Cells and membranes Flashcards
What is the difference between cell death through necrosis and apoptosis?
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
What is the difference between pluripotent and multipotent stem cells?
Pluripotent can turn into all cell types in the body, multipotent can turn into all cell types in certain tissues
What characteristics separate prokaryote cells from eukaryote cells?
Prokaryotes have no nuclear membrane, no mitochondria and do not have organelles surrounded by membranes
Name five different classes of cell-cell junctions
Gap junctions tight junctions desmosomes (intermediate keratin filaments) adherens junctions (actin filaments) hemidesmosomes
What different types of structures make up the cytoskeleton?
Microfilaments (actin)
intermediate filaments (fibrous keratin)
microtubules
What are the main characteristics of mitochondria?
their own DNA, ribosomes and proteins
self replicate
an inner membrane arranged in cristae
produce energy from breakdown of molecules
What are the main characteristics of the nucleus?
Contain DNA (heterochromatin or euchromatin), membrane bound with pores
What are the structural and functional differences of the smooth and rough endoplasmic reticulum?
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)
What is the role of lysosomes?
They contain digestive enzymes for breakdown of cell’s or foreign molecules
What are the 10 main elements of life?
H - hydrogen, O - oxygen, N - nitrogen, C - carbon, Na - sodium, S - sulphur, P - phosphorus, Cl - chloride, K - potassium, Ca - calcium
List the five chemical reaction of life
Reduction/oxidation Making/breaking C-C bonds Group transfers Internal rearrangements Condensation/hydrolysis
What do oxidation and reduction mean respectively?
Oxidation Is Loss of electron (OIL)
Reduction Is Gain of electron (RIG)
define configuration and conformation of a molecule
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
what ties together nucleic acid monomers?
covalent phosphodiester bonds
what are the purines in nucleic acid and their characteristics?
Guanine
Alanine
double ring bases
what are the pirimidines in nucleic acid and their characteristics?
thymine
uracil
cytosine
single ring bases
what is the chiral centre of a molecule?
the center of an asymmetric molecule
what are features of glucose that causes it to have reducing and non-reducing ends?
when polymers are made glucose sits in ring shape (non reducing)
the end group of the molecule is linear (ALDEHYDE) and reducing
what is the concept of energy coupling in cells?
coupling an anabolic with a catabolic reaction, to use energy from spontaneous reaction to fuel an energetically unfavourable reaction
what do endergonic and exergonic reactions mean?
exergonic - catabolic reaction
endergonic - anabolic reaction
what is the dissociation constant for water and for OH and H respectively?
water: 1x10^-14
OH: 1x10^-7
H: 1x10^-7
what is the definition of weak and strong acids/bases?
strong - fully dissociate
weak - partially dissociate
what is the pH of water normally?
pH = pOH = 7
is water a polar or non-polar compound, and why?
polar compound, because O is negative and H is positive
are oxygen and carbon dioxide polar or non-polar, and how does this affect their solubility?
both non-polar
poor water solubility, have to be carried by hemoglobin and bicarbonate
which molecules can form hydrogen bonds?
any electronegative ions can form hydrogen bonds with positive H+
what is the strongest hydrogen bond configuration?
all atoms in a straight line
how are charged molecules desolved in water?
they attract water molecules which arrange themselves around molecule and form a coating
how do hydrophobic molecules arrange themselves in water?
don’t desolve
hydrophobic effect - cluster together to exclude water (eg oil in water)
how do phospholipids arrange themselves in water?
form bilayer structures to exclude water (eg micelles, cell membranes)
what does the p stand for in the dissociation equation of water?
-log10
what are the properties of acid and basic solutions?
acids: high H and low OH
basic: high OH and low H
what are conjugate acid-base pairs?
molecules in which the acid has given up one of its protons to a base
what is the acid dissociation constant called?
pKa
what is the purpose of the Henderson-Hasselbalch equation?
it allows calculation of how a pH will change depending on the buffer systems it comes into contact with
what are the main buffer systems in the body?
in cells - phosphate buffer
in blood - bicarbonate buffer
what is the purpose of buffer systems in the body?
maintaining pH at optimal level by binding or unbinding H+ ions depending on whether solution has become too acidotic or too alkaline
what ions and molecules have higher concentrations in cells compared to outside cells?
K
proteins
phosphates
what ions and molecules have higher concentrations outside cell compared to inside cells?
Na
Cl
bicarbonate
what are the four main classes of membrane proteins?
receptors
transporters
enzymes
peripheral proteins
what is an example of a peripheral protein, where are they found in the membrane and what is a major function?
glycoproteins: cell-cell recognition
always on outside of membrane
what are the two different types of transporter membrane proteins?
channel proteins (gated or open) carrier proteins
what is the protein content of cell membranes?
depends on the function of that cell
what is the main characteristic of a molecule to allow it to cross a membrane?
has to be UNCHARGED
what are the three characteristics of a molecule to allow it to cross a membrane?
small size
lipophilic
uncharged
what uses up 40% of the body’s resting energy, and to do what?
Na/K ATPase pump
pumps out 3Na
pumps in 2K
what is the normal human plasma osmolarity?
285 mOsmol (300)
what is the main difference between osmolarity and tonicity?
osmolarity: measure total number of particles in solution (penetrating + non penetrating)
tonicity: only measures number of non-penetrating particles in solution
