The Cell

Question 1

The cell

Answer 1

the basic functional unit of all living things

Question 2

Plasma membrane (function)

Answer 2

separates the internal metabolic events from the external environment and controls the movement of materials into and out of the cell.

Question 3

cytoplasm

Answer 3

consists of specialized organelles suspended in the cytosol

Question 4

cytosol

Answer 4

fluid matrix within the cytoplasm which consists of water and dissolved substances such as proteins and nutrients

Question 5

Plasma membrane (constituents)

Answer 5

a double phospholipid membrane (lipid bilayer) with polar hydrophilic heads forming the two outer faces and non polar hydrophobic tails facing inside the membrane.

Question 6

Peripheral proteins

Answer 6

proteins that may attach loosely to the inner and outer surface of the membrane

Question 7

Integral proteins

Answer 7

proteins that may extend into the membrane or across the membrane appearing at both surfaces. They are also amphipathic like the phospholipids.

Question 8

fluid mosaic model

Answer 8

described by the mosaic nature of scattered proteins within a flexible matrix of phospholipid molecules

Question 9

What does it mean for the phospholipid layer to be selectively permeable?

Answer 9

Only small uncharged polar molecules (like H2O and CO2) and hyrdrophobic molecules (non polar O2 and lipid soluble hydrocarbons) freely pass the membrane.

Question 10

Channel proteins

Answer 10

allow the passage of certain hydrophillic substances such as polar and charged molecules to pass through the membrane

Question 11

ion channels

Answer 11

allow the passage of ions across the membrane.

Question 12

gated channels

Answer 12

ion channels in nerves and muscle cells that open and close in response to specific chemical or electrical stimuli to allow specific ions (Na+ or K+)

Question 13

Porins

Answer 13

proteins that allow the passage of certain ions and small polar molecules through membranes.

Question 14

AquAporins

Answer 14

found in the plasma membrane of certain cells dramatically increasing the passage rate of H2O

Question 15

Carrier proteins

Answer 15

bind to specific molecules which are then transferred across the membrane after the carrier protein changes shape. such as glucose

Question 16

Transport proteins

Answer 16

use energy (ATP) to transport materials across the membrane. When energy is used for this purpose, the materials are said to be actively transported.

Question 17

Active transport

Answer 17

when energy is used to carry materials across the membrane.

Question 18

Na+K+ pump

Answer 18

uses active transport to maintain high concentrations of Na+ and K+ on opposite sides of the plasma membrane

Question 19

recognition proteins

Answer 19

give each cell type a unique identification. this helps with the id of self and foreign cells and normal and infected. It is a glycoprotein because they have a short oligosaccharide attached that extends from the surface

Question 20

adhesion proteins

Answer 20

attach cells to neighboring cells or provide anchors for the internal filaments and tubules that give stability to the cell.

Question 21

receptor proteins

Answer 21

provide binding sites for hormones or other trigger molecules. In response to the hormone or trigger molecule a specific cell response is activated.

Question 22

what is the function of cholesterol in the phosopholipid bilayer

Answer 22

they are distributed throughout to provide some rigidity to the plasma membrane of animal cells. in plant cells sterol provides a similar functions.

Question 23

glycolax

Answer 23

a carbohydrate coat that covers the outer face of the cell wall of some bacteria and the outer face of plasma membrane of some animal cells. It consists of various oligosaccs that are attached to the glycolipids and glycoproteins

Question 24

organelles

Answer 24

bodies within the cytoplasm that serve to physically separate the various metabolic reactions that occur within the cells.

Question 25

Nucleus

Answer 25

bounded by a nuclear envelope, contains DNA also where DNA is replicated, components of ribosomes are manufactured and serves as the site for separation of chromosomes during cell division.

Question 26

nuclear envelope

Answer 26

encases the nucleus consisting of two phospholipid bilayers each similar to the plasma membrane.

Question 27

Deoxyribonucleic Acid

Answer 27

DNA the hereditary information of the cell. Normally spread out within the nucleus as a threadlike matrix called chromatin.

Question 28

chromosomes

Answer 28

rod shaped bodies formed from chromatin during the beginning of cell division (all within the nucleus). Made up of two long DNA molecules and various histone molecules

Question 29

Histones

Answer 29

serve to organize the lengthy DNA, coiling it into bundles called nucleosomes.

Question 30

Nucleoli

Answer 30

concentrations of DNA in the process of manufacturing ribosomes.

Question 31

ribosomes

Answer 31

subunits made in the nucleus and consist of RNA molecules and proteins. The subunits are 40S and 60S they move across the nuclear envelope and into the cytoplasm where they are assembled into a single 80S ribosome. in the cytoplasm ribosomes assist in the assembly of amino acids into proteins.

Question 32

Svedburg Unit

Answer 32

S unit on ribosomes expresses how readily a product forms a sediment in a centrifuge, with larger values representing larger and heavier products.

Question 33

The endoplasmic reticulum

Answer 33

ER, consists of stacks of flattened sacs involved in the production of various materials. closely associated with the nucleus.

Question 34

Rough ER

Answer 34

ribosomes that present on the ER, it creates glycoproteins by attaching polysacchride groups to polypeptides as they are assembled by ribosomes.

Question 35

Smooth ER

Answer 35

responsible for the synthesis of lipids and hormones, especially in cells that produce these substances for export from the cell. in liver cells it is involve in the breakdown of toxins, drugs and toxic byproducts

Question 36

Golgi apparatus

Answer 36

Golgi complex, golgi bodies, a group of flattened sacs arranged like a stack of bowls. They modify and package proteins and lipids into vesicles.

Question 37

Vesicles

Answer 37

modified and packaged small spherical shaped sacs that bud from the outside surface of the golgi appatratus. that migrate and merge with the plasma membrane, releasing their content to the outside of the cell.

Question 38

Lysosomes

Answer 38

vesicles from a golgi body that contain digestive enzymes. they break down food, cellular debris and foreign invaders like bacteria. They maintain the the low pH (acidic) inside. So any enzyme that escapes the lysosomes is inactive in the neutral cytosol. None in plants

Question 39

Peroxisomes in animals

Answer 39

break down various substances including hydrogen peroxide (forming water and oxygen), fatty acids and amino acids. Common in liver and kidney cells where they break down toxic substances.

Question 40

peroxixomes in plants

Answer 40

modify by-products of photorespiration. in germinating seeds, they are called glyoxysomes breaking down stored fatty acids to help generate energy for growth.

Question 41

Photorespiration

Answer 41

a process by which CO2 is diverted from its use in photosynthesis.

Question 42

Mitochondria

Answer 42

carry out aerobic respiration, a process in which energy (ATP) is obtained from carbohydrates.

Question 43

Chloroplasts

Answer 43

carry out photosynthesis, the plant process of incorporating energy form son light into carbohydrates.

Question 44

Cytoskeleton

Answer 44

the internal structure of the cytoplasm made up of microtubules, intermediate filaments, and microfilaments. Involved in the shape and movement.

Question 45

Microtubules

Answer 45

made up of protein tubulin and provide support and motility for the cellular activities. They are found in spindle apparatus and in flagella and cilla

Question 46

Intermediate filaments

Answer 46

provide support for maintaining the shape of a cell

Question 47

Microfilaments

Answer 47

are made up of protein actin and are involved in cell motility. They are found in muscle cells and cells that move by changing shape such as phagocytes

Question 48

phagocytes

Answer 48

white blood cells that wander throughout the body attacking bacteria and other foreign invaders.

Question 49

Flagella and cilla

Answer 49

structures that protrude from the cell membrane and make wave like movements. They are classified by their length, numbers per cell and movement.

Question 50

Flagella

Answer 50

long, few and move in a snake like motion. a single flagellum propels sperm. it consists of microtublues arranged in 9+2 array

Question 51

Cilla

Answer 51

short, many, move back and forth, found numerous , an example that lines a respiratory tract to sweep away debris. consists of microtubules in a 9+2 array.

Question 52

Centrioles

Answer 52

act as mictrotuble organizing centers. a pair of centrioles located outside the nuclear envelope gives rise to the microtubules that make up the spindle apparatus used in cellular division. not in plants

Question 53

Transport vesicles

Answer 53

move materails between organelles or between organelles and the plasma membrane

Question 54

food vacuoles

Answer 54

ate temporary receptacles of nutrients. often merge with lysosomes so that it can break down the food

Question 55

storage vacuoles

Answer 55

in plants store starch, pigments and toxic substances

Question 56

central vacuoles

Answer 56

large bodies occupying most of the interior of certain plant cells. When fully filled they exert turgor, pressure, on the cell walls thus maintianing the rigidity in the cell. also act as lysosomes

Question 57

contractile vacuoles

Answer 57

are specialized organelles in single cell organisms that collect and pump excess water out of the cell.

Question 58

Extracellular region

Answer 58

area outside of the plasma membrane

Question 59

Cell wall

Answer 59

found in plants, fungi, protists and bacteria. tehy develop outside of the plasma membrane and provide support for the cell.

Question 60

Cell wall of plants

Answer 60

consists mainly of cellulose, a polysacc made of beta glucose

Question 61

cell wall of fungi

Answer 61

usually made of cellulose or chitin.

Question 62

chitin

Answer 62

a modified polysacc differing from cellulose in that one of the hydroxyl groups is replaced by a group containing nitrogen.

Question 63

extracellular matrix

Answer 63

is found in animals, in the area between adjacent cells. the area is occupied by fibrous structural proteins, adhesion proteins and polysaccs secreted by the cells. provides mechanical support and helps bind adjacent cells together, most common substance is the protein collagen.

Question 64

Cell junctions

Answer 64

serve to anchor cells to another or to provide a passageway for cellular exchange.

Question 65

anchoring junctions

Answer 65

are protein attachments between animal cells. example is the desmosome

Question 66

desmosome

Answer 66

consists of proteins that bind adjacent cells together, providing mechanical stability to tissues. also associated with protein filaments that hold cellular structures together.

Question 67

tight junctions

Answer 67

tightly attached seams between animal cells. the junction completely encircles each cell, producing a seal that prevents the passage of materials between the cells.

Question 68

communicating junctions

Answer 68

passageways between cells that allow the transfer of chemical or electrical signals. two kinds are gap junctions and plasmodesmata.

Question 69

gap junctions

Answer 69

narrow tunnels between animal cells that consist of proteins called connexins. the proteins prevent the cytoplasms of each cell from mixing but allow the passage of ions and small molecules. Channels for two adjacent cells that are closely aligned.

Question 70

Plasmodesmata

Answer 70

are narrow channels between plant cells. a narrow tube of endoplasmic reticulum called desmotubule, surrounded by cytoplasm and the plasma membrane passes through the channel. the exchange occurs through the cytoplasm

Question 71

Eukaryotes

Answer 71

include all organisms except for bacteria, cyanobacteria and archeabacteria. and have multi organelles.

Question 72

prokaryotes

Answer 72

consist of bacteria, cyanobacteria and archeabacteria and lack all teh organelles. they generally only consist of a plasma membrane, DNA molecule, robosomes, cytoplasm and maybe a cell wall.

Question 73

prokaryotes and DNA

Answer 73

the hereditary material in a prokaryote exists as a single naked DNA molecule with out proteins

Question 74

Prokaryotic ribosomes

Answer 74

are smaller (70S, with 50S and 30S subunits)

Question 75

Cell walls of bacteria and cyanobacteria

Answer 75

when present are constructed from peptidoglycans a polysacc protein molecule

Question 76

cell walls of archeabacteria

Answer 76

contain various polysaccs but not peptidoglycan, cellulose or chitin

Question 77

flagella in prokaryotes

Answer 77

not constructed of microtubles

Question 78

selectively permeable membrane

Answer 78

allows only specific substances to pass

Question 79

solvent

Answer 79

water (liquid)

Question 80

solute

Answer 80

substance being dissolved in the water (liquid)

Question 81

down the concentration gradient

Answer 81

movement of substances occurring from higher to lower concentrations

Question 82

against the concentration gradient

Answer 82

substances moving from lower to higher concentrations.

Question 83

Hypertonic

Answer 83

(shrink or crenate) a solute may be at a higher concentration relative to another region

Question 84

Hypotonic

Answer 84

(pop or lyse) a lower concentration of solutes relative to another region

Question 85

Isotonic

Answer 85

an equal concentration of of solutes relative to another region

Question 86

Passive transport

Answer 86

processes describe the movement of substances from regions of higher to lower concentration and do not require expenditure of energy.

Question 87

Bulk flow

Answer 87

the collective movement of substances in the same direction in response to to a force or pressure. Blood moving through a vessel is a bulk flow

Question 88

Simple diffusion

Answer 88

the net movement of substances from an area of higher concentration to an area of lower concentration. this movement occurs as a result of the random and constant motion characteristic of all molecules

Question 89

osmosis

Answer 89

the diffusion of water molecules across a selectively permeable membrane. When water moves into a body by osmosis, a hydrostatic pressure (osmotic pressure) may build up inside the body. Turgor pressure is the osmotic pressure that develops when water enters the cells of plants and microorganisms.

Question 90

Dialysis

Answer 90

is the diffusion of solutes across a selectively permeable membrane. The term dialysis is usually used when different solutes are separated by a selectively permeable membrane

Question 91

plasmolysis

Answer 91

the movement of water out of a cell that results in a calapse of cell especially plant cells.

Question 92

Facilitated diffusion

Answer 92

the diffusion of solutes or water through channel proteins in the plasma membrane. Note water can move through without help but aquaporins assist in making it move faster which is facilitated diffusion.

Question 93

countercurrent exchange

Answer 93

the diffusion of substances between two regions in which the substances are moving by bulk flow in opposite directions. Example water coming in by fish gills and blood flow within the vessels of the fish. they are maximized due to the correlation

Question 94

vesicular transport

Answer 94

uses vesicles or other bodies in the cytoplasm to move macromolecules or large particles across the plasma membrane.

Question 95

exocytosis

Answer 95

describes the process of vesicles fusing with the plasma membrane and releasing their contents to the outside of the cell. this is common when a cell produces substances for export

Question 96

endocytosis

Answer 96

describes the capture of a substance outside the cell when the plasma membrane merges to engulf it. the substance subsequently enters the cytoplasm enclosed in a vesicle.

Question 97

phagocytosis

Answer 97

cellular eating- occurs when undissolved material enters the cell. the plasma membrane wraps around the solid material and engulfs it forming a phagocytic vesicle

Question 98

pinocytosis

Answer 98

cellular drinking- occurs when dissolved substances enter the cell. the plasma membrane folds inward to form a channel allowing the liquid to enter.

Question 99

receptor mediated endocytosis

Answer 99

a form on pinocytosis, occurs when specific molecules in the fluid surrounding the cell bind to specialized receptors that concentrate coated pits in the plasma membrane. proteins that transport cholesterol in the blood (LDLs) and certain hormones target specific cells by receptor mediated endocytosis.