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Transcript
Chapter 6 A Tour of the Cell Student Guided Notes Overview: The Fundamental Units of Life The cell is the simplest collection of matter that can be alive. Cells are an organism’s basic units of ___________________________. Evolution is the unifying biological theme. Concept 6.1 Biologists use microscopes and the tools of biochemistry to study cells In a light microscope (LM), ___________________________________________________________ __________________________________________________________________________________. ○ Magnification is __________________________________________________________________. ○ Resolution is a measure of image clarity, _______________________________________________ ________________________________________________________________________________. An electron microscope (EM) _________________________________________________________ ___________________________________________________________________________________. Scanning electron microscopes (SEMs) are useful for studying _______________________________ ___________________________________________________________________________________. Transmission electron microscopes (TEMs) are used to study ________________________________ ___________________________________________________________________________________ Although EMs reveal organelles that are impossible to resolve with LMs, the methods used to prepare cells for viewing under an EM kills them. Cytology combined with biochemistry, ___________________________________________________ ___________________________________________________________produced modern cell biology. Cell biologists can isolate organelles to study their functions. Cell structure and function can by studied by cell fractionation, a technique _________________ ______________________________________________________________________________. ○ A centrifuge spins test tubes holding mixtures of disrupted cells. 6-1 ○ The resulting forces cause a fraction of the cell components to settle to the bottom of the tube, forming a pellet. Concept 6.2 Eukaryotic cells have internal membranes that compartmentalize their functions Prokaryotic and eukaryotic cells differ in size and complexity. All cells are surrounded by a ______________________________. The semifluid substance within the membrane is the cytosol. All cells contain chromosomes and all cells have ribosomes. ○ In a eukaryotic cell, most of the DNA is in the _______________________________________. ○ In a prokaryotic cell, the DNA is concentrated in the __________________________________. The interior of a prokaryotic cell and the region between the _________________________ and the _____________________________________ of a eukaryotic cell is the cytoplasm. The logistics of carrying out cellular metabolism set limits on cell size. The plasma membrane functions as a __________________________________________________ __________________________________________________________________________________ __________________________________________________________________________________. As a cell increases in size, its volume increases faster than its_________________________________. Internal membranes compartmentalize the functions of a eukaryotic cell. A eukaryotic cell has extensive and elaborate internal membranes, which partition the cell. ○ These membranes also participate directly in metabolism. Each type of membrane has a unique combination of lipids and proteins for its specific functions. Concept 6.3 The eukaryotic cell’s genetic instructions are housed in the nucleus and carried out by the ribosomes The nucleus contains ______________________________________________________________. The nucleus is separated from the cytoplasm by a double membrane called the ____________________ ______________________________ . ○ The envelope is perforated by pores. 6-2 The nuclear side of the envelope is lined by the nuclear lamina, _____________________________ __________________________________________________________________________________. The DNA and associated proteins are organized into _______________________________________. ○ Each chromosome contains _________________________________________________________ _______________________________________________________________________________. Each eukaryotic species has a characteristic number of chromosomes. ○ A typical human cell has ________ chromosomes. In the nucleus is ____________________________________________________________________. In the nucleolus, ribosomal RNA (rRNA) is synthesized and assembled with proteins to form ribosomal subunits. The nucleus directs protein synthesis by _________________________________________________. Ribosomes are protein factories. Ribosomes, containing rRNA and protein carry out ________________________________________. Free ribosomes _____________________________________________________________________. Bound ribosomes are attached to the ___________________________________ or __________________________________. ○ Bound ribosomes synthesize proteins that are ___________________________________________ _______________________________________________________________________________. Concept 6.4 The endomembrane system regulates protein traffic and performs metabolic functions in the cell Many of the internal membranes are part of the endomembrane system, which includes ___________ ____________________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________ The tasks include _____________________________________________________________________ ___________________________________________________________________________________ __________________________________________________________________________________. These membranes are either directly continuous or connected via ______________________________. 6-3 The endoplasmic reticulum manufactures membranes and performs many other biosynthetic functions. The endoplasmic reticulum (ER) includes a network of membranous tubules and sacs called _____________________________________ that separate the __________________________ ___________________________________. There are two regions of ER. ○ Smooth ER looks smooth because ____________________________________________________. ○ Rough ER looks rough because ______________________________________________________. Smooth ER is rich in enzymes and plays a role in a variety of metabolic processes, including ____________________________________________________________________________________ ___________________________________________________________________________________. In the smooth ER of the liver, enzymes help _______________________________________________ ___________________________________________________________________________________. Rough ER is especially abundant in cells that ______________________________________________. Most secretory polypeptides are glycoproteins. Secretory proteins are packaged in ____________________________________________. Rough ER is also a ____________________________________ factory for the cell. The Golgi apparatus is the shipping and receiving center for cell products. Many transport vesicles from the ER travel to the Golgi apparatus for modification of their contents. The Golgi apparatus is a center of ______________________________________________________ _________________________________________________________________________________. The Golgi apparatus consists of flattened membranous sacs—cisternae—that look like a stack of pita bread. One side of the Golgi apparatus, the cis face, ___________________________________________. Golgi products that will be secreted depart from the _______________________________________. ○ Transport vesicles from the Golgi may have external molecules that recognize “docking sites” on the surface of specific organelles or on the plasma membrane. 6-4 Lysosomes are digestive compartments. A lysosome is ______________________________________________________________________ __________________________________________________________________. ○ Some lysosomes arise by __________________________________________________________ _______________________________________________________________________________. Lysosomes carry out intracellular digestion in a variety of circumstances. ○ Amoebas eat by _________________________________________________________________. ○ Human macrophages help defend the body by ___________________________________________ __________________________________________________________. Lysosomes can play a role in _________________________________________________________ ______________________________________________. This recycling, or ___________________________________, renews the cell. In people who have Tay-Sachs disease, a _________________________________________________ is missing or inactive, and the brain becomes impaired by ____________________________________ __________________________________________________________________________________. Vacuoles have diverse functions in cell maintenance. Food vacuoles are formed by ____________________________________________ and fuse with _______________________________. Contractile vacuoles, found in freshwater protists, __________________________________________. In plants and fungi, vacuoles carry out enzymatic hydrolysis, like animal lysosomes do. A large central vacuole is found in ______________________________________________________. ○ The vacuolar membrane is selective in its transport of solutes into the central vacuole. The functions of the central vacuole include ________________________________________________ ____________________________________________________________________________________ ___________________________________________________________________________________. Concept 6.5 Mitochondria and chloroplasts change energy from one form to another Mitochondria are the sites of __________________________________________________________ ___________________________________________________________________________________. 6-5 Chloroplasts, found in plants and algae, are the sites of _____________________________________ ___________________________________________________________________________________. Mitochondria and chloroplasts have a similar evolutionary origin. The endosymbiont theory states that ____________________________________________________ ___________________________________________________________________________________ There is considerable evidence to support the endosymbiont theory for the origin of mitochondria and chloroplasts. ○ Each mitochondrion or chloroplast has two membranes. ○ Mitochondria and chloroplasts contain ribosomes and __________________________________. ○ Mitochondria and chloroplasts grow and reproduce as ____________________________________. Mitochondria convert chemical energy within eukaryotic cells. Almost all eukaryotic cells have mitochondria. ○ The number of mitochondria is correlated with __________________________________________. ○ Mitochondria have a smooth outer membrane and a convoluted inner membrane with infoldings called ___________________________. ○ The inner membrane encloses the _____________________________________________________ __________________________________________________________________. Chloroplasts capture light energy and convert it to chemical energy. Chloroplasts contain the green pigment ___________________________________. Inside the innermost membrane is a fluid-filled space, the stroma, in which float __________________ ___________________________________________________________________________________. ○ In some regions, thylakoids are stacked like ____________________________________________. The chloroplast belongs to a family of plant structures called plastids. ○ Amyloplasts are __________________________________________________________________. ○ Chromoplasts ____________________________________________________________________. The peroxisome is an oxidative organelle. Peroxisomes contain enzymes that transfer ________________________________________________ _______________________________, producing __________________________________________ as a byproduct. 6-6 Some peroxisomes use oxygen to ________________________________________________________. The H2O2 formed is toxic, but peroxisomes contain _________________________________________ ___________________________________________________________________________________. Concept 6.6 The cytoskeleton is a network of fibers that organizes structures and activities in the cell The cytoskeleton provides support, motility, and regulation. The cytoskeleton is _________________________________________________________________ _________________________________________________________________________________ ________________________________________________________________________________. The cytoskeleton provides anchorage for many organelles and enzymes. The cytoskeleton also plays a major role in cell motility. ○ ________________________________ bring about movements of cilia and flagella. Three main types of fibers make up the cytoskeleton: ________________________________________, ____________________________________, and ____________________________________________. Microtubules are the thickest of the three types of fibers; microfilaments (or ___________________ filaments) are the thinnest; and intermediate filaments are fibers with diameters in a middle range. Microtubules are ___________________________________________________________________. Microtubules shape and support the cell and serve as tracks to guide motor proteins. In many animal cells, microtubules grow out from a _________________________near the nucleus. Within the centrosome is a pair of centrioles, each with ____________________________________ _________________________________________________________________________________. Although centrosomes with centrioles may help organize microtubule assembly in animal cells, they are not essential for this function. A specialized arrangement of microtubules is responsible for the beating of _____________________ and ____________________________________. ○ The sperm of ____________________________, _____________________________ , and some _______________________have flagella. ○ Cilia lining the trachea _____________________________________________________________ ________________________________________________________________________________. 6-7 Cilia usually occur in large numbers on the cell surface and there are usually just one or a few flagella per cell. The cilium or flagellum is anchored in the cell by a ________________________________________, __________________________________________________________________________________. Each outer doublet also has pairs of ___________________________________________________ that are responsible for the bending movements. Microfilaments or ________________________________ are _______________________________. The structural role of microfilaments in the cytoskeleton is to ________________________________. Microfilaments are important in cell motility, especially in ______________________________ cells. ○ In muscle cells, thousands of actin filaments are arranged parallel to one another; actin and myosin work together for muscle contraction. In plant cells, actin-myosin interactions drive cytoplasmic streaming, which creates_______________ __________________________________________________________________________________. Intermediate filaments are larger than microfilaments but smaller than microtubules, built from __________________________________________________________________________________ __________________________________________________________________________________. __________________________________________ are more permanent fixtures of the cytoskeleton. Concept 6.7 Extracellular components and connections between cells help coordinate cellular activities Plant cells are encased by cell walls. In plants, the cell wall ________________________________________________________________ ___________________________________________________________________________________ ___________________________________________________________________________________. The basic design of cell walls consists of ______________________________. A young plant cell secretes a relatively thin and flexible wall called the __________________________. Between the primary walls of adjacent cells is a middle lamella, a thin layer with sticky polysaccharides called __________________________________ that _______________________________________. 6-8 When a plant cell stops growing, it ____________________________________________________or by adding a secondary cell wall. ○ __________________________ consists mainly of secondary walls. The extracellular matrix of animal cells provides support, adhesion, movement, and regulation. Though lacking cell walls, animal cells do have an elaborate extracellular matrix (ECM). The primary constituents of the ECM are _______________________________________________ _________________________________________________________________________________ In many cells, fibronectins in the ECM connect to ________________________________, ________ ___________________________________________________________________________________ ___________________________________________________________________________________. The ECM can regulate cell behavior. ○ The ECM can influence the activity of genes. Intercellular junctions help integrate cells into higher levels of structure and function. Plant cells are perforated with plasmodesmata, ____________________________________________ ___________________________________________________________________________________. Animals have three main types of intercellular links. In tight junctions, _____________________________________________________________ _____________________________________________________________________________. Desmosomes (or anchoring junctions) ______________________________________________. Gap junctions (or communicating junctions)_________________________________________ _____________________________________________________________________________. 6-9