Genetics CH 11
How many different types of histones are found in the nucleosome that packages mitochondrial DNA?
0
How many base pairs per turn of the helix would most likely correspond to a relaxed DNA molecule?
10
How many complete rotations would most likely correspond to a relaxed DNA molecule that is 100 bp in length?
10
You are studying a small eukaryotic gene of about 2000 bp in length. Estimate how many copies of histone H1 you would find along this region of the chromosome.
10
How many base pairs per turn of the helix would most likely correspond to a negatively supercoiled DNA molecule?
15
How many complete rotations would most likely correspond to a positively supercoiled DNA molecule that is 100 bp in length?
15
How many membranes separate the mitochondrial matrix from the cytoplasm?
2
The human Y chromosome is about 50 million base pairs long. About how many nucleosomes would you expect to find associated with this chromosome?
2,500
You are studying a small eukaryotic gene of about 2000 bp in length. Estimate how many copies of histone H4 you would find along this region of the chromosome.
20
How many base pairs per turn of the helix would most likely correspond to a positively supercoiled DNA molecule?
5
How many complete rotations would most likely correspond to a negatively supercoiled DNA molecule that is 100 bp in length?
5
Which statement about mitochondrial genomes is not true? In most animals, the mitochondrial genome consists of a single circular DNA molecule. Plant mitochondrial genomes often include multiple circular DNA molecules. Each mitochondrion typically contains many copies of the mitochondrial genome. All copies of the mitochondrial genome within a cell are identical.
All copies of the mitochondrial genome within a cell are identical.
Which of the following amino acids has a positive charge that helps to hold the DNA in contact with the histones?
Arginine
Which of the following is not true of bacterial DNA? Most bacterial genomes consist of a single circular DNA molecule. Bacterial DNA is not attached to any proteins that help to compact it. Bacterial DNA is confined to a region in the cell called the nucleoid. Many bacteria contain additional DNA in the form of small circular molecules called plasmids. About 3 to 4 million base pairs of DNA are found in a typical bacterial genome.
Bacterial DNA is not attached to any proteins that help to compact it.
The __________ theory states that the ancestors of mitochondria and chloroplasts were free-living bacteria.
Endosymbiotic
es of a gene that arose by gene duplication are part of a gene _______.
Family
Which of the following is not true of negatively supercoiled DNA?
Has less than 10 bp per turn of its helix.
The presence of more than one type of DNA in the organelles of a single cell is called __________.
Heteroplasmy
A centromere is an example of which type of DNA sequence in eukaryotes?
Highly repetitive DNA
A telomere is an example of which type of DNA sequence in eukaryotes?'
Highly repetitive DNA
The agouti locus helps determine coat color in mice, and this phenotype can vary from light to dark between genetically identical individuals. You have discovered a drug that reduces the variation in the agouti phenotype. What is a likely explanation for this drug's mechanism of action.
Inhibits DNA methyl transferases
How does histone acetylation affect chromatin?
It loosens the chromatin and allows increased transcription.
Which of the following is not true of heterochromatin? Remains in a highly condensed state throughout the cell cycle Makes up most chromosomal material and is where most transcription occurs Exists at the centromeres and telomeres Occurs along one entire X chromosome in female mammals when this X becomes inactivated Is characterized by the absence of crossing over and replication late in the S phase
Makes up most chromosomal material and is where most transcription occurs
A ribosomal RNA gene is an example of which type of DNA sequence in eukaryotes?
Moderately repetitive DNA
A tRNA gene is an example of which type of DNA sequence in eukaryotes?
Moderately repetitive DNA
Which of the following statements is true? Most proteins in the human mitochondrion are encoded by nuclear genes. One piece of evidence supporting the endosymbiotic theory is the extreme similarity between mitochondrial DNAs from different organisms. Heteroplasmy refers to the presence of different alleles in a single organelle. Plants contain chloroplasts, not mitochondria. cpDNA evolves faster than nuclear DNA.
Most proteins in the human mitochondrion are encoded by nuclear genes.
A normal chromosome in a higher eukaryotic species would be expected to contain all of the following except: One centromere One telomere Two copies of histone 2A per nucleosome Satellite DNA Tandem repeat sequences
One telomere
An Alu sequence is an example of which type of DNA sequence in eukaryotes?
Short interspersed elements
Which of the following is an example of an epigenetic change in eukaryotes? A loss of an AT base pair from a gene The addition of methyl groups to cytosines in the promoter region of a gene The substitution of an AT base pair by a GC base pair in a gene as a result of a mistake during DNA replication A deletion that simultaneously removes two genes from the genome None of the above represent epigenetic changes.
The addition of methyl groups to cytosines in the promoter region of a gene
Pea plants produce both pollen and eggs. A pea plant inherits a mutation for cytoplasmic male sterility. How will this affect the plant and/or its progeny?
The plant will be able to reproduce only by cross-fertilization.
The __________ membrane of the chloroplast bears the enzymes and pigments required for photophosphorylation.
Thylakoid
Which of the following has repetitive DNA and heterochromatin? Telomere Centromere Mitochondria Chloroplast a and b
a and b
What kind of gene would not be found in a chloroplast genome?
a gene for a histone protein
Where would you expect to find the variant histone CenH3?
centromere
Paternal transmission of mitochondria is common in which group?
most gymnosperms
Telomeres exist to help with the _________ of the ends of eukaryotic chromosomes.
replication