bio 101 mastering biology chapter 4
The cellular organization and extracellular environments of plants and animals are very different. Drag the labels to their appropriate locations in the table below. Labels of Group 2 may be used more than once. Group 1 - Structure -tight junctions -cellulose -gap junctions -collagen -plasmodesmata -desmosomes Group 2 - Plant or Animal? -plant -animal 1) Membrane protein complexes that strengthen the adhesion between adjacent cells, like rivets, to protect against pulling forces. 2) Small channels that form across the plasma membranes of adjacent cells; especially important in intercellular communication. 3) Membrane proteins that create a watertight seal between cells. 4) Small channels between cells that are otherwise surrounded by walls; enable movement of water and solutes between cells. 5) A polysaccharide that is used to synthesize cell walls, which protect cells and help maintain their shape. 6) Long fibers of protein found in the extracellular matrix that provide structural support for cells.
1- Structure: desmosomes Plant or Animal?: animal 2- Structure: gap junctions Plant or Animal?: animal 3- Structure: tight junctions Plant or Animal?: animal 4- Structure: plasmodesmata Plant or Animal?: plant 5- Structure: cellulose Plant or Animal?: plant 6- Structure: collagen Plant or Animal?: animal A primary distinction between plant cells and animal cells is the fact that plant cells are surrounded by cell walls. If it were not for plasmodesmata, the cell walls would essentially imprison the plant's cells, making intercellular communication and the distribution of nutrients nearly impossible. Animal cells have a variety of intercellular junctions, including tight junctions, desmosomes, and gap junctions. The gap junctions of animal cells are most similar to the plasmodesmata of plants. Gap junctions tend to be limited to tissues that require rapid and coordinated signal relay systems, such as heart muscle; they play no role in nutrient distribution.
Two fundamental types of cells are known to exist in nature: prokaryotic cells and eukaryotic cells (like the one shown in the Tour of an Animal Cell animation). Both prokaryotic and eukaryotic cells carry out all of the processes necessary for life, but they differ in some important ways. In this activity, you will identify which cell structures are found only in prokaryotic cells, only in eukaryotic cells, or in both types of cells. -nucleoid -ribosomes -plasma membrane -flagella -lysosome -mitochondria -nucleolus
Prokaryotic Only -nucleoid Eukaryotic Only -nucleolus -mitochondria -lysosome Both -ribosomes -plasma membrane -flagella Only bacteria and archaea have prokaryotic cells, which lack a nucleus and other membrane-enclosed organelles. Prokaryotic cells are smaller and, at the level of the individual cell, are generally less versatile than eukaryotic cells, which compartmentalize many of their metabolic pathways into organelles. Nevertheless, prokaryotes are indispensable in every known ecosystem, and certain species are capable of surviving in some of the harshest and most nutrient-limiting environments on Earth.
During muscle contractions, myosin motor proteins move across tracks of _________ a-microfilaments b-microtubules c-intermediate filaments
a-microfilaments Microfilaments are responsible for cell locomotion and the cell's structural characteristics.
he extension of pseudopodia in amoeba is due to the regulated assembly and destruction of __________ a-microfilaments b-microtubules c-intermediate filaments
a-microfilaments Microfilaments are responsible for cell locomotion and the cell's structural characteristics.
The _____ is the bacterial structure that acts as a selective barrier, allowing nutrients to enter the cell and wastes to leave the cell. a-plasma membrane b-nucleoid region c-ribosome d-pili e-cell wall
a-plasma membrane The plasma membrane is selectively permeable.
In a bacterium, where are proteins synthesized? a-ribosomes b-nucleus c-peroxisome d-nucleoid region e-capsule
a-ribosomes Ribosomes are involved in the manufacture of polypeptides (proteins).
Nucleoplasmin is a nuclear protein. This protein was divided into two segments and linked to the same large cytoplasmic protein, generating two fusion proteins. After injecting these fusion proteins into a cell, one of the proteins was found in the nucleus and the other in the cytoplasm. Which of the following conclusions can be drawn from these results? a-Nucleoplasmin does not have a nuclear localization signal. b-Only one of the two fusion proteins possesses a nuclear localization signal. c-The cytoplasmic protein contains a nuclear localization signal. d-One of the fusion proteins entered the nucleus by passive transport.
b-Only one of the two fusion proteins possesses a nuclear localization signal. The nuclear localization signal is only present in the fusion protein that enters the nucleus.
The primary role of _____ is to bind animal cells together. a-plasmodesmata b-desmosomes c-tight junctions d-the cytoskeleton e-gap (communicating) junctions
b-desmosomes The primary role of desmosomes (anchoring junctions) is to bind cells together.
To understand how cells function as the fundamental unit of life, you must first become familiar with the individual roles of the cellular structures and organelles. Drag the labels on the left onto the diagram of the animal cell to correctly identify the function performed by each cellular structure. Image link: https://d2vlcm61l7u1fs.cloudfront.net/media%2F72d%2F72d967e8-463c-4a03-8314-f494cd9a1d5f%2FphpXmRmdL.png
a-synthesizes lipids b-assembles ribosomes c-defines cell shape d-produces secretory proteins e-modifies and sorts proteins f-digests proteins g-generates ATP The eukaryotic cell has well-defined structures that serve discrete functional roles. An organism's ability to perform essential functions such as metabolism, reproduction, and maintaining homeostasis depends on the proper functioning of structures at the cellular level. Although these structures are present in all animal cells, their number or activity level may vary depending on the cell type. For example, cells in the pancreas that produce the hormone insulin have extensive rough endoplasmic reticula, while muscle cells contain numerous mitochondria. link to image labeled: https://s3.amazonaws.com/classconnection/757/flashcards/8965757/png/cell-1503504541372C05DAA-thumb400.png
_____ are surface appendages that allow a bacterium to stick to a surface. a-Flagella b-Fimbriae c-Ribosomes d-Mitochondria e-Cell walls
b-Fimbriae Fimbriae enable bacterial cells to stick to a surface.
A small protein (molecular weight = 25,000 daltons) is injected into a cell and observed in the nucleus a short time later. What type of transport has taken place? a-Osmosis b-Passive transport c-Active transport
b-Passive transport A 25,000-dalton protein is small enough to diffuse through nuclear pores without any expenditure of energy.
Centrosomes are sites where protein dimers assemble into __________ a-microfilaments b-microtubules c-intermediate filaments
b-microtubules Microtubules serve as intracellular highways for transporting vesicles and organelles; they are also required for cellular locomotion via flagella and cilia.
In eukaryotic flagella, the fibers that slide past one another due to the activity of dynein proteins are ________ a-microfilaments b-microtubules c-intermediate filaments
b-microtubules Microtubules serve as intracellular highways for transporting vesicles and organelles; they are also required for cellular locomotion via flagella and cilia.
Beginning within the nucleus, the first step leading to the synthesis of a polypeptide is _____. a-translation of a DNA nucleotide sequence into a sequence of amino acids b-transferring of information from DNA to messenger RNA c-removal of introns from RNA and the stitching together of exons d-linking of nucleotides to form a polypeptide e-translation of an RNA nucleotide sequence into a sequence of amino acids
b-transferring of information from DNA to messenger RNA Transcription is the first of the two main steps of protein synthesis.
The structure that regulates the passage of material into and out of this bacterial cell is indicated by the letter _____. Image link: https://lh6.googleusercontent.com/proxy/FtVfFUM4QnotMThisjsjWY-_7t0VWsNVXPtz-yhPP9x4dULZQ147206tfv6oYIFDBMldNqWWkBcFIbPLtK4KCukj6C3jV9bmxM6etpVNkG-xJYIPkmzLwQ=w1200-h630-p-k-no-nu a-A (capsule) b-B (fimbriae) c-C (plasma membrane) d-D (nucleoid region) e-E (flagellum)
c-C (plasma membrane) The plasma membrane is selectively permeable.
_____ aid in the coordination of the activities of adjacent animal cells. a-Plasmodesmata b-Desmosomes c-Gap (communicating) junctions d-Tight junctions e-Keratin fibers
c-Gap (communicating) junctions Gap junctions allow for the passage of material between cells, thus facilitating communication between these cells.
Which of the following statements about the nuclear envelope is false? a-Nuclear pores are made up of a group of proteins that are collectively called the nuclear pore complex. b-The nuclear envelope is composed of two lipid bilayers. c-The nuclear envelope is continuous with the Golgi apparatus. d-Molecules pass into and out of the nucleus through nuclear pores.
c-The nuclear envelope is continuous with the Golgi apparatus. This statement is false; the nuclear envelope is continuous with the endoplasmic reticulum.
What name is given to the rigid structure, found outside the plasma membrane, that surrounds and supports the bacterial cell? a-capsule b-pili c-cell wall d-flagella e-nucleoid region
c-cell wall The cell wall is a rigid supporting structure.
Many cell organelles, most notably the nucleus, are anchored by _________ which are assembled from a diverse class of proteins. a-microfilaments b-microtubules c-intermediate filaments
c-intermediate filaments Intermediate filaments are rope-like structures that anchor organelles and intercellular junctions called desmosomes. They are specialized for bearing tension.
The only cytoskeletal fibers not associated with intracellular movement or whole cell locomotion are the _________ a-microfilaments b-microtubules c-intermediate filaments
c-intermediate filaments Intermediate filaments are rope-like structures that anchor organelles and intercellular junctions called desmosomes. They are specialized for bearing tension.
Which of these cell junctions form a barrier to the passage of materials? a-gap (communicating) junctions b-keratin fibers c-tight junctions d-plasmodesmata e-desmosomes (anchoring junctions)
c-tight junctions Tight junctions form a barrier that prevents fluids from moving between cells.
The DNA-containing region of this bacterial cell is indicated by the letter _____. Image link: https://lh6.googleusercontent.com/proxy/FtVfFUM4QnotMThisjsjWY-_7t0VWsNVXPtz-yhPP9x4dULZQ147206tfv6oYIFDBMldNqWWkBcFIbPLtK4KCukj6C3jV9bmxM6etpVNkG-xJYIPkmzLwQ=w1200-h630-p-k-no-nu a-A (capsule) b-B (fimbriae) c-C (plasma membrane) d-D (nucleoid region) e-E (flagellum)
d-D (nucleoid region) The nucleoid region contains DNA.
Which molecules do not normally cross the nuclear membrane? a-mRNA b-Proteins c-Nucleotide triphosphates d-DNA
d-DNA All processes involving DNA take place in the nucleus.
In experiments to test whether a protein can enter the nucleus, why would proteins be labeled with fluorescent molecules? a-To make the proteins bigger b-To give the protein molecules energy c-To target the proteins to the nucleus d-To make the proteins easy to see
d-To make the proteins easy to see Fluorescent tags make the location of the proteins easy to visualize.
Where is a bacterial cell's DNA found? a-ribosomes b-nucleus c-peroxisome d-nucleoid region e-capsule
d-nucleoid region Bacteria lack a nucleus; their DNA is found in the nucleoid region.
What is a function of a bacterium's capsule? a-DNA storage b-protein synthesis c-propulsion d-protection
d-protection A bacterium's capsule has a protective role.
Which organelle plays a role in intracellular digestion? a-plasmodesma b-ribosome c-Golgi apparatus d-chloroplast e-lysosome
e-lysosome The prefix "lyso-" means decomposition.
True or false? Large proteins containing a nuclear localization signal (NLS) bind to the nuclear pore and enter the nucleus without any expenditure of energy.
false Cytoplasmic proteins called importins bind to large proteins containing an NLS and mediate their transport across the nuclear membrane through an active transport (energy-requiring) process.
