Cell Bio - Ch. 5
What type of bond connect base pairs? A) covalent bond B) ionic bond C) hydrogen bond
C) hydrogen bond
The human genome has enough DNA to stretch more than 2 m. However, this DNA is not contained in a single molecule; it is divided into linear segments and packaged into structures called chromosomes. What is the total number of chromosomes found in each of the somatic cells in your body? A) 22 B) 23 C) 44 D) 46
D) 46
Which of the following sequences can fully base-pair with itself? A) 5′-AAGCCGAA-3′ B) 5′-AAGCCGTT-3′ C) 5′-AAGCGCAA-3′ D) 5′-AAGCGCTT-3′
D) 5'-AAGCGCTT-3'
The human genome comprises 23 pairs of chromosomes found in nearly every cell in the body. How many telomeres are in each cell? A) 23 B) 46 C) 69 D) 92 E) >200
D) 92
The octameric histone core is composed of four different histone proteins, assembled in a stepwise manner. Once the core octamer has been formed, DNA wraps around it to form a nucleosome core particle. Which of the following histone proteins does not form part of the octameric core? A) H4 B) H2A C) H3 D) H1
D) H1
Which of the following is true for most genes? A) a gene is a segment of DNA that contains the instructions for making a particular protein B) a gene is a segment of DNA that contains the instructions for making a particular RNA C) a gene is a region of DNA that controls a discrete hereditary characteristic of an organism D) all of the above
D) all of the above
The complex of DNA and protein in chromosomes is called: A) centromeres B) histone C) centrosome D) chromatin
D) chromatin
True or false - there are five different nucleotides that become incorporated into a DNA strand.
False
The structure that allows each duplicated eukaryotic chromosome to be pulled into a daughter cell is called a: A) centromere B) telomere C) mitotic spindle D) histone
A) centromere
What is the most highly condensed form of chromatin? A) heterochromatin B) 30-nm chromatin fibers C) euchromatin
A) heterochromatin
What structure in an interphase cell contains ribosomal RNA and proteins for the formation of ribosomes? A) chromatin B) nucleolus C) nuclear lamina
B) nucleolus
What does the term genome refer to? A) all of the proteins expressed in an organism B) the complete set of information in an organism's DNA C) the set of genes turned on in an organism, tissue, or cell
B) the complete set of information in an organism's DNA
What form of inheritance describes how a cell passes down chromatin structure (i.e., heterochromatin or euchromatin) from parent to daughter cells? A) genetic inheritance B) perigenetic inheritance C) epigenetic inheritance D) filial inheritance
C) epigenetic inheritance
Mitotic chromosomes are _____ times more compact than a DNA molecule in its extended form. A) 10,000 B) 100,000 C) 1000 D) 100
A) 10,000
Which of the following is not true? A) a cell can temporarily decondense its chromatin to silence genes during differentiation B) a cell can temporarily decondense its chromatin to give proteins rapid, localized access to specific DNA sequences C) a cell can temporarily decondense its chromatin to allow access to specific DNA sequences for replication, repair, or gene expression
A) a cell can temporarily decondense its chromatin to silence genes during differentiation
What histone protein (considered a "linker" histone) is thought to pull nucleosomes together into a regular repeating array, resulting in a 30-nm fiber? A) histone H1 B) histone H2A C) histone H2B D) histone H3 E) histone H4
A) histone H1
Which statement is true about the tight association of histone proteins and DNA? A) histone proteins have a high proportion of positively charged amino acids, which attract the negatively charged phosphate groups on DNA B) histone proteins have deep grooves into which a DNA double helix tightly fits
A) histone proteins have a high proportion of positively charged amino acids, which attract the negatively charged phosphate groups on DNA
The polarity in a DNA strand is indicated by referring to one end as the 3' end and the other as the 5' end. Which structure is on the 3' end? A) hydroxyl group B) phosphate group C) nitrogenous base
A) hydroxyl group
The classic "beads-on-a-string" structure is the most decondensed chromatin structure possible and is produced experimentally. Which chromatin components are not retained when this structure is generated? A) linker histones B) linker DNA C) nucleosome core particles D) core histones
A) linker histones
The images of chromosomes we typically see are isolated from mitotic cells. These mitotic chromosomes are in the most highly condensed form. Interphase cells contain chromosomes that are less densely packed and __________________________. A) occupy discrete territories in the nucleus B) share the same nuclear territory as their homolog C) are restricted to the nucleolus D) are completely tangled with other chromosomes
A) occupy discrete territories in the nucleus
Each chromosome contains: A) one long DNA molecule B) one long RNA molecule C) one long sequence of amino acids D) a single gene for a protein
A) one long DNA molecule
The DNA from two different species can often be distinguished by a difference in the ______________________. A) ratio of A + T to G + C B) ratio of A + G to C + T C) ratio of sugar to phosphate D) presence of bases other than A, G, C, and T
A) ratio of A + T to G + C
How do chromatin-remodeling complexes work? A) they use the energy from ATP hydrolysis to alter nucleosomes and make certain regions of the DNA more accessible to other proteins B) they bind to nucleosomes in the 30-nm fiber and induce another level of packing, obscuring DNA from binding by other proteins C) they add methyl groups to the tails of histone in order to attract other proteins
A) they use the energy from ATP hydrolysis to alter nucleosomes and make certain regions of the DNA more accessible to other proteins
Nucleosomes are formed when DNA wraps _____ times around the histone octamer in a ______ coil. A) 2.0; right-handed B) 2.5; left-handed C) 1.7; left-handed D) 1.3; right-handed
C) 1.7; left-handed
When there is a well-established segment of heterochromatin on an interphase chromosome, there is usually a special barrier sequence that prevents the heterochromatin from expanding along the entire chromosome. Gene A, which is normally expressed, has been moved by DNA recombination near an area of heterochromatin. None of the daughter cells produced after this recombination event express gene A, even though its DNA sequence is unchanged. What is this the best way to describe what has happened to the function of gene A in these cells? A) barrier destruction B) heterochromatization C) epigenetic inheritance D) euchromatin depletion
C) epigenetic inheritance
The core histones are small, basic proteins that have a globular domain at the C-terminus and a long extended conformation at the N-terminus. Which of the following is not true of the N terminal "tail" of these histones? A) It is subject to covalent modifications, B) It extends out of the nucleosome core. C) It binds to DNA in a sequence-specific manner. D) It helps DNA pack tightly.
C) it binds to DNA in a sequence-specific manner
What statement about nucleosomes is false? A) a nucleosome is a "bead" on a string of unfolded chromatin B) a nucleosome produces a 3-fold packing ratio of DNA C) nucleosomes are found only in mitotic chromosomes D) a nucleosome consists of DNA wrapped around 8 histone proteins, plus a shorter segment of linker DNA
C) nucleosomes are found only in mitotic chromosomes
The process of sorting human chromosomes pairs by size and morphology is called karyotyping. A modern method employed for karyotyping is called chromosome painting. How are individual chromosomes "painted"? A) with a laser B) using fluorescent antibodies C) using fluorescent DNA molecules D) using green fluorescent protein
C) using fluorescent DNA molecules
Although the chromatin structure of interphase and mitotic chromosomes is very compact, DNA-binding proteins and protein complexes must be able to gain access to the DNA molecule. Chromatin-remodeling complexes provide this access by __________________. A) recruiting other enzymes B) modifying the N-terminal tails of core histones C) using the energy of ATP hydrolysis to move nucleosomes D) denaturing the DNA by interfering with hydrogen-bonding between base pairs
C) using the energy of ATP hydrolysis to move nucleosomes
The core histone proteins have tails that can be chemically modified by what type of group? A) acetyl B) phosphate C) methyl D) any of the above
D) any of the above
The complete set of information found in a given organism's DNA is called its ____________. A) genetic code B) coding sequence C) gene D) genome
D) genome
Which of the following chemical groups is not used to construct a DNA molecule? A) five-carbon strand B) phosphate C) nitrogen-containing base D) six-carbon sugar
D) six-carbon sugar
In a DNA double helix... A) the two DNA strands are identical B) purines pair with purines C) thymine pairs with cytosines D) the two DNA strands run antiparallel
D) the two DNA strands run antiparallel
The human genome comprises 23 pairs of chromosomes found in nearly every cell in the body. How many replication origins are in each cell? A) 23 B) 46 C) 69 D) 92 E) >200
E) >200
True or false - Comparing the relative number of chromosome pairs is a good way to determine whether two species are closely related.
False
True or false - DNA molecules, like proteins, consist of a single, long polymeric chain that is assembled from small monomeric subunits.
False
True or false - Gene expression is the process of duplicating genes during DNA replication.
False
True or false - Hydrogen bonds between each nucleotide hold individual DNA strand together
False
True or false - In the chromatin of interphase chromosomes, regions of the chromosome that contain genes being expressed are generally more compact, while those that contain quiescent genes are more generally more extended.
False
True or false - The telomere is a specialized DNA sequence where microtubules from the mitotic spindle attach to the chromosome so that duplicate copies move to opposite ends of the dividing cell.
False
True or false - all functional DNA sequences inside a cell code for protein products.
False
True or false - gene sequences correspond exactly to the respective protein sequences produced from them
False
True or false - Each strand of DNA contains all the information needed to create a new double-stranded DNA molecule with the same sequence information.
True
True or false - Eukaryotic chromosomes contain many different sites where DNA replication can be initiated.
True
True or false - Histone tail modifications establish and maintain the different chromatin structures found in heterochromatin and euchromatin.
True
True or false - The polarity of a DNA strand results from the polarity of the nucleotide subunits.
True
True or false - Chromosomes exist at different levels of condensation, depending on the stage of the cell cycle.
True
The structures that cap the ends of eukaryotic chromosomes are called: A) centromeres B) telomeres C) mitotic spindles D) histones
B) telomeres
A cell can pass certain types of chromatin structure to daughter cells during cell reproduction. What molecules are key to this type of inheritance? A) DNA molecules B) histone proteins C) RNA molecules
B) histone proteins
Histone proteins pack DNA into a repeating array of DNA-protein particles called: A) heterochromatin B) nucleosomes C) euchromatin D) nucleoli
B) nucleosomes
The DNA in eukaryotic chromosomes is folded into a compact form by interactions with: A) RNA B) proteins C) euchromatin D) microtubules E) centromeres
B) proteins
Interphase chromosomes are about______ times less compact than mitotic chromosomes, but still are about______ times more compact than a DNA molecule in its extended form. A) 10; 1000 B) 20; 500 C) 5; 2000 D) 50; 200
B) 20; 500
The human genome contains approximately how many genes? A) 500 B) 25,000 C) 100,000 D) 3,000,000,000
B) 25,000
The human genome comprises 23 pairs of chromosomes found in nearly every cell in the body. How many centromeres are in each cell? A) 23 B) 46 C) 69 D) 92 E) >200
B) 46
Which base pairs are found in DNA? A) A-C and T-G B) A-T and C-G C) A-G and C-T D) A-U and C-G
B) A-T and C-G
What evidence suggests that the large amount of excess "junk" DNA in a genome may serve an important function? A) all organisms have excess "junk" DNA B) a portion of "junk" DNA is highly conserved in its DNA sequence among many different eukaryotic species
B) a portion of "junk" DNA is highly conserved in its DNA sequence among many different eukaryotic species
Mitotic chromosomes were first vizualized in the 1880s with the use of very simple tools: a basic light microscope and some dyes. Which of the following characteristics of mitotic chromosomes reflects how they were named? A) motion B) color C) shape D) location
B) color
Stepwise condensation of linear DNA happens in five different packing processes. Which of the following four processes has a direct requirement for histone H1? A) formation of "beads-on-a-string" B) formation of the 30 nm fiber C) looping of the 30 nm fiber D) packing of loops to form interphase chromosomes
B) formation of the 30 nm fiber
The N-terminal tail of histone H3 can be extensively modified, and depending on the number, location, and combination of these modifications, these changes may promote the formation of heterochromatin. What is the result of heterochromatin formation? A) increase in gene expression B) gene silencing C) recruitment of remodeling complexes D) displacement of histone H1
B) gene silencing
The manner in which a gene sequence is related to its respective protein sequence is referred to as the _________ code. A) protein B) genetic C) translational D) expression
B) genetic
