Chapter 3 Cells Flashcards
Vacuole
Membrane-Bounded storage sac in a cell, especially the large central vacuole in a plant cell
Smooth Endoplasmic Reticulum
Portion of the ER that lipids and detoxifies poisons
Within a single cell, which of the following is physically the smallest?
Phospholipid Molecule
How do plant cells form cell walls?
A plant cell secretes the components of its cell wall through its plasma membrane. The primary wall is the first to be secreted; it is thin and flexible compared to the secondary wall, which is thicker and tougher. The secondary wall is internal to the primary wall.
List the features that all cells share; then name three structures found in eukaryotic cells but not in bacteria or archaea.
All cells have DNA, RNA, protein, ribosomes, cytoplasm, and a cell membrane. Three examples of structures found only in eukaryotic cells include a nucleus, endoplasmic reticulum, and mitochondria. (Other answers are possible as well.)
Anchoring Junctions
Connection between two adjacent animal cells that anchors intermediate filaments in a single spot on the cell membrane
Contemporary cell biology focuses on what?
the role of genetic information, the cell’s chemical components, and the metabolic processes inside cells
Eukaryotic
Organism composed of one or more cells containing a nucleus and other membrane-bounded organelles
Describe how animal cells use junctions in different ways.
Tight junctions create an impermeable seal between adjacent cells. Anchoring junctions act as “rivets” that secure cells in place. Gap junctions allow adjacent cells to exchange ions and other materials.
Pioneered Cell Biology
Robert Hooke and Antony van Leeuwenhoek
Cytoskeleton
Framework of protein rods and tubules in eukaryotic cells
One property that distinguishes cells in domain Eukarya from those in domain Bacteria is the presence of
Membranous Organelles
What type of cellular junction prevents stomach acid from leaking into the abdomen and digesting internal organs?
Tight Junctions
Lysosomes
Organelle in a eukaryotic cell that buds from the Golgi apparatus and enzymatically dismantles molecules, bacteria, and worn-out cell parts
List the chemicals that make up cell membranes.
The main chemicals in cell membranes are phospholipids, steroids, and proteins.
Nucleolus
A structure within the nucleus where components of ribosomes are assembled
Gap Junction
Connection between two adjacent animal cells that allows cytoplasm to flow between them
Cilium (pl. cilia)
One of many short, movable protein projections extending form a cell
Rank the following in order from smallest to largest: ant, prokaryotic cell, actin molecule, microtubule, nitrogen atom. What type of microscope (if any) would you need if you wanted to see each?
From smallest to largest, the order would be nitrogen atom, actin molecule, microtubule, prokaryotic cell, ant. The nitrogen atom and individual actin molecule could only be seen with an electron microscope. Microtubules and prokaryotic cells are best seen with an electron microscope, although they are visible with a light microscope. An ant is visible with the unaided eye.
Microfilament
Component of the cytoskeleton; made of the protein actin
Scientists that formulated Cell Theory
Schneider, Schwann, and Virchow
How does the formation of the cell theory illustrate the process of science?
Schleiden and Schwann integrated their own observations with those of many other scientists as they developed their theory, which at first had two parts. Virchow added a third component in 1855, and the theory has expanded further since that time, illustrating that scientific theories are subject to change as new information becomes available. The cell theory includes many testable hypotheses and although it is potentially falsifiable, all observations to date have supported the theory.
Imagine that you found a cell that releases many proteins into the bloodstream. What organelles might be especially active in this cell? What would each of these organelles be doing?
The organelles of the endomembrane system work together to synthesize, package, and release proteins from a cell, so they would be especially active. DNA is transcribed into RNA in the nucleus. The RNA molecule leaves the nucleus and moves to the rough endoplasmic reticulum, where a ribosome translates the nucleic acid message into a protein. The ER then packages the protein in a vesicle, which transports it to the Golgi apparatus. The protein is modified in the Golgi apparatus, packaged in another vesicle, and released from the cell.
Imagine that you could engineer a cell that exchanges gases efficiently with the environment and quickly metabolizes sugars. Describe your cell’s size and shape. What organelles would be abundant?
Gas exchange occurs most efficiently in small cells with highly folded membranes. Mitochondria are the organelles that convert sugars into energy that the cell can use. So this cell would likely be small, with a folded membrane and abundant mitochondria
Prokaryote
A cell that lacks a nucleus and other membrane-bounded organelles: bacteria and archaea
What advantages does compartmentalization confer on a large cell?
Compartmentalization means that a cell must maintain high concentrations of each biochemical only in certain organelles and not throughout the entire cell. Internal compartments also increase the membrane surface area available for chemical reactions.
If a eukaryotic cell is like a house, how is a prokaryotic cell like an efficiency (one-room) apartment?
A eukaryotic cell is like a house with many different internal compartments and specialized areas. A prokaryotic cell is more like an efficiency apartment because it is smaller and has a simpler structure with fewer internal compartments. However, the apartment still carries out the same basic functions as the house.
Cytoskeleton
The fluid portion of the cytoplasm
Cell Membrane
the boundary of a cell, consisting of proteins embedded in a phospholipid bilayer
Chapter 1 explains emergent properties and describes the characteristics of life. Use this information to explain why life is an emergent property that appears at the level of the cell.
All life is organized; requires energy; maintains internal constancy; reproduces, grows, and develops; and evolves. Molecules are smaller than cells and are not considered alive because they do not require energy, maintain internal constancy, or grow. However, when many molecules interact in a cell, all of the characteristics of life emerge. Lipids, proteins, and sugars form the membrane that encloses the cell and helps it to maintain a constant internal environment. The cell grows as proteins and nucleic acids interact to synthesize new proteins, which in turn synthesize other structures. The many reactions occurring within a cell require energy.
Endomembrane System
Eukaryotic organelles that exchange materials in transport vesicles
Cell
Smallest unit of life that can function independently
Suppose you find a sample of cells at a crime scene. What criteria might you use to determine if the cells are from prokaryotes, plants, or animals?
One approach would be to look at the cells with a microscope. If they lack a nucleus, they are prokaryotic; if they contain a nucleus, they are eukaryotic. A eukaryotic cell with a cell wall is likely to be a plant cell (although it could also come from a fungus or some types of protists). A eukaryotic cell without a cell wall is likely to come from an animal (although it could also belong to a protist).
Which of the following organelles are associated with the job of cellular digestion?
Lysosomes and Peroxisomes
A human nerve cell that has an abnormal shape most likely has a defective
Cytoskeleton
Fluid Mosaic
Two-dimensional structure of movable phospholipids and proteins that form biological membranes
Nucleus (cell)
The membrane-bounded sac that contains DNA in a eukaryotic cell
Vesicle
A membrane-bounded sac that transports materials in a cell
Phospholipid Bilateral
Double layer of phospholipids that forms in water; forms the majority of a cell’s membranes
Cell Theory
the ideas that all living matter consists of cells, cells are the structural and functional units of life, and all cells come from preexisting cells
Rough Endoplasmic Reticulum
Ribosome-studded portion of the ER where secreted proteins are synthesized
How does the cytoskeleton interact with other structures in eukaryotic cells?
Organelles can move within the cell along the cytoskeleton’s “tracks.” The cytoskeleton also protects the cell’s organelles by helping maintain the cell’s shape and resisting mechanical stress. Some components of the cytoskeleton tug on chromosomes as the cell divides. The cytoskeleton also links adjacent cells together through the cell membrane.
Cytoplasm
The watery mixture that occupies much of a cell’s volume. In eukaryotic cells, it consists of all materials, including organelles, between the nuclear envelope and the cell membrane
One way to understand cell function is to compare the parts of a cell to the parts of a factory. For example, the Golgi apparatus would be analogous to the factory’s shipping department. How would the other cell parts fit into this analogy?
The nucleus would be the management office where product orders are issued, and the production sites would be the ribosomes and smooth ER. The transport vesicles would be forklifts carrying raw materials and products within the factory, and the mitochondria would be power generators. The cytoskeleton would be girders and steel beams that make up the structure of the building.
Nucleoid
The part of a prokaryotic cell where the DNA is located
Mitochondrion (pl. mitochondria)
Organelle that houses the reactions of cellular respiration in eukaryotes
Ribosome
A structure built of RNA and protein where mRNA anchors during protein synthesis
Nuclear Pore
A hold in the nuclear envelope
Plasmodesma (pl. plasmodesmata)
Connection that allows cytoplasm to flow between adjacent plant cells
Which of the following is NOT a feature found in all cells?
Cell Wall
What chemical property of phospholipids is key to the formation of the cell membrane?
The hydrophilic head and hydrophobic tails
Chloroplast
Organelle housing the reactions of photosynthesis in eukaryotes
Nuclear Envelope
The two membranes bounding a cell’s nucleus
Centrosome
Pat of the cell that organizes microtubules
Tight Junction
Connection between two adjacent animal cells that prevents fluid from flowing past the cells
List three structural differences between plant and animal cells. Explain how each structural difference reflects a functional difference between plants and animals.
Plant cells have chloroplasts; animal cells do not. Chloroplasts are the organelles where photosynthesis occurs. Animals are heterotrophs and do not carry out photosynthesis.
A plant cell also has a central vacuole, a sac that occupies most of the cell’s volume; animal cells do not. Turgor pressure exerted by the vacuole on the cell wall helps a plant stay upright.
A plant cell has a cell wall, which provides rigidity and support. Animal cells lack cell walls and typically rely on skeletal and muscular systems for movement and support.
Golgi Apparatus
A system of flat, stacked, membrane-bounded sacs that packages cell products for export
Organelle
Compartment of a eukaryotic cell that performs a specialized function
Peroxisome
Membrane-bounded sac that houses enzymes that break down fatty acids and dispose of toxic chemicals
Cell Wall
A Rigid boundary surrounding cells of many prokaryotes, protists, plants, and fungi
Crystal (pl. cristae)
Fold of the inner mitochondrial membrane along which many of the reactions of cellular respiration occur
Flagellum (pl. flagella)
A long, whiplike appendage a cell uses for motility
