MICRB 106 Lecture Notes - Lecture 5: Nitrogenous Base, Deoxyribose, Heredity

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8 Mar 2018

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Genetics: the study of inheritance, or heredity, of living things. Genome: sum total of genetic material of an organism. Most exists in the form of chromosomes. Can also appear in non chromosomal sites. Ex: bacteria and some fungi contain tiny extra pieces of dna (plasmids), and certain organelles of eukaryotes (mitochondria and chloroplasts) are equipped with their own dna. Viruses contain either dna or rna as principal genetic material. Chromosome: discrete cellular structure composed of a neatly packaged dna molecule. Eukaryotic chromosomes: consists of a dna molecule tightly wound around histone proteins. Vary in number (from a few to hundreds) Can occur in pairs (diploid), or singles (haploid), and they have a linear appearance. Bacterial chromosomes: condensed into a packet by means of histone like proteins. Singular, circular (double-stranded) chromosome, although many bacteria have multiple circular chromosomes and some have linear chromosomes. Fundamental unit of heredity responsible for a given trait in an organism.

Related Questions

21) Which of the following is not primarily used for attachment?

A. glycocalyx

B. flagella

C. pili

D. fimbria

E. S layer

30) You have isolated DNA from an E. coli bacteria. The DNA would originate from what structures? (CIRCLE ALL THAT APPLY)

A. inner plasma membrane

B. mitochondria

C. microcompartments

D. nucleus

E. plasmids

31) Many cellular reactions require multiple enzymes. For efficiency, bacteria will package these enzymes together within:

A. fimbria

B. inclusion bodies

C. lysosomes

D. microcompartments

E. vesicles

32) Why can archaea be considered a separate domain from bacteria?

(CIRCLE ALL THAT APPLY)

A. Archaea ribosomal structure and protein synthesis are similar to eukaryotes.

B. They exhibit a novel method of DNA compaction.

C. Like eukaryotes, they contain simple, membrane-bound organelles.

D. Their cell walls are composed of different substances than bacterial or eukaryotic cell walls.

E. They contain a circular chromosome.

33) How are eukaryotic flagella different from bacterial flagella?

A. They are much bigger in size.

B. They move in a whip-like fashion, as opposed to a circular fashion.

C. They are covered by the plasma membrane.

D. A & B only

E. all of the above

36) The primary function of of the rough endoplasmic reticulum is:

A. aerobic respiration

B. the breakdown of phagocytized material

C. assembly of ribosomal subunits

D. polysaccharide and lipid modification of proteins

E. protein synthesis of membrane-bound and secreted proteins

I have a fill in the blank homework assignment on cells I reallyneed help with! Thank you!

The (1) ________ is the fundamental unit unit of life whosecontrol center is the (2) ________, a double membrane-boundorganelle which contains the information storage molecule (3)________. It can be copied to form (4) ________, which leaves viaopenings called (5) ________ ________ and attaches to small,membrane-bound organelles, (6) ________, the sites of proteinsynthesis. If they are attached to the outer surface of the ER orendoplasmic reticulum, this combination forms the (7) ________ ERthat transports the proteins through a system of channels. If theER lacks the protein synthesizing organelles on its membranesurface, it is (8) ________ ER.

Manufactured substances transported by the ER may eventually behoused in membrane-bound ER transport (9) ________ which form whenpart of the ER membrane pinches off. They are sent to the (10)________ ________, chemically modified and repackaged into (11)________ ________. One example of these repackaged organelles, (12)________, contain digestive enzymes which can consume food, damagedorganelles, or invading bacteria.

(13) ________ are double-membrane bound organelles in whichcellular respiration occurs. As glucose is metabolized, theharvested energy is stored in energy storage molecules, (14)________. Each of these organelles contains its own singular,circular chromosome. Autotrophic organisms such as plants traplight energy and (15)_______, organelles which possess the greenpigment chlorophyll, are the sites of photosynthesis. Theseorganelles also possess circular chromosomes.

limeskunk818

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.

MICRB 106 Lecture Notes - Lecture 5: Nitrogenous Base, Deoxyribose, Heredity

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