A Tour of the Cell: Chp 6

Question 1

where are prokaryotic cells found

Answer 1

in the domains Bacteria and Archaea

Question 2

where are eukaryotic cells found

Answer 2

in the domains Eukarya and include animals, fungi, plants, and protists

Question 3

important details regarding prokaryotes

Answer 3

• chromosomes are grouped together in a region called the nucleoid, but there is no nuclear membrane and therefore no tru nucleus
• no membrane-bound organelles are found in the cytosol (ribosomes are found but are not membrane bound)
• prokaryotes are smaller than eukaryotes

Question 4

important details regarding eukaryotic cells

Answer 4

• a membrane enclosed nucleus contains the cell’s chromosomes
• many membrane bound organelles are found in the cytoplasm
• on average, eukaryotes are much larger than prokaryotes

Question 5

plasma membrane

Answer 5

forms the boundary for a cell. It is selectively permeable and permits the passage of materials into and out of the cell
-made up of phospholipids, proteins, and associated carbohydrates

Question 6

how does the surface area to volume ratio change as the cell increases in size

Answer 6

as the cell increases in size the total volume grows proportionately more than the surface area.

Question 7

nucleus characteristics

Answer 7

• contains most of the cell’s DNA
• most noticable organelle in the cell because of its large size
• surrounded by a double membrane nuclear envelope which contains nuclear pores that control what enters and leaves the nucleus

Question 8

chromatin

Answer 8

complex of DNA and protein housed in the nucleus that makes up the chromosomes. as a cell gets ready for cell division, the diffuse threads of chromatin condense into visible chromosomes

Question 9

nucleolus

Answer 9

a region of the nucleus where rRNA complexes with proteins to form ribosomal subunits

Question 10

ribosomes

Answer 10

protein factories. they are composed of rRNA and protein, and are sites of protein synthesis in the cell. Each ribosome consists of a large and small subunit

Question 11

free ribosomes

Answer 11

found floating in the cytosol and generally produce proteins that are used within the cell

Question 12

bound ribosomes

Answer 12

attached to the endoplasmic reticulum, and male proteins destined for expeort from the cell

Question 13

endoplasmic reticulum (ER)

Answer 13

makes up more than half the total membrane structure in many cells. The ER is a network of membranes and sacs whose internal area is called cisternal space. Two types: smooth and rough

Question 14

smooth ER

Answer 14

has three primary functions: synthesis of lipids, metabolism of carbohydrates, and detoxification of drugs and poisons

Question 15

rough ER

Answer 15

associated with ribosomes. As the proteins are produced by the ER-bound ribosomes, the polypeptide chains travel across the ER membrane and into the cisternal space. Within the cisternal space the proteins are packaged into transport vesicles which bud off the ER and move toawrd the GOlgi apparatus

Question 16

golgi apparatus

Answer 16

where proteins from the transport vesicles are modified, stored, and shipped. GA consists of flattened sacs of membranes, called cisternae, arranged in stacks. Golgi stacks have polarity-the cis face receives vesicles, whereas the trans face ships vesicles

Question 17

lysosomes

Answer 17

membrane-bound sacs of hydrolytic enzymes that can digest large molecule, including proteins, polysaccharides, fats, and nucleic acids.

Question 18

vacuoles

Answer 18

membrane bound vesicles
food vacuoles are formed by phagocytosis of protists
contractile vacuoles maintain water balance in paramecia and other protists

Question 19

central vacuoles

Answer 19

in plant cells may concentrate and contain compounds not found in the cytosol

Question 20

mitochondria

Answer 20

sites of cellular respiration, the metabolic process that uses oxygen to generate ATP by extracting energy from sugars, fats, and other fuels

Question 21

structure of mitochondria

Answer 21

• consists of an outer and inner membrane. The inner membrane is highly folded. These cristae (folds) increase the surface area, enhancing productivity of cellular respiration.
• the inner compartment, mitochondrial matrix, is fluid-filled

Question 22

chloroplasts

Answer 22

found in plants and algae, sites of photosynthesis

Question 23

endosymbiont theory

Answer 23

proposes that both mitochondria and chloroplasts shar a similar origin. this theory states that these organelles descended from prokaryotic cells once engulfed by ancestors of eukaryotic cells. evidence is:

• both organelles have a double-membrane structure
• both organelles have their own ribosomes and DNA
• both reproduce independently within the cell

Question 24

peroxisomes

Answer 24

single-membrane bound compartments int he cell responsible for various metabolic functions that involve the transfer of hydrogen from compounds to oxygen, producing hydrogen peroxide. Peroxisomes break down fatty acids to be sent to the mitochondria for fuel and detoxify alcohol by transferring hydrogen from the poison to oxygen

Question 25

cytoskeleton

Answer 25

a network of protein fibers that runs throughout the cytoplasm, where it is responsible for support, motility, and regulating some chemical activities. microtubules, microfilaments, and intermediate filaments make up the cytoskeleton

Question 26

microtubules

Answer 26

made of the protein tubulin. shapes and supports the cell and serves as track along which organelles equipped with motor molecules can move. separates chromosomes during mitosis and meiosis and are the structural components of cilia and flagella

Question 27

microfilaments

Answer 27

composed of the protein actin. much smaller than microtubules,microfilaments function insmaller-scale support. when coupled with the motor molecules myosin, microfilaments can be involved with movement

Question 28

intermediate filaments

Answer 28

slightly larger than microfilaments and smaller than microtubules. intermediate fibers are more permanent fixtures in the cell, where they are important in maintaining the shape of the cell and fixing the position of certain organelles

Question 29

controsomes

Answer 29

region located near the nucleus, fromwith microtubules grow

Question 30

centrioles

Answer 30

located within the centrosomes of animal cells, where they replicate before cell division

Question 31

flagella

Answer 31

long and few in number. many unicellular eukaryotic organisms are propelled through the water by flagella

Question 32

cilia

Answer 32

much shorter and more numerous. cilia can be used in locomotion or can move fluid over the surface of the tissue

Question 33

extracellular matric (ECM)

Answer 33

situated just external to the plasma membrane; it is composed of glycoproteins secreted by the cell. the ECM greatly strengthens tissues and serves as a conduit for transmitting external stimuli into the cell, which can turn genes on and modify biochemical activity

Question 34

tight junctions

Answer 34

secretions of animal cell membrane where two neighboring cells are fused, making the membranes watertight

Question 35

desmosomes

Answer 35

fasten adjacent animal cells together, functioning like rivets to fasten cells into strong sheets

Question 36

gap junctions

Answer 36

proviide channels between adjacent animalcells through which ions, sugarms and other small molecules can pass

Question 37

cell wall

Answer 37

of a plant protects the plant and helps maintain its shape. the primary component of cell walls is the carbohydrate cellulose

Question 38

plasmodesmata

Answer 38

channels that perforate adjacent plant cell walls and allow the passage of some molecules from cell to cell