Life at cellular level Flashcards
mitochondria
outer membrane contains pores
inner membrane has cristae
matrix contains binding sites for calcium and also most of the enzymes for oxidation of FA’s
have own circular DNA and own ribosomes
what are cristae
convoluted folds increase surface area to fit in more proteins
what are nucleoli
sites of rRNA synthesis and ribosomal production and assembly
what is rough Endoplasmic reticulum
inside the cell-
site of post-translational modifications to protein and transport
what is smooth Endoplasmic reticulum
used mainly to breakdown compounds either from inside the cell or ones that have been brought in e.g drugs and glycogen
or synthesise some like lipids
lysosome
used to separate enzymes from rest of cell
what is the cytoskeleton
a microscopic network of protein filaments and tubules in the cytoplasm
includes microfilaments, microtubules, intermediate filaments
what are microfilaments
made up of actin
break down actin for cell to move around
what are intermediate filaments
made up of fibrous proteins- tough
stabilise cell’s structures
what are microtubules
made up of tubulin protein
hollow cylinders
2 subunits alpha and beta tubulin
what are cilia and flagella made up of
microtubules
which elements make up 90% of humans
H
O
N
C
what type of bonds can carbon make
single
single and double
single, double and sometimes triple bonds with other C atoms
what do functional groups define
biomolecular function
how does the arrangement of atoms relate to the function of the molecule
c=c is a rigid confirmation- can only have two distinct configuration- cis and trans
how can you interconvert between cis and trans
by breaking bonds and reforming them
only way you can do this is through function of enzymes as it requires too much energy otherwise
what happens when rod proteins in the eye detect light
the light changes cis isomers (bent) to straight by an enzyme
this is a time dependent reversal process- temporary blindness
what are the two forms of chiral centre
Laevo- L (left handed)
Dextro- D (right handed)
which type of amino acids are all proteins made from
L-amino acids only
bonds that can rotate allow many different what?
conformations
what are the 5 chemical reactions of life
REDOX making and breaking C-C bonds internal rearrangements group transfers condensation and hydrolysis
how many H+ atoms are usually transferred in dehydrogenation reactions?
2
what is an example of making/breaking C-C bonds
cleavage of Glucose in the glycolysis pathway
what bond links nucleotide monomers together?
3’,5’- phosphodiester bonds
which bases come under ‘purine’? and what are purines like
A and G
flat, double rings
which bases come under ‘pyrimidines’? and what are pyrimidines like
flat, single rings
C and T and uracil
what structure do bases take on in DNA that allows the double helix
flat planar
how many bonds are there between G-C
3
how many bonds are there between A-T
2
starch and glycogen are both polymers of what?
D-glucose
why is D-glucose termed a reducing sugar?
linear form has aldehyde group that can be oxidised and if it is then the other reactant would be reduced so glucose is termed a reducing sugar
1st law of thermodynamics
energy can’t be created or removed
it can only be transformed or transferred
2nd law of thermodynamics
energy transformations ultimately lead to a more disordered universe
define entropy
degree of disorder within a closed system
what is a useless form of energy
heat- once produced, it can’t be brought back
if reactions within cells release heat what does this do to the environment outside the cell
creates disorder outside our cells
how can spontaneous reactions occur
if a system gives up energy or becomes more random and increases in entropy
Gibbs free energy equation
G=H-TS
used to measure free (potential) energy
if it’s a spontaneous reaction what must happen to the enthalpy and entropy
enthalpy must decrease
entropy must increase
how is glucose broken down in the body
sequentially
approx how much of human is made up of water
approx by mass 60%
most in ICF (2/3)
how is heat dissipitated in the body
by water
when are H bonds strongest
when 3 atoms involved are in a straight line
protein-enzyme interaction and water
so protein and enzyme have shell of water molecules around them
when substrate moves close to binding site- a lot of disorder is created and this allows things to react
what is the hydrophobic effect
non- polar molecules arrange themselves in H20 so as to minimise disruption of H bonding surrounding H20 molecules.
highly ordered water molecules form cages around hydrophobic alkyl chains
amphipathic
are both polar and non-polar
fatty acids
lipids and water
only the lipid hydrophobic chain part causes hydrophobic effect- H20 becomes highly disordered around here
how do phospholipids further minimise disruption of H bonds in H20 molecules
by forming micelles or bilayers
liposome
spherical configuration
bilayer, hydrophobic tails tucked in centre
useful for drug delivery
what is the dissociation constant of water
Kw= 1.0 x 10^(-14)
strong acids
HCl
fully dissociate into ions
what is the Henderson-hasslebalch equation
pH = pKa + log [A-]/[HA]
indicates the amount of weak acid or conjugate base are in a biological system
give an example of buffer system in the plasma
the bicarbonate buffer system
without B.B.S pH in body would fluctuate wildly as lactic acid product would lower plasma pH
function:- neutralise gastric acid and stabilise the intracellular pH of epithelial cells
how can HH equation be used clinically
by calculating how the pH of a physiological solution responds to changes in either conjugate acid or base then you can see what state someone is in physiologically
respiratory/ metabolic acidosis and alkalosis
acidosis
excessively acidic conditions in body fluids/tissues
alkalosis is opposite
which buffer system is important in your cells
phosphate buffer system
