ch.3

Question 1

what are the 3 major parts of the cell?

Answer 1

-nucleus
-cytoplasm
-cell membrane

Question 2

define nuclear envelope

Answer 2

a thin membrane that encloses the nucleus

Question 3

true or false. the cells membrane is the site of many important rxns and it allows molecules to communicate with each other

Answer 3

true

Question 4

list the general characteristics of the cell membrane

Answer 4

-extremely thin and only visible with election microscope
-flexible and somewhat elastic
-there is outpouching and infloding to increase surface area
-it will quickly seal tiny breaks but if it’s extremely damaged the cell will die
-a conduit between cell and extracellular fluid
-cell receives and responds to incoming messages (signal translation)

Question 5

the basic framework of the cell membrane is a ___ ___. describe the composition of it

Answer 5

-phospholipid bilayer
-hydrophilic heads made from phosphate group and hydrophobic tails made from fatty acid

Question 6

the bilayer is permeable to … the bilayer is impermeable to ….

Answer 6

-molecules soluble in lipids
-water soluble molecules

Question 7

the relatively rigid structure of ___ molecules help stabilize the cell membrane

Answer 7

cholesterol

Question 8

based on position a membrane protein may be ___ or ___. describe these terms

Answer 8

-intergral: extends into lipid bilayer and may produce from one or both sides (if it extends through it is transmebrane)
-peripheal: associate with one side of the bilayer

Question 9

certain compact and globular integral provides …

Answer 9

routes for small molecules and ions to cross otherwise impermeable membrane

Question 10

what do peripheral proteins do? what happens when carbohydrates attach to these proteins?

Answer 10

-receptors to extracellular signals, enzymes, parts of signal transduction pathways, enable certain cells to touch or bond, identify cells
-forms glycoprotein that allow cells to recognize and interact (identify cells as “self” and “nonself”

Question 11

what is the function of cellular adhesion molecules (CAM)? what do selectin and integrin do?

Answer 11

-guide cells on the move (help identify place of injury)
-selectin: slow down the turbulence of blood stream
-integrin: contracts an adhesion receptor protruding into capillary space

Question 12

what are the critical functions of CAM?

Answer 12

-guide cells surrounding an embryo to grow toward maternal cells; forming placenta
-sequences of CAM help establish connections between nerve cells that underline learning and memory

Question 13

define inclusions

Answer 13

chemicals in the cytoplasm temporarily ( nutrients and pigments)

Question 14

define cytoskeleton

Answer 14

abundant protein rods and tubules that form a supportive framework in the cytoplasm

Question 15

describe ribosomes

Answer 15

-composed of protein and RNA
-provide structural support and enzymatic activity to link amino acids to synthesize proteins

Question 16

describe the endoplasmic reticulum (ER)

Answer 16

-composed of membranous flattened sac, clyinder, and vesicles
-provides tubualr transport system
-participates in the synthesis of protein and lipid molecules

Question 17

describe the rough endoplasmic reticulum (rough ER)

Answer 17

-studded with ribsomes
-protein synthesis occurs here

Question 18

describe the smooth endoplasmic reticulum (smooth ER)

Answer 18

-lacks ribosomes
-important in synthesizing lipids, absorbing fats, breakdown of drugs
-lipids are synthesized in smooth ER and added to proteins from rough ER
-abundant in liver cells

Question 19

describe golgi apparatus

Answer 19

-contains membranous sacs (cisternae)
-refines, packages, and delivers proteins synthesized in rough ER

Question 20

describe mitochondria

Answer 20

-move slowly in cytoplasm and can divide
-inner layer has folds forming cristea that increase surface area
-important in cellular respiration
-captures and transfers newly released energy into AT{
-powerhouse of the cell

Question 21

describe lysosomes

Answer 21

-garbage disposals of the cell
-they bud off of sections of the golgi membrane
-break down organic molecules

Question 22

describe peroxisomes

Answer 22

-membranous sacs that resemble lysomomes in size and shape
-catalyze metabolic rxns that release H2O2
-synthesis of bile acids in fat digestion, breakdown of lipids, detoxification of alcohol,

Question 23

describe centrosome

Answer 23

-nonmebranous structure composed of 2 rod like centroiles
-helps distribute chromsomes to new cells during division

Question 24

describe cilia

Answer 24

-motile projections attachted to basal bodies beneath the cell membrane

Question 25

describe microfilaments and microtubules

Answer 25

-thin rods and tubules -support cytoplasm, help move substances

Question 26

describe flagellum

Answer 26

-projection attachted to basal body beneath cell membrane -enables sperm to move

Question 27

describe the nuclear envelope

Answer 27

-selectively permeable double membrane that separates the nuclear contents from the cytoplasm -maintains the integrity of the nucleus, controls the passage of materials

Question 28

describe chromatin

Answer 28

-fibers composed to protein and DNA molecules -carrier info for synthesizing proteisn

Question 29

describe nucleolus

Answer 29

-dense, nonmembrane body composed of protein and RNA -site of ribosome function

Question 30

list the types of passive transport. list the types of active transport

Answer 30

-diffusion, osmosis, facilitated diffusion, filtration -endocytosis, exocytosis, transcytosis

Question 31

describe diffusion

Answer 31

-movement of particles from high concentration to low concentration (concentration gradient)

Question 32

describe facilitated diffusion

Answer 32

-small solutes that aren't lipid soluble may diffuse through specific protein channels -follows concentration gradient

Question 33

describe osmosis

Answer 33

-movement of water across selectively permeable membrane into compartment containing solute that can't cross -follows concentration gradient

Question 34

define isostonic. define hypertonic. define hypotonic

Answer 34

-solutions that have the same osmotic pressure as body fluid -solutions that have higher osmotic pressure as body fluid (cells shrink) -solutions that have lower osmotic pressure as body fluid (cells swell)

Question 35

describe filtration

Answer 35

-process that forces molecules though membrane using pressue

Question 36

describe endocytosis

Answer 36

conveys molecules, that are too large to enter the cell by other means, to the inside of cell in a vesicle (active)

Question 37

describe pinocytosis

Answer 37

cells take in tiny droplets (active)

Question 38

describe phagocytosis

Answer 38

cells take in solids (active)

Question 39

describe exocytosis

Answer 39

packaging substances made in the cell into vesicles that fuse with the cell membrane and are released to outside (active)

Question 40

describe transcytosis

Answer 40

combines endo-and exo-cytosis to transport substance from one end of cell to other (active)

Question 41

describe cell cycle

Answer 41

-interphase -mitosis (prophase, metaphase, anaphase, telophase) -cytokinesis

Question 42

describe telomeres

Answer 42

DNA at the tips of chromosomes that are the basis for the mitotic clock

Question 43

describe stem cells

Answer 43

divide mitotically to yield 2 daughter cells like itself that can continue dividing (1 is stem and 1 is specialized)

Question 44

describe progenitor cell

Answer 44

partly specialized cell that is the daighter of stem cell

Question 45

define apoptosis

Answer 45

programmed form of cell death

Question 46

define necrosis

Answer 46

cell death from damage