bioe 1 Flashcards
ionic bonds
exchange of electrons from valence shell
atoms become ions
electrostatic force of attraction
high activation energy to break ionic bonds
non-polarised covalent bonds
shared electrons
not ionic charge
weaker bond than ionic
polarised covalent bonds
unequal sharing of electrons
usually atom with higher affinity for electrons being shared
one atom more electron dense so shared electrons spend more time circulating atom
partial delta positive and delta negative charges
conservation of mass
mass neither created nor destroyed in chemical reactions
synthesis
a + b -> ab
anabolic
endergonic
condensation
amino acids to proteins
decomposition
ab-> a + b
catabolic
exergonic
hydrolysis
glycogen to glucose
exchange
ab + c -> ac+ b
anabolic + catabolic
endergonic and exergonic
glucose + ATP
condensation
anabolic process
yields water
e.g. two glucose molecules -> maltose
hydrolysis
catabolic process
ATP hydrolysis essential for muscle contractions
hydrolysis of a dipeptide into two amino acids
increase co2
dissolves in h2o
releases h+
creates carbonic acid
increase h+
leads to acidosis (increase respiratory and pulmonary response to overcome)
eventually leads to fatigue
metabolic acidosis
accumulation of metabolic acid
salts
ionic bonds
structural components
electrolyte properties
dissociate in water
damaging in high conc
acids and bases
covalent bonds
metabolic control
homeostasis (reversible)
dissociate in water
damaging in high conc
acids
proton donors
dissociates in water
hcl
in stomach for digestion
ph enzymes most efficient
carbonic acid
weak acid
chemical buffering
citric acid
second stage of carbohydrate breakdown
strong acid
fully dissociates in water
irreversible
weak acid
partial dissociation
reversible and conc driven
bases
proton acceptor
dissociate in water
release oh-
concentartion
molarity
moles per litre
pH
quantitative measure of acidity or alkalinity of solution
ph = -log10 [h+]
distilled water [h+] = [oh-] pH = 7
human body pH average 7.4
buffers
chemical and physiological mechanisms that moderate change in [h+]
increase [h+] = acidosis
decrease [h+] = alkolosis
physiological buffers
second line of defence
only occurs when change in ph is already occurred
renal buffering
ventilatory buffering
pulmonary ventilation
renal buffering
response time hours / days
regulate acidity through complex chemical reactions that restores bicarbonate into blood
secrete ammonia and h+ into urine
only pathway to eliminate acids other than carbonic acid
ventilatory buffering
faster response
changes the co2 conc
increase h+ stimulates ventilatory control
increase alveolar ventilation
increase co2 removal
ventilatory buffering
faster response
changes the co2 conc
increase h+ stimulates ventilatory control
increase alveolar ventilation
increase co2 removal
pulmonary ventilation
measures chemical state of blood in the medulla
variations in arterial
- partial pressure o2
- pp co2
- pH
- temp
adjust ventilation and maintain arterial blood chemistry
alkalosis and ventilation
decrease co2
due to hyperventilation (lots of breathing out so co2 forced out)
acidosis and ventilation
increase co2
due to hypoventilation (decrease ventilation)
not breathing out much co2 cause build up
pre exercise hyperventilation
causes alveolar co2 partial pressure to decrease
have a larger increase in co2 before needing to breathe
intense exercise on acid-base balance
increase [h+] from co2 production and lactate formation
large temp disturbance in acid-base balance
low pH cause nausea, headaches and dizziness
energy
the strength and vitality required for sustained physical or mental activity
thermodynamics law I
energy cannot be created nor destroyed but simply changed from one form to another
fuel
compound for which some of its chemical energy can be transformed into other forms when a chemical reaction takes place
triglycerides stored in adipose tissue
glucose used in brain
amino acids
glycogen
stored in liver and muscle
stored with water
1g glycogen with about 3g water
triacylglycerol
stored in adipose tissue
huge range in body fat from 2% to 70%
thermodynamics law II
all potential energy in a system degrades to unusable form of kinetic or heat energy
process of change reflects entropy
mechanical work
muscle contraction
convert chemical to mechanical energy
energy supports myosin head crossbridge formation
chemical work
maintenance and growth
muscle tissue synthesis in response to chronic overload in training
transport work
high -> low conc in diffusion = no energy
low -> high conc in active transport = energy
na+/ k+ -> atpase
Kcal
amount energy to increase temp of 1kg water by 1 degrees
1Kcal = 4.184 kj
joule
is the energy expended when 1 newton moves a distance of 1m
measurement of food energy
bomb calorimeters measures gross energy value of macronutrients
direct calorimetry measures heat liberated as food burns
heat of combustion is total energy value of the food
gross and net energy in food
gross energy from bomb calorimetry not the same as net energy due to protein
body cannot oxidize nitrogen component of protein
nitrogen combines with hydrogen to form urea and excreted from kidneys as urine
elimination of hydrogen in manner represents loss of approx 19% of proteins potential energy
coefficient of digestibility
ability of body’s digestive processes to extract potential energy
Atwater general factors
energy from food is corrected for loses in digestion, absorption and urinary excretion of urea
much less than calculated in a bomb calorimeter and what is available for fuel from what we digest
4Kcal / g dietary carbohydrates
4Kcal/ g dietary protein
9 Kcal / g dietary lipid
7 Kcal / g dietary alcohol
enzymes
specific protein catalyst that accelerates forward and reverses rates of chemical reactions without being consumed or changed
lowers the activation energy
lock and key theory
substrate matches active site of enzyme
enzyme-substrate complex splits to yield product
induced fit theory
in presence of substrate induces the active site of the enzyme to change shape slightly
key for delayed action needed for enzymes
allosteric enzymes
can be positively and negatively effected
have separate allosteric sites
positive effector allosteric enzyme
increases enzyme activity
less time to Km
negative effector allosteric enzyme
reduces enzyme activity
impact pH on enzyme
extreme pH denatures enzyme and changes struct
smaller changes modify behaviour
effect of temp on enzyme
increase temp increases rate of reaction
thermal denature occurs >50 and reaction rate falls
optimal range for humans 30-40
homeostasis
ability of body or cell to seek and maintain condition of equilibrium or stability within its internal environment when dealing with external chnages
positive feedback loop
expands initial stimulus response towards change direction
cell membrane
primary function is barrier
regulates rate of transport into the cell
provides surface for attachment proteins
phospholipid bilayer
- hydrophilic head
- hydrophobic tails
- fluidity
passive transport
simple diffusion
facilitated diffusion
osmosis
filtration
simple diffusion
passive movement of molecules from higher to lower conc
water molecules, o2, co2, small uncharged, lipid soluble molecules
facilitated diffusion
transport of substances across a membrane from area higher to lower conc by means of carrier molecule
can be voltage dependent
can be open or shut
osmosis
movement of water from higher water potential to a lower water potential
isotonic solution osmosis
no net movement water
hypotonic solution osmosis
water moves into cell
water potential of solution higher
may cause cell to burst if wall weak or damaged (osmotic lysis)
hypertonic solution osmosis
water moves out of the cell
water potential of solution lower
causes cytoplasm to shrink (plasmolysis)
filtration
movement of water and solutes across membrane due to hydrostatic pressure from cardiovascular system
e.g. nephron in the kidney
filters out water, ions, drugs and urea
higher blood pressure = higher filtration
active transport
bulk transport
- endocytosis
- exocytosis
- phagocytosis
primary active transport
secondary active transport
primary active transport
use of ATP to provide energy for movement against conc gradient
Na+/K+ pump most common
takes Na+ out and K+ into the cell against conc gardient
important to maintain resting membrane potential
secondary active transport
ion conc gradient created by primary active transport helps to move another substance into the cell
either symporter or antiporter
symporter
movement same direction to ion
antiporter
movement opposite direction to ion
bomb calorimetry
burn something in oxygen atmosphere
measure temp change of water due to combustion and determine how much energy released
steps of bomb calorimetry
- weigh the sample
- place sample in bomb
- pressurise the bomb with oxygen
- place the water in calorimeter
- calorimeter into insulated bucket and bomb connected to electrodes and then fully submerged in the water
- leave for about five mins until steady temp reached
- fire
8.watch temp change and record every 30 secs until steady
ATP
composed of adenine, ribose and phosphate
energy release when phosphate bond is broken
exergonic reaction and hydrolysis
cannot be accumulated or transferred from cell to cell
cells die if no more ATP generated
maintenance of ATP/ADP conc ratio in cells usually takes precedence over cell function
50:1
ATP:ADP ratio
50:1
energy released by hydrolysis of ATP
liberated for muscle contraction
7.3 Kcal per mol
catalysed by ATPase or adenosine triphosphatase
ATP formation from ADP
2ADP ->ATP + AMP
catalysed by adenylate kinase
more energy in one ATP than two ADPs
ATP splitting
ATP hydrolysis doesn’t require oxygen
energy rapidly available
transport of atmospheric 02 to cites of requirement is long process so would impair immediate energy source
ATP storage and use
ATP heavy compound so limited stored at a time
80-100g of ATP at any time
at exhaustion not ran out of ATP
rapid re synthesis essential to allow normal functioning
replenishment sites present in mitochondria (aerobic) and cystol (anaerobic)
PCr
instant replenishment of ATP achieved by high energy phosphate phosphocreatine
mediated by creatine kinase enzyme
cells store about 18 mmol per kg of muscle
PCr theoretically depleted within about 8-12 secs
provides energy ‘buffer’ while longer term energy pathways ‘getting going’
mass
amount of matter in an object (g/kg)
weight
product of mass and gravity on earth (N)
1kg = 9.81 N
density
mass per unit of material substance
mass / vol g/cm^3
molecules
two atoms of the same element
compound
two atoms of different elements
free radicals
charged atoms or group with unpaired electron in outmost shell
highly reactive
unstable
enthalpy change (∆H )
change in energy of the reactants when turned into products
measured as total heat energy change
negative delta H = exergonic
positive delta H = endergonic
entropy change (∆s)
measure of energy dispersal
energy wants to spread from conc to spread out
feasible when delta s > 0
free energy change (∆G)
max energy available from reaction that can be harnessed to be useful
energy released ∆G<0 and exergonic reaction
∆G>0 not feasible
∆G = ∆H-T∆s
enzymes in redox reactions
dehydrogenases (removal of H)
oxidases (removal of O)
coenzymes
less specific than enzymes
temporary carriers
reversible electron and hydrogen acceptors
NAD+
FAD
some created in liver
transamination
transfer of amino group from an amino acid to an alpha-ketoacid in presence of a transaminase
important for production of non-essential amino acids
often include use of glutamate
deamination
removal of ammonia group
amino acid forms alpha keto-acid and ammonia
glutamine synthesis
from glutamate
has 2 nitrogens
gluconeogenic precursor -> enables net synthesis of glucose
nitrogen excretion
catabolic (breaking down)
removes nitrogen via ammonia in purine nucleotide cycle
ammonia is toxic
ammonia -> urea -> urine -> excreted
proteins
contain amino acids
joined by peptide bonds
peptides 2-10 amino acids
every protein has function
no storage
functions of proteins
enzymes
cell membrane transporters and receptors
transport and signal
structure of cell, muscle, bones and connective tissue
regulatory function: immune system and hormones
primary struct proteins
how amino acids are linked
the amino acid sequence
secondary struct proteins
backbone torsion angles in amino acid residues due to hydrogen bonds
tertiary struct proteins
coordinates of all the atoms in the protein
quaternary struct proteins
position and orientation of all proteins in a complex
causes changes in protein struct
temperature
pH
enzymatic action
temp changing protein struct
increase kinetic energy breaks hydrogen bonds denaturing proteins
pH changing protein struct
causes ionic and hydrogen bonds to break
enzymatic action changing protein struct
remove unwanted and ineffective part of amino acid chain
non essential amino acids
can be made in the body
essential amino acids
need to be taken in via diet
extraction of energy from glucose through
glycolysis
TCA cycle
oxidative phosphorylation
glycolysis
start product glucose or glycogen
takes place in cytoplasm
aerobic glycolysis -> pyruvate
anaerobic glycolysis -> lactate
requires glucose, enzymes, NAD+, ATP , ADP
produces pyruvate, NADH, ATP
lactate
produced all the time
rate of glycolysis faster than subsequent stages of CHO metabolism
high metabolic rate NADH high and NAD+ low
favours conversion of pyruvate to lactate
NAD+ produced helps maintain glycolytic rate
beta oxidation
occurs in mitochondria
2c fragments removed from carboxyl end of fatty acid
rate limiting enzymes
lipoprotein lipase
breaks down TAG to take it up into tissue
hormone sensitive lipase
breaks down TAG within tissue
adipose tissue
not h2o soluble
break down TAG ->glycerol -> gluconeogenesis process -> glucose
fatty acids -> ketogenesis -> ketones
endogenous
in the body
exogenous
external from the body from food digested
adipose tissue
TAG - main storage form
9Kcal per gram
5Kg adipose same as 31Kg glycogen
specialist tissue
unlimited storage
mobilisation of stored TAG and oxidation of FFA
- release of FFA from TAG
- alpha- oxidation of FFA (branched chain FFA only)
- beta- oxidation of FFA -> TCA cycle + ETC ->ATP
release FFA from TAG
- lipolysis
- fate of glycerol
- fate of FFA
lipolysis
hormone sensitive lipase
triglyceride lipase -> removes 1st fatty acid
diglyceride lipase -> remove 2nd fatty acid
monoglyceride lipase -> remove 3rd
creates 3 FFA + glycerol
fate of glycerol
not used in adipose
glycerol phosphate
dihydroxyacetone phosphate
glucose glyceraldehyde
fate of FFA
FFA move out and bind to Albumin
carried to tissues
transport across membrane by fatty acid binging proteins
branched chain FFA undergo alpha oxidation
coA derivatives
phospholipids
component of cell membrane
a diglyceride (2 fatty acids)
hydrophobic fatty acid
hydrophilic phosphate
function of lipids
maintain functional and structural integrity of cell membrane
surfactant - reduce surface tension from breathing and prevent lungs from collapsing
provide insulation and protection to organs
hormone and neurotransmitter action
sterols
found naturally in foods
compound with multiple ring structure
synthesis of steroid hormones and vitamin D
FFA
free fatty acids
even numbers of carbons (4-28)
carboxyl group and methyl group either end
hydrogen, carbon and oxygen
classification by no carbons, double bonds and location of first double bond
no of carbons FFA
short chain -> less than 8
medium chain -> 8-14
long chain -> 16-28
cis- fat molecule
hydrogens on same side of double bond
found in nature
trans- fat molecule
hydrogens on opposite side of double bond
milk and butter
hydrogenation
removes double bond
protects from oxidation
texture
polyunsaturated act like saturated
triglycerides (TAG)
1 glycerol and 3 fatty acids
95% of all dietary lipids
storage in form of adipose tissue
9 Kcal per gram
1kg = 7000 Kcal
role and function of triglycerides
energy -> muscle contraction
insulation -> TAG is a poor conductor
protection -> vital organs
spare other fuels -> carbs sparing
carbohydrate
carbon, hydrogen and oxygen
monosaccharide, disaccharide and polysaccharide
carbonyl group (CHO)
glycosidic bonds
blood glucose
normal conc 3-5 mmol/L (euglycemia)
regulated by hormones
primary cerebral fuel
glucogenesis
formation of glycogen from sugar molecules
gluconeogenesis
formation of glycogen from amino acids, fats and other noncarbohydrates
glycogenolysis
breakdown of glycogen into glucose
catalysed by enzyme glycogen phosphorylase
how to generate ATP
PCr
glycolysis
oxidative phosphorylation
PCr in generating ATP
low capacity
max rate achieved in seconds
glycolysis in generating ATP
intermediate capacity
intermediate rate
oxidative phosphorylation in generating ATP
high capacity
low rate, max rate achieved in 1-3 mins
ATP synthesis in cystol
glycolysis
PCr hydrolysis
ATP synthesis in mitochondrion
TCA cycle, oxidative phosphorylation and beta- oxidation
