4.E: Biochemistry of the Genome (Exercises)
4.1: The Structure and Function of Cellular Genomes
The entire genetic content of a cell is its genome. Genes code for proteins, or stable RNA molecules, each of which carries out a specific function in the cell. Although the genotype that a cell possesses remains constant, expression of genes is dependent on environmental conditions. A phenotype is the observable characteristics of a cell (or organism) at a given point in time and results from the complement of genes currently being used.
Multiple Choice
Which of the following correctly describes the structure of the typical eukaryotic genome?
- diploid
- linear
- singular
- double stranded
- Answer
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A
Which of the following is typically found as part of the prokaryotic genome?
- chloroplast DNA
- linear chromosomes
- plasmids
- mitochondrial DNA
- Answer
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C
Serratia marcescens cells produce a red pigment at room temperature. The red color of the colonies is an example of which of the following?
- genotype
- phenotype
- change in DNA base composition
- adaptation to the environment
- Answer
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B
Which of the following genes would not likely be encoded on a plasmid?
- genes encoding toxins that damage host tissue
- genes encoding antibacterial resistance
- gene encoding enzymes for glycolysis
- genes encoding enzymes for the degradation of an unusual substrate
- Answer
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C
Histones are DNA binding proteins that are important for DNA packaging in which of the following?
- double-stranded and single-stranded DNA viruses
- archaea and bacteria
- bacteria and eukaryotes
- eukaryotes and archaea
- Answer
-
D
True/False
Within an organism, phenotypes may change while genotypes remain constant.
- Answer
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True
Noncoding DNA has no biological purpose.
- Answer
-
False
Fill in the Blank
Plasmids are typically transferred among members of a bacterial community by ________ gene transfer.
- Answer
-
horizontal
Short Answer
What are some differences in chromosomal structures between prokaryotes and eukaryotes?
How do prokaryotes and eukaryotes manage to fit their lengthy DNA inside of cells? Why is this necessary?
What are some functions of noncoding DNA?
In the chromatin of eukaryotic cells, which regions of the chromosome would you expect to be more compact: the regions that contain genes being actively copied into RNA or those that contain inactive genes?
Critical Thinking
A new type of bacteriophage has been isolated and you are in charge of characterizing its genome. The base composition of the bacteriophage is A (15%), C (20%), T (35%), and G (30%). What can you conclude about the genome of the virus?