you calculate map units of a gene?
Multiply the recombination frequency by .5.
