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Model organism sapling
Terms in this set (42)
Which one of the following is the most inclusive definition of a model organism (model system)?
an organism with a biological system that is representative of the same system in other organisms
The wild mustard Arabidopsis thaliana is used as a model organism in genetic studies of plants. Why is Arabidopsis an excellent model organism? Select all of the statements that apply.
produces offspring in short amount of time
small and requires few resources to grow
able to self-fertilize and cross-fertilize
most common form of naturally occurring trait or allele in a species
How are different mouse strains valuable in studies of human disease?
Thousands of strains of mice have been bred, each predisposed to a specific human disease
What do bacteriophages, or phages, infect?
What is a phosphodiester bond?
a covalent bond that forms the backbone of DNA and RNA molecules
Erwin Chargaff\'s experiments on the composition of DNA provided clues about the structure of DNA. Select the statements that describe what Chargaff discovered about the base pair composition of DNA.
The proportions of A:T base pairs and C:G base pairs are similar for members of the same species and vary between species
DNA molecules contain similar numbers of A and T bases and similar numbers of G and C bases
Using X-ray crystallography, Rosalind Franklin was able to produce X-ray diffraction images of DNA that were clearer than any previously produced images. What did the images show regarding the structure of DNA?
The complementary strands of a DNA molecule form the shape of a double helix
Which phrase describes a sister chromatid?
one member of a replicated chromosome
What are the functions of mitotic cell division?
replacement of cells
cell prepares to replicate DNA
sister chromatids are present
DNA is wrapped around histone proteins and coiled to form a dense fiber called chromatin. Which of the following statements describes the function of the chromatin conformation of DNA?
DNA is wrapped around histone proteins to regulate gene expression
As genetic material replicates, sister chromatids are linked in an X-shaped structure. What is the term used to describe the area where the two chromatids are linked?
Cell division by mitosis is a mechanism of asexual cell replication. Some single-cell organisms reproduce by cell division, and cell division enables multicellular organisms to grow and to repair damaged cells. Which of the following are products of cell division by mitosis?
2 daughter cells with identical chromosomes
During which phase of mitosis do nuclear membranes reform around the separated copies of DNA?
What is the function of the mitotic spindle?
separating sister chromatids
What functions do centrosomes have during mitosis?
help produce mitotic spindle
organize spindle microtubules
How does mitosis and cytokinesis in eukaryotes differ from binary fission in prokaryotes?
sister chromatids attach to spindle fibers during mitosis, whereas binary fission does not use spindle fibers to separate the replicated chromosome
the cell determines whether resources are sufficient to proceed w the cell cycle
DNA checked to be sure all chromosomes have been duplicated without damage
All chromatids checked for proper attachment to spindle fibers
During the cell cycle, the cell must pass through several checkpoints that confirm that the cell is ready to progress to the next phase of the cycle. If the requirements of one phase have not been met, the cell cannot proceed to the next phase. These checkpoints help control the rate of cell division. If a mutation disables one of these checkpoints, what is most likely to happen?
The cell begins dividing too often, forming a tumor
In general, what causes normal cells to become cancer cells?
loss of cell cycle control
Benign tumors are non-cancerous tumors. How are malignant tumors different from benign tumors?
Cells in a malignant tumor grow uncontrollably, invade and damage nearby tissues, and may metastasize
Which of the following is not part of the cell cycle for the plasmodial form of the slime mold Physarum polycephalum?
Meiosis is a critical process for many living organisms. If an organism became unable to complete meiosis, what effect would it have on the organism?
the organism would no longer produce sex cells
Some strains of yeast are haploid. How do these strains undergo meiosis?
two haploid yeast fuse to form a diploid state that can undergo meiosis
How does the structure of DNA encode genetic information?
the sequence of bases
What is the key feature of DNA that allows it to be copied?
complementary base pairing
Since DNA is replicated semiconservatively, what does each new daughter cell receive from the parent cell after replication and mitosis?
one of the original strands and one new strand
Which enzyme joins fragments of DNA into a continuous strand?
Which enzyme pairs corresponding nucleotides to a preexisting DNA chain in order to synthesize a new strand of DNA?
DNA replication involves various steps that require different enzymes. Which process does primase catalyze in DNA replication?
synthesis of a short RNA sequence that initiates DNA synthesis
Two daughter strands of DNA are synthesized during DNA replication. Which term describes the new chain of DNA that begins at the replication fork and is synthesized in discontinuous fragments.
These discontinuous sequences of DNA nucleotides are synthesized by DNA polymerase and fused together by DNA ligase.
What are telomeres?
The DNA positioned at the ends of eukaryotic DNA strands
What strategies do cells use to ensure that newly replicated DNA does not contain errors?
As DNA polymerase synthesizes new DNA, it finds and corrects misplaced nucleotides
Enzymes proofread the DNA after the DNA has been replicated and replace any mismatched nucleotides
Enzymes remove and resynthesize any misshapen sequences of DNA prior to replication
Which of the following describes what happens during mismatch repair of DNA?
Enzymes identify the newly synthesized DNA strand, remove a segment surrounding the mismatched nucleotides, and resynthesize the DNA segment correctly
DNA damage can occur as a result of exposure to chemicals or ultraviolet radiation. What happens during nucleotide excision repair of damaged DNA?
Enzymes unwind the DNA, cut out a section on one strand that contains the DNA damage, and resynthesize the section with the correct DNA sequence
What generally causes thymine dimers to form in a strand of DNA, and why are thymine dimers a problem?
Thymine dimers, which can be produced by ultraviolet radiation, can lead to cancer-causing mutations
The primary manner in which cells manage their energy resources in order to do work is called energy coupling. What statement accurately defines energy coupling?
T or F The chromatids are held together at a region called the centromere.
What are the names of the three energy systems?
Atrazine binds to proteins in the electron transfer chain in chloroplasts of weeds, reducing the transfer of electrons down the chain. Explain how this reduces the rate of photosynthesis in weeds (4)
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