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BIOL 1201 : Bio Exam 3

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azuremammoth471
15 Mar 2019
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LSU
Department
Biological Sciences
Course
BIOL 1201
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All

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Bio exam 3
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LECTURE ONE
3/8/16
How do cells reproduce?
Cells need to possess the genetic material characteristic of the
organism
• Genetic material is DNA
• The “daughter” cells need the complete genetic complement
The genetic material of prokaryotes is: circular DNA
Prokaryotes
• Circular strands of DNA
• Replicate the DNA and pass it on to the “daughter” cells
• Divide by binary fission
• Figure 12.12
Eukaryotes
• A problem
• Genetic material is found in linear chromosomes
o Linear strands of dna complexed with proteins
o Multiple chromosomes
How to insure that each daughter cell gets the complete set of
chromosomes?
• Need a mechanism to allow each daughter cell to have a copy
of each chromosome
The solution
• A process call mitosis
Cell Division: Mitosis
• Reproduction
• Growth
• Repair
Somatic Cells
• All body cells except cells which give rise to gametes
Chromosomes
• A complex of linear DNA and protein
• Each eukaryotic species has a characteristic number
• Found in nucleus
Chromatin
• Long and linear strand of dna and complexed proteins
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Duplicated chromosomes
• Consist of two sister chromatids
• Identical copies of DNA
• Attached at a specialized region called the centromere
How many centromeres per chromosome? 1
how many centromeres per chromosome consisting of 2 sister
chromatids? 1
Figure 12.6
Majority of cell cycle consists of interphase (G1, S, G2)
Cell Cycle
• Interphase
• Mitotic phase
o Mitosis
o Cytokinesis
Interphase
• Generally 90% of the cell cycle
• Gap 1 (G1)
o Synthesis of cell components
• S phase
o Synthesis (replication) of DNA
o Doubling of the genetic material
• Gap 2 (G2)
o Centrioles replicate in animal cells
o Structure for cytokinesis put in place
Figure 6.24
Centrioles
• In animals
• 9 sets of triplet microtubules arranged in a ring
• found in the centrosome
o a region from which microtubules grow out
• help organize microtubule growth
o but centrioles are not necessary
o most plants lack centrioles
What does a centriole resemble? ……..
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Document Summary

Cells need to possess the genetic material characteristic of the organism: genetic material is dna, the daughter cells need the complete genetic complement. The genetic material of prokaryotes is: circular dna. Prokaryotes: circular strands of dna, replicate the dna and pass it on to the daughter cells, divide by binary fission, figure 12. 12. Eukaryotes: a problem, genetic material is found in linear chromosomes, linear strands of dna complexed with proteins, multiple chromosomes. How to insure that each daughter cell gets the complete set of chromosomes: need a mechanism to allow each daughter cell to have a copy of each chromosome. Somatic cells: all body cells except cells which give rise to gametes. Chromosomes: a complex of linear dna and protein, each eukaryotic species has a characteristic number, found in nucleus. Chromatin: long and linear strand of dna and complexed proteins. Duplicated chromosomes: consist of two sister chromatids, identical copies of dna, attached at a specialized region called the centromere.

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Related Questions

What is the difference between chromatin and chromosomes?

Question options:

chromatin is one of two identical strands of DNA.

chromosomes are chromatin that has been tightly packed and coiled.

chromosomes are composed of nucleosomes and chromatin is composed of sister chromatids.

chromosomes are important in mitosis and chromatin is essential to meiosis.

Bacterial cells only reproduce asexually and cannot exchange genetic material.

Question options:

True, because they undergo binary fission.

False, because they transfer genetic material with other bacterial cells.

True, because they have a cell wall that prevents sharing of genetic material.

After a visit to a specialist, Dan was diagnosed with liver cancer. Six months later additional tumors were found in his stomach and small intestine. This is an example of

Question options:

malignant tumors.

benign tumors.

Both malignant tumors and metastasis are correct.

Which of the following does NOT occur during mitosis?

Question options:

DNA is replicated.

Replicated chromosomes divide.

Cells line up along the equator of the cell.

Which of the following is INCORRECTLY matched?

Question options:

prophase -- mitotic spindle forms

metaphase -- chromosomes line up along the equator

telophase -- cytoplasm divides



Why is hair loss a common side effect of cancer treatments?

Question options:

Hair cells are at the surface of the body so die easily.

Hair cells divide rapidly and so are targeted by the cancer drugs.

Cancer drugs often target and kill random cells within the body.

From "Investigating Life: Cutting Off a Tumor's Supply Lines in the War on Cancer," how are endostatins used to treat cancerous cells?

Question options:

They prevent angiogenesis by cancerous cells.

They promote growth of new blood vessels to feed cells.

They bind to receptors on cancerous cells and prevent cells from reproducing.

1. In addition to identifying the genetic material, the experiments of Avery, MacLeod, and McCarty with different strains of Streptococcus pneumoniae demonstrated that
DNA is a double helix.
DNA may be taken up by bacterial cells and be active.
DNA is present in bacteriophage T2.
eukaryotic cells may be genetically transformed.
DNA binds to the cell wall of the bacterium.
2. In order to show that DNA in cell extracts is responsible for genetic transformation in Streptococcus pneumoniae, important corroborating evidence should indicate that _______ also destroy transforming activity.
temperatures high enough to kill cells
enzymes that hydrolyze proteins
enzymes that hydrolyze DNA
enzymes that hydrolyze polysaccharides
enzymes that hydrolyze RNA
3. Based on what you have learned about the experiments conducted by Griffith and Avery and colleagues with bacteria, which of the following would result in transformation of living R cells?
Pure RNA from S cells
Cell-membrane extracts from S cells
A mixture of pure RNA and protein from S cells
Cell-free extracts from S cells
Pure protein from S cells
4. A-T base pairs in a DNA double helix
form three hydrogen bonds with each other.
are more heat-stable than G-C base pairs.
are of a substantially different length than G-C base pairs.
are not accessible to DNA binding proteins.
are chemically distinct from G-C base pairs.
5. If 23 percent of the bases in a sample of double-stranded DNA are adenine, what percentage of the bases are uracil?
27
50
0
73
23
6. The uniform diameter of the DNA structure provides evidence for
antiparallel DNA strands.
a right-handed helix.
a double-stranded helix.
3′ end phosphorylation.
purine–pyrimidine pairing.
7. If a sequence of one strand of DNA is 5′-TGACTATC-3′, what is the complementary strand?
5′-ACTGATAG-3′
3′-TGACTATC-5′
3′-ACTGATAG-5′
3′-ACTGATAG-3′
5′-TGACTATC-3′
8. What structural aspect of the DNA facilitates dissociation of the two DNA strands for replication?
3′ end phosphorylation
Purine–pyrimidine pairing
Antiparallel DNA strands
Covalent bonds between sugars and phosphate groups
Hydrogen bonding between paired bases
9. If the Meselson–Stahl density gradient experiment had resulted in two bands of DNA molecules after only one round of replication, one containing only 15N and the second only 14N, this result would have indicated that replication was
unidirectional.
dispersive.
conservative.
bidirectional.

semiconservative.
10. The nucleoside analogue acyclovir, which is used to treat herpes simplex virus (HSV) infections, lacks a 3′ hydroxyl group (–OH). Predict what will happen if the host cell DNA polymerase incorporates a molecule of acyclovir into an elongating strand of HSV DNA.
The replication complex will no longer bind to origins of replication.
The DNA polymerase will only incorporate acyclovir molecules.
Acyclovir will bind single-strand binding proteins.
DNA polymerase will not be able to link a successive nucleotide.
Acyclovir will block the activity of the DNA helicase.
11. Which of the following does not demonstrate the stability of the DNA double helix?
Single-strand binding proteins are required to keep the strands apart.
Paired bases form hydrogen bonds.
High temperatures are required to denature it.
DNA synthesis requires energy.
DNA helicases require ATP.
12. What effect would a primase inhibitor have on DNA replication?
DNA polymerase would not be able to add bases to the DNA.
Primase would be blocked from joining the DNA replication complex.
Primase would not be able to provide primers for DNA polymerases.
DNA polymerase would not be able to use DNA as a template.
There would be no effect on DNA replication.
13. To replicate their DNA in a timely manner, most eukaryotic chromosomes
normally have uncoiled DNA.
have multiple origins of replication.
contain linear molecules of single-stranded DNA.
have two replication forks that move in the same direction.
are composed entirely of DNA.
14. Which statement about DNA replication is false?
Okazaki fragments are synthesized as parts of the leading strand.
Error rates for DNA replication are reduced by proofreading of the DNA polymerase.
The sliding clamp increases the rate of DNA synthesis.
Replication forks represent areas of active DNA synthesis on the chromosomes.
Ligases and polymerases function in the vicinity of replication forks.
15. In many eukaryotes, there are repetitive sequences called telomeres at the ends of chromosomes. After successive rounds of DNA replication, the _______ strand becomes shorter. In some cells, an enzyme called _______ repairs the shortened strand.
leading; telomerase
lagging; telomerase
lagging; DNA polymerase I
leading; DNA polymerase I
leading; replicase
16. A researcher studies normal human fibroblast cells. They can be maintained in culture but die off after about 30 cell generations. Unexpectedly, a colony of cells continues to survive and divide past 30 generations. Which scenario is most likely true for these cells?
DNA polymerase is constantly active.
Primase is able to extend the telomeres.
The mismatch repair system is extra efficient.
The telomerase gene is being expressed.
The cells do not need the ends of their chromosomes.
17. If DNA polymerase III introduces an incorrect nucleotide, what is the first corrective action made by the DNA repair system?
The replication complex excises the incorrect nucleotide.
The excision repair proteins remove the incorrect nucleotide.
The mismatch repair system scans for base-pairing mismatches.
There is no correction, because nucleotide errors by DNA polymerases are not repaired.
DNA ligase connects the correct nucleotide.
18. Choose the correct order of the following four events in the excision repair of DNA:
(1) Base-paired DNA is made complementary to the template.
(2) Damaged bases are recognized.
(3) DNA ligase seals the new strand to existing DNA.
(4) Part of a single strand is excised.
1, 2, 3, 4
2, 1, 3, 4
3, 4, 2, 1
2, 4, 1, 3
4, 2, 3, 1
19. Six complete cycles of PCR should result in a _______-fold increase in the amount of DNA.
64
32
12
128
6
20. When double-stranded DNA is heated to temperatures above 90°C, it denatures. Denaturation is a process that
breaks covalent bonds.
hydrolyzes DNA.
separates double-stranded DNA into two single strands.
causes new hydrogen bonds to form.
irreversibly destroys the double helical structure.

What is a genome? What is a genome made of? Describe the bacterial genome. How do bacteria reproduce? What is binary fission? Distinguish between a chromosome and chromatin. Where are chromosomes located in eukaryotic cells? What is the chromosome made of? What is a centromere? What is the centromere's role? What are sister chromatids and how do they arise? Distinguish between somatic cells and germ (gametes) cells. Describe the cell cycle. What are the different phases? What occurs during S phase? What is interphase? How is the cell cycle controlled?

Describe mitosis. What are the phases of mitosis? What occurs in each of the phases of mitosis? What is cytokinesis? How does this differ between plant and animal cells? What is a kinetochore? Where does it form? What is its role? What is the role of microtubules in mitosis? What is a centriole and what is it composed of? What is a centrosome and what is its role in mitosis? What is the metaphase plate and why is this important? What is the mitotic spindle, its role and its makeup? What defines a diploid cell? How many copies of each chromosome is in a diploid cell? What about a haploid cell? Why do the daughter cells of mitosis always have the same complement of chromosomes?

Describe meiosis. What are the phases of meiosis? What occurs in each of the phases of meiosis? Distinguish between meiosis I and meiosis II and describe how each of these processes compare to mitosis. Why do animal cells undergo meiosis? What is a gamete? What is a zygote? What are recombination, crossing-over, and chiasma? When and why does this occur? What is meant by 'homologous pair of chromosomes'? Why don't the daughter cells of meiosis have the same genetic makeup? What controls the segregation of chromosomes into the gametes?

What are genetic characters? What are genetic traits? What is an allele? What is a locus? How many alleles at each locus would a human cell have and why? Distinguish between genotype and phenotype. What is meant by a dominant gene? What is meant by a recessive gene? How do these differ? What is the genotype of a homozygous dominant organism? What is its phenotype? What is the genotype of a homozygous recessive organism? What is its phenotype? What is the genotype of a heterozygous organism? What is its phenotype? What is a genetic cross? Distinguish between the P, F1, and F2 generations. What is a true-breeding line? What is the genotype and phenotype of a cross between homozygous dominant and homozygous recessive parents? If the F1 progeny are crossed, what would be the genotype and phenotype of the F2 generation? What would be the phenotypic ratio? What would be the genotypic ratio? Be ready to generate Punnet square tests or probability analyses of crosses involving more than one genetic locus. Describe a dihybrid cross where two alleles are homozygous dominant in one parent and homozygous recessive in the other. What would be the phenotypic ratio of the F2 generation from this dihybrid cross? What is meant by independent assortment? Be prepared to calculate probabilities resulting from different crosses.

Distinguish between complete and incomplete dominance. How would incomplete dominance alter the results of a hybrid cross? What would the resulting F2 generation phenotype and genotype ratios be? What is codominance? How does this affect the results of crosses? Be prepared to determine likely blood types of parents based on the blood types of their offspring. What is a polygenic trait? What is a carrier state for a genetic disease? What is meant by linked genes? How does this affect expected outcomes of genetic crosses? How is gene linkage used for chromosomal mapping? Distinguish between autosomes and sex chromosomes. What sex chromosomes are found in women? What sex chromosomes are found in men? What are sex-linked traits? Be prepared to give the results of crosses that involve sex-linked recessive traits. What is the process of nondisjunction? What are the likely results? Why is this important? What is a Barr body? Recognize the genetic abnormality of Downs Syndrome, Turner's Syndrome, and Klinefelter's Syndrome.