Cells and membranes

Question 1

What is the difference between cell death through necrosis and apoptosis?

Answer 1

Apoptosis is physiological, individual cells die over hours and cause no damage/inflammation to adjacent cells;
Necrosis is pathological, groups of cells die over days, their membranes burst and cell contents cause damage and inflammation to adjacent cells

Question 2

What is the difference between pluripotent and multipotent stem cells?

Answer 2

Pluripotent can turn into all cell types in the body, multipotent can turn into all cell types in certain tissues

Question 3

What characteristics separate prokaryote cells from eukaryote cells?

Answer 3

Prokaryotes have no nuclear membrane, no mitochondria and do not have organelles surrounded by membranes

Question 4

Name five different classes of cell-cell junctions

Answer 4

Gap junctions
tight junctions
desmosomes (intermediate keratin filaments)
adherens junctions (actin filaments)
hemidesmosomes

Question 5

What different types of structures make up the cytoskeleton?

Answer 5

Microfilaments (actin)
intermediate filaments (fibrous keratin)
microtubules

Question 6

What are the main characteristics of mitochondria?

Answer 6

their own DNA, ribosomes and proteins
self replicate
an inner membrane arranged in cristae
produce energy from breakdown of molecules

Question 7

What are the main characteristics of the nucleus?

Answer 7

Contain DNA (heterochromatin or euchromatin), membrane bound with pores

Question 8

What are the structural and functional differences of the smooth and rough endoplasmic reticulum?

Answer 8

RER - has ribosomes on its surface, it’s mainly involved in protein synthesis (RNA translation into amino acid sequences)
ER - mostly involved in breakdown of molecules (eg drugs) and synthesis of some molecules (eg lipids)

Question 9

What is the role of lysosomes?

Answer 9

They contain digestive enzymes for breakdown of cell’s or foreign molecules

Question 10

What are the 10 main elements of life?

Answer 10

H - hydrogen, O - oxygen, N - nitrogen, C - carbon, Na - sodium, S - sulphur, P - phosphorus, Cl - chloride, K - potassium, Ca - calcium

Question 11

List the five chemical reaction of life

Answer 11

Reduction/oxidation
Making/breaking C-C bonds
Group transfers
Internal rearrangements
Condensation/hydrolysis

Question 12

What do oxidation and reduction mean respectively?

Answer 12

Oxidation Is Loss of electron (OIL)

Reduction Is Gain of electron (RIG)

Question 13

define configuration and conformation of a molecule

Answer 13

configuration - fixed arrangement of molecules, can only be altered by breaking and reforming bonds
conformation - specific arrangement of molecules, which can change depending on their interaction without making/breaking bonds

Question 14

what ties together nucleic acid monomers?

Answer 14

covalent phosphodiester bonds

Question 15

what are the purines in nucleic acid and their characteristics?

Answer 15

Guanine
Alanine
double ring bases

Question 16

what are the pirimidines in nucleic acid and their characteristics?

Answer 16

thymine
uracil
cytosine
single ring bases

Question 17

what is the chiral centre of a molecule?

Answer 17

the center of an asymmetric molecule

Question 18

what are features of glucose that causes it to have reducing and non-reducing ends?

Answer 18

when polymers are made glucose sits in ring shape (non reducing)
the end group of the molecule is linear (ALDEHYDE) and reducing

Question 19

what is the concept of energy coupling in cells?

Answer 19

coupling an anabolic with a catabolic reaction, to use energy from spontaneous reaction to fuel an energetically unfavourable reaction

Question 20

what do endergonic and exergonic reactions mean?

Answer 20

exergonic - catabolic reaction

endergonic - anabolic reaction

Question 21

what is the dissociation constant for water and for OH and H respectively?

Answer 21

water: 1x10^-14
OH: 1x10^-7
H: 1x10^-7

Question 22

what is the definition of weak and strong acids/bases?

Answer 22

strong - fully dissociate

weak - partially dissociate

Question 23

what is the pH of water normally?

Answer 23

pH = pOH = 7

Question 24

is water a polar or non-polar compound, and why?

Answer 24

polar compound, because O is negative and H is positive

Question 25

are oxygen and carbon dioxide polar or non-polar, and how does this affect their solubility?

Answer 25

both non-polar

poor water solubility, have to be carried by hemoglobin and bicarbonate

Question 26

which molecules can form hydrogen bonds?

Answer 26

any electronegative ions can form hydrogen bonds with positive H+

Question 27

what is the strongest hydrogen bond configuration?

Answer 27

all atoms in a straight line

Question 28

how are charged molecules desolved in water?

Answer 28

they attract water molecules which arrange themselves around molecule and form a coating

Question 29

how do hydrophobic molecules arrange themselves in water?

Answer 29

don’t desolve

hydrophobic effect - cluster together to exclude water (eg oil in water)

Question 30

how do phospholipids arrange themselves in water?

Answer 30

form bilayer structures to exclude water (eg micelles, cell membranes)

Question 31

what does the p stand for in the dissociation equation of water?

Answer 31

-log10

Question 32

what are the properties of acid and basic solutions?

Answer 32

acids: high H and low OH
basic: high OH and low H

Question 33

what are conjugate acid-base pairs?

Answer 33

molecules in which the acid has given up one of its protons to a base

Question 34

what is the acid dissociation constant called?

Answer 34

pKa

Question 35

what is the purpose of the Henderson-Hasselbalch equation?

Answer 35

it allows calculation of how a pH will change depending on the buffer systems it comes into contact with

Question 36

what are the main buffer systems in the body?

Answer 36

in cells - phosphate buffer

in blood - bicarbonate buffer

Question 37

what is the purpose of buffer systems in the body?

Answer 37

maintaining pH at optimal level by binding or unbinding H+ ions depending on whether solution has become too acidotic or too alkaline

Question 38

what ions and molecules have higher concentrations in cells compared to outside cells?

Answer 38

K
proteins
phosphates

Question 39

what ions and molecules have higher concentrations outside cell compared to inside cells?

Answer 39

Na
Cl
bicarbonate

Question 40

what are the four main classes of membrane proteins?

Answer 40

receptors
transporters
enzymes
peripheral proteins

Question 41

what is an example of a peripheral protein, where are they found in the membrane and what is a major function?

Answer 41

glycoproteins: cell-cell recognition

always on outside of membrane

Question 42

what are the two different types of transporter membrane proteins?

Answer 42

channel proteins (gated or open)
carrier proteins

Question 43

what is the protein content of cell membranes?

Answer 43

depends on the function of that cell

Question 44

what is the main characteristic of a molecule to allow it to cross a membrane?

Answer 44

has to be UNCHARGED

Question 45

what are the three characteristics of a molecule to allow it to cross a membrane?

Answer 45

small size
lipophilic
uncharged

Question 46

what uses up 40% of the body’s resting energy, and to do what?

Answer 46

Na/K ATPase pump
pumps out 3Na
pumps in 2K

Question 47

what is the normal human plasma osmolarity?

Answer 47

285 mOsmol (300)

Question 48

what is the main difference between osmolarity and tonicity?

Answer 48

osmolarity: measure total number of particles in solution (penetrating + non penetrating)
tonicity: only measures number of non-penetrating particles in solution