BIOL 1500 Lecture Notes - Genetic Recombination, Lysogenic Cycle, Lytic Cycle

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amaranthhamster130

20 Mar 2013

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Sugar-phosphate backbone of dna is held by strong covalent bonds. Base pairs in dna are held by weak hydrogen bonds. Recombination occurs between similar regions in dna. Homology allows different dna molecules to line up and recombine precisely. Once homologous regions of dna are paired, enzymes break a covalent bond in each of the four sugar-phosphate backbones. The free ends of each backbone are then exchanged and reattached to those of the other dna molecule. Cutting and pasting four dna backbones= one recombination event. E. coli and other bacteria can be grown in minimal medium. Detectable differences related to nutrition that occurred during changing combinations were used. Phototrophs: strains that were able to make the necessary amino acids. Auxotrophs: mutant strains that are unable to make amino acids, the required amino acid needed to be provided. X-rays), two different strains of e. coli were isolated which carried distinctive combinations of alleles for various metabolic genes.

Related Questions

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.

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

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

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.

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

The uniform diameter of the DNA structure provides evidence for

	antiparallel DNA strands.
	a right-handed helix.
	a double-stranded helix.
	3â² end phosphorylation.
	purineâpyrimidine pairing.

If a sequence of one strand of DNA is 5â²-TGACTATC-3â², what is the complementary strand?

	5â²-ACTGATAG-3â²
	3â²-TGACTATC-5â²
	3â²-ACTGATAG-5â²
	3â²-ACTGATAG-3â²
	5â²-TGACTATC-3â²

What structural aspect of the DNA facilitates dissociation of the two DNA strands for replication?

	3â² end phosphorylation
	Purineâpyrimidine pairing
	Antiparallel DNA strands
	Covalent bonds between sugars and phosphate groups
	Hydrogen bonding between paired bases

If the MeselsonâStahl 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 3â² hydroxyl group (âOH). 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 90Â°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.

Question 401 pts

Kinetic energy is the stored energy that can be used for motion.

True

False

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Question 411 pts

When an electron is transferred from one atom to another, and the two atoms are then electrically attracted to one another, a(n) ________________ bond is formed.

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Question 421 pts

Changing the number of ____________ of an atom would change the chemical properties of the atom.

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Question 431 pts

Forming molecules and breaking down molecules in biological organisms usually requires the use of _________ to help the reaction proceed faster.

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Question 441 pts

Organic molecules have a core composed of .

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Question 451 pts

The building blocks of carbohydrates are

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Question 461 pts

Water molecules crossing a membrane from high to low concentration is .

active transport

cell fate

facilitated diffusion

osmosis

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Question 471 pts

Choose the membrane molecule responsible for the passage of polar molecules and ions into and out of the cell.

phospholipids

transmembrane channel proteins

cell surface proteins

carbohydrate chains

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Question 481 pts

The simplest cells are .

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Question 491 pts

Which of the following membrane bound organelles are found inside bacterial cells:

nucleus

organelles are not found in prokaryotic cells

mitochondria

chloroplasts

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Question 501 pts

Which of the following is a specialized components of the cell, is associated with the rough endoplasmic reticulum, and is responsible for making proteins.

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Question 511 pts

Proteins are sorted, modified, and packaged by the _____________ and later transported to the outside of the cell.

ribosomes

golgi bodies (golgi apparatus)

nucleus

mitochondria

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Question 521 pts

Dehydration synthesis is a process of linking two smaller subunits together to form a polymer. Which of the following statements below is true of dehydration synthesis?

Oxygen is consumed.

A water molecule is removed from the molecules.

A water molecule is added to the molecules

Carbon dioxide is given off.

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Question 531 pts

Proteins are made up of _________ held together by peptide bonds.

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Question 541 pts

Which of the following gives an amino acid its properties?

NH2

R Group or functional group

COOH

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Question 551 pts

The final three-dimensional shape of a protein that includes the bonding of two or more polypeptide chains is call its _____ structure.

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Question 561 pts

How do DNA and RNA differ?

all statements are differences between DNA and RNA.

DNA is double stranded while RNA is single stranded.

They have different sugars.

Thymine is present in DNA but not in RNA.

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Question 571 pts

Which of the following is a component of a DNA nucleotide?

phosphate

a nitrogen containing base

All are components of a nucleotide.

5-carbon sugar

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Question 581 pts

Cell membranes are made up of several different types of molecules. Select the membrane molecule below that is made up of a polar region and two non-polar fatty acid tails.

transmembrane proteins

carbohydrate chains

phospholipids

cell surface proteins

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Question 591 pts

Two organelles which are believed to have once been free-living bacterial cells are ____________ and ______________.

chloroplasts and mitochondria

golgi apparatus and endoplasmic reticulum

ribosomes and nucleolus

peroxisomes and lysosomes

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