CH. 1 Molecular and Cell Bio Q&As

What is the smallest distance two points can be separated and still resolved using light microscopy?

0.2 µm

On average, eukaryotic cells are __________ times longer and have _________ times more volume than prokaryotic cells.

10, 100

All proteins in the cell are made from the same _______.

20 amino acids

Given what you know about the differences between prokaryotic cells and eukaryotic cells, rate the following things as "good" or "bad" processes to study in the model organism E. coli. A. formation of the endoplasmic reticulum B. DNA replication C. how the actin cytoskeleton contributes to cell shape D. how cells decode their genetic instructions to make proteins E. how mitochondria get distributed to cells during cell division

A. Bad B. Good C. Bad D. Good E. Bad E. coli is a type of bacteria

What model organism would be best to study the process of... A. Programmed cell death B. Chloroplast function C. Immunology D. Development of a multicellular tissue

A. C. elegans B. Arabidopsis C. mouse D. Drosophilia

Indicate whether the following statements are true or false. If the statement is false, explain why it is false. A. With respect to cellular respiration, the only organelles used by animal cells are mitochondria, while plant cells use both mitochondria and chloroplasts. B. The number of mitochondria inside a cell remains constant over the life of the cell.

A. False. In plants, only mitochondria perform cellular respiration (using oxygen to break down organic molecules to produce carbon dioxide) just as in animal cells. Chloroplasts perform photosynthesis in which water molecules are split to generate oxygen and fix carbon dioxide molecules. B. False. Mitochondria have their own division cycle and their numbers change based on the rate of division.

Indicate whether the following statements are true or false. If the statement is false, explain why it is false. A. The Paramecium is a multicellular microorganism covered with hairlike cilia. B. Cells of different types can have different chemical requirements. C. The branchlike extensions that sprout from a single nerve cell in a mammalian brain can extend over several hundred micrometers

A. False. The Paramecium is a single-celled organism. B. True. C. True.

Indicate whether the following statements are true or false. If the statement is false, explain why it is false. A. Oxygen is toxic to certain prokaryotic organisms. B. Mitochondria are thought to have evolved from anaerobic bacteria. C. Photosynthetic bacteria contain chloroplasts.

A. True B. False. Mitochondria are thought to have evolved from aerobic bacteria. C. False. Photosynthetic bacteria have enzyme systems similar to those found in chloroplasts, which allow them to harvest light energy to fix carbon dioxide.

Indicate whether the following statements are true or false. If the statement is false, explain why it is false. A. The human genome is roughly 30 times larger than the Arabidopsis genome, but contains approximately the same number of protein-coding genes. B. The variation in genome size among protozoans is larger than that observed across all species of mammals, birds, and reptiles. C. The vast majority of our genome encodes functional RNA molecules or proteins and most of the intervening DNA is nonfunctional.

A. True B. True. C. False. It is a relatively small proportion of our DNA that encodes RNA and protein molecules. The majority of nonencoding sequences is probably involved in critical regulatory processes.

Indicate whether the following statements are true or false. If the statement is false, explain why it is false. A. Membrane components in the cell are made in the endoplasmic reticulum. B. The Golgi apparatus is made up of a series of membrane-enclosed compartments through which materials destined for secretion must pass. C. Lysosomes are small organelles where fatty acid synthesis occurs.

A. True. B. True. C. False. Lysosomes house enzymes that break down nutrients for use by the cell and help recycle materials that cannot be used, which will later be excreted from the cell.

Genes that have homologs in a variety of species have been discovered through the analysis of genome sequences. Explain what it is about the origins of cells that makes it possible for proteins expressed by homologous genes to be functionally interchangeable in different organisms

All cells are thought to have derived from a common ancestor. This cell would have found solutions to many of the essential challenges and since these challenges are the same as those facing the ancestral cell, the ancient solutions are often still effective.

What inorganic molecule would you predict to the be predominant building block for fats, sugars, and proteins?

CO2

Description of Transmission Electron Microscopy:

Can resolve cellular components as small as 2nm.

Despite the differences between eukaryotic and prokaryotic cells, prokaryotes have proteins that are distantly related to eukaryotic actin filaments and microtubules. What is likely to be the most ancient function of the cytoskeleton?

Cell division

Events/conclusions from studies during the mid-1800s surrounding the discovery of cells.

Cells came to be known as the smallest universal building block of living organisms. Light microscopy was essential in demonstrating the commonalities between plant and animal tissues. New cells arise from the growth and division of previously existing cells.

How does cellular specialization serve multicellular organisms and how might a high degree of specialization be detrimental?

Cellular specialization allows multicellular organisms to grow larger and perform more complicated tasks. The cells become highly efficient in the tasks they perform. However, this degree of specialization requires more nutrients to be taken and lessens the ability of the cells within the organism to adapt to changing circumstances as they rely on other cells for life.

The protozoan Didinium feeds on other organisms by engulfing them. Why are bacteria, in general, unable to feed on other cells in this way?

Didinium engulfs prey by changing its shape, and for this it uses its cytoskeleton. Bacteria have no cytoskeleton and cannot easily change their shape because they are generally surrounded by a tough cell wall

Many of the mechanisms that cells use for maintenance and reproduction were first studied at the molecular level in bacteria. Which bacterial species had a central role in advancing the field of molecular biology?

E. Coli

The cell constantly exchanges materials by bringing nutrients in from the external environment and shuttling unwanted by-products back out. What term describes the process by which external materials are captured inside vesicles and brought into the cell?

Endocytosis

Mitochondria contain their own genome, are able to duplicate, and actually divide on a different time line from the rest of the cell. Nevertheless, mitochondria cannot function for long when isolated from the cell because they are ___________.

Endosymbionts

You fertilize egg cells from a healthy plant with pollen (which contains the male germ cells) that has been treated with DNA-damaging agents. You find that some of the offspring have defective chloroplasts, and that this characteristic can be passed on to future generations. This surprises you at first because you happen to know that the male germ cell in the pollen grain contributes no chloroplasts to the fertilized egg cell and thus to the offspring. What can you deduce from these results?

Genetic information is carried only in DNA, so the defect in the chloroplasts must be due to a mutation in DNA. But all of the chloroplasts in the offspring (and thus all of the chloroplast DNA) must derive from those in the female egg cell, since chloroplasts only arise from other chloroplasts. Hence, all of the chloroplasts contain undamaged DNA from the female parent's chloroplasts. In all the cells of the offspring, however, half of the nuclear DNA will have come from the male germ-cell nucleus, which combined with the female egg nucleus at fertilization. Since this DNA has been treated with DNA-damaging agents, it must be the source of the heritable chloroplast defect. Thus, some of the information required for making a chloroplast is encoded by the nuclear DNA.

Chloroplasts are found only in eukaryotic cells that carry out photosynthesis: plants and algae. Plants and algae appear green as a result of the presence of chlorophyll. Where is chlorophyll located in the chloroplast?

In the third, innermost membrane

Description of Scanning Electron Microscopy:

It requires coating the sample with a thin layer of a heavy metal to produce three-dimensional images of the surface of a sample

Description of Fluorescence Microscopy:

It requires the use of two sets of filters. The first filter narrows the wavelength range that reaches the specimen and the second blocks out all wavelengths that pass back up to the eyepiece except for those emitted by the dye in the sample

Description of Phase-contrast:

It uses a light microscope with an optical component to take advantage of the different refractive indices of light passing through different regions of the cell

Prokaryotic cells are able to evolve very fast, which helps them to rapidly adapt to new food sources and develop resistance to antibiotics. What are the three main characteristics that support the rapid evolution of prokaryotic populations?

Large population, rapid growth, and can exchange DNA

Eukaryotic cells are bigger and more elaborate than prokaryotic cells. By definition, all eukaryotic cells have a __________________, usually the most prominent organelle. Another organelle found in essentially all eukaryotic cells is the __________________, which generates the chemical energy for the cell. In contrast, the __________________ is a type of organelle found only in the cells of plants and algae, and performs photosynthesis. If we were to strip away the plasma membrane from a eukaryotic cell and remove all of its membrane-enclosed organelles, we would be left with the __________________, which contains many long, fine filaments of protein that are responsible for cell shape and structure and thereby form the cell's __________________.

Nucleus, mitochondrion, chloroplast, cytosol, cytoskeleton

Which of the following characteristics would not support the idea that the ancestral eukaryote was a predator cell that captured and consumed other cells? (a) dynamic cytoskeleton (b) large cell size (c) ability to move (d) rigid membrane

Rigid membrane

What is the role of the lysosome?

The clean-up, recycling, and disposal of macromolecules

Scientists learned that cell death is a normal and even important part of life by studying the development of the nematode worm C. elegans. What was the most important feature of C. elegans for the study of programmed cell death?

The developmental pathway for each cell in the adult worm was known.

By definition, prokaryotic cells do not possess __________.

a nucleus

Although there are many distinct prokaryotic species, most have a small range of shapes, sizes, and growth rates. Which of the following characteristics are not observed in prokaryotes? (a) a highly structured cytoplasm (b) endoplasmic reticulum (c) the ability to divide rapidly (d) a cell wall

a) a highly structured cytoplasm b) endoplasmic reticulum

Match each model organism with the biological process that is best suited or most specifically useful for its study, based on information provided in your textbook. You may list individual processes more than once. a) A. thaliana (Arabidopsis) b) M. musculus (mouse) c) S. pombe d) C. elegans e) S. cerevisiae f) D. rerio (zebrafish) g) D. melanogaster

a) development & photosynthesis b) development & immunology c) cell division d) programmed cell death e) cell division f) development g) development

Biologists cannot possibly study all living species. Instead, they try to understand cell behavior by studying a select subset of them. What characteristics are useful in an organism chosen for use as a model in laboratory studies?

ability to grow under controlled conditions, rapid rate of reproduction, and amenability to genetic reproduction

Zebrafish (Danio rerio) are especially useful in the study of early development because their embryos ______________.

are transparent

Brewer's yeast, apart from being an irreplaceable asset in the brewery and in the bakery, is an experimental organism used to study eukaryotic cells. However, it does have some limitations. Which of the processes below cannot be studied in yeast? (a) DNA replication (b) cell motility (c) exocytosis (d) cell division

b) Cell motility

Which of the following organelles has both an outer and an inner membrane? (a) endoplasmic reticulum (b) mitochondrion (c) lysosome (d) peroxisome

b) mitochondrion

Which statement is NOT true about mutations? (a) A mutation is a change in the DNA that can generate offspring less fit for survival than their parents. (b) A mutation can be a result of imperfect DNA duplication. (c) A mutation is a result of sexual reproduction. (d) A mutation is a change in the DNA that can generate offspring that are as fit for survival as their parents are.

c) a mutation is a result of sexual reproduction

Choose the phrase that best completes this sentence: Microtubules ____________ and are required to pull duplicated chromosomes to opposite poles of dividing cells.

can rapidly reorganize

The nucleus, an organelle found in eukaryotic cells, confines the __________, keeping them separated from other components of the cell.

chromosomes

A cell's genome ___________.

contains all of a cell's DNA

Description of Bright-field Microscopy:

employs a light microscope and requires that samples be fixed and stained in order to reveal cellular details

The process of change and selection over the course of many generations is the basis of __________.

evolution

Eukaryotic cells are able to trigger the release of material from secretory vesicles to the extracellular space using a process called exocytosis. An example of materials commonly released this way is _____________.

hormones

Drosophila melanogaster is an __________.

insect

A. thaliana, or Arabidopsis, is a common weed. Biologists have selected it over hundreds of thousands of other flowering plant species to serve as an experimental model organism because __________________.

it can reproduce in 8-10 weeks

Cells can be very diverse: superficially, they come in various sizes, ranging from bacterial cells such as Lactobacillus, which is a few __________________ in length, to larger cells such as a frog's egg, which has a diameter of about one __________________. Despite the diversity, cells resemble each other to an astonishing degree in their chemistry. For example, the same 20 __________________ are used to make proteins. Similarly, the genetic information of all cells is stored in their __________________. Although __________________ contain the same types of molecules as cells, their inability to reproduce themselves by their own efforts means that they are not considered living matter.

micrometers, millimeter, amino acids, DNA, viruses

The __________ __________ is made up of two concentric membranes and is continuous with the membrane of the endoplasmic reticulum.

nuclear envolope

The flow of genetic information is controlled by a series of biochemical reactions that result in the production of proteins, each with its own specific order of amino acids. Write the correct series of biochemical reactions

replication --> transcription --> translation

Description of Confocal Microscopy:

scans the specimen with a focused laser beam to obtain a series of two dimensional optical sections, which can be used to reconstruct an image of the specimen in three dimensions. The laser excites a fluorescent dye molecule, and the emitted light from each illuminated point is captured through a pinhole and recorded by a detector.

Mitochondria perform cellular respiration, a process that uses oxygen, generates carbon dioxide, and produces chemical energy for the cell. What is a correct pairing of material "burned" and the form of energy produced during cellular respiration?

sugar & ATP

Evolution is a process ______________.

that can be understood based on the principles of mutation and selection.

Even though fluorescence permits better visualization, the resolving power is essentially the same as that of a standard light microscope because the resolving power of a microscope is limited by the _______________.

wavelength of light

What structures/molecules can be found in plant cells?

DNA, nucleus, plasma membrane, chloroplast, cell wall, lysosome, mitochondrion, golgi apparatus

What structures/molecules can be found in animal cells?

DNA, nucleus, plasma membrane, lysosome, mitochondrion, golgi apparatus

What structures/molecules can be found in bacterial cells?

DNA, plasma membrane, chloroplast, cell wall

Indicate whether the following statements are true or false. If the statement is false, explain why it is false. A. Plants do not require a cytoskeleton because they have a cell wall that lends structure and support to the cell. B. The cytoskeleton is used as a transportation grid for the efficient, directional movement of cytosolic components. C. Thermal energy promotes random movement of proteins, vesicles, and small molecules in the cytosol.

A. False. Although plant cells do have a cell wall that lends structure and support, they still need a cytoskeleton, which also helps with connections between cells and the transport of vesicles inside the cell. B. True C. True

Indicate whether the following statements are true or false. If the statement is false, explain why it is false. A. The terms "prokaryote" and "bacterium" are synonyms. B. Prokaryotes can adopt several different basic shapes, including spherical, rod-shaped, and spiral. C. Some prokaryotes have cell walls surrounding the plasma membrane

A. False. Archaea make up a class of prokaryotic organisms that are significantly different than bacteria. B. True. C. True.

Indicate whether the following statements are true or false. If the statement is false, explain why it is false. A. Primitive plant, animal, and fungal cells probably acquired mitochondria after they diverged from a common ancestor. B. Protozoans are single-celled eukaryotes with cell morphologies and behaviors that can be as complex as those of some multicellular organisms. C. The first eukaryotic cells on Earth must have been aerobic; otherwise, they would not have been able to survive when the planet's atmosphere became oxygen-rich.

A. False. The mitochondria in modern plant, animal, and fungal cells are very similar, implying that these lines diverged after the mitochondrion was acquired by the ancestral eukaryote. B. True. C. False. The first eukaryotic cells likely contained a nucleus but no mitochondria. These ancestral eukaryotes subsequently adapted to survive in a world filled with oxygen by engulfing primitive aerobic prokaryotic cells.

Indicate whether the following statements are true or false. If the statement is false, explain why it is false. A. The nucleus of an animal cell is round, small, and difficult to distinguish using light microscopy. B. The presence of the plasma membrane can be inferred by the well-defined boundary of the cell. C. The cytosol is fairly empty, containing a limited number of organelles, which allows room for rapid movement via diffusion.

A. False. The nucleus is one of the largest organelles and is the easiest organelle to discern within a typical cell. B. True. C. False. The cytosol is actually brimming with individual proteins, protein fibers, extended membrane systems, transport vesicles, and small molecules. And although cellular components do move by diffusion, the rate of movement is limited by the space available and the size of the component in question.

You wish to explore how mutations in specific genes affecting sugar metabolism might alter tooth development. Which organism is likely to provide the best model system for your studies, and why?

Mice will likely be the best organism because they have been well studied and have a relativity fast reproduction rates. Also, they have teeth.

What unit of measurement would you generally use to measure a typical plant or animal cell?

Micrometers

The cytoskeleton provides support, structure, motility, and organization, and it forms tracks to direct organelle and vesicle transport. Which of the cytoskeletal elements is the thickest?

Microtubules

The mitochondrial proteins found in the inner membrane are involved in the conversion of ADP to ATP, a source of energy for the cell. This process consumes which of the following substances? oxygen, nitrogen, sulfur, or carbon dioxide

Oxygen

__________ are fairly small organelles that provide a safe place within the cell to carry out certain biochemical reactions that generate harmful, highly reactive oxygen species. These chemicals are both generated and broken down in the same location.

Peroxisomes

Photosynthesis enables plants to capture the energy from sunlight. In this essential process, plants incorporate the carbon from CO2 into high-energy __________ molecules, which the plant cell mitochondria use to produce ATP.

Sugar

Caenorhabditis elegans is a nematode. During its development, it produces more than 1000 cells. However, the adult worm has only 959 somatic cells. The process by which 131 cells are specifically targeted for destruction is called ______________.

programmed cell death