Chapter 16: The Structural Basis of Cellular Info: DNA, chromosomes, and the nucleus

Which characteristics is shared between most prokaryotic and mitochondrial genomes?

circular chromosomes

Heterochromatin is highly _______, thus constitutive heterochromatin plays a(n) __________ role and facultative heterochromatin functions in _________.

compacted; structural; regulation of gene expression

An example of a purine is

guanine

Circular DNA molecules found in nature are

negatively supercoiled

Each of the following structures is found within the nucleus of a eukaryotic cell except - transfer RNA. - histones. - plasmids. - the nucleolus. - All of these are found in the nucleus.

plasmids

When examining a five-carbon sugar to determine if it is ribose or deoxyribose, one looks to see if there are two H on the _______ carbon in the structure.

2'

Unusual eukaryotic-like (possessing a defined nucleus) cells were obtained from a sample of water from a subglacial antarctic lake. To investigate the properties of the new organism's genome, the nucleus was carefully isolated and the chromatin obtained. The fibers had a "beads on a string" appearance, suggesting some type of "histones." Following digestion with micrococcal nuclease, protein removal, and gel electrophoresis, DNA fragments were obtained that are multiples of 280 base pairs in length. Longer incubation with micrococcal nuclease prior to protein removal results in fragments 200 base pairs in length. The amount of DNA that is wrapped around the "core histones" is therefore

200 base pairs in length

The base composition in DNA isolated from cow liver cells is 28% adenine; what percent of the bases are cytosine?

22%

DNA is isolated form Aspergillis has an adenine content of 25%. Based upon this information, what is the %G + %C within the Aspergillis DNA?

50%

Which of the following are components of Chargaff's rules of bases? - % purines = % pyrimidines - %C + %T = %A + %G - %A = %T - %G = %C - All of these are true

All of these are true

You are using genetic engineering to design a protein that needs to be synthesized in the cytoplasm and then localized in the nucleus of the cell. To accomplish this, you could add

DNA sequence for a nuclear localization signal into the DNA that will be present in the mature protein.

_______ demonstrated that there were equivalent amounts of adenine and thymine and equivalent amounts of guanine and cytosine.

Erwin Chargaff

_________ is a DNA hybridization technique that can localize specific sequences and chromosomes inside a cell.

Fluorescent in situ hybridization (FISH).

A recently isolated bacterial strain has been given to you for general characterization of the genome. You begin by isolating the DNA and subjecting it to thermal denaturation. You use Escherichia coli (E. coli) DNA as a reference. Based on the information in the graph, you can determine that the DNA of the new strain has a high?

G-C content with respect to E. coli

In the Ran/importin pathway ________ provides the energy for transport of proteins into the nucleus.

GTP hydrolysis

The scientist credited with the discovery of DNA (nucleon) from WBC in pus on surgical bandages is

Johann Friedrich Meischer

Two classes of transposable elements associated with interspersed repeated DNA are ______ and __________.

LINES, SINES

________ are amino acid sequences that are recognized by importin, allowing proteins to enter the nucleus.

Nuclear localization signals (NLSs)

DNA is different form RNA in that

RNA contains an additional oxygen atom on the ribose sugar

Which of the following statements regarding the Watson-Crick model of DNA is false? - It is the most common biological form of DNA. - The two DNA strands form a left-handed helix. - The two DNA strands are antiparallel. - The bases are "stacked" in the center of the molecule. - The backbone consists of alternating sugars and phosphates.

The two DNA strands form a left-handed helix.

Which of the following statements is true regarding mitochondrial and chloroplast genomes? - They contain mostly interspersed and tenderly repeated DNA. - They are able to replicate independently of the nuclear DNA. - They contain all the genes necessary for aerobic respiration. - They are degenerate bacterial genomes that don't contain important protein-coding genes. - They only encode for ribosomal and transfer RNAs.

They are able to replicate independently of the nuclear DNA.

________ is the process of creating an RNA copt of the information in DNA.

Transcription

_______ is the process of synthesizing proteins based on the base sequences in mRNA molecules.

Translation

_________, also known as "jumping genes," are examples of mobile DNA elements.

Transposons

Avery, MacLeod, and McCarty (1944) demonstrated that DNA was the genetic material by treating heat-killed Streptococcus pneumoniae S (smooth) strain with DNase, thereby preventing transfer of the "transforming substance" from the killed S strain to the live R (rough) strain when the two were mixed together and injected into mice. Another way that one could demonstrate transformation in bacteria would be to extract DNA from

an S strain and mix it with cells of an R strain

Long interspersed nuclear elements (LINEs) found in eukaryotic genomes

are mobile pieces of DNA called transposons that can copy themselves and move around the genome, and they are thought to create genomic variability important to evolutionary adaption.

Which of the following model organisms were used in experiments demonstrating that DNA was the genetic material?

bacteria and bacteriophages.

Interspersed repeated DNA

constitutes 20-40% of most mammalian genomes and can be classified into gene families, such as the Alu family.

The nucleolus

contains tRNA

DNA is often referred to as _______ because two strands of DNA are intertwined in the most common conformation in the cell.

double helix.

Which of the following shows Chargaff's equivalence?

double-stranded DNA

Mitochondrial and chloroplast genomes typically

encode some of the proteins needed for aerobic respiration and photosynthesis, respectively, as well as ribosomal and transfer RNA.

About half of the human genome is composed of mobile elements that are thought to function in ________.

evolution OR evolutionary adaption OR genomic variation OR gene regulation

Which type of DNA makes up the smallest portion of the human genome?

exons

In 1928, Frederick Griffith's experiments with Streptococcus pneumoniae suggested that

heat-killed bacteria could somehow "transform" live bacteria.

In an experiment like that of the 1952 Hershey and Chase experiments, 35S was added to a phage replicating within its bacterial host. The new phage particles were carefully isolated and used to infect fresh bacterial cells in the absence of any radioisotopes. Where would you expect to find the 35S radioisotope immediately after infection?

in the phage ghosts outside the bacterial cells

Which type of DNA makes up the largest portion of the human genome?

interspersed repeated DNA

Packaging of prokaryotic chromosomes

involves structural RNA molecules that contribute to the formation of looped domains. is essentially the same as eukaryotic DNA packaging.

The proteins that compose the nuclear matrix and are implicated in a number of degenerative diseases are called ________.

lamins

Repeating DNA sequences that catalyze their own replication and can mov to a new location in a genome are called _________.

long interspersed nuclear elements (LINEs)

Which of the following is the correct order of the levels of DNA packaging in eukaryotic chromosomes?

nucleosome--> chromatin fiber--> looped domains--> heterochromatin

Which of the following structures contains the receptor protein importin?

nucleus

The 5' end of a DNA molecule can be chemically distinguished from the 3' end because there is a(n) ___________ group at the 5' end and a(n) ________ grip at the 3' end.

phosphate; hydroxyl

Following reports that the amount of DNA varied over time within cells, scientists in the early 1900s concluded that the genetic material had to be

protein

Alteration of histones by addition of methyl and acetyl groups to particular amino acids

results n the remodeling of chromatin that can activate or inhibit gene expression

The nuclear envelope functions as a

selective barrier that separates nuclear and cytoplasmic constituents, localizes chromosomes within the cell, and sequesters many of the mRNA processing activities from the cytosol.

The name given to double-stranded DNA that is twisted upon itself is ________.

supercoiled DNA

Numerous Xenopus cells were exposed to varying amounts of ultraviolet light. Some of the resulting cells were observed to lack nucleoli. As a result, one would expect that the cell could not

synthesize ribosomal RNA

Mitochondrial DNA can be used to identify a species based upon

the 648 bp DNA bar code region

Fluorescent in situ hybridization (FISH) would be helpful in determining

the position of particular chromosomes or sequences inside the nucleus.

The information encoded in DNA is used within a cell in a two-stage process. The two stages of this process are called

transcription and translation