T1 Cells and Molecules Flashcards
How can peripheral proteins be removed from a cell membrane?
Salt solutions to disrupt ionic bonds, detergent or phospholipases
How many columns of tubulin polymer are arranged together to form a microtubule?
13
What is spectrin?
A cytoskeletal protein that lines the intracellular side of the plasma membranes. Spectrin helps maintain plasma membrane integrity and cytoskeletal structure
What may be raised in the blood due to tissue damage?
ALT, troponin, CK
Which way will kinesin move along a microtubule?
In the positive direction
What is the smallest size resolvable by a light microscope?
200 nm
What is normal blood volume?
5L
What is the diameter of an actin filament?
7 nm
Describe linolenic acid.
Essential fatty acid C18:3, omega 3
What is sphingomyelin?
A phospholipid which has no glycerol backbone
How many actin subunits are there per turn of the double helix?
13
Which amino acid is a precursor of adrenaline and dopamine?
Tyrosine
What can inhibit acetylcholine esterase reversibly?
Neostigmine
What causes Creutzfeldt Jakob Disease?
A prion, an infectious pathogen, converts the body’s proteins from normal form to pathogenic form by forming B sheets where there were a-helixes
What size are mitochondria?
About 1 um
What shape is the curve in allosteric enzyme control?
Sigmoid
What kind of saccharide is galactose?
Monosaccharide
What are amyloid proteins?
Stable proteins which aggregate to form plaque s
Which enzyme is defective in phenylketonuria, what does this enzyme do?
Phenylalanine hydroxylase, converts phenylalanine –> tyrosine
Which organelle does myoclonic epilepsy with ragged red fibres affect?
Mitochondria
What happens in Alzheimer’s?
Microtubule associated protein, Tau, is hyperphosphorylated and forms neurofibrillary tangles
What do lyases do?
Catalyse cleavage of C-C, C-O or C-N bonds
What are lamellipodia?
Exploratory processes formed by actin and intergrins
What kind of protein is GABA-A?
Membrane ion channel
Is valine polar or non polar?
Non polar
Which neurotransmitter is formed from tryptophan?
Serotoninin
What is allosteric control of enzymes affected by?
The end product
What is the Michealis Menton equation?
Vo = Vmax [S]/ Km + [S]
What kind of enzyme is lactate dehydrogenase?
An oxoreductase
How does DNA compare to RNA?
It has one fewer O2 in each pentose sugar than RNA
Is tryptophan polar or non polar?
Non polar
What is the diameter of a microtubule?
25 nm
What size are perixisomes?
0.5-1.5 um
Which amino acid acts as a neurotransmitter?
Glutamate
What kind of enzyme is tryspin?
Hydrolase
How many rings does cholesterol have?
4
What is an amphipathic constituent of cell membranes?
Glycolipids
What enzyme class do kinases fall into?
Transferase
Which subunits polymerise to form microtubules?
Alpha and beta tubulin
Which way will dynein move along a microtubule?
In the negative direction
How can we describe stearic acid?
C18:0 a saturated fatty acid
Name an intermediate filament disease.
Epidermolysis bullosa symplex
What are the cofactors for cytochrome oxidase?
Cu2+ and Fe2+/3+
How does cell movement occur?
When actin filaments polymerise and depolymerise rapidly
How thick are cell membranes?
5 nm
Name two microtubule diseases.
Alzheimers and hereditary spastic paraplegia
What is a normal size for a bacterium?
1 um
What are the cofactors for glutathione peroxidase?
Se2+
What is the structure of actin?
Double helix
What is Kcat?
The turnover number, equivalent to the number of substrate molecules converted to product in a unit of time on a single enzyme molecule saturated with substrate
How can anchored proteins be removed from a cell membrane?
Phospholipases only
What are the cofactors for carbonic anhydrase?
Zn2+
What does taxol do?
Stabilise microtubules
Describe myoclonic epilepsy with ragged red fibres (MERRF)
Mutation of mitochondrial gene for tRNA-lys, disruption of enzymes for oxidative phosphorylation
What is a normal size for a virus?
50 nm
Describe palmitic acid.
Saturated fatty acid C16:0
What is a normal size for a human cell?
30 um
Which neurotransmitter is formed from histidine?
Histamine
What joins intermediate filaments to actin and microtubules?
Plectin
What charge does the R-group of lysine have?
+
What are some characteristics of Creutzfeldt Jakob Disease?
Inital symptoms: difficulty walking, slurred speech, dizzy, numb, vision issues, severe depression, anxiety, withdrawal, irritable, insomnia eventually fatal
What is another name for tocopherol?
Vitamin E
What is Km?
Km= k2+ (k-1) / k1 And it represents the affinity of an enzyme for substrate when K2 is negligible
What charge does the R-group of glutamate have?
-
When is tyrosine present in low levels and phenylalanine present in high levels?
In phenylketonuria
Describe linoleic acid.
Essential fatty acid C18:2, omega 6
Which enzyme is Ni+ a cofactor for?
Urease
What do pathogenic prions polymerise to form?
Fibrils
How big is the nucleus?
3-10um
What is chromatin?
A complex of DNA, histones and non-histone proteins in nucleus
What is F-actin a polymer of? (filament actin)
G-actin (globular actin)
What may fibrin have a high proportion of?
B-pleated sheets
What divides the cell into different functional compartments?
Cellular organelles
What lowers Vmax?
Non competitive inhibitors
How does the drug colchicine prevent cell division?
Inhibits microtubule polymerisation by binding to tubulin
What does polymerisation of actin filaments require?
ATP to be bound to actin filament
What is produced when you combine glucose and fructose?
Sucrose
Which way are collagen helices?
Left handed
What increases Km?
Competitive inhibitors
How are intermediate filaments formed?
From tetramers linked in a staggered manner
How do lamellipodia or filopodia attach to the extracellular matrix?
Through the formation of focal adhesions
What is Fick’s law?
That the maximum size of a cell is limited by rate of diffusion across membrane
What are cilia movements associated with?
Microtubules and dynein
What is the Lineweaver-Burk plot?
The inverse of Michealis Menton
What kind of secondary structure do fibrillar proteins have?
B- pleated sheets
Where are phospholipids synthesised?
Perioxisomes
What happens to axons lacking in intermediate filaments?
They are reduced in diameter
What are the cofactors for pyruvate kinase?
Mg2+ and K+
Describe Tay-Sachs disease.
Mutation of lysosomal hexosamidase-A enzyme. Causes accumulation of ganglioside which is pathogenic
What kind of molecule is cholesterol?
Amphipathic
What do dyenin and kinesin do?
Associated with movement of vesicles along microtubules
How do listeria bacteria spread between cells?
By causing actin to polymerise behind the bacteria
What does phospholipase C do?
Cleaves the bond within phospholipids between glycerol molecule and phosphate group
What binds to microtubule monomers when it is assembled?
GTP
What does oxidation of tyrosine produce?
Melanin
Where does ribosomal subunit assembly occur?
The nucleolus
Where are lipids and steroids synthesised in the cell?
Smooth endoplasmic reticulum
What charge does the R-group of arginine have?
+
Name two actin associated diseases, which protein is each associated with?
Duchenne or Becker muscular dystrophy- dystrophin
Usher’s disease- Myosin VII
Where are sterocilia found, how do they work?
In the ear, the cells are depolarised or hyperpolarised by deflections caused by sound. Actin filaments keep the sterocilia stable
When does Km= [S]?
When Vo = 1/2 Vmax
What supports the shape of microvilli?
Bundles of actin filaments
What do peroxisomes do?
Breakdown long chain or branched fatty acids and amino acids
What do colchcine and vinblastine do?
Destabilise microtubules
Is rate of diffusion proportional to distance to diffuse?
No
When are hexoses labelled alpha?
When the -OH group falls below the anomeric carbon
Which organelle does Hutchinson-Gilford progeria effect?
Cell nucleus
What does amphiphatic mean?
Both hydrophilic and hydrophobic
Where is 1/Vmax on the Lineweaver Burk plot?
At the intercept of the y-axis
What enzyme class do dehydrogenases fall into?
Oxoreductase
What enzyme class do lipase and sucrose fall into?
Hydrolases
Which amino acid is necessary for skin pigmentation?
Tyrosine
What is profilin?
An actin sequestering protein
What is the smallest size resolvable by an electron microscope?
0.2 nm
Which organelle does Zellweger syndrome affect?
Perixisomes
What is the Golgi?
A structure with cis and trans faces which creates lysosomes as well as packaging proteins from the endoplasmic reticulum
What is ankyrin?
Ankyrins are a family of adaptor proteins that mediate the attachment of integral membrane proteins to the spectrin-actin based membrane cytoskeleton
What size are lysosomes?
80-800 nm
How does Oubain work?
It is a cardiac glycoside which inhibits Na+/K+ATPase so there is a higher concentration of Na+ inside the cell. this inhibits Na+/Ca+ so less Ca2+ is pumped out and intracellular Ca2+ increases
What kind of protein is Ras?
Anchored membrane protein
What is the cytoskeleton made of?
Actin, intermediate filaments, microtubules
Which organelle does Tay-Sachs disease effect?
Lysosomes
What are the 4 classes of phospholipase and what do they do?
PLA1 and PLA2- break ester bonds between fatty acid and glycerol.
PLC- breaks phosphate to glycerol bond
PLD- breaks bond of polar group to phosphate
What is transgelin?
A cross linking protein which binds actin
Which enzyme is deficient in lactose intolerance?
Lactase or B-galactosidae
Which enzyme is Mg+ a cofactor for?
Hexokinase, G-6-phosphatase, pyruvate kinase
Which neurotransmitters are formed from tyrosine?
Adrenaline, dopamine
Describe Hutchinson-Gilford Progeria.
Mutation in lamin A part of nuclear envelope, distorts shape of nucleus (blebbed) production of unique progerin protein
Name 4 intermediate filaments.
Keratin, vimetin, neurofilamin, glial fibrillary acidic protein
How can intergral proteins be removed from a cell membrane?
Detergent or phospolipases
