Unit 1 Flashcards
What are allosteric enzymes?
Enzymes which change conformation in response to a modulator.
What is an alpha helix?
A polypeptide chain coiled into a helix with hydrogen bonding occurring to maintain the arrangement.
What is alternative RNA splicing?
Removal of non-coding introns from a primary mRNA transcript to leave only the coding exons. Several mature transcripts can be produced from a single primary transcript.
What is an antibody?
A Y-shaped globular protein with specificity to an antigen.
What are aseptic techniques?
Procedures in place to prevent contamination including sterilisation of equipment and work surfaces.
What are beta sheets?
Polypeptide chain arranged in rows with the chain coiling in parallel or anti-parallel arrangements.
What is a buffer?
Used to set and maintain a particular pH.
What is the caspase cascade?
Caspase proteins are involved in a series of reactions (a cascade) which destroy a cell.
What are cell cycle checkpoints?
Checkpoints which assess the readiness of a cell to enter the next stage of the cell cycle. They occur during G1, G2 and Metaphase.
What is a centrifuge?
Apparatus which spins very quickly to separate materials due to their density - heavier components move to the bottom of the tube.
What is a centrosome?
Microtubules radiate from the Centrosome and are active during cell division as microtubules form the spindle fibres.
What is chromatography?
Has a stationary phase (e.g. paper or gel) which the mobile phase (e.g. a solvent) moves through carrying the substance being examined - different distances moved by substances of different solubility.
What is cooperativity in proteins?
Proteins composed of several polypeptides (subunits) can show cooperativity. Changes in binding of one subunit give the other subunits a greater affinity for the molecule.
For example, binding of oxygen to one haemoglobin subunit gives the other subunits a greater affinity for oxygen.
What is cyclic GMP (cGMP)?
Molecule that is broken down by phosphodiesterase in retinal cells. Reduction in the concentration of cGMP causes ion channels to close which triggers a nerve impulse in the neurons in the retina.
What are cyclins?
Proteins that control the progression of cells through the cell cycle by activating cyclin-dependent kinase (CDK) enzymes
Cyclins are essential for regulating the cell cycle and ensuring proper cell division.
What is the function of cyclin-dependent kinases (CDKs)?
Cause the phosphorylation of proteins which stimulate the cell cycle when activated by cyclin
CDKs are crucial for the progression of the cell cycle and are activated at specific points.
Define cytoskeleton.
A microscopic network of protein filaments and tubules in the cytoplasm that supports cell shape and function
The cytoskeleton is involved in various cellular processes including movement and division.
What is cytosol?
The liquid part of the cytoplasm which contains the components of the cytoskeleton and in which the cell’s organelles are suspended
Cytosol plays a key role in cellular metabolism and the transport of materials.
What is depolarization?
A reduction in the difference of electrical potential across the plasma membrane of a nerve or muscle cell
Depolarization is critical for the generation and propagation of action potentials in neurons.
What is diabetes?
Inability to regulate blood glucose levels
There are two main types: Type 1 (failure to produce insulin) and Type 2 (loss of function of insulin receptors on cell surface).
What is the endoplasmic reticulum (ER)?
Network of membrane tubules continuous with the nuclear membrane, site of protein synthesis and modification
The ER is divided into Rough ER (with ribosomes) and Smooth ER (lipid synthesis).
What distinguishes Rough ER from Smooth ER?
Rough ER has ribosomes on its surface; Smooth ER synthesizes lipids
Rough ER is involved in protein synthesis while Smooth ER is involved in lipid production and detoxification.
Define G-Protein.
Guanine nucleotide-binding proteins that act as molecular switches inside cells
G-Proteins are involved in transmitting signals from a variety of stimuli outside a cell to its interior.
What are Gated Channels?
Channel forming proteins controlled by signalling molecules or ion concentration
Gated channels play a critical role in maintaining the cell’s ion balance and in signal transduction.
What is gel electrophoresis used for?
To separate samples of nucleic acid and protein by size
In gel electrophoresis, smaller fragments move further than larger fragments due to an electric current.
What is a genome?
The complete set of genes or genetic material present in a cell or organism
The genome contains all the information needed for the growth, development, and function of an organism.
What is GLUT4?
The insulin-regulated glucose transporter
Insulin triggers the movement of GLUT4 transporters to the membrane surface, increasing glucose uptake.
What is the Golgi apparatus responsible for?
Post-translational modification of proteins
The Golgi apparatus processes and packages proteins for secretion or use within the cell.
What is a haemocytometer used for?
To estimate the total number of cells within a sample
Originally used to count the number of blood cells, it provides a manual method of cell counting.
What does ‘Hazard’ refer to?
Anything that poses a potential risk or threat to an individual or the environment.
What does ‘Hydrophilic’ mean?
From the Greek meaning water loving. Having a strong affinity for water.
What are ‘Hydrophilic signals’?
Signalling molecules which are not able to pass through the membrane and must have receptor molecules on the cell surface. The signal is transduced across the membrane.
What does ‘Hydrophobic’ mean?
Literally means ‘water-fearing’. The tendency of nonpolar substances to aggregate in aqueous solution and exclude water molecules.
What are ‘Hydrophobic signals’?
Signalling molecules which can diffuse through membranes so their receptor molecules can be within the nucleus.
What is an ‘immunoassay’?
Uses antibodies linked with reporter enzymes to cause a colour change in the presence of a specific antigen.
What is ‘Induced fit’?
Model to describe the action of enzymes. When the substrate binds to the enzyme’s active site, there is a temporary conformational change to the enzyme which increases binding and interaction with the substrate, lowering the activation energy required for the reaction.
What is ‘Inoculum’?
The starting material used to grow a culture from, e.g., bacterial culture.
What is ‘Interphase’?
The phase of the cell cycle in which the cell spends the majority of its time. In preparation for cellular division, it increases in size and DNA replication occurs.
What are the stages of Interphase?
G1 - Initial growth phase of the cell including production of more cell organelles.
S - Cell growth continues, and replication of chromosomes occurs.
G2 - Assessment of DNA replication and final preparations for Mitosis.
What is the ‘Iso-electric point’?
The specific pH at which a soluble protein has no net charge and will precipitate out of a solution.
What does ‘Kinase’ do?
Catalyses the transfer of a phosphate group from a donor molecule (usually ATP) to an acceptor.
What is a ‘Ligand’?
A substance which can bind to a protein, e.g., hormones. The protein has a shape complementary to the ligand to allow binding to occur.
What is a ‘Lysosome’?
Membrane-bound organelles containing a variety of hydrolases that digest proteins, lipids, nucleic acids, and carbohydrates.
What is ‘M Phase’?
Division of the nucleus and division of the cell itself.
What are microtubules?
They are composed of hollow straight rods made of globular proteins called tubulins that govern the location and movement of membrane-bound organelles and other cell components.
What is Na/K ATPase?
The enzyme which acts as the Sodium/Potassium pump which removes 3 Sodium ions from the cell and takes 2 Potassium ions into the cell.
What are native gels?
Gels used in electrophoresis that do not denature the molecule, so the proteins are separated by size, charge, and shape.
What is the function of the p53 protein?
Protein which can activate a Caspase cascade.
What is a phosphatase?
An enzyme that removes a phosphate group from its substrate.
What is phosphodiesterase (PDE)?
Enzyme activated by G-proteins that catalyses the hydrolysis of CGMP.
What is phosphorylation?
The addition of a phosphate group to a protein or other organic molecule.
What is post-translational modification?
Addition of different chemical groups to or modification of a protein to allow a particular function.
What is a prosthetic group?
Non-protein unit tightly bound to a protein and necessary for its function.
What is protein structure?
The different levels of arrangement of polypeptides within a protein.
What are the levels of protein structure?
Primary - The sequence in which the amino acids are found within a protein.
Secondary - Hydrogen bonding occurring within a polypeptide forming alpha helices or beta pleated sheets.
Tertiary - Bonding of many types occurring between the R-groups of amino acids within a protein.
Quaternary - The arrangement of multiple folded polypeptides connected together.
What is proteolytic cleavage?
Post-translational modification whereby proteins are cut to activate them.
What is a proteome?
The entire set of proteins expressed by a genome (proteome much larger than genome).
What is mitosis?
Division of the nucleus to form 2 new nuclei, each with a full complement of chromosomes.
What is cytokinesis?
Division of cytoplasm to form 2 daughter cells.
What is an R-group?
A variable group in amino acids that provides the ability for different bonding between them.
What is resting potential?
The difference in ion concentration maintained by a neurone between the inside and outside of the cell.
What is retinal?
A light-sensitive molecule in the eye that binds to opsin to form photoreceptors.
What is retinoblastoma (Rb)?
A tumour suppressor protein that prevents excessive cell growth by inhibiting cell cycle progression until a cell is ready to divide.
What is SDS-PAGE?
A type of gel electrophoresis that denatures molecules and separates them by size alone.
What is signal transduction?
The conversion of extracellular signals to an intracellular response in a cell.
What is symport?
An integral membrane protein that simultaneously transports two substances across a membrane in the same direction.
What is a synapse?
A structure that allows a neurone to pass a signal to another neurone or another cell.
What is a transcription factor?
A protein that binds to specific DNA sequences, controlling the rate of transcription from DNA to messenger RNA.
What does transmembrane refer to?
Proteins that span a membrane and act as channels or transporters of ions.
What is turbidity?
The cloudiness or haziness of a fluid caused by large numbers of individual particles that are generally invisible to the naked eye.
What are vesicles?
Small membrane-bound sacs within the cytoplasm that transport materials between membrane compartments.
What is vital staining?
A technique using a harmless dye to stain living tissue for microscopical observation.
Afinity
The degree to which a substance tends to combine with another
modulators
These bind to a secondary site on an enzyme to alter its conformation. They can be positive modulators to activate the enzyme or negative modulators to deactivate it.
