Ch1: Pre-Lecture

Is the following statement true, false, or impossible to determine? An individual ribosome can be seen with a fluorescence microscope. Choose one: A) true B) false C) impossible to determine

A) true

What is a drawback to using electron microscopy? Choose one: A)It cannot be used to view living cells. B) It can be used only to view samples that are sliced very thinly. C) It requires the use of fluorescent probes. D It cannot be used to view a whole cell or organism. E)It can be used only to view atomic details in structures larger than a ribosome.

A)It cannot be used to view living cells.

What is a drawback to using light microscopy? Choose one: A. It cannot be used to view structures smaller than a bacterium. B. It requires the use of fluorescent probes. C. It can be used only to view samples that are sliced very thinly. D. It cannot be used to view a whole cell or organism. E. It cannot be used to view living cells.

A. It cannot be used to view structures smaller than a bacterium.

Which of these statements is consistent with the data presented in the evolutionary tree? Choose one: A. Saccharomyces cerevisiae do not contain chloroplasts. B. Drosophila melanogaster do not contain mitochondria. C. Caenorhabditis elegans contain chloroplasts. D. All of these choices are correct regarding these organelles.

A. Saccharomyces cerevisiae do not contain chloroplasts. The yeast Saccharomyces cerevisiae is a model eukaryote. These organisms are unicellular fungi, and according to the evolutionary tree, fungi are not derived from the genetic lineage from where the chloroplast developed. Chloroplasts almost certainly evolved from engulfed photosynthetic bacteria. The bacteria are thought to have been taken up by early eukaryotic cells that already contained mitochondria, but this happened along a different evolutionary path from which fungi had already separated. Drosophila melanogaster is an animal and all animal cells have mitochondria. Like D. melanogaster, Caenorhabditis elegans is an animal and animal cells do not contain chloroplasts.

When comparing liver cells and kidney cells within an organism, many differences can be observed and documented. Which of following is not a difference between liver cells and kidney cells in the same animal?Choose one: A. The different cells have different DNA. B. The different cells are generated during the animal's development. C. The different cells have different roles in the body. D. The different cells express different genes. E. The different cells produce different proteins.

A. The different cells have different DNA.

What do eukaryotic cells have that prokaryotes lack?Choose one: A. a nucleus and membrane-bound organelles B. ribosomes C. a cell wall D. nucleic acids E. a means of using chemical energy

A. a nucleus and membrane-bound organelles

Which cellular component separates the DNA of eukaryotic cells from the cytoplasm? Choose one: A. nuclear membrane B. plasma membrane C. cell wall D. smooth endoplasmic reticulum

A. nuclear membrane

Which statement represents the cell theory? Choose one: A. All cells can be seen using a microscope. B. All cells are formed by the growth and division of existing cells. C. All cells resemble square or rectangular chambers. D. All cells contain DNA. E. All cells require a continual input of energy to sustain life.

B. All cells are formed by the growth and division of existing cells. Observations made with the light microscope in the nineteenth century by biologists, including the seminal work by Matthias Schleiden and Theodor Schwann, documented that all plant and animal tissues were composed of cells. With repeated examination, a concept slowly emerged that all living organisms are composed of cells and that new cells are formed by the division of existing cells. Later experiments by Louis Pasteur helped confirm the cell theory and dispel the competing idea of spontaneous generation.

Which of the following is a stack of flattened membrane-enclosed sacs that receives molecules made in the endoplasmic reticulum, often chemically modifies them, and then directs them to the exterior of the cell or to various locations inside the cell? Choose one: A. lysosome B. Golgi apparatus C. peroxisome D. ribosome E. endoplasmic reticulum

B. Golgi apparatus

Which is not evidence for the endosymbiotic origins of mitochondria and chloroplasts?Choose one: A. Mitochondria and chloroplasts contain their own DNA. B. Mitochondria and chloroplasts have similar DNA. C. Mitochondria and chloroplasts resemble bacteria. D. Mitochondria and chloroplasts reproduce by dividing in two. E. Mitochondria and chloroplasts are each surrounded by a double membrane.

B. Mitochondria and chloroplasts have similar DNA.

Which statement is not true of mitochondria? Choose one: A. Mitochondria contain their own DNA. B. Mitochondria are not present in plant cells. C. Mitochondria are involved in the chemical energy cycle of the cell. D. Mitochondria have an inner and outer membrane. E. Mitochondria are thought to have originated from bacteria.

B. Mitochondria are not present in plant cells.

Mitochondria are essentially the same in all eukaryotes, including plants, animals, and fungi. Based on this observation, how were mitochondria most likely acquired?Choose one: A. by a prokaryotic cell approximately 1000 years ago B. by an ancestral eukaryotic cell before the lines that led to animal cells, plant cells, and fungi diverged C. by an ancestral eukaryotic cell and then replaced by chloroplasts in the line that led to plant cells D. from a free-living, photosynthetic bacterium E. by an ancestral prokaryote and then lost in the line that led to archaea

B. by an ancestral eukaryotic cell before the lines that led to animal cells, plant cells, and fungi diverged

Is the following statement true, false, or impossible to determine? Like the differentiated cells in an individual plant or animal, all bacteria have the same DNA. Choose one: A. true B. false C. impossible to determine

B. false Unlike the differentiated cells in an individual plant or animal, all bacteria do not have the same DNA. Each bacterial species has its own characteristic nucleotide sequence. The specialized cells within a multicellular organism develop from a single fertilized egg and thus share the same DNA. Bacteria belong to different species, each of which has evolved independently, becoming gradually modified and adapted to suit specific environments.

Is the following statement true, false, or impossible to determine? Photosynthetic bacteria contain chloroplasts. Choose one: A. true B. false C. impossible to determine

B. false Photosynthetic bacteria do not contain chloroplasts. Photosynthetic bacteria are prokaryotic, and prokaryotic cells do not contain any membrane-bound organelles. The chloroplast is a membrane-bound organelle that is part of some eukaryotic cells. For photosynthetic bacteria, the photosystem complexes that absorb light energy are embedded in the plasma membrane of the cell; this functions analagously to the inner membrane of the chloroplast of eukaryotic cells.

In 1970, Frye and Edidin published research describing the mobility of plasma membrane proteins. They fused mouse and human cells together, creating a hybrid cell, and then examined the localization of mouse and human proteins over time. Initially mouse and human proteins were each restricted to one-half of the heterokaryon, but over time the mouse and human proteins mixed, with each being present over the entire cell surface. What technique did Frye and Edidin likely use to examine the mouse and human proteins? Choose one: A. scanning electron microscopy B. fluorescence microscopy C. transmission electron microscopy D. interference contrast light microscopy

B. fluorescence microscopy

Why do cell biologists study yeast?Choose one or more: A.Yeast lacks a nucleus, so it is easy to genetically manipulate. B.Yeast carries out all the basic tasks that a eukaryotic cell must perform. C.Yeast is as closely related to animals as it is to plants. D.Yeast is a bacterium and therefore very easy to grow.

B.Yeast carries out all the basic tasks that a eukaryotic cell must perform. C.Yeast is as closely related to animals as it is to plants.

Which statement is not true of chloroplasts? Choose one: A. Chloroplasts contain their own DNA. B. Chloroplasts absorb light and generate oxygen and carbohydrate. C. Chloroplasts are present in essentially all eukaryotic cells and in certain photosynthetic bacteria. D. Chloroplasts are thought to have originated from bacteria. E. Each has an internal stack of membranes and is enclosed by two membranes.

C. Chloroplasts are present in essentially all eukaryotic cells and in certain photosynthetic bacteria.

Which is not a function of proteins? Choose one: A. acting as molecular motors B. catalyzing biochemical reactions C. encoding genetic information D. encasing certain virusesE. providing cells with structural support

C. encoding genetic information

Which organelle's ancestor was likely engulfed by primitive eukaryotes to help the cell survive in an oxygen-rich atmosphere? Choose one: A. lysosome B. peroxisome C. mitochondrion D. Golgi apparatus E. endoplasmic reticulum

C. mitochondrion The mitochondrion is an organelle that contains a double membrane—that is, two lipid bilayers that surround it. This organelle's ancestor was likely engulfed by primitive eukaryotes to help the cell survive in an oxygen-rich atmosphere. Thus, the inner mitochondrial membrane derived from the plasma membrane of the engulfed cell, and the outer mitochondrial membrane derived from the evolving eukaryotic cell's plasma membrane. The Golgi apparatus, endoplasmic reticulum, lysosome, and peroxisome are not surrounded by a double membrane.

Which of the following is a model plant used by scientists? Choose one: A. Caenorhabditis elegans B. Homo sapiens C. Saccharomyces cerevisiae D. Arabidopsis thaliana E. Homo floresiensis

D. Arabidopsis thaliana Arabidopsis thaliana, the common wall cress, is a model plant that is favored by plant biologists for a number of reasons: it can be grown indoors and reproduces quickly, with one plant giving rise to thousands of offspring in just 8-10 weeks, and it is related to plants of agricultural value, making research with it relevant to the production of crops that feed humans. A. thaliana, like S. cerevisiae, C. elegans, and other model organisms, has its strengths and limitations, but all are indispensable in helping researchers understand the cellular and molecular processes that govern life.

Which model organism is represented in this microscopic image? Choose one: A. Caenorhabditis elegans B. Drosophila melanogaster C. Arabidopsis thaliana D. Saccharomyces cerevisiae E. Escherichia coli

D. Saccharomyces cerevisiae The brewer's yeast, Saccharomyces cerevisiae, is an important model system that has been instrumental in understanding basic aspects of processes, including cell division and cell-cycle control. As a single-celled organism, S. cerevisiae can be grown more quickly and easily than multicellular organisms. Because it is a eukaryote, many of its cellular mechanisms are more closely related to humans than bacterial model systems like Escherichia coli.

Scientists were studying yeast cells in which a mutation inactivated a gene required for cell division. Without this gene—and the protein it encoded—these mutant yeast cells were unable to divide normally. But the scientists discovered that introducing a related protein from human cells could "rescue" these mutant yeast cells, allowing the cells to resume normal division. Based on this finding, what is the most likely conclusion you could make?Choose one: A. Modern humans most likely obtained their cell-division proteins from ancient yeast. B. Yeast cells most likely obtained their cell-division proteins from the cells of early humans. C. Yeast and humans diverged from a common ancestor much more recently than previously thought, perhaps fewer than a million years ago. D. The proteins that control cell division in yeast and humans are functionally equivalent and have been conserved, almost unchanged, for more than a billion years. E. Yeast cells require human proteins to divide.

D. The proteins that control cell division in yeast and humans are functionally equivalent and have been conserved, almost unchanged, for more than a billion years.

Identify the three fundamental processes that are involved in the central dogma of molecular biology by dragging the three labels to their targets.

DNA synthesis: Replication RNA synthesis: Transcription Protein Synthesis: Translation

What is the name of the process by which eukaryotic cells engulf material captured from an external medium?Choose one: A. endomitosis B. cytokinesis C. endosymbiosis D. exocytosis E. endocytosis

E. endocytosis

Which of these cannot be resolved with a conventional light microscope? Choose one: A. mitochondrion B. embryonic cell C. bacterium D. cell nucleus E. ribosome

E. ribosome

Is the following statement true or false, and why?Within a developed multicellular organism, all cells possess the ability to divide and do so regularly. Choose one: A. It is true, because all cells can always replicate their DNA in the same manner. B. It is true, because all cells can always split into two cells in the same manner. C. It is false, because some cells lose the ability to replicate their DNA and divide. D. It is false, because most multicellular organisms cannot reproduce at all.

It is false, because some cells lose the ability to replicate their DNA and divide.

Identify the eukaryotic cellular locations of the fundamental processes that are involved in the central dogma of molecular biology by dragging the correct labels to their targets.

Transcription happens in the Nucleus Translation happens in the Cytoplasm