Unit 1 Flashcards
proteomics is
study of the proteome
proteome is
entire set of proteins expressed by genome
what is larger proteome or genome and why
proteome because of alternative splicing and post translational modification
types of RNA
rRNA mRNA tRNA non coding RNA
transcriptome
all mRNA molecules produced by genome
how to find out transcriptome
microarray analysis
amino acids are made of
carboxyl group, hydrogen, carbon, amine group, R group
environmental factors that affect protein shape and function
ph and temperature
binding of proteins cause a ____ change which can consequently change the function. this can/cannot be reversible
conformational , can
when binding, shapes must be ______
complementary
primary structure
order in which amino acids are synthesised into amine polypeptides
types of secondary structure
alpha helix, beta sheets, turns, hydrogen bonds between atoms of same chain
alpha helix
spiral, r groups sticking out
beta sheets
running alongside each other, can be antiparallel or parallel
what determines whether beta sheet is parallel or antiparallel
N and C terminus. if they are at opposite termini then they are parallel
turns
reverse the direction of the polypeptide chain
tertiary structure
R GROUPS. folding and shape depends on these. bonding can influence folding- ionic, disulphide, hydrogen, van Der Waals, add prosthetic group eg haem
quartenary structure
links subunits (polypeptide chains) together
ionic bonds are
electrostatic
hydrogen bonds are
electromagnetic
disulphide bonds are
covalent
folding can hide the ____ R groups and have the _____ R groups on the outside
hydrophobic, hydrophilic
how are peripheral proteins held in place
charged or polar amino acids or hydrophobic interactions
how are integral proteins held in place
hydrophobic interactions
integral proteins
some transmembrane- channels, transporters, some not
fluid mosaic model is
membrane. phospholipid bilayer- moves around a lot, mosaic because of integral proteins, peripheral proteins
phospholipid bilayer has
hydrophilic polar head, hydrophobic non polar tail
ligands are
substances that can bind to a protein
what allows substances to bind to proteins
R groups and complementary binding sites
DNA binds to proteins a lot. Name one protein it binds to
histones
what part of DNA binds to protein
sugar phosphate backbone because negatively charged
DNA wraps around histones to form
nucleosomes
what environmental factors affect ligands
ph and temp
cooperativity
binding increases affinity of remaining sites
allosteric enzymes
modulators bind at secondary site, changing affinity of active site (increase or decrease)
phosphorylation
addition or removal of phosphate from R groups which causes a reversible conformational change
phosphorylation is a type of ___ _______ ______
post translation modification
phosphorylation regulates ____/_____ activity
enzyme/ receptor
which enzyme catalyses dephosphorylation
phosphatase
which enzyme catalyses phosphorylation
kinase
what enzyme uses ATP for phosphorylation
ATPases
water channels
aquaporins
facilitated transport
involves conformational change. does not require energy
transmembrane proteins function
control the concentration of ions and other molecules within the cell
voltage gated channels
controlled by changes in ion concentration.
ligand gated channels
neurotransmitters required to open binds to receptor site
active transport
conformational change requires energy from hydrolysis of ATP
sodium potassium pump
3 Na out 2 K in. phosphorylation of ADP + Pi uses active transport
glucose uses ____ to transport
facilitated transport
signal transductions
receptor proteins convert extracellular chemical signals to specific intracellular response
signal transductions can (3)
activate proteins that regulate gene transcription, rearrange cytoskeleton, change uptake/secretion of molecules
G proteins
transmits signals from outside to inside the cell
G proteins are active by
GTP
G proteins are inactivated by
GDP
sodium potassium pump is used for (4)
maintaining osmotic balance, glucose symport, resting potential neurons, ion gradient for kidney tubules
glucose symport
sodium and glucose in. glucose against conc gradient so need energy from sodium going down gradient
membrane potential
electrical potential difference (voltage) across plasma membrane
resting potential value
-70mV
minus sign for voltage means
inside of cell is negative relative to outside
the resting potential is generated and maintained by
sodium potassium pump
nerve transmission is
a wave of depolarisation of resting potential
depolarisation is stimulated by
neurotransmitter opening ligand gated ion channels, causing resting potential to increase and action potential to begin
order of action potential
neurotransmitters act as ligand and open ligand gated channel, allows ions to enter and voltage increases, voltage gated channels open, wave of depolarisation, wave passes, channels close, restore resting potential
depolarised value
40mV
polarised
more K+ inside. negative membrane potential
graded potential
small change
action potential
big change
graph of action potential
depolarisation, repolarisation, hyperpolarisation
refractory period
axon can’t respond to any other stimulus
rod cells
changes due to light intensity, longer than cones, very sensitive to light
cone cells
less sensitive to light, absorb different wavelengths of light, colours
rhodopsin
combination of retinal and opsin
photoreceptor proteins are
light sensitive and sense and respond to light
how rhodopsin reacts to photon of light
becomes excited, nerve impulse generated, G protein activated, enzymes activated, ion channels close, sodium leak inward, membrane potential increases, hyper polarisation stimulates nerve impulse
communication between cells caused by
extracellular signalling molecules, receptors and responses
receptor molecules are
on target cells and have binding site for signalling molecule,
the signals are s____
specific for specific receptors
signal transduction occurs when
signalling molecules bind to and activates specific receptor which is on surface or within cell
hydrophobic signalling molecules can/cannot pass through membrane
can
examples of hydrophobic signalling molecules
steroid hormones eg oestrogen and testosterone and thyroxine
hydrophilic signalling molecules can/cannot pass through membrane
cannot but signal can be transduced
the binding of insulin triggers
GLUT4 glucose transporters to cell membrane of fat and muscle cells and this facilitates uptake of glucose into cells
type 1 diabetes
due to lack of insulin production
type 2 diabetes
due to loss of insulin receptor proteins. exercise triggers GLUt4 too so can help
Cytoskeleton is made of
Proteins. Microfilaments, microtubules, intermediate filaments
Cytoskeleton is
Network of proteins extending throughout cytoplasm constantly breaking down and reforming
Function of cytoskeleton
Provide mechanical support
Provide anchorage for organelles
Enable whole cell to move
Enable organelles within cell to move
Microtubules are
Hollow, straight cylinders made of tubulins
Types of tubulin
Alpha and beta
Tubulin governs…
Location and movement of membrane bound organelles
Microtubules originate from
Microtubules organising centre MTOC in centrosome
Spindle fibres are formed by
Microtubules
Cell cycle order
M
G1
S
G2
Decreasing rate of cell cycle causes
Degenerative diseases
G1 phase
Growth phase where proteins are synthesised
S phase
Cell continues to grow and copies chromosomes in preparation for mitosis
G2
Growth phase where proteins are synthesised
M phase
2 part- mitosis and cytokinesis
Parts of mitosis
PMAT prophase Metaphase Anaphase Telophase
First part of cell cycle is collectively called
Interphase
Spindle fibres join to ____ to pull apart chromatids
Kinetochore
Cytokinesis
Separation of cytoplasm into daughter cells
G1 checkpoint
Occurs at end of G1 and checks for sufficient growth and other conditions satisfied
If don’t pass G1
G0 phase which is non dividing phase
S phase checkpoint
None
G2 checkpoint
Occurs at end of G2 DNA replication must be completed
M phase checkpoint
Occurs during metaphase and controls entry to anaphase. Checks chromosomes are aligned correctly and ensure each daughter cell receive correct number of chromosomes
CDKs are
Cyclin dependant kinases. Cause phosphorylation of proteins that stimulate cell cycle if enough phosphorylation is reached, can proceed
Types of regulatory proteins
Retinoblastoma Rb and P53
Retinoblastoma
If non phosphorylation then restricts progression from G1 to S phase. Phosphorylation inhibits Rb activity so it can no longer bind to transcription factor so transcription factor is released and genes are trans opted for S phase to begin
P53
Repairs, arrests or causes cell death.
Is there if DNA damage or cell damage
If mutation in p53
Cancer
Apoptosis is
Destruction of cells. Programmed cell death
Death signals results in activation of enzymes called
DNAases and Proteinases (caspases)
DNAases
Catalyse breakdown of DNA
proteinases
Bring about degradation of cellular proteins
Fragments at end of apoptosis are
Engulfed by phagocytes
Extrinsic death signals
Lymphocytes can express death activator ligand called Fas which activated protein cascade that introduces caspases and causes apoptosis
Intrinsic death signal
DNA damage
Receptor proteins for steroid hormones
Transcription factors
What happens to receptor protein when a signal molecule binds
G protein activation
Enzyme activation
Ion channels close
Role of ligand gated ion channels in transmission of nerve impulses
Neurotransmitter triggers opening of ligand gated ion channels, if sufficient ion movement occurs then voltage gated ion channels open and this triggers sequence of voltage gated channels to open and a wave of depolarisation.
Intracellular responses as a result of signal transduction
Activation of enzyme
Activation of G protein
Change in uptake or secretion of molecules
Rearrangement of cytoskeleton
Steroid hormones are hydrophobic/hydrophilic
Hydrophobic
Insulin is hydrophilic/hydrophobic and steroid/ peptide
Hydrophilic and peptide
Tubulin is integral/ globular
Globular
types of amino acid
acidic, basic, polar, hydrophobic
r group of acidic amino acid
carboxylic acid COOH
r group of basic amino acid
amine group NH2
r group of polar amino acid
hydroxide group OH
r group of hydrophobic amino acid
hydrocarbon CH (benzene ring)
acidic amino acids are what charge
negatively
basic amino acids are what charge
positive
polar amino acids are what charge
slightly charged and hydrophilic
hydrophobic amino acids are what
non polar
peptide bonds are formed by what reaction
condensation H20 is removed
what does peptide bond look like
N-H- C=0