General Ecology Finals Part 2 Flashcards by Elisheba Jean

When was DNA first noticed and who noticed it?

in 1869; Friedrich Miescher

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How was DNA first discovered and what was it called?

Friedrich Miescher isolated it from nuclei of white blood cells; He called it “nuclein”

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In 1895, Edmund Wilson first suggested that DNA might be [..]. He observed that [..] and [..] contribute the same number of [….] during reproduction.

hereditary material; sperm and eggs; chromosomes

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DNA is a polynucleotide consisting of what four repeating subunits and held together by what bonds?

adenine (A), thymine (T), cytosine (C), and guanine (G), held together by covalent bonds

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In 1923, DNA was localized to […] and made a candidate for the […]. However both […] and […] are found in […].

chromosomes; the hereditary material; proteins and RNA; chromosomes

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What other candidates are there for the hereditary material besides DNA?

Lipids and carbohydrates

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Frederick Griffith identified two strains of Pneumococcus: S, which caused […] in mice, and R which […]. A single gene mutation change can convert an […] strain to an […] strain of the same antigenic type.

fatal pneumonia; did not;
S (smooth); R (rough)

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Griffith proposed the transformation factor as the molecule that transformed the […] into […]. He said the transforming factor carried […] but he could not identify the […]

R I I ; S I I I; hereditary information; molecule

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Avery, MacLeod, and McCarty used […] and [..] to infect mice. The […] of heat-killed S I I I bacteria was divided into […] and treated to destroy either [..], [..], [..], or [..] and [..] before mixing with live RII bacteria.

heat-killed S I I I bacteria; live R I I bacteria; extract; aliquots; DNA, RNA, proteins, or lipids and polysaccharides

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[..] in 1952, showed that D N A is responsible for bacteriophage infection of bacteria cells. What are bacteriophages? Phages such as T2 have a […] that attaches to the host cell and a head that contains [..]

Hershey and Chase; viruses that infect bacteria; protein shell with a tail segment; D N A

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Phages must infect [..] to reproduce. How does infection begin?

bacterial hosts; when the phage injects DNA into the bacterial cell and leaves its protein shell on the surface;

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The phage DNA replicates in the bacterium and produces [..] that are assembled into […]—these are released by [..]

proteins; progeny phage; the host cell

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DNA structure identified by […] and modeled by [..] and [..].

Rosalind Franklin;Watson; Crick

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DNA composed of four kinds of [..], A, T, C, and G, joined by […] with [..] that come together to form a [..]

nucleotides; covalent phosphodiester bonds; two polynucleotide chains; double helix

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What is a DNA nucleotide composed of?

sugar, one of four nitrogenous bases, and up to three phosphate groups

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What is deoxyribose? How many carbons does it have and what are they identified as?

the sugar of DNA nucleotides; it has five carbons, identified as 1′, 2′, 3′, 4′, and 5′

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A nucleotide base is attached to what? A hydroxyl group is attached to what? 1-3 phosphates are attached to what?

1′ carbon; 3′ carbon; 5′ carbon

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How many rings do pyrimidines and purines have. Which nucleotides are pyrimidines and which are purines?

pyrimidines (thymine and cytosine) - single ring. purines (adenine and guanine) - double ring

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Deoxynucleotide monophosphates that are part of a polynucleotide chain have [..] and are called [..] where N refers to what? Deoxynucleotide triphosphates (d N T P s) are not part of a [..].

single phosphates; dNMPs; four bases; polynucleotide chain

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Individual nucleotides are assembled into [..] by the enzyme [..]. It catalyzes the formation of a [..] between the […] and the […] of an adjacent one

chains; DNA polymerase; phosphodiester bond; 3′ hydroxyl group of one nucleotide; 5′ phosphate

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Each polynucleotide chain has a [..] , consisting of [..] and [..]

sugar-phosphate backbone; alternating sugar; phosphate groups

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DNA polymerase catalyzes chain growth in [..].

5 ‘ to 3’ direction

The two polynucleotide chains of a double helix form a [..] that follows two rules: The bases of one strand are [..] to the bases in the [..] The bases pair by [..].
The two strands are [..] with respect to their [..].

stable structure; complementary; corresponding strand; hydrogen bonding; antiparallel; 5′ and 3′ ends

The [..] of D N A is the most common and has a […] of the helix, as does the A-form. [..] D N A is occasionally detected in [..] and is common in [..]. [..] D N A was discovered by [..] and colleagues in 1970 and is commonly found near […].

B-form; right-handed twist; A-form; cells; bacteriophage
Z-form; Robert Wells; transcription start sites

There is a [...] to the sugar-phosphate backbone of [...], due to its [...] twist of the helix

zigzag appearance; Z-form D N A; left-handed

The integrity of the nucleotide sequence of D N A is of [..] importance. The general mechanism of D N A replication is the [..] in all organisms. As organisms [..] and became more [..], some differences did develop in the [..] and [...].

paramount; same; diverged; complex; replication proteins; enzymes

Each strand of the [...] molecule remains intact during replication. Each parental strand serves as a [...] for formation of an [...]. Completion of replication results in the formation of [...] composed of [...]

parental DNA; template; antiparallel, complementary daughter strand. two identical daughter duplexes; one parental and one daughter strand

A consequence of complementary base pairing is that nucleotides on one strand of the duplex can be used to identify nucleotides on the [..]. After the D N A structure was identified, [...] competing models of D N A replication emerged All shared the idea that the original strands of the duplex act as [...].

other strand; three; daughter strand synthesis

[...] DNA replication- [..] daughter duplex contains [...] parental and [...] daughter strand. [...] DNA replication- [...] daughter duplex contains [...] parental strands and the other contains [...] daughter strands. [...] DNA replication- [...] daughter duplex contains [...] parental and daughter segments

Semiconservative; each; one; one daughter strand; Conservative; one; both; both; Dispersive; each; interspersed

In 1958, Meselson and Stahl used [...] centrifugation to test the models of D N A replication. This method is capable of [...] molecules with slightly different molecular weights. They began by growing [...] in a medium containing [...] for many generations

cesium chloride; separating; E. coli; heavy nitrogen;

Once all the [...] in the culture had DNA containing only the heavy nitrogen, they transferred the bacteria to medium containing 14N. After one round of replication, the DNA of an [...] was isolated and centrifuged to determine its [..]. The same was done after successive [..]

bacterial cells; aliquot of cells; density;replication cycles.

D N A replication is most often [...], proceeding in both directions from a single origin of replication in bacterial chromosomes.[...] have multiple origins of replication

bidirectional; Eukaryotic chromosomes

[...] work showed expansion around the origin of replication, forming a [...] , once replication gets under way in bacteria At each end of the replication bubble is a [...] ; replication is complete when the replication forks [...].

John Cairn’s; replication bubble; replication fork; meet

Electron micrograph analysis shows multiple [...] on eukaryotic chromosomes. [...] contain hundreds to thousands of origins of replication The human genome may contain more than [...] origins.

origins of replication; Eukaryotic genomes; 50,000

Replication origins have sequences that attract [...]. The origin of replication sequence of E. coli is called [...], which contains about [...] bp of A-T rich D N A The origin is subdivided by [...] 13-bp sequences followed by [...] 9-b p sequences.

replication enzymes; oriC; 245; three; four

Replication origins of bacterial species have [...] but not identical sequences. Comparison within and among related species leads to identification of [...] the nucleotides found most often at each position of D N A in the [...]. The 13-mer and 9-mer sequences of oriC are [...] —they play an essential role in replication

similar; consensus sequences; conserved region; conserved

[...] has the most fully characterized origin-of-replication sequences. The multiple origins of replication are called [...]. ARS organization and sequence is similar throughout the [...]. Replication origins of other [...] are less well characterized.

Saccharomyces cerevisiae (yeast); autonomously replicating sequences (ARS); yeast genome; eukaryotes

Replication in E. coli requires that [...] locate and bind to oriC consensus sequences; these enzymes are [...], [...], and [...].

replication-initiating enzymes; D n a A, D n a B, D n a C

D n a A first binds the 9-mer sequences, bends the [..] , and breaks [...] in the A-T rich 13-mer region. D n a B is a [...] that breaks hydrogen bonds to separate the [...] and unwind the [...]. (DnaC delivers DnaB to the oriC region). The unwound D N A strands are kept from [...] by [...]

DNA; hydrogen bonds; helicase; strands; helix; reannealing; single-stranded binding protein (S S B)

DNA polymerase [...] DNA strands by adding nucleotides to the [...] end of a preexisting strand. They cannot initiate DNA strand synthesis on their own [...] are needed; these are synthesized by a specialized R N A polymerase called [...]. In E. coli, primase joins DnaA, DnaB, and DnaC at [..]

elongates; 3′; RNA; PRIMASE; oriC

In E. coli, daughter D N A strands are synthesized by the [...]. The [...] is a large protein complex found at each replication fork.

DNA polymerase III (pol III)holoenzyme; REPLISOME

The replisome includes [...] different DNA pol III holoenzymes. Replisomes also contain other proteins that hold the two DNA pol III holoenzymes together within the replisome for [...] and [...] strand DNA synthesis

two; leading; lagging

One copy of pol III synthesizes one daughter strand continuously in the [...] direction as fork progression. This is the [...] The other copy of pol III elongates the other daughter strand [...] , in the [...] direction to fork progression, via short segments (Okazaki fragments). This is the [...]

same; leading strand; discontinuously; opposing; lagging strand

DNA Polymerase I uses two activities to complete replication: Its 5′-3′ [...] removes the RNA primers. Its 5′-3′ polymerase activity adds [...] to the 3′ end of the DNA segment preceding the primer. [...] seals the gap among the resulting DNA segments.

exonuclease activity; DNA nucleotides; DNA ligase

Each replisome complex carries out replication of the leading and lagging strand [...]. DNA polymerases do not have the [...] on their own for daughter strand synthesis and progression along the template. To enhance the processivity of polymerases, an [...] called the sliding clamp is used

simultaneously; momentum; auxiliary protein complex

The [...] can close around the double-stranded D N A during replication. It has a “doughnut hole” of about into which the [...] fits. The sliding clamp [...] the DNA pol III core enzyme to the template. It is key to the [...] level of pol III activity.

sliding clamp; DNA; anchors; high

DNA replication is very [...], mainly because most DNA polymerases undertake [...] to correct occasional errors. Errors in replication occur once about every [...] nucleotides in E. coli. Proofreading ability of D N A polymerase enzymes is due to a 3′-to-5′ [...]

accurate;DNA proofreading; billion; exonuclease activity

Replication errors produce a [...] and inability of the mismatched bases to form the appropriate [...]. This leads to [...] of the 3′ O H into the 3′-to-5′ exonuclease site of the enzyme Several nucleotides (including the incorrect one) are [...] and new nucleotides are [...].

DNA mismatch; H bonds; displacement; removed; incorporated

Unwinding of chromosomes during DNA replication will create [...], potentially leading to supercoiling of DNA. Enzymes called [...] catalyze controlled cleavage and rejoining of D N A to relieve supercoiling

torsional stress; DNA topoisomerases

The leading strand of [...] can be replicated to the end. The lagging strand requirement for a primer means that lagging strands cannot be [...]. This problem is solved by [...] at the ends of linear chromosomes, called [...]. These repeats ensure that a portion of a telomere can be safely lost without [...] to the organism

linear chromosomes; completely replicated; repetitive sequences; telomeres; consequence

Most human [...] experience telomere shortening with successive divisions; Telomeres are synthesized in [...] (and selected other cells) by the [...]. The RNA in telomerase is [...] to the telomere repeat sequence and acts as a [...] for addition of DNA.

somatic cells; germ line cells; ribonucleoprotein telomerase; complementary; template

The template RNA of telomerase allows [...] DNA replication to lengthen the telomere sequences. Once telomeres are sufficiently elongated, DNA replication fills out the chromosome [...]. Telomere sequences differ along [...].

new; ends; species lines

In addition to the repetitive DNA sequence, most eukaryotic telomeres also contain a DNA sequence that forms a [...]. The T loop protects the telomeres from [...] by binding the protein complex [...]. Despite protective measures of telomeres with repetitive sequences and T loops, telomere shortening eventually triggers [...]. The [...] represents the number of cell cycles of a vertebrate cell before the cell succumbs to apoptosis

knotted fold (T loop); degradation; shelterin; apoptosis; Hayflick limit

Telomere length is important for [...] , [...], and [...]. Some research suggests activating telomerase in somatic cells for [...] and [...]. However, a majority of [...] cells also show activation of telomerase activity, complicating the idea of such action for longevity purposes

chromosome stability, cell longevity, and reproductive success; cell longevity and longer life spans; cancer