Cell Biology Chapter 4

Question 1

Three Domains

Answer 1

Bacteria, Archaea, Eukaryotes

Question 2

Details of Prokaryotes

Answer 2

can be divided into the widely divergent bacteria and archaea

Question 3

Ancestors, Genetic Information, and DNA Archaea

Answer 3

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

Question 4

Structure and how is DNA organized Eukaryotes

Answer 4

Has a true, membrane-bounded nucleus; Eukaryotic DNA is organized into linear molecules complexed with large amounts of a protein called histones

Question 5

Bacteria DNA, Genetic Information, and Organelles

Answer 5

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.

Question 6

What is the Cytoplasm and its structure in eukarya

Answer 6

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

Question 7

What is the semifluid

Answer 7

is not a thin, watery liquid; it is a viscous material with a consistency closer to that of honey or soft gelatin

Question 8

What do cells need to maintain for various processes?

What must happen for chemical reactions to occur?

Answer 8

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

Question 9

Collisions in a cell

Answer 9

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

Question 10

What are organelles and their function?

Answer 10

membrane bounded compartments that are specialized for specific functions

Question 11

What are organelles surrounded by and how does it carry out cellular functions

Answer 11

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;

Question 12

Eukaryotic cell structure includes…

Answer 12

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

Question 13

What does the plasma membrane look like and what does it do?

Answer 13

is organized in two layers; Surrounds every cell; ensures that the cell contents are retained; consist of lipids including phospholipids and membrane proteins

Question 14

Plasma Membrane Two layers

Answer 14

Each phospholipid molecule consists of two hydrophobic “tails” and a hydrophillic “head” and is therefore an amphipathic molecule

Question 15

What is the Lipid Bilayer

Answer 15

Formed when the hydrophillic heads face outward and the tails face inward

Question 16

Membrane proteins are what and what is attached to them?

Answer 16

amphipathic; have polysaccharides attached to them called glycoproteins;

Question 17

Enzymes function in plasma membrane and anchors functions?

Answer 17

Enzymes catalyze reactions associated with the membranes such as cell wall synthesis; others serve as anchors for structural components of the cytoskeleton

Question 18

Transport proteins function and what do they act like?

Answer 18

Move substances across the membrane; proteins that act as receptors for external signals trigger processes within the cell

Question 19

What are the Transmembrane Proteins names?

Answer 19

Transport proteins

Receptors

Question 20

What does the nucleus contain and what is it surrounded by?

Answer 20

Contains the DNA and is surrounded by the nuclear envelope composed of inner and outer membranes;

Question 21

Nuclear Envelope structure and function

Answer 21

Has numerous openings called pores, each of which is a transport channel lined with a nuclear pore complex

Question 22

When are chromosomes easily visualized?

Answer 22

Most easily visualized during mitosis whereas during interphase they are dispersed as chromatin (DNA+protein) and difficult to visualize

Question 23

What is the nucleolus responsible for and what is the nucleoli associated with?

Answer 23

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

Question 24

What is the mitochondria involved in, assist with, the site of, and its size? What do most eukaryotic cells contain?

Answer 24

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;

Question 25

Inner mitochondrial membrane enclose and what fills the mitochondria? What does the matrix include?

Answer 25

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

Question 26

What does the mitochondria contain and where is it found? What needs mitochondria the most?

Answer 26

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

Question 27

What is chloroplasts involved in and what does it do? Where is it found, what is its size and what is its structure?

Answer 27

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

Question 28

Thylakoids structure

Answer 28

third membrane system of flattened membranous sacs interconnected by stroma thylakoids stacked into the grana

Question 29

What is photosynthesis and what is found in photosynthetic cells and what does it contain?

Answer 29

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

Question 30

Stroma of chloroplasts contain and what is its structure?

Answer 30

Contain their own ribosomes and a small circular DNA molecule that encodes some RNAs and proteins needed in the chloroplast

Question 31

Mitochondria and Chloroplast similarities to bacteria

Answer 31

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

Question 32

Mitochondria, Chloroplasts, and Bacteria Similarities

Answer 32

rRNA sequences; ribosomes size; sensitivities to inhibitors of RNA and protein synthesis; protein factors used in protein synthesis are all similar

Question 33

What is the Endosymbiont Theory

Answer 33

suggest that mitochondria and chloroplasts originated from ancient bacteria

Question 34

What does the Endomembrane system synthesize , where is it destined, and what is it responsible for?

Answer 34

Synthesizes proteins destined for various organelles, cellular membranes, or secretion; responsible for trafficking substances through the cell

Question 35

Endomembrane System Structures

Answer 35

ER, Golgi, Secretory vesicles, and Lysosomes

Question 36

Proteins route in the Endomembrane System

Answer 36

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

Question 37

What does lysosomes do?

Answer 37

Involved in degradation of food ingested by phagocytosis and in recycling cellular components

Question 38

Where is the Endoplasmic Reticulum found and what is its structure?

Answer 38

in almost every eukaryotic cell, there is a network of membranes in the cytoplasm called the ER; Cisternae; Lumen

Question 39

Cristae structure

Answer 39

Tubular membranes and flattened sacs

Question 40

Lumen structure

Answer 40

Internal space of the ER

Question 41

Rough ER Function and Structure

Answer 41

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;

Question 42

Protein Synthesis in the RER and where does it also occur, what are the proteins made of and what are the protein intended use?

Answer 42

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

Question 43

Smooth ER Function and what is it responsible for?

Answer 43

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

Question 44

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?

Answer 44

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

Question 45

Cisternae structure

Answer 45

Stack of flattened vesicles

Question 46

What happens once substances are processed by the Golgi Complex?

Answer 46

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)

Question 47

What are Lysosomes?

Answer 47

Are Single-membrane organelles that store hydrolases, enzymes that can digest biological molecules

Question 48

What happens to lysosomes enzymes?

Answer 48

Synthesized on the RER, transported to the Golgi apparatus, Packaged into vesicles that can become lysosomes

Question 49

Why are hydrolases sequestered?

Answer 49

To prevent them from digesting the contents of the cell

Question 50

What is the inner face of the lysosome membrane?

Answer 50

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

Question 51

What do peroxisomes resemble and in what and what are they surrounded by and what can they do? Where are they prominent?

Answer 51

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

Question 52

What is H2O2 to cells and where can they be formed? What also produces H2O2? Where are the reactions confined to and why?

Answer 52

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

Question 53

What do Peroxisomes detoxify and catabolize and what role do the play in animals?

Answer 53

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

Question 54

What are vacuoles? What are their roles in animal and yeast cells? What happens when it fuses with a lysosome?

Answer 54

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

Question 55

What does phagocytosis lead to ?

Answer 55

The formation of a membrane bounded particle called a phagosome

Question 56

Most plant cells contain what? The main function of it and what causes tissues to wilt?

Answer 56

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)

Question 57

Ribosomes are the site of what? Can be seen under which microscope? Where are they found? Each has its own type of what?

Answer 57

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

Question 58

Ribosomes are more numerous that what? Ribosomes in where are similar and an example?

Answer 58

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

Question 59

What is the cytoskeleton, what does it give cells, what does it play a role in?

Answer 59

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

Question 60

Proteins related to eukaryotic cytoskeleton have recently been discovered where and play what role? What does the cytoskeleton serve as within the cell?

Answer 60

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

Question 61

4 Structural Elements of the Cytoskeleton

Answer 61

Microtubules, Microfilaments, Intermediate filaments, and Septins found in animal and fungi not plants

Question 62

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?

Answer 62

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

Question 63

What does the processes regulated by the ECM include and in animal and plant cells?

Answer 63

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

Question 64

What do several types of agents do to cells and what do they include?

Answer 64

Invade cells, disrupt cell function, kill host cell; they include viruses, and the less understood viroids and prions

Question 65

What are viruses, what do they not have and what do they do have? What do they do and are responsible for?

Answer 65

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

Question 66

They are significant research tools for who and how are they named? What do they call viruses that infect bacteria?

Answer 66

For cell and molecular biologist; typically named after the disease they cause; called bacteriophages, or phages

Question 67

Living things have the fundamental properties of? Why viruses are not living?

Answer 67

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

Question 68

What are viroids, where are they found, and how do the exist and transmit?

Answer 68

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

Question 69

What are prions and how are they folded? Can it be destroyed?

Answer 69

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.