Exam 3 Flashcards
Heterochromatin is , whereas euchromatin is .
Highly condensed, less compact
What is the role of DNA ligase in the elongation of the lagging strand during DNA replication?
It joins Okazaki fragments together.
In E. coli, which enzyme catalyzes the elongation of a new strand in the 5’ –> 3’ direction?
DNA polymerase III
Which of the following helps to hold the DNA strands apart while they’re being replicated
Single-stranded DNA binding proteins
In DNA for many species, the amount of adenine equals the amount of thymine, The amount of guanine equals the amount of cytosine. Which scientist is responsible for this discovery
Erwin Chargaff
Which of the following results from Griffith’s experiment is an example of transformation?
Most dies after being injected with a mixture of heat killed S and a living R cells
Antiparallel referring to the strains the make up DNA
The 5’ to 3’ Direction of one strand runs counter to the direction of the other strand
Replication in prokaryotes differs from the replication in eukaryotes for which of the following reasons
Prokaryotic chromosomes have a single origin of replication where is eukaryotic chromosomes have many
In the polymerization of DNA, a phosphodiester bond is formed between phosphate group of the nucleotide being added and of the last nucleotide in the polymer
The 3’ OH
Codons are part of the
mRNA
A single peptide
Helps target a protein to the ER
carries in amino acid to the strand of mRNA
tRNA
In the process of transcription
RNA is synthesized
A particular triplet of bases in the template strand of DNA is a 5’ AGT 3’. The corresponding codon for the mRNA transcribed is
3’ UCA 5’
The first event to take place in translation in eukaryotes is
The small subunit of the Ribosome recognizes and attaches to the cap of the mRNA
are noncoding segments of mRNA and are segments that code for functional products
Introns, exons
Once researchers identified DNA as the subunit of inheritance, they asked how information is transferred from DNA in the nucleus to the site of protein synthesis in the cytoplasm. What is the mechanism of information transfer in eukaryotes
Messenger RNA is transcribed from a single gene and transfers information from the DNA in the nucleus to the cytoplasm, where protein synthesis takes place
To repair a thymine dimer by nucleotide excision repair, in which order do the enzymes act
Endonuclease, DNA polymerase l, DNA ligase
An okazaki fragment has which of the following arrangements?
5’ RNA nucleotides, DNA nucleotides 3’
There are 61 mRNA codons that specify an amino acid, but only 45 tRNAs
The rules for bass pairing Between the third-base of a codon tRNA are flexible
It became apparent to Watson and crick after completion of their model that the DNA molecule could carry a vast amount of hereditary information in which of the following
Sequence of bases
During splicing which molecular component of the spliceosome catalyzes the excision
RNA
Which of the following is a function of a single peptide
To translocate polypeptides ER membrane
Cytosine makes a 42% of the nucleotides in a sample of DNA from an organism. Approximately what percentage of the nucleotides in the sample will be thymine
8%
Which of the following can be determined directly from x-ray diffraction photographs of crystallized DNA
The diameter of the helix
A particular triplet of bases in the coding sequence of DNA is AAA. The anti-codon on the tRNA that binds the mRNA codon is
UUU
The nitrogenous base Adenine is found in all members of which group
ATP, RNA and DNA
Which of the following nucleotide triplets best represents a codon
A triplet in the same reading frame as an upstream AUG
What is the role of DNA ligase in the elongation of the lagging strand during DNA replication
It joins okazaki fragments together
If a cell or unable to produce histone proteins, which of the following would be a likely affect
The cells DNA couldn’t be packed into its nucleus
Transcription in eukaryotes requires which of the following in addition to RNA polymerase
Several transcription factors (TF’s)
In his transformation experiments, what did Griffith observe
Mixing he he killed Photogenic strain of bacteria with a living nonpathogenic strain can convert some of the living cells into pathogenic form
Which is on catalyzes the elongation of a DNA strand In the 5’ –> 3’ direction
DNA Polymerase III
Which of the following would you expect of a eukaryote lacking telomerase
A reduction in chromosome length in gametes
Which of the following helps to hold the DNA strands apart while they are being replicated
Single-stranded binding proteins
Which of the following is a function of a poly-A signal sequence?
It codesfor a sequence in eurkaryotic transripts that signals enzymatic cleavage ~1035 nucleotides away
From your understanding of the cell structure, when the newly made polypeptide is to be secreted from the cell where it has been made, what must occur?
Its signal sequence must lead it to the ER from which it goes to the golgi
At a specific area of a chromosome, the sequence of nucleotides below is present where the chain opens to form a replication fork: 3’CCTAGGCtGCAATCC5’. An RNA primer is formed starting t the t of the template. Primer seuence?
5’ACGUUAGG3’
Which of the following does not return any prokaryotic and eukaryotic gene expression but does in and eukaryotic gene expression
A polyA tail is added to the 3’ of an mRNA and a capnis added to the 5’ end
A new DNA strand elongation only In the 5’ to 3’ direction because
DNA polymerase can only add nucleotides to the three prime end
Which of the following is the first event to take place in translation in eukaryotes
The small city at the Radisson recognizes it touches to the five prime cap of mRNA
Why do histamines bind tightly to DNA
Histons are positively charged in DNA is negatively charged
Accuracy in the translation of mRNA into the primary structure of a polypeptide depends on specificity in the
Bonding of the anti-codon to the codon and the attachment of amino acids to tRNAs
Topoisomerase
Relieving Strain in the DNA ahead of the replication fork
What is the function of DNA polymerase lll
To add nucleotides to the 3’ end of a growing DNA strand
The tRNA shown in figure as it’s 3’ and project and beyond it’s 5’ end. What will occur at this 3’ end?
The amino acid binds covalently
Ribozyme
And RNA enzymatic activity
What is the function of GTP in translation
GTP energizes the formation of the initiation complex, using initiation factors
Transcription unit that is 8,000 nucleotides long me use 1,200 nucleotides to make a protein. How many amino acids are made in this process? This is best explained by the fact that
Many non-coding streches of the nucleotides are present in mRNA
What is the affect of nonsense mutation in a gene
It introduces a premature stop codon in mRNA
What is the function of the release factor (RF)
It binds to the stop codon in the a site in place of a tRNA
A frameshift mutation could result from
Either insertion or a deletion of the base
Individuals with the disorder Xeroderma pigmentation are hypersensitive sunlight. This occurs because their cells are impaired in what way
They cannot read pair thymine dimers
The leading in the lagging strand’s differ in that
The leading strand is synthesized in the same direction as the movement of the replication fork, in the lagging strand is synthesized in the opposite direction
Why might a point mutation in DNA make a difference in the level of proteins activity
My substitute an amino acid in the active site
A couple has a child with down syndrome. The mother is 39 years old at the time of delivery. Which of the following is the most probable cause of the child’s condition
One member of the couple underwood non-disjunction in gamete production
Of the following aneuploides, which ois the one that generally has the mist severe impact on the health of the individual
47,+21
Two plants crossed, resulting in the offspring with a 3:1 ratio for a particular trait. What does this suggest?
That the parents were both heterozygous for a single trait
What is a syndrome
A group of treats typically found in conjunction with a particular chromosome abbreviation for Gene mutation
Which of the following statements is true of linkage
The closer two genes are on a chromosome, the lower the probability that crossover will occur between
In humans, clear gender differentiation occurs, not at fertilization, but after the second month of gestation. What is the event of this differentiation
Activation of SRY in mail embryos and masculinization of the gonads
Blackford in mice Dominic to Branford. Short hills are dumb it to long tails. What fraction of the progeny of crosses BbTt x BBtt Will be expected to have black fur and long tails
1/2
What does a frequency of recombination of 50% indicate
The two genes are likely to be located on different chromosomes
Which of the following is an example of polygenetic inheritance
Skin pigmentation humans
Red green colorblind this is a sex linked recessive trait in humans. Two people with normal color vision have a colorblind son. What are the genotypes of the parents
xRxr and xRy
Cystic fibrosis affects the lungs, the pancreas, the digestive system and other organs resulting in symptoms ranging from breathing difficulties to recurrent infections. Which of the following term best describes this?
Pleiotropy
In cattle, roan coat color (mixed red and white hairs) occurs in heterozygous offspring of red and white homozygous. Which of the following crosses would produce offspring in the ratio of 1 red: 2 roan: 1 white
Roan x Roan
Morfan syndrome in humans is caused by an abnormality of the connective tissue protein fibrillin. Patients are usually very tall and thin, with long fingers, curvature of the spine, sometimes weakened arterial walls, and sometimes ocular problems such as Lens dislocation. Which of the following would you conclude for this information?
Its pleiotropic
Abnormal chromosomes are frequently found in malignant tumors. Errors such as translocation may place a gene in close proximity to different control regions. Which of the following might then occur to make the cancer worse
Expression of inappropriate gene product
Epistasis example
In rabbits and many other mammals, one genotype prevents any fur color from developing
Which phase is it preferable to Perform a karyotype
Late prophase or metaphase
One possible result of chromosomal breakage is for a fragment to join a nonhomologous chromosome. What is this alteration called?
Translocation
The CentiMorgan is a unit named Thomas Morgan. Tell what is equal?
1% frequency of recombination between two genes
How many unique gametes could be produced by an individual with the genotype AaBbCCDdEE
Eight
Which of the following is known as a Philadelphia chromosome
The human chromosome 22 that has had a specific translocation
Why did the F1 offspring of Modelz classic P cross always look like one of the two parental varieties
One was completely dominant over another
In certain plants tall is dominant to short. If It is crossed with a homozygous tall plant, what is the probability that the offspring will be short
Zero
Which of the following is true of aneuploidies in general
45 x is the only known human live born monosomy
What do we mean when we use the terms monohybrid cross and Dihybrid cross?
A dihybrid cross involves organisms that are heterozygous for two characters in a mono hybrid cross involves only one
Which of the following is the meaning of the chromosome theory of inheritance is expressed in the early 20th century
Mendelian genes are at specific loci on the chromosome and in turn segregate during meiosis
An obstetrician knows that one of her patients is a pregnant woman who’s fetus is at risk for serious disorder that is detectable biochemically in fetal cells. The ob would most reasonably offer which of the following procedures to her patient
Amniocentesis
Males are more often affected by sex linked traits than are females because
Males are hemiztgous for the x chromosome
A Nonreciprocal crossover causes which the following products
Deletion and duplication
SRY is best described in which of the following ways
A gene region present on the Y chromosome that triggers male development
Which of the following is a map of four genes on a chromosome
A and G
Recombination between linked genes comes about for what reason
Crossovers between these genes resilt in chromosomal exchange
When Thomas Moore just crossed his red F1 generation flies to each other, the F2 generation included both red eyed and white eyed flies. Remarkably all the way White flies were mail. What was the explanation for this result eyed
The gene involved is on the x chrmosome
When crossing an organism that is homozygous recessive for single trait was a heterozygote, what is the chance of producing offspring with homozygous recessive phenotype
50%
Gene S controls the sharpness of spines in the type of a cactus. The cactuses with the don the Elio’s syrup spines where is homozygous recessive SS cactuses have dual spines. At the same time is second gene determines whether or not Catuti is have spines. Homozygous recessive cactuses have the spins of the relationship between the jeans of us
Episyasis
What is recombination between linked genes continue to occur
New allele combinations are acted upon by natural selection
What is the reason that linked genes are inherited togetger
They are located together on the same Chromosomally some
Which of the source of an extra chromosome 21 it individually
Nondisjunction orm trabslocaeion in either either.
Which of the following is the best statement of the use of the addition rule of probability
The probability that either one of two independent events will occur
Mendels second law of independent assortment it has its basis in which of the following events of meiosis one
Alignment of tetrads at the equator
PKU is a recessive disorder in which an individual cannot appropriately metabolize a particular amino acid. The littlest it is not otherwise produced in humans. Therefore the most efficient effective treatment is which of the following
Where you lead the diet of the defective persons to severely limit the update of the amino acid
