Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
108 Cards in this Set
- Front
- Back
|
The process of copying one DNA double helix into two identical double helices is called...? |
DNA replication |
|
|
Environmental influences called ______ cause mutations in humans |
mutagens |
|
|
mathematician that proved that traits are passed from parent to offspring but didn't identify mechanism; he called them factors (not genes); he did not observe chromosomes |
Mendel |
|
|
physician who extracted acidic substance from pus-soaked bandages; calls it "nuclein" (but of course it's DNA) |
Meischer |
|
|
proved chromosomes are functional units of heredity-- made connection to Mendel's "factors" (called theory of heredity) |
Boveri & Sutton |
|
|
Chromosomes are made up of what? |
both DNA & protein |
|
|
worked w/ fruit flies, proved genes are located linearly on chromosomes; also made connection to Mendel |
Morgan |
|
|
microbiologist that showed that the "transforming factor/substabce" can be transferred from lethal bacteria to harmless bacteria, rendering the formerly harmless bacteria lethal; doesn't know what that "factor" is but prompted others to begin looking for it |
Griffith |
|
|
proved the "transforming factor" was DNA |
Avery, Macleod & McCarty |
|
|
reports on chemistry of DNA; nucleotides occur in equal amounts; he created certain rules |
Chargaff |
|
|
what are Chargaff's rules |
amount of adenine= amount of thymine amount of guanine=amount of cytosine |
|
|
use viruses in ingenious experiment- proved DNA carries hereditary info (not protein); they really just continued Avery's work |
Hershey & Chase |
|
|
took pictures, using x-ray crystallography, of DNA, suggested helix |
Franklin & Wilkins |
|
|
built 3D model of DNA; get the glory and a nobel prize |
Watson & Crick |
|
|
what was the monomer in Watson & Crick's model? aka DNA is a polymer of what? |
nucleotides |
|
|
what was the sugar in watson & crick's model? |
deoxyribose |
|
|
what was the phosphate attached to in watson & crick's model? |
5' carbon |
|
|
how many nitrogenous bases possibilities are there? |
4 |
|
|
what was the 1 of 4 nitrogenous attached to in Watson & Crick's model? |
1' carbon |
|
|
what is the defining feature of purines? |
double ring |
|
|
what are the two purines? |
adenine & guanine |
|
|
what is the defining feature of pyrimidines? |
single ring |
|
|
what are the two pyrimidines? |
thymine & cytosine |
|
|
What geneticists of the 20th century were busy determining |
that DNA is the genetic material of life |
|
|
what does DNA stand for |
deoxyribonucleic acid |
|
|
Geneticists of the 20th century were busy determining that DNA is the genetic material of life, but biochemists were in a frantic race to describe what? |
the structure of DNA |
|
|
When researchers began their work on DNA, they knew what 2 things about the genetic material? |
that the genetic material must: (1) be able to store information that pertains to the development, structure, and metabolic activities of the cell or organism (2) be stable so that it can be replicated with high accuracy during cell division and be transmitted from generation to generation |
|
|
He was attempting to develop a vaccine against a form of bacteria that causes pneumonia in mammals when he performed a classic experiment with the bacterium---he noticed that some substance necessary for the bacteria to produce a capsule and be virulent must have passed from the dead S strain bacteria to the living R strain bacteria |
Griffith |
|
|
In Griffith's experiment, under the microscope, S strain bacteria have a ______ that makes them smooth, but R strain do not |
capsule (mucous coat) |
|
|
What happened in Griffith's experiment when he injected mice with the (encapsulated) S strain of bacteria? |
the mice died |
|
|
What happened in Griffith's experiment when he injected mice with the (nonencapsulated) R strain? |
the mice did not die |
|
|
In an effort to determine whether the capsule alone (part of S strain) was responsible for the virulence of the S strain bacteria, in his experiment, what happened when Griffith injected the mice with heat-killed S strain bacteria? |
the mice did not die |
|
|
What happened in Griffith's experiment when he injected the mice with a mixture of heat-killed S strain and live R strain bacteria? |
the mice died because the R strain bacteria have been transformed into the virulent (poisonous) S strain |
|
|
By the 1940s, scientists recognized that genes are on what? |
chromosomes |
|
|
What do chromosomes contain? |
both proteins & nucleic acids |
|
|
Why did many scientists think that the protein component of chromosomes must be the genetic material? |
because proteins contain up to 20 different amino acids that can be sequenced in any particular way (more variation) ---ppl argued that DNA did not have enough variability to be able to store information & be the genetic material |
|
|
How many types of nucleotides do DNA & RNA (nucleic acids) contain? |
4 types of nucleotides |
|
|
They published a paper demonstrating that the transforming substance that allows the bacteria that causes pneumonia to produce a capsule and be virulent is DNA (basically they proved that DNA is the genetic material |
Avery, MacLeod, McCarty |
|
|
Avery & his people found out that the addition of DNase, an enzyme that digests DNA, prevents what? & That the addition of RNase, an enzyme that digests RNA, has what? |
-DNASE prevents transformation from occurring -RNase has no effect on the transforming substance (So protein nor RNA infs the genetic material) |
|
|
An experiment using a virus called T phage, composed of radioactively labeled DNA & capsid coat proteins to infect e.coli bacteria was done by who? |
Hershey & Chase |
|
|
Hershey & Chase's experiment with e.coli bacteria led them to discover that the radioactive tracers for DNA, but not protein, ended up ________the bacterial cells, causing them to become transformed |
inside |
|
|
Hershey & Chase's experiments concluded that ____? |
viral DNA, not protein, was responsible for directing the production of new viruses |
|
|
Who determined the structure of DNA? |
Watson & Crick |
|
|
DNA is a chain of what? |
nucleotides |
|
|
What are the 3 complex subunits of each nucleotide on the DNA chain? |
-phosphate -pentose sugar (deoxyribose) -nitrogenous base |
|
|
What are the two (main) kinds of nitrogen-containing bases? (Four total--2 main categories) |
-Purines -pryimidines |
|
|
A DNA polynucleotide strand has a backbone made up of what? |
alternating phosphate and sugar molecules |
|
|
How many strands does DNA have? |
2 |
|
|
The two strands of DNA twist about one another in the form of what? |
double helix |
|
|
What holds the two strands of DNA together in the double helix? |
hydrogen bonds |
|
|
A always pair with _____ by forming _____ hydrogen bonds |
T; two |
|
|
G always pairs with _____ by forming _____ hydrogen bonds |
C; three |
|
|
What is a purine always bonded to? |
a pyrimidine |
|
|
What is the name for the pairing of a purine with a pyrimidine? |
complementary base pairing |
|
|
What does the DNA helix resemble when it unwinds? |
a ladder |
|
|
Since DNA resembles a ladder, what do the uprights (sides) of the ladder represent & what do the rungs represent? |
sides: sugar & phosphate molecules rungs: complementary paired bases |
|
|
The two DNA strands are _______ meaning that they are _________ _____ _________ ________ |
antiparallel; oriented in opposite directions |
|
|
the bases in a DNA pair are oriented how? |
in different directions |
|
|
In the sugar molecules of DNA, what carbon atom is uppermost in the strand on the left? |
(5') |
|
|
In the sugar molecules of DNA, what carbon atom is uppermost in the strand on the right? |
(3') |
|
|
Who set out to not only determine the structure of DNA, but also to build a model that would explain how DNA can vary from species to sepcies & even from individual to individual? In the process they also proposed what? |
Watson & Crick; how DNA replicates |
|
|
He determined that regardless of the species under consideration, the # of purines in DNA always equals the # of pyrimidines |
Chargaff |
|
|
They prepared an x-ray diffraction photograph of DNA |
Franklin & Wilkins |
|
|
what did Franklin's x-ray diffraction photograph of DNA show? |
that DNA is a double helix of constant diameter & that the bases are regularly stacked on top of one another |
|
|
what did Watson & Crick build the actual model of DNA out of? |
wire & tin |
|
|
Why can the double-helix model indeed allow for differences in DNA structure between species? |
because the base pairs can be in any order |
|
|
What did the crossed (X) pattern in the center of Franklin's x-ray diffraction photograph tell investigators? |
that DNA is a helix |
|
|
What did the dark portions at the top and bottom of Franklin's x-ray diffraction photograph tell investigators? |
that some feature is repeated over & over (Watson & Crick determined that this was the result of hydrogen bonding between bases) |
|
|
What happens when the body grows or heals itself? What does each new cell require from this? |
cells divide; each new cell requires an exact copy of the DNA contained in the chromosomes |
|
|
the process of copying one DNA double helix into two identical double helices is called? |
DNA replication |
|
|
What enzyme carries out the process of DNA replication? |
polymerase |
|
|
Why is DNA replication termed semiconservative? |
because each new double helix has one conserved old (parental) strand and one new (daughter) strand |
|
|
What does DNA replication result in? |
2 DNA helices that are identical to each other and to the original molecule |
|
|
What is the first step of DNA replication? |
the enzyme DNA helicase unwinds & unzips |
|
|
How does the helicase unzip & unwind the double-stranded DNA in replication? |
by breaking the weak hydrogen bonds between the paired bases |
|
|
What enzyme positions and joins DNA nucleotides in the new complementary strand? |
DNA polymerase |
|
|
Synthesis of the new DNA molecules occurs in opposite directions due to what? |
the orientation of the original DNA strands |
|
|
What does the leading strand follow? |
the helicase enzyme |
|
|
Synthesis on the lagging strand results in the formation of short segments of DNA called? |
Okazaki fragments |
|
|
To complete replication, the enzyme DNA ______ connects the Okazaki fragments and seals any breaks in the sugar phosphate backbone |
ligase |
|
|
The two double helix molecules are ______ to each other and to the original DNA molecule |
identical |
|
|
In the direction of the fork, replication is ______ and this strand is the _______ strand because it is quick |
rcontinuous; leading |
|
|
In the direction away from the fork, replication is ____________ and this strand is the ______ strand because it is slower |
discontinuous; lagging |
|
|
Where is energy power from for DNA replication? |
from nucleotide tri-phosphates found in nucleoplasm |
|
|
Why is DNA replication important to the growth and development of a multi-cellular organism? |
new cells need to be created to replace the old |
|
|
What are somethings that can cause DNA mutations? |
x-rays, gamma rays, UV rays, & organic solvents |
|
|
What prevents the unwound & unzipped DNA from twisting back? |
single-strand binding proteins |
|
|
Which enzyme is the key player in replication? What is this enzyme's limitation? |
DNA polymerase; can only go in a 3' to 5' direction so it needs and RNA primer |
|
|
Explain elongation stage of replication (lengthening) |
on the leading strand, polymerase follows the helicase (continuous) & on the lagging strand, polymerase & the helicase are in opposite directions (not continuous) |
|
|
What joins Okazaki fragments on the lagging strand into one continuous strand? |
primase |
|
|
How do eukaryotes speed the process of replication? |
they open many relication sites at once bc they have multiple long chromosomes |
|
|
Why might you need to test human DNA? |
genetic testing, body identification, analysis of forensic evidence |
|
|
What are the 4 main steps in DNA extraction? |
1) collect cells 2) burst cells open to release DNA 3) separate DNA from proteins & cellular debris 4) isolate concentrated DNA |
|
|
What does the lysis solution do in DNA extraction? |
the detergent disrupts the cell membrane & nuclear envelope & causes the cells to burst open |
|
|
What does the salt do in DNA extraction? |
causes proteins & other cellular debris to clump together (separters DNA from proteins & debris) |
|
|
What happens to the DNA when you add the isoprpyl alcohol? |
it precipitates & becomes visible |
|
|
Do animals & humans have the same method for DNA extraction? |
yes |
|
|
How is DNA extraction different for plants? |
cell wall in plants can be a barrier to getting to the DNA |
|
|
DNA is ______ in water, but ______ in ethanol |
soluable; insoluable |
|
|
How does detergent break the cell membrane & nuclear membrane? |
soaps & detergents are emulsifiers (hydrophobic & hydrophilic ends) |
|
|
After extraction, is there anything left in the DNA? |
RNA |
|
|
How can the structure of DNA be seen? |
x-ray crystalography |
|
|
Process that creates hydrogen bonds |
dehydration |
|
|
Process that breaks hydrogen bonds |
hydrolysis |
|
|
what type of bonding is polymerization? |
covalent (strong) |
|
|
Name given to an error in the replication of a DNA sequence |
mutation |
|
|
Split created in the DNA strand by replication |
Replication FOrk |
|
|
Function of ethanol in DNA extraction |
helps the DNA to precipitate out |
