Cell Biology Chapter 4 Flashcards
Three Domains
Bacteria, Archaea, Eukaryotes
Details of Prokaryotes
can be divided into the widely divergent bacteria and archaea
Ancestors, Genetic Information, and DNA Archaea
considered to have descended from a common ancestor that also gave rise to eukaryotes long after diverging from bacteria; Genetic information of a archaeal cell is in the nucleoid ; Archaeal DNA is circular and complexed with proteins similar to eukaryotic histone proteins
Structure and how is DNA organized Eukaryotes
Has a true, membrane-bounded nucleus; Eukaryotic DNA is organized into linear molecules complexed with large amounts of a protein called histones
Bacteria DNA, Genetic Information, and Organelles
Bacterial DNA has chromosomes associated with a few proteins; The genetic information of a bacterial cell is in the nucleoid; does not have membrane bounded organelles but still compartmentalize activities often through large molecular complexes that are found at specific location within the cell.
What is the Cytoplasm and its structure in eukarya
The internal volume of the cell except the nucleus; in eukarya, the cytoplasm is occupied by organelles, cytoskeletal fibers and the semifluid cytosol in which they are suspended
What is the semifluid
is not a thin, watery liquid; it is a viscous material with a consistency closer to that of honey or soft gelatin
What do cells need to maintain for various processes?
What must happen for chemical reactions to occur?
Cells need to maintain adequate concentrations of the essential compounds and enzymes needed for the various processes; For a chemical reaction to occur in a cell, the appropriate reactants must collide with and bind to a particular enzyme
Collisions in a cell
the frequency of such collisions will be greatly increased by higher concentration of the reactants and the enzyme being in close proximity; if all the enzymes and compounds necessary for a particular process are localized within a specific region, high concentrations of those substances are needed only in that region rather than throughout the whole cell
What are organelles and their function?
membrane bounded compartments that are specialized for specific functions
What are organelles surrounded by and how does it carry out cellular functions
Each organelles is surrounded by its own characteristic membrane that can have a distinctive chemical composition; localized within each organelle is the molecular machinery needed to carry out the particular cellular functions;
Eukaryotic cell structure includes…
Plasma membrane
nucleus
membrane-bounded organelles
cytosol interlaced by a cytoskeleton
*actin (microfilaments), Microtubules, Intermediate filaments, and Septins
Plant and fungal cells have rigid cell wall
Animal cells don’t have cell wall; surrounded by an extracellular matrix consisting primarily of proteins that provide structural support
What does the plasma membrane look like and what does it do?
is organized in two layers; Surrounds every cell; ensures that the cell contents are retained; consist of lipids including phospholipids and membrane proteins
Plasma Membrane Two layers
Each phospholipid molecule consists of two hydrophobic “tails” and a hydrophillic “head” and is therefore an amphipathic molecule
What is the Lipid Bilayer
Formed when the hydrophillic heads face outward and the tails face inward
Membrane proteins are what and what is attached to them?
amphipathic; have polysaccharides attached to them called glycoproteins;
Enzymes function in plasma membrane and anchors functions?
Enzymes catalyze reactions associated with the membranes such as cell wall synthesis; others serve as anchors for structural components of the cytoskeleton
Transport proteins function and what do they act like?
Move substances across the membrane; proteins that act as receptors for external signals trigger processes within the cell
What are the Transmembrane Proteins names?
Transport proteins
Receptors
What does the nucleus contain and what is it surrounded by?
Contains the DNA and is surrounded by the nuclear envelope composed of inner and outer membranes;
Nuclear Envelope structure and function
Has numerous openings called pores, each of which is a transport channel lined with a nuclear pore complex
When are chromosomes easily visualized?
Most easily visualized during mitosis whereas during interphase they are dispersed as chromatin (DNA+protein) and difficult to visualize
What is the nucleolus responsible for and what is the nucleoli associated with?
Responsible for synthesizing ribosomal RNA and beginning the assembly of the protein components needed to form ribosomes; Nucleoli are associated with specific regions of particular chromosomes that contain the genes encoding ribosomal RNAs
What is the mitochondria involved in, assist with, the site of, and its size? What do most eukaryotic cells contain?
involved in energy production for cells; assist in the degradation of sugars; in all eukaryotic cells are the site of aerobic respiration; comparable in size to bacteria; Most eukaryotic cells contain hundreds of mitochondria each surrounded by an inner and outer mitochondrial membrane;
Inner mitochondrial membrane enclose and what fills the mitochondria? What does the matrix include?
Encloses the matrix, a semifluid material filling the mitochondria; the matrix includes small circular DNA molecules that encode some RNAs and proteins needed in the mitochondria
What does the mitochondria contain and where is it found? What needs mitochondria the most?
Contains ribosomes involved in protein synthesis; contains enzymes and intermediates needed for oxidation of sugars and generation of adenosine triphosphate (ATP); many of these found on cristae, infoldings of the mitochondrial membrane; Cells with high energy needs have many mitochondria in the region where the energy is needed the most example: muscle cells
What is chloroplasts involved in and what does it do? Where is it found, what is its size and what is its structure?
involved in energy production for cells; harvest solar energy and converts it to chemical energy in the form of ATP; is the site of photosynthesis in plants and algae; are large and can be quite numerous in the cells of green plants; surrounded by both inner and outer membranes
Thylakoids structure
third membrane system of flattened membranous sacs interconnected by stroma thylakoids stacked into the grana
What is photosynthesis and what is found in photosynthetic cells and what does it contain?
a process that uses solar energy and CO2 to produce sugars and other organic compounds; chloroplast are found in photosynthetic cells and contain most of the enzymes needed for photosynthesis
Stroma of chloroplasts contain and what is its structure?
Contain their own ribosomes and a small circular DNA molecule that encodes some RNAs and proteins needed in the chloroplast
Mitochondria and Chloroplast similarities to bacteria
semiautonomous organelles; can divide on their own; DNA, mRNA, tRNA, and ribosomes; both resemble bacteria in size and shape and surrounded by double membranes, the inner of which has bacterial-type lipids; all have DNA molecules without associated histones
Mitochondria, Chloroplasts, and Bacteria Similarities
rRNA sequences; ribosomes size; sensitivities to inhibitors of RNA and protein synthesis; protein factors used in protein synthesis are all similar
What is the Endosymbiont Theory
suggest that mitochondria and chloroplasts originated from ancient bacteria
What does the Endomembrane system synthesize , where is it destined, and what is it responsible for?
Synthesizes proteins destined for various organelles, cellular membranes, or secretion; responsible for trafficking substances through the cell
Endomembrane System Structures
ER, Golgi, Secretory vesicles, and Lysosomes
Proteins route in the Endomembrane System
Synthesized in the ER; Processed and packaged in the Golgi apparatus; directed to various destinations in and out of the cell in small membrane-bound vesicles
What does lysosomes do?
Involved in degradation of food ingested by phagocytosis and in recycling cellular components
Where is the Endoplasmic Reticulum found and what is its structure?
in almost every eukaryotic cell, there is a network of membranes in the cytoplasm called the ER; Cisternae; Lumen
Cristae structure
Tubular membranes and flattened sacs
Lumen structure
Internal space of the ER
Rough ER Function and Structure
studded with ribosomes on the cytoplasmic side of the membrane; these ribosomes synthesize polypeptide that accumulate within the membrane or are transported across it to the ER lumen; Free ribosomes are not associated with the ER;
Protein Synthesis in the RER and where does it also occur, what are the proteins made of and what are the protein intended use?
Protein synthesized from the RER travel to the appropriate membrane or to the cell surface via the golgi apparatus and secretory vesicles; also occurs on ribosomes not attached to the ER and are free in the cytosol; Secretory and membrane proteins are made by ribosomes in the RER; proteins intended for use within the cytosol or for import into organelles are made on free ribosomes
Smooth ER Function and what is it responsible for?
has no role in protein synthesis; involved in the synthesis of lipids and steroids such as cholesterol and its derivatives; SER is responsible for inactivating and detoxifying potentially harmful substances
Golgi apparatus structure and important role, synthesis, what does it accept, what contents from the vesicles, where do some process begin, what do processed substances move to?
Cisternae; plays an important role in processing and packaging secretory proteins; synthesis of complex polysaccharides; accepts transition vesicles that bud off from the ER; contents of the vesicles from the ER are modified and processed in the Golgi complex; Some process begin in ER and completed in Golgi complex; processed substances then move to other locations in the cell through vesicles that bud off the Golgi complex
Cisternae structure
Stack of flattened vesicles
What happens once substances are processed by the Golgi Complex?
their Materials are exported from the cell are packaged into secretory vesicles; these move to the plasma membrane and fuse with it, releasing their contents outside the cell (exocytosis)
What are Lysosomes?
Are Single-membrane organelles that store hydrolases, enzymes that can digest biological molecules
What happens to lysosomes enzymes?
Synthesized on the RER, transported to the Golgi apparatus, Packaged into vesicles that can become lysosomes
Why are hydrolases sequestered?
To prevent them from digesting the contents of the cell
What is the inner face of the lysosome membrane?
Highly glycosylated, forming a special carbohydrate covering that protects this membrane and the cell; the lysosome can break down virtually any kind of biological molecule
What do peroxisomes resemble and in what and what are they surrounded by and what can they do? Where are they prominent?
Resemble lysosomes in size and appearance; surrounded by a single membrane and perform several functions depending on cell type; Highly prominent in the liver and kidney cells of animals
What is H2O2 to cells and where can they be formed? What also produces H2O2? Where are the reactions confined to and why?
Highly toxic to cells but can be formed into water and oxygen by the enzyme catalase; Eukaryotic cells have metabolic processes that produce H2O2; Reactions are confined to peroxisomes that contain catalase so that cells are protected from the harmful effects of peroxide
What do Peroxisomes detoxify and catabolize and what role do the play in animals?
Detoxify other harmful compounds and catabolize unusual substances; They play roles in the oxidative breakdown of fatty acids, especially longer chain fatty acids (22 carbon atoms) that the mitochondria are too slow to do
What are vacuoles? What are their roles in animal and yeast cells? What happens when it fuses with a lysosome?
membrane bounded; in animal and yeast cells vacuoles are used for temporary storage or transport; when it fuses with a lysosomes the contents are hydrolyzed to provide nutrients to a cell
What does phagocytosis lead to ?
The formation of a membrane bounded particle called a phagosome
Most plant cells contain what? The main function of it and what causes tissues to wilt?
Single large vacuole called a central vacuole; main function is to maintain the turgor pressure that keeps the plant from wilting; tissues wilt when the central vacuole no longer presses against the cell contents(fails to provide adequate pressure)
Ribosomes are the site of what? Can be seen under which microscope? Where are they found? Each has its own type of what?
Are a site of protein synthesis and are far more numerous than most other intracellular structures; can be seen only under the light microscope; found in all cells but differ slightly in bacteria, archaea, and eukaryotes in their size and composition; has its own unique rRNA
Ribosomes are more numerous that what? Ribosomes in where are similar and an example?
Much more numerous than most other cellular structures; In mitochondria and chloroplast similar in size and composition to those of bacteria; particularly true of the nucleotide sequences of their rRNA
What is the cytoskeleton, what does it give cells, what does it play a role in?
The cytoplasm of eukaryotic cells contains an intricate, organized 3-D array of interconnect proteinaceous structure; gives a cell its distinctive shape and internal organization; plays a role in cell movement and cell division
Proteins related to eukaryotic cytoskeleton have recently been discovered where and play what role? What does the cytoskeleton serve as within the cell?
Recently discovered in bacteria and archaea and appear to play a role in maintaining cell shape; Serves as a framework for positioning and moving organelles and macromolecules within the cell
4 Structural Elements of the Cytoskeleton
Microtubules, Microfilaments, Intermediate filaments, and Septins found in animal and fungi not plants
What are most cells characterized by? What are they called in animal cells and what do they consist of ? What are they called in other cells?
Characterized by extracellular structures that give physical support to cells; animal cells are called extracellular matrix and consist mainly of collagen fibrils and proteoglycans; bacteria, archaea, plant, and fungal cells call them cell walls
What does the processes regulated by the ECM include and in animal and plant cells?
Cell motility and migration; Cell division; Cell recognition and adhesion; Cell differentiation during embryonic development; in animal cells, ECM contains several types of junctions connecting neighboring cells; plant cells use plasmodesmata, a space between cell walls of plant cells for communication and exchange
What do several types of agents do to cells and what do they include?
Invade cells, disrupt cell function, kill host cell; they include viruses, and the less understood viroids and prions
What are viruses, what do they not have and what do they do have? What do they do and are responsible for?
Are acellular parasitic particles incapable of a free-living existence; have no cytoplasm, organelles, or ribosomes consist of a few different molecules of nucleic acid and proteins; the invade and infect cells using the host’s synthetic machinery to produce more virus particles; Responsible for many diseases in humans, animals, and plants
They are significant research tools for who and how are they named? What do they call viruses that infect bacteria?
For cell and molecular biologist; typically named after the disease they cause; called bacteriophages, or phages
Living things have the fundamental properties of? Why viruses are not living?
Metabolism (cellular reactions in pathways)
Irritability (perception of and response to external stimuli)
Ability to reproduce; viruses doesn’t satisfy the first two and they only reproduce via the machinery of a living cell
What are viroids, where are they found, and how do the exist and transmit?
Viroids are small circular RNA molecules and are the smallest known infectious agents; Found in some plant cells, simpler than viruses; don’t exist freely and are transmitted when the surfaces of adjacent plant cells are damaged
What are prions and how are they folded? Can it be destroyed?
Prions are proteinaceous ineffective proteins that are responsible for neurological diseases such as scrapie, kuru, and mad cow disease; are abnormally folded versions of normal cellular proteins; Prion can’t be destroyed by cooking or boiling.
