Chapter 1 learning objectives Flashcards
(32 cards)
Compare, with examples, some ways in which cells may vary in appearance and function.
Cells can vary widely in appearance and function, and these differences reflect the specialized roles that cells play within different organisms. For example, cells in the human body can vary in size, shape, and function. Red blood cells, which are responsible for carrying oxygen to the body’s tissues, are small and round, while muscle cells, which are responsible for contracting to produce movement, are longer and cylindrical. Additionally, cells can have different shapes depending on their function, such as the spiral-shaped cells of the cochlea in the inner ear, which are responsible for detecting sound.
Outline, with examples, ways in which cells share a basic fundamental chemistry.
All cells, regardless of their appearance or function, share a number of fundamental chemical features and processes. For example, all cells contain DNA, RNA, and proteins, which are essential for the synthesis and regulation of cellular processes. Additionally, all cells carry out metabolism, the process by which they acquire and use energy to maintain their functions. All cells also contain cell membranes, which separate the inside of the cell from the outside environment, and they are capable of communicating with other cells through chemical signaling.
Explain how the relationship between DNA, RNA, and protein—as laid out in the central dogma—makes the self-replication of living cells possible.
The central dogma is a fundamental concept in molecular biology that explains the relationship between DNA, RNA, and protein. According to the central dogma, DNA is the genetic material that contains the instructions for making proteins, and RNA is the intermediate molecule that carries out the instructions encoded in DNA. Protein is the final product of gene expression, and it performs a wide range of functions within cells, such as catalyzing chemical reactions, transporting molecules, and providing structural support.
The relationship between DNA, RNA, and protein allows for the self-replication of living cells, which is essential for the continuation of life. During the process of replication, the DNA molecule is copied into a new molecule, and this new molecule is then used to synthesize proteins. The DNA and protein molecules are then passed on to the next generation of cells, ensuring the continuation of the organism’s genetic information.
Summarize how the processes of mutation and selection promote the gradual evolution of individuals best suited for survival in a wide range of habitats.
Mutation is a process by which the genetic material of an organism is changed, and it is a driving force behind evolution. Mutations can occur naturally or be induced by environmental factors, such as radiation or chemicals, and they can affect the characteristics of an organism. Some mutations are neutral and have no effect on the organism, while others can be harmful or beneficial. Natural selection is the process by which organisms that are better adapted to their environment are more likely to survive and reproduce, and this process drives the evolution of populations over time.
Explain how differentiated cell types can vary widely in form and function despite having the same genome sequence.
Differentiated cell types are cells that have undergone specialization and have specific functions within an organism. These cell types can vary widely in form and function despite having the same genome sequence because the expression of certain genes is regulated differently in different cell types. This regulation occurs through the process of gene expression, which determines which genes are activated or silenced in a particular cell. The regulation of gene expression allows cells with the same genome sequence to differentiate into different cell types and perform different functions within an organism.
List the three tenets of cell theory and explain their ramifications for the study of cell biology.
The three tenets of cell theory are:
All living organisms are composed of cells.
Cells are the basic unit of structure and function in living organisms.
Cells arise only from other cells.
The ramifications of cell theory for the study of cell biology are significant. The first tenet of cell theory highlights the importance of studying cells as the fundamental unit of life, and the second tenet emphasizes the central role that cells play in the functioning of living organisms. The third tenet of cell theory suggests that understanding the processes of cell growth, division, and specialization is crucial for understanding how organisms develop and function.
Contrast light microscopy, super-resolution fluorescence light microscopy, and electron microscopy in terms of the cell components that can generally be distinguished using each.
Light microscopy is a technique that uses light to image small structures and is commonly used to view cells and tissues. Light microscopes can generally distinguish structures that are a few hundred nanometers in size, such as organelles within cells, but they are limited by the diffraction of light, which prevents them from resolving structures that are smaller than about 200 nanometers.
Super-resolution fluorescence light microscopy is a more advanced form of light microscopy that uses specialized techniques to overcome the diffraction limit and resolve smaller structures, down to the size of individual proteins. This technique involves the use of fluorescent labels that are specifically designed to emit light at different wavelengths, which allows for the simultaneous visualization of multiple structures within a cell.
Electron microscopy is a technique that uses a beam of electrons to image small structures and is capable of resolving much smaller structures than light microscopy. Electron microscopes can generally distinguish structures that are a few nanometers in size, such as individual proteins or individual atoms. There are two main types of electron microscopy: transmission electron microscopy (TEM), which images thin sections of cells, and scanning electron microscopy (SEM), which images the surface of cells.
Compare how samples are prepared for light versus electron microscopy and explain how these preparations affect whether the technique can be used for viewing living cells or tissues.
Samples for light microscopy are usually prepared by staining them with dyes or fluorescent labels that highlight specific structures or molecules. These preparations are typically performed on fixed cells, meaning that the cells have been killed and preserved using chemicals. This preparation method allows for the visualization of cells and tissues in great detail, but it does not allow for the observation of living cells.
Samples for electron microscopy are typically prepared by fixing and dehydrating them, and then coating them with a thin layer of metal, such as gold or platinum. This preparation method allows for the imaging of cells and tissues at very high resolutions, but it does not allow for the observation of living cells. Some advanced techniques, such as cryo-electron microscopy, can be used to study living cells, but these techniques are more complex and require specialized equipment.
Describe the structural differences between prokaryotes and eukaryotes.
Prokaryotes are single-celled organisms that lack a nucleus and other membrane-bound organelles. They are generally smaller and simpler in structure than eukaryotes, which have a nucleus and other membrane-bound organelles. Prokaryotes have a single chromosome, a simple cytoskeleton, a cell wall, and a cell membrane. Eukaryotes are more complex in structure and have a more complex cytoskeleton, a larger, more organized genome, and a variety of membrane-bound organelles.
Analyze how eukaryotic cells and organisms rely on the function of prokaryotic cells and their descendants.
Eukaryotic cells and organisms rely on the function of prokaryotic cells and their descendants in a number of ways. Prokaryotes perform essential functions within eukaryotic cells, such as synthesizing nutrients and degrading organic matter. Prokaryotes are also thought to be the oldest forms of life on Earth and have evolved to adapt to a wide range of environments, which has contributed to the evolution of eukaryotes through a process called endosymbiosis.
Compare prokaryotes and eukaryotes in terms of their relative preponderance on Earth, their range of habitat, and their tendency toward multicellularity.
Prokaryotes are the most abundant and diverse organisms on Earth, and they can be found in almost every habitat, including soil, water, and the human body. They are generally smaller and simpler in structure than eukaryotes and are able to reproduce quickly, which allows them to adapt to changing environments. Prokaryotes are mostly single-celled, although some can form multicellular structures called biofilms.
Eukaryotes are less common and diverse than prokaryotes, but they are found in a wide range of habitats, including land, water, and the human body. They are generally larger and more complex in structure than prokaryotes, and they have a slower reproduction rate. Eukaryotes can be single-celled or multicellular, and they are more likely to form multicellular structures than prokaryotes.
Justify the division of prokaryotes into bacteria and archaea.
Prokaryotes are divided into two main groups: bacteria and archaea. These groups are distinguished from each other based on their genetic, biochemical, and evolutionary characteristics. Bacteria and archaea share many similarities, but they also have some important differences. Bacteria are the most well-known and widely studied group of prokaryotes, and they are found in almost every habitat on Earth
State the function of the nucleus and describe its structural features.
The nucleus is the central organelle of the eukaryotic cell and is responsible for storing and managing the genetic material of the cell. It is enclosed by a double membrane called the nuclear envelope and contains chromatin, the combination of DNA and proteins that make up the genetic material, and the nucleolus, a small structure involved in the synthesis of ribosomes. The nucleus also contains enzymes and other proteins that help maintain the structure and function of the DNA.
Explain how the structure of the mitochondrion supports its function.
The mitochondrion is a double-membraned organelle that is the site of cellular respiration, the process by which cells produce energy from nutrients. The inner membrane is highly folded into cristae, which increase the surface area available for energy production, and contains enzymes and other proteins involved in energy production. The space between the inner and outer membranes is called the matrix and contains enzymes and other proteins involved in the synthesis of ATP, the main energy-carrying molecule in cells.
Outline the evolution of mitochondria and chloroplasts and cite the evidence for these origins.
Mitochondria and chloroplasts are thought to have evolved from prokaryotic cells that were engulfed by eukaryotic cells in a process called endosymbiosis. Evidence for this includes the fact that both organelles have their own DNA and reproduce independently of the cell, and they also have a number of structural and biochemical features that are similar to those of prokaryotes.
Explain how chloroplasts and mitochondria cooperate as plant cells convert light energy into chemical energy.
Chloroplasts and mitochondria cooperate in plant cells to convert light energy into chemical energy. Chloroplasts absorb light energy and use it to convert carbon dioxide and water into glucose, which is then stored as starch. The mitochondria use the energy stored in the glucose to synthesize ATP, the main energy-carrying molecule in cells.
Compare the function of lysosomes and peroxisomes.
Lysosomes are organelles that contain hydrolytic enzymes that break down and recycle various types of molecules. Peroxisomes contain enzymes that detoxify harmful substances and also break down fatty acids.
Compare the structure, location, and function of the endoplasmic reticulum and Golgi apparatus.
Endoplasmic Reticulum (ER):
Location: Found in the cytoplasm of eukaryotic cells.
Structure: Network of flattened sacs and tubes.
Function: Synthesizes and modifies proteins (rough ER) and lipids (smooth ER).
Golgi Apparatus:
Location: Found in the cytoplasm of eukaryotic cells.
Structure: Stack of flattened sacs.
Function: Sorts, modifies, and transports proteins and lipids. Receives vesicles from the ER and sorts them into different vesicles for transport to their final destination. Modifies proteins and lipids by adding or removing sugars, lipids, and other chemical groups.
Outline the role that transport vesicles play in endocytosis, exocytosis, and the movement of materials between one membrane-enclosed organelle and another.
Transport vesicles are small, membrane-enclosed sacs that play a role in the transport of materials within and between cells.
They are involved in the movement of materials between one membrane-enclosed organelle and another, such as the movement of proteins from the endoplasmic reticulum to the Golgi apparatus, and in the process of endocytosis and exocytosis.
Relate the location of the cytosol with respect to the cell’s membrane-enclosed organelles.
The cytosol is the gel-like fluid that fills the cell and surrounds the organelles.
It is bounded by the cell membrane and contains the cytoskeleton, ribosomes, and other proteins.
The cytosol is separated from the organelles by the membranes of the organelles.
List the three major filaments of the cytoskeleton and contrast the roles they have in animal cells.
- Microfilaments: Thin, flexible filaments made of actin protein that provide structural support and participate in cell movements.
- Intermediate filaments: Stiffer filaments made of intermediate proteins that provide structural support and anchor organelles to the cytoskeleton.
- Microtubules: Thicker, more rigid filaments made of tubulin protein that provide structural support and help transport materials within the cell.
Outline the role the cytoskeleton has in plant cells.
The cytoskeleton is a network of protein filaments that provides structural support and helps to maintain the shape of plant cells.
It is involved in cell division, and it helps to anchor the cell wall to the cell membrane.
The cytoskeleton is also involved in the movement of organelles within the cell and in the movement of the cell itself, such as in the growth and movement of plant roots and shoots.
Describe the ancestral cell that likely engulfed the aerobic bacteria that gave rise to mitochondria and explain why this event is thought to have preceded the acquisition of chloroplasts.
- It is thought that the ancestral cell that gave rise to mitochondria was a prokaryotic cell that engulfed an aerobic bacterium.
- This event likely preceded the acquisition of chloroplasts because mitochondria are thought to have evolved before chloroplasts, and because mitochondria are involved in the production of energy, which would have been necessary for the evolution of more complex cells.
Review why scientists study model organisms.
- Scientists study model organisms to understand fundamental biological processes that are conserved across diverse species, including humans.
- Model organisms are chosen for their simplicity, ease of manipulation, and the availability of genetic and molecular tools.
- Studying model organisms can provide insight into processes that are difficult or impossible to study in humans, such as development or aging.
