Section I

Question 1

cells are surrounded by

Answer 1

plasma membrane

Question 2

interior of the cells can be most basically defined by two compartments

Answer 2

cytoplasm and nucleus

Question 3

cytoplasm are must of the

Answer 3

sub-cellular organelles

Question 4

nucleus is operated from

Answer 4

the cytoplasm by the nuclear envelope which is a double lipid membrane

Question 5

cytoplasmic organelles are surrounded by

Answer 5

lipid membranes

Question 6

cytoplasmic organelles

Answer 6

mitochondria
endoplasmic or sarcopaslmic reticulum
golgi comples
lysosomes

Question 7

plasma membrane and other organelle membrane

Answer 7

lipid bilayer

Question 8

lipid bilayer is composed of

Answer 8

phospholipids and cholesterol

Question 9

proteins are part of the plasma membrane

Answer 9

they can span the membrane, be embedded in one layer of membrane or attached peripherally to the membrane

Question 10

phospholipids

Answer 10

polar head group and a hydrophobic tail region
poor head group face the aqueous environment, outside of the cell

this arrangement restricts the movement of polar, hydrophilic molecules between the inside and the outside of cells

Question 11

intergral protein

Answer 11

protein span the membrane or embedded in the membrane

ex: ion channels, transporters, receptors, receptors for hormones or neurotransmitters, phospholipase

Question 12

peripheral protein

Answer 12

associated with membranes via electrostatic interactions with the polar heads groups of the phospholipids or with integral proteins or via covalent attachments to special lipids
ex: actin, spectrins, signal transductions intermidaires

Question 13

glycocalyx

Answer 13

glycocalyx is presented on the outer layer of the membrane
carbs attached to proteins and lipids on the cell surface, make up 2-10 % of the weight of the plasma

Oligasaccharides are attached to protein through either N-glyosidic (asparagine) or O-glycosadic (serene) bonds. referred to glycoproteins

Makes cell surface very hydrophilic and restricts hydrophobic molecule passage

Question 14

key concept plasma membrane

Answer 14

serves a protective function by acting as a general barrier to movement of biochemical compounds both into and out of cells

barrier function and regulate what goes in and out
same applies to membrane nucleus and other organelles in cytoplasm

Question 15

passive and active transport

vesicular transport

Answer 15

active-requires energy
passive- does not

transport generally moves larger cargo into cells

Question 16

passive transport

simple diffusion

Answer 16

molecules can freely cross the membrane
direction of movement is determined by the concentration gradient

physiological steroids and steroid-based drugs enter cell through simple diffusion
ex. estradiol, testosterone, progesterione, cortisol, aldosterone. (five classes of steroids)

Question 17

passive transport

facilitative diffusion

Answer 17

transported after binding to a specific protein in the membrane
- not require energy, still transported through concentration gradient
due to the required binding event, process exhibits saturation kinetics
ex: pores, carrier proteins and gated channel

Question 18

facilitative diffusion

gated channel

Answer 18

require stimulus to perforce their transport function
ex: ion channel

variety of ion channels only open the member is subject to an electrical signal (voltage)

calcium channel blockers target voltage-gated calcium channel

Question 19

active transport

Answer 19

against its concentration gradient
energy is used to concentrate the molecule/ion on one side of the membrane
ex: Na+, ATPase, Na+/glucose transporter

Question 20

Na+, K+, ATPase

Answer 20

Na+ is concentrated out side of the cell
K+ is concentrated inside the cell
3Na/2K

Question 21

Hydrolysis of ATP and phosphorylation cause

Dephosphorylation cause

Answer 21

conformational change in the protein that allows Na+ to move for inside to outside cell and K+ ions to bind the protein outside the cell
Dephosphorylation occurs too

Question 22

Dephosphorylation

Answer 22

protein changes the conformation again and allows the bound K+ ions to be released into the cell

Question 23

Na+ glucose cotransporter

Answer 23

lumen of the intestine epithelial cell
Na+ concentration is high in the lumen while glucose is high in the cell

elector chemical gradient
the movement of Na+ with its concentration gradient generates electrochemical energy that allow glucose to move against its concentration gradient
thus, ATP hydrolysis is not required
amino acids are also moved into cell by Na+ co transport

Question 24

glucose is moved out of epithelial cell how?

Answer 24

transported via a different carrier protein from the epithelial cell into the extracellular space by passive diffusion because its concentration is high in the cell and low in the extracellular space

Question 25

vesicular transport

Answer 25

endocytosis- process by which the plasma membrane invaginate around compounds or proteins or microbes and encloses them in a vesicle which then moves into the cytoplasm of a cell

Question 26

Phangocytosis

Answer 26

engulfment of particulate matter such as microbes

Question 27

pinocytosis

Answer 27

vesicles forms around fluid containing dispersed molecules

Question 28

receptor-mediated endocytosis

Answer 28

receptors bounded to ligands such as hormones cluster in plasma membrane and are engulfed in coated vesicles

Question 29

exocytosis

Answer 29

vesicles inside the cells fuse with plasma membrane and their contents are extruded not the extracellular fluid

from inside the cell such as the Golgi Complex, and endoplasmic reticulum

secreted or cellular waste