Term
Humans have ? chromosomes
? autosomes
? sex chromosomes |
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Definition
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Term
| Males are heterogametic meaning |
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Definition
| they contain one x and one y chromosome |
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Term
| Females are homogametic meaning |
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Definition
| they have two x chromosomes |
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Term
| What determines maleness? |
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Definition
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Term
| A pedigree for an X-linked disease shows mostly ? affected with their mothers as carriers |
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Definition
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Term
| A typical chromosome contains many hundred or even a few thousand different ? |
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Definition
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Term
| What are the two meanings of linkage? |
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Definition
1. Two or more genes can be located on the same chromosome
2. Genes that are close together tend to be transmitted as a unit |
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Term
| What does linkage influence? |
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Definition
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Term
| The number of linkage groups is the number of types of ? of the species |
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Definition
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Term
| Genes that are far apart on the same chromosome may... |
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Definition
| independently assort from each other |
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Term
| Genes that are far apart on the same chromosome may independently assort from each other, which is due to |
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Definition
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Term
| In diploid eukaryotic species, what can be altered during meiosis as a result of crossing over? |
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Definition
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Term
| When does crossing over occur? |
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Definition
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Term
| What were Morgans 3 Hypotheses that explained his idea of linkage among x-linked genes? |
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Definition
1. The genes for body color, eye color and wing length are all located on the X-chromosome
2. Due to crossing over, the homologous X chromosomes (in the female) can exchange pieces of chromosomes
3. The likelihood of crossing over depends on the distance between the two genes |
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Term
Morgan tried to induce mutations in the fruit fly Drosophila melanogaster
Treatments included... |
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Definition
Rearing in the dark
X-rays
Radium |
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Term
| Genes that are physically located on the X chromosome are called |
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Definition
| X-linked genes or X-linked alleles |
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Term
| To a large extent, our knowledge of genetics comes from our knowledge of |
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Definition
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Term
| To fulfill its role, the genetic material must meet several criteria, they are: |
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Definition
| Information, Transmission, Replication, Variation |
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Term
| To fulfill its role, the genetic material must meet several criteria: Information, Transmission, Replication, and Variation. Describe these 4 criteria. |
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Definition
1. Information: It must contain the information necessary to make an entire organism
2. Transmission: It must be passed from parent to offspring
3. Replication: It must be copied
In order to be passed from parent to offspring
4. Variation: It must be capable of changes
To account for the known phenotypic variation in each species |
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Term
| DNA and RNA are large macromolecules with several levels of complexity, they are... (4) |
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Definition
1. Nucleotides form the repeating units
2. Nucleotides are linked to form a strand
3. Two strands can interact to form a double helix
4. The double helix folds, bends and interacts with proteins resulting in 3-D structures in the form of chromosomes |
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Term
| The ? is the repeating structural unit of DNA and RNA |
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Definition
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Term
| What are the three components of a nucleotide? |
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Definition
A phosphate group
A pentose sugar
A nitrogenous base |
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Term
| Nucleotides are covalently linked together by |
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Definition
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Term
| A phosphate connects the ? carbon of one nucleotide to the ? carbon of another |
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Definition
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Term
| Nucleotide strands have the directionality |
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Definition
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Term
| The phosphates and sugar molecules form the ? of the nucleic acid strand |
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Definition
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Term
| In the early 1950s, he proposed that regions of protein can fold into a secondary structure, called a ? |
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Definition
| Linus Pauling, alpha helix |
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Term
| She used X-ray diffraction to study wet fibers of DNA |
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Definition
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Term
| ? pioneered many of the biochemical techniques for the isolation, purification and measurement of nucleic acids from living cells |
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Definition
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Term
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Definition
Percent of adenine = percent of thymine
Percent of cytosine = percent of guanine |
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Term
| Describe the general structural features of a DNA double helix |
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Definition
Two strands are twisted together around a common axis
There are 10 bases and 3.4 nm per complete twist
The two strands are antiparallel
The helix is right-handed |
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Term
| What is the DNA double bonded structure stabilized by? |
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Definition
1. Hydrogen bonding between complementary bases
2. Base stacking |
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Term
| Hydrogen bonding between complementary bases in the DNA double helix means |
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Definition
A bonded to T by two hydrogen bonds
C bonded to G by three hydrogen bonds |
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Term
| Base stacking in the DNA double helix means |
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Definition
| the bases are oriented so that the flattened regions are facing each other |
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Term
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Definition
| the process by which the genetic material is copied |
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Term
| In DNA replication, The original DNA strands are used as... |
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Definition
| templates for the synthesis of new strands |
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Term
| DNA replication relies on the complementarity of... |
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Definition
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Term
| Briefly explain the process of DNA replication |
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Definition
The two DNA strands come apart
Each serves as a template strand for the synthesis of new strands
The two newly-made strands = daughter strands
The two original ones = parental strands |
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Term
| In the late 1950s, three different mechanisms were proposed for the replication of DNA, they are... |
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Definition
| Conservative model, semi-conservative model, dispersive model |
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Term
| Both parental strands stay together after DNA replication |
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Definition
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Term
| The double-stranded DNA contains one parental and one daughter strand following replication |
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Definition
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Term
| Parental and daughter DNA are interspersed in both strands following replication |
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Definition
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Term
| DNA synthesis begins at a site termed the |
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Definition
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Term
| DNA synthesis begins at a site termed the |
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Definition
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Term
| Synthesis of DNA proceeds ? around the bacterial chromosome |
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Definition
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Term
| DNA helicase separates the two DNA strands by |
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Definition
| breaking the hydrogen bonds between them |
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Term
| Three types of DNA sequences in oriC are functionally significant. They are... |
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Definition
AT-rich region
DnaA boxes
GATC methylation sites |
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Term
| ? bind to the separated DNA strands to keep them apart |
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Definition
| Single-strand binding proteins |
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Term
| ? are the enzymes that catalyze the attachment of nucleotides to make new DNA |
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Definition
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Term
| In E. coli there are five proteins with polymerase activity. What are they and what ones have normal replication vs. DNA repair and replication of DNA |
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Definition
DNA pol I and III
Normal replication
DNA pol II, IV and V
DNA repair and replication of damaged DNA |
|
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Term
| what is DNA pol I composed of and what does it do? |
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Definition
Composed of a single polypeptide
Removes the RNA primers and replaces them with DNA |
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Term
| What is DNA pol III composed of and what does it do? |
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Definition
Responsible for most of the DNA replication
Composed of 10 different subunits
The a subunit synthesizes DNA
The other 9 fulfill other functions |
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Term
| Bacterial DNA polymerases may vary in |
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Definition
| their subunit composition |
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Term
| How is the leading strand synthesized? |
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Definition
One RNA primer is made at the origin
DNA pol III attaches nucleotides in a 5’ to 3’ direction as it slides toward the opening of the replication fork |
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Term
| How is the lagging strand synthesized? |
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Definition
Synthesis is also in the 5’ to 3’ direction
However it occurs away from the replication fork
Many RNA primers are required
DNA pol III uses the RNA primers to synthesize small DNA fragments (1000 to 2000 nucleotides each)
These are termed Okazaki fragments after their discoverers |
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Term
| DNA pol I removes the ? and fills the resulting gap with ? |
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Definition
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Term
| How does DNA pol I remove the RNA primers and fills the resulting gap with DNA |
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Definition
It uses its 5’ to 3’ exonuclease activity to digest the RNA
and its 5’ to 3’ polymerase activity to replace it with DNA |
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Term
| What catalyzes a phosphodiester bond thereby connecting the DNA fragments |
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Definition
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Term
| DNA polymerases catalyzes a phosphodiester bond between the |
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Definition
Innermost phosphate group of the incoming deoxynucleoside triphosphate
AND
3’-OH of the sugar of the previous deoxynucleotide |
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Term
| Opposite to oriC is a pair of ? called ter sequences |
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Definition
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Term
| The protein tus (termination utilization substance) binds to these sequences and then... |
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Definition
| stops the movement of the replication forks |
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Term
| DNA helicase and primase are physically bound to each other to form a complex called the ?, which... |
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Definition
| primosome, leads the way at the replication fork |
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Term
| The primosome is physically associated with the DNA polymerase holoenzyme forming the |
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Definition
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Term
| DNA polymerases can only synthesize DNA in the ? direction |
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Definition
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Term
DNA polymerases can only synthesize DNA in the 5’ to 3’ direction
So synthesis of the leading strand is ?
And that of the lagging strand is ? |
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Definition
| continuous; discontinuous |
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Term
Two DNA pol III proteins act in concert to replicate both the leading and lagging strands
The two proteins form a ? that moves as a unit toward the replication fork |
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Definition
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Term
| DNA replication exhibits a high degree of ?, meaning that mistakes during the process are extremely rare. DNA pol III makes only one mistake per ? bases made |
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Definition
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Term
| What are the reasons that the fidelity of DNA is high? (3) |
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Definition
1. Instability of mismatched pairs
2. Configuration of the DNA polymerase active site
3. Proofreading function of DNA polymerase |
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Term
| Instability of mismatched pairs in DNA means... |
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Definition
| Complementary base pairs have much higher stability than mismatched pairs |
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Term
| Configuration of the DNA polymerase active site means... |
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Definition
| DNA polymerase is unlikely to catalyze bond formation between mismatched pairs |
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Term
| Explain the proofreading function of DNA polymerase (3 Parts) |
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Definition
DNA polymerases can identify a mismatched nucleotide and remove it from the daughter strand
The enzyme uses its 3’ to 5’ exonuclease activity to remove the incorrect nucleotide
It then changes direction and resumes DNA synthesis in the 5’ to 3’ direction |
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Term
| Although it is very similar in its mechanism, name three reasons eukaryotic cell division is more complex than bacterial cell division |
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Definition
Large linear chromosomes
Tight packaging within nucleosomes
More complicated cell cycle regulation |
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Term
Eukaryotes have long linear chromosomes
They therefore require ?
to ensure that the DNA can be replicated in a reasonable time |
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Definition
| multiple origins of replication |
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Term
| DNA replication proceeds ? from many origins of replication |
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Definition
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Term
| Binding of at least ? additional ? is required to initiate synthesis during S phase |
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Definition
|
|
Term
| the replication fork is the site where... |
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Definition
| the parental DNA strands have separated and new daughter strands are being made |
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Term
| What are the four primarily DNA polymerases that function in DNA replication? What ones are for nuclear DNA? Mitochondrial DNA? |
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Definition
Four: alpha (a), delta (d), epsilon (e) and gamma (g) have the primary function of replicating DNA
a, d and e Nuclear DNA
g Mitochondrial DNA |
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Term
| Telomeric sequences consist of |
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Definition
Moderately repetitive tandem arrays
3’ overhang that is 12-16 nucleotides long |
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Term
| DNA pol a is the only polymerase to associate with ?; The DNA pol a/primase complex synthesizes a ? |
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Definition
| primase; short RNA-DNA hybrid |
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Term
| The exchange of DNA pol a for d or e is called a |
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Definition
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Term
| When does a polymerase switch occur? |
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Definition
| only after the RNA-DNA hybrid is made |
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Term
DNA pol b is not involved in DNA replication
It plays a role in ? |
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Definition
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|
Term
| What is base-excision repair? |
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Definition
| Removal of incorrect bases from damaged DNA |
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Term
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Definition
| a segment of DNA used to make a functional product |
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Term
| ? is the first step in gene expression |
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Definition
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Term
| Transcription literally means ?. In genetics it means ? |
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Definition
| the act or process of making a copy; the copying of a DNA sequence into an RNA sequence |
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Term
| What encodes the amino acids of a polypeptide? |
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Definition
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Term
| Transcription of a structural gene produces ? |
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Definition
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Term
| The mRNA sequence determines |
|
Definition
| the amino acids in the polypeptide |
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Term
| The function of the protein determines ? |
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Definition
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Term
| This path from gene to trait is called the |
|
Definition
| central dogma of genetics |
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Term
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Definition
| the overall process by which the information within a gene is used to produce a functional product which can determine a trait in concert with the environment |
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Term
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Definition
| Specifies first amino acid in polypeptide sequence |
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Term
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Definition
| Specifies end of polypeptide sequence |
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Term
| What is the ribosome binding site? |
|
Definition
| site for ribosome binding. translation begins near this site in the mRNA |
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Term
| The strand that is actually transcribed (used as the template) is termed the |
|
Definition
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|
Term
| The opposite strand to the template strand is termed the |
|
Definition
| coding strand or the sense strand |
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Term
? factors recognize the promoter and regulatory sequences to control transcription
mRNA sequences such as the and codons direct translation |
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Definition
| Transcription; ribosomal-binding site |
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Term
| Three stages of transcription |
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Definition
Initiation
Elongation
Termination |
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Term
| Well over 90% of all genes are |
|
Definition
| structural genes producing mRNA |
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Term
| The RNA transcripts from nonstructural genes are not translated but they do have ? and can still ? |
|
Definition
various important cellular functions;
confer traits |
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Term
| In some cases, the RNA transcript becomes part of a complex that contains protein subunits, for example... |
|
Definition
Ribosomes
Spliceosomes
Signal recognition particles |
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|
Term
| Where does our understanding of gene transcription primarily come from? |
|
Definition
| studies of bacteria and bacteriaphages, primarily e. coli |
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Term
|
Definition
| DNA sequences that “promote” gene expression |
|
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Term
|
Definition
| exact location for the initiation of transcription |
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Term
| Promoters are typically located |
|
Definition
| just upstream of the site where transcription of a gene actually begins |
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Term
| How are the bases in the promoter sequence numbered? |
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Definition
| in relation to the transcription start site |
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Term
| ? is the enzyme that catalyzes the synthesis of RNA |
|
Definition
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|
Term
| In E. coli, the RNA polymerase holoenzyme is composed of |
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Definition
| core enzyme (5 subunits) sigma enzyme (1 subunit) |
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Term
| The RNA polymerase ? binds loosely to the DNA |
|
Definition
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|
Term
| The binding of the RNA polymerase to the promoter forms the |
|
Definition
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Term
| In bacterial transcription The RNA transcript is synthesized during the |
|
Definition
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|
Term
| The DNA strand used as a template for RNA synthesis is termed the ?or ? |
|
Definition
| template; noncoding strand |
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Term
The opposite DNA strand is called the ?
It has the same base sequence as the ? |
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Definition
| coding strand;RNA transcript |
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Term
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Definition
|
|
Term
| Termination occurs when the... |
|
Definition
| short RNA-DNA hybrid of the open complex is forced to separate |
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Term
| E. coli has two different mechanisms for termination. What are they and what are their differences? |
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Definition
1. rho-dependent termination
Requires a protein known as r (rho)
2. rho-independent termination
Does not require r |
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Term
| What are some reasons gene transcription in eukaryotes is more complex than that of bacteria? |
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Definition
Larger organisms and cells
Cellular complexity such as organelles
added complexity means more genes
Multicellularity
increased regulation to express only in right cells at right time |
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Term
| Nuclear DNA is transcribed by three different RNA polymerases. What are they? |
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Definition
| RNA pol I, RNA pol II, & RNA pol III |
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Term
| Transcribes all rRNA genes (except for the 5S rRNA) |
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Definition
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|
Term
Transcribes all structural genes
Thus, synthesizes all mRNAs
Transcribes some snRNA genes |
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Definition
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|
Term
Transcribes all tRNA genes
And the 5S rRNA gene |
|
Definition
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|
Term
| Eukaryotic promoter sequences are ? than those of bacteria |
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Definition
| more variable and often more complex |
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Term
| For structural genes, at least three features are found in most promoters, they are... |
|
Definition
Regulatory elements
TATA box
Transcriptional start site |
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Term
| Describe the core promoter |
|
Definition
relatively short
It consists of the TATA box
Important in determining the precise start point for transcription |
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|
Term
| What is basal transcription? |
|
Definition
| the low level of transcription produced by the core promoter |
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Term
| Regulatory elements affect the binding of RNA polymerase to the promoter. What are the two types and what do they do? |
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Definition
Enhancers-Stimulate transcription
Silencers-Inhibit transcription |
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Term
|
Definition
| DNA sequences that exert their effect only over a particular gene |
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Term
|
Definition
| Regulatory proteins that bind to such DNA sequences |
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Term
| The third component for transcription is a large protein complex termed |
|
Definition
|
|
Term
| What does the mediator do? |
|
Definition
| mediates interactions between RNA pol II and various regulatory transcription factors |
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Term
| Most transcription occurs in |
|
Definition
|
|
Term
| What inhibits the function of RNA pol within the nucleosome? |
|
Definition
| The tight wrapping of DNA |
|
|
Term
| what is the function of the spliceosome? |
|
Definition
| splices mRNA in eukaryotes |
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|
Term
| What do all cases of splicing involve? |
|
Definition
Removal of the intron RNA
Linkage of the exon RNA by a phosphodiester bond |
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Term
| In eukaryotes, the transcription of structural genes, produces a long transcript known as |
|
Definition
|
|
Term
| The subunits of a spliceosome carry out several functions |
|
Definition
1. Bind to an intron sequence and precisely recognize the intron-exon boundaries
2. Hold the pre-mRNA in the correct configuration
3. Catalyze the chemical reactions that remove introns and covalently link exons |
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Term
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Definition
| string of adenine nucleotides at the 3' end of mature mRNAs, not encoded in gene sequence |
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|
Term
A variety of cellular components play important roles in translation
These include |
|
Definition
| proteins, RNAs and small molecules |
|
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Term
| The ? of the mRNA codons into amino acid sequences leads to the synthesis of proteins |
|
Definition
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|
Term
Genes that encode polypeptides are termed ?
These are transcribed into ? |
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Definition
| structural genes; messenger RNA (mRNA) |
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Term
| What is the main function of the genetic material? |
|
Definition
| encode the production of cellular proteins |
|
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Term
|
Definition
| that a relationship exists between the inheritance of the trait and the inheritance of a defective enzyme |
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|
Term
The term ? denotes structure
The term ? denotes function |
|
Definition
|
|
Term
| The genetic information is coded within mRNA in groups of three nucleotides known as ? |
|
Definition
|
|
Term
| ? (which specifies methionine) = start codon |
|
Definition
|
|
Term
| ? ? and ? = termination, or stop, codons |
|
Definition
|
|
Term
| In most instances, the ? base is the degenerate base. Also known as the ? |
|
Definition
|
|
Term
| During each cycle of elongation, a ? is formed between the last amino acid in the polypeptide chain and the amino acid being added |
|
Definition
|
|
Term
| There are four levels of structures in proteins. What are they? |
|
Definition
1. Primary
2. Secondary
3. Tertiary
4. Quaternary |
|
|
Term
| WHat is a proteins primary structure? |
|
Definition
|
|
Term
| WHy are nonpolar amino acids often buried within the interior of a folded protein? |
|
Definition
| because they are hydrophobic |
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|
Term
| Polar and charged amino acids are more likely to be found near the surface. Why? |
|
Definition
|
|
Term
| The primary structure of a protein folds to form regular, repeating shapes known as |
|
Definition
|
|
Term
| There are two types of secondary structures. What are they and what stabilizes them? |
|
Definition
| alpha and beta sheets and they are stabilized by hydrogen bonds |
|
|
Term
| The short regions of secondary structure in a protein fold into a three-dimensional ?. What is their structure determined by? |
|
Definition
tertiary structure;
by hydrophobic and ionic interactions as well as hydrogen bonds and Van der Waals interactions |
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Term
| Proteins made up of two or more polypeptides have a ? structure. It is formed when the... |
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Definition
| Quaternary; various polypeptides associate together to make a functional protein |
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|
Term
| A key category of proteins are enzymes. What do they do and what are the two categories they can be broken down into? |
|
Definition
Anabolic enzymes Synthesize molecules and macromolecules
Catabolic enzymes Break down large molecules into small ones |
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Term
| The enzymes that attach amino acids to tRNAs are known as ?. how many types are there? |
|
Definition
aminoacyl-tRNA synthetases;
There are 20 types |
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|
Term
| The aminoacyl-tRNA synthetases are responsible for the |
|
Definition
|
|
Term
| During mRNA-tRNA recognition, the anticodon in tRNA binds to a |
|
Definition
| complementary codon in mRNA |
|
|
Term
| Translation occurs on the surface of a large macromolecular complex termed the |
|
Definition
|
|
Term
Bacterial cells have one type of ribosome
Found in their |
|
Definition
|
|
Term
Eukaryotic cells have two types of ribosomes
One type is found in the ?
The other is found in ? |
|
Definition
| cytoplasm; organelles (mitochondria and chloroplasts) |
|
|
Term
| Unless otherwise noted the term eukaryotic ribosome refers to the ribosomes in the |
|
Definition
|
|
Term
A ribosome is composed of structures called the large and small subunits
Each subunit is formed from the assembly of |
|
Definition
|
|
Term
| During bacterial translation, the mRNA lies on the surface of the ? |
|
Definition
|
|
Term
| Ribosomes contain three discrete sites |
|
Definition
Peptidyl site (P site)
Aminoacyl site (A site)
Exit site (E site) |
|
|
Term
| Translation can be viewed as occurring in three stages |
|
Definition
Initiation
Elongation
Termination |
|
|
Term
| Explain the steps in initiation |
|
Definition
| mRNA, initiator tRNA, and ribosomal subunits form an initiation complex then initiator tRNArecognizes the start codon in mRNA. |
|
|
Term
| How does eukaryotic initiation differ from bacterial initiation? |
|
Definition
initiator tRNA is designated tRNAmet
It carries a methionine rather than a formylmethionine |
|
|
Term
| What happens during elongation? |
|
Definition
| the amino acids are added to the polypeptide chain, one at a time |
|
|
Term
| What is important in maintaining the high fidelity in mRNA translation |
|
Definition
|
|
Term
| In most species there are three stop or nonsense codons |
|
Definition
|
|
Term
| In most species there are three stop or nonsense codons |
|
Definition
|
|
Term
| These codons are not recognized by tRNAs, but by proteins called ? |
|
Definition
|
|
Term
| How does termination differ in bacteria and eukaryotes? |
|
Definition
Bacteria have three release factors (one for reach stop codon)
Eukaryotes only have one release factor which recognizes all three stop codons |
|
|
Term
Bacteria lack a nucleus
Therefore, both transcription and translation occur in the ? |
|
Definition
|
|
Term
|
Definition
| as soon as an mRNA strand is long enough, a ribosome will attach to its 5' end, so translation begins before transcription ends |
|
|
Term
| A ? or ? is an mRNA transcript that has many bound ribosomes in the act of translation |
|
Definition
|
|
Term
| ? (short amino acid sequences) direct a protein to its correct location |
|
Definition
|
|
Term
| In eukaryotes, there are two main types of sorting. What are they and when do they occur? |
|
Definition
Cotranslational sorting: During translation
Posttranslational sorting: After translation |
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|
