General Biology 2

Question 1

defines the borders of the

cell and keep the cell
functional

• selectively permeable
• 5-10 nm thin

Answer 1

PLASMA MEMBRANE

Question 2

act both as
receivers of extracellular inputs and as
activators of intracellular processes;
attachment site

Answer 2

Proteins - Integral (Receptors)

Question 3

mosaic of components/fluid character

Answer 3

Fluid Mosaic Model

Question 4

consist of Glycerol, 2
Fatty Acids and Phosphate-linked head
group

Answer 4

Phospholipid

Question 5

composed of 4 fused
Carbon Rings found alongside the
phospholipid

Answer 5

Cholesterol

Question 6

are present only on the
exterior surface of the plasma membrane.

Answer 6

Carbohydrates

Question 7

→If attached to proteins

Answer 7

GLYCOPROTEINS

Question 8

→If attached to lipids

Answer 8

GLYCOLIPIDS

Question 9

forms H Bonds
with water and other polar
molecules on both exterior and
interior of the cellq

Answer 9

HYDROPHILIC

Question 10

non-polar and
prefer non-polar environment.

Answer 10

HYDROPHOBIC

Question 11

integrated completely into

the membrane structure

Answer 11

A.Integral Proteins

Question 12

found on the exterior and interior surfaces of membranes; attached
either to Integral proteins or to
Phospholipids

• serve as enzymes, as structural attachments for the fibers of the
  cytoskeleton and as recognition sites
• “cell-specific” proteins

Answer 12

Peripheral Proteins

Question 13

Always found on the exterior surface of
the cells and are bound to either
proteins (Glycoproteins) or to lipids
(Glycolipids).

In chains, 2-60 monosaccharide units
and can be either straight or branched

• Specialized sites/features to be
  recognized

Answer 13

CARBOHYDRATES

Question 14

“sugar coating”; hydrophilic and
attracts larger amounts of water to the surface of
the cell

Answer 14

GLYCOCALYX

Question 15

• nature of Phospholipids
• unsaturated Fatty Acids kinks
  making elbow rooms which is the
  reason for its fluidity

Answer 15

Membrane Fluidity

Question 16

A few molecules move freely

Answer 16

–Water, Carbon dioxide, Ammonia, Oxygen

Question 17

describes fluid nature
of a lipid bilayer with proteins

Answer 17

–Fluid mosaic model

Question 18

they allow some substances to pass

through but not others

Answer 18

SELECTIVELY PERMEABLE

Question 19

material with a low
molecular weight can easily slip
through the hydrophobic lipid core of
the membrane.

Answer 19

→Lipid-soluble

Question 20

can
pass through the plasma membranes in
the digestive tract and other tissues.

Answer 20

Vits. A, D, E K (fat soluble)

Question 21

• passive process of transport
• substance moves from higher concentration to lower concentration until the concentration is equal across a space; e.g. Perfume
• no energy needed
• there will be different rates of diffusion of the different substances in the medium
  according to their concentration gradient.

Answer 21

DIFFUSION

Question 22

the greater the
difference in concentration, the more
rapid the diffusion. The closer the
distribution of the materials gets to
equilibrium, the slower the rate of
diffusion.

Answer 22

Concentration Gradient

Question 23

heavier molecules move slowly; reverse is
true for lighter materials.`

Answer 23

Mass of the molecules diffusing

Question 24

higher temperature increase
the energy and therefore the movement of the
molecules, increasing the rate of diffusion.

Answer 24

Temperature

Question 25

as the density of a solvent increases, the rate of diffusion decreases.

Answer 25

Solvent Density

Question 26

non-polar or lipid-soluble materials pass through plasma membranes more easily than polar materials, allowing a faster rate of diffusion.

Answer 26

Solubility

Question 27

increased surface area increases the rate of diffusion, whereas a thicker membrane reduces it.

Answer 27

Surface area and thickness of the plasma membrane

Question 28

the greater the distance that a substance must travel, the slower the rate of diffusion.

Answer 28

Distance travelled

Question 29

→Transports only water across a membrane → special case of diffusion

Answer 29

OSMOSIS

Question 30

The movement of water into and out of a cell is known as

Answer 30

osmosis.

Question 31

When the number of water molecules inside and outside the cell is the same, _____ is reached.

Answer 31

equilibrium (balance)

Question 32

solute concentration is equal to that of the inside cell.

Answer 32

ISOTONIC SOLUTION/ENVIRONMENT

Question 33

→Describes how an extracellular solution can change the volume of a cell by affecting osmosis.

Answer 33

TONICITY

Question 34

describes the total solute concentration of the solution

Answer 34

OSMOLARITY

Question 35

the extracellular fluid has lower osmolarity than the fluid inside the cell. → Water enters the cell

Answer 35

Hypotonic Solution

Question 36

the extracellular fluid has higher osmolarity than the fluid inside the cell. →Water leaves the cell

Answer 36

Hypertonic Solution

Question 37

the extracellular fluid has the same osmolarity as the cell. → No net movement of water into or out of the cell

Answer 37

Isotonic Solution

Question 38

→Materials diffuse across the plasma membrane with the help of

Answer 38

membrane proteins

Question 39

→The material being transported is first attached to a _____ receptors on the exterior surface of the plasma membrane.

Answer 39

protein or glycoprotein

Question 40

The substances are then passed to specific ____ that facilitate their passage.

Answer 40

integral proteins

Question 41

Others are _____ which bind with the substance and aid its diffusion through the membrane

Answer 41

carrier proteins

Question 42

an integral protein which is also referred to as Transport Proteins - they function as either channels for the material or carriers

Answer 42

Channels

Question 43

hydrophilic; open and close as they respond to stimuli. - some channel proteins open or close when a specific substance, other than the substance to be transported, binds to the channel e.g. Aquaporins – channel proteins that allow water to pass through the membrane at a very high rate

Answer 43

Channel Protein

Question 44

binds a substance and triggers a change of its own shape, moving the bound molecule from the outside of the cell to its interior. - specific for a single substance. - e.g. Glucose filtration in the kidneys (diabetic)

Answer 44

Carrier Proteins

Question 45

facilitate diffusion at a rate of tens of millions of molecules per second,

Answer 45

Channel proteins

Question 46

work at a rate of a thousand to a million molecules per second.

Answer 46

carrier proteins

Question 47

→moving of solutes across a membrane, up the concentration gradient →requires the expenditure of energy; it utilizes ATP (energy currency of the cell) →the movement across the membranes is unidirectional

Answer 47

ACTIVE TRANSPORT

Question 48

IMPORTANCE

Answer 48

1. It enables the transport of nutrients to the cell even when their concentration on the inside is already higher. 2. It makes possible the removal of waste materials from the cell despite their higher concentration outside the cell. 3. It enables the cell to maintain the concentration of essential ions such as K+, Na+, Ca2+, and H+ .

Question 49

→Large molecules, such as proteins and polysaccharides cross the membranes in bulk through the processes of exocytosis and endocytosis.

Answer 49

BULK TRANSPORT

Question 50

the process of removing materials from the cell through the vesicles that fuse with the plasma membrane, releasing their contents outside the cell → example: secretion of digestive enzymes through the vesicles from the Golgi Apparatus.

Answer 50

the process of removing materials from the cell through the vesicles that fuse with the plasma membrane, releasing their contents outside the cell → example: secretion of digestive enzymes through the vesicles from the Golgi Apparatus.

Question 51

the reverse of exocytosis wherein cells engulf materials; the engulfed substance then enters the cytoplasm while enclosed in a vesicle.

Answer 51

ENDOCYTOSIS

Question 52

“cellular eating”; the plasma membrane wraps around the solid material and engulfs it. Example: how the Amoeba captures food and how white blood cells engulf bacteria

Answer 52

Phagocytosis

Question 53

“cellular drinking”; the plasma membrane wraps around the dissolved materials and forms a vesicle that contains the engulfed materials. Example: the human egg cell’s uptake of nutrients from its surroundings

Answer 53

Pinocytosis