Biological Molecules and Cell Biology 2 Flashcards
What is the most important, complex, and diverse group of biological compounds?
Proteins
Name some of the functions of proteins?
Structure, enzymes, Transport, hormones, receptors, antibodies, storage, blood, clotting, toxins, lubrication
What are the levels in protein structure?
Amino acid, dipeptide, polypeptide, protein
What is the amino group in an amino acid structure?
H2N
What is the carboxyl group in a general amino acid structure?
COOH
in a diagram of an amino acid, what does the R mean?
The R group varies in different amino acids
What is the general structure of an amino acid?
A carbon a carbon with four things attached to it: in our group, a carboxyl group, and amino group, and a hydrogen atom
What does a peptide bond look like?
The hydroxyl of one amino acid will bond with the hydrogen of the amino group of another, then the carbon and nitrogen will be attached.
What is a bond between amino acids called?
Peptide bond
What are the four levels of protein structure called?
primary, secondary, tertiary, or quaternary structure
What is the primary structure of a protein?
The sequence of amino acids that makes the polypeptide chain, primary structure determines the ultimate shape of the protein. There are limitless number of combinations.
What is the secondary structure of a protein?
this is the way the primary polypeptide chain folds. Structure is determined by hydrogen bonding between the amino and carboxyl groups of the amino acids. The two key secondary structure is: alpha helix and beta pleated sheet.
What is the alpha helix in secondary structure of a protein?
polypeptides wind into a helix, they are held together by H bonds and a very stable
What is the beta pleated sheet in secondary protein structure?
Chain zigzag forming a pleated sheet, held together by hydrogen bonds
what is the tertiary structure of a protein?
Polypeptide chain (in at secondary structure) is twisted and folded into the complex and very specific 3-D shape. This is the tertiary structure.
It’s held together by disulphide, H and ionic bonds.
What is the quaternary structure of a protein?
some proteins are made of several polypeptide (each with their own tertiary structure) linked together in various ways.
Give a description of the hydrogen bonds in the tertiary structure of proteins?
hydrogen bonds are formed between hydrogen atom from the amine group and one amino acid and electronegative oxygen from the carboxyl group on an adjacent amino acid. Electrons from the hydrogen tend to be attracted to the more positive protons in the oxygen. H, bonds are we can easily broken
give a description of disulphide bonds in the tertiary structure of proteins?
this is a single covalent bond between two sulphur atoms on adjacent cysteine amino acids. This is a very strong bond and difficult to break.
Give a description of ionic bonds in the tertiary structure of proteins?
between any carboxyl and amino acid groups not in a peptide bond, they are easily broken by changes and pH
What is the biochemical test to find out if a substance contains a protein?
Biuret test, add biuret solution to the substance and gently mix if it turns from blue to purple, it contains protein.
Which elements are present in an amino acid?
Nitrogen, oxygen, hydrogen, carbon
What is chromatography?
This is the technique that can be used to distinguish between different biological molecules. It is based off different substances having different solubilities in different solvents
Why would a hydrophilic molecules move less quickly up filterpaper when a solvent is hydrophobic?
Because the solvent repels it, and so the hydrophilic molecules are more attracted to paper.
What is an RF value?
The distance, the molecule moved through the filter paper divided by the distance of the solvent moved through the paper.
Give a method to chromatography?
first, draw a straight line in pencil on filterpaper, then place the dots on the line of paper. Then lower the paper into a beaker with the solvent, just below where the line is.
What is metabolism?
The sum of all the reactions in a cell or a body.
What are enzymes?
Specific biological catalysts, the increase the speed of metabolic reactions. They are proteins with very specific tertiary structures that insure the shape of the active site will be complimentary to the substrate.
What is the active site?
The part of the enzyme that the substrate attaches to
What are enzymes made up from?
Proteins
Why do enzymes need to be folded into a very specific tertiary structure?
Because it insures the shape of the active site is complimentary to the substrate.
What is activation energy?
The amount of energy needed to make a reaction happen. (Break bonds before new bonds can be formed)
In chemistry activation energy is often provided by heating the reaction.
Living organisms cannot do this, what do they have that can lower activation energy?
enzymes lower the activation energy by splitting the reaction into smaller steps and weakening bonds in the substrate
What is formed when a substrate enters an active site?
An enzyme substrate complex.
What are enzymes do to substrates?
they lower activation energy by weakening/distorting bonds in the substrate.
What is turnover number?
The number of substrate molecules turned into product per minute by one molecule of enzyme. It is a measure of speed of the enzyme.
What is the lock and key model of enzymes?
The active site is exactly complimentary to the substrate. The substrate fits into the active site like a key in the lock
What is the induced fit model of enzymes?
The active site is not complimentary to the substrate.
The active site is flexible and changes shape (conformational shape change) as the substrate enters in order to facilitate the reaction. This stresses and distorts the bonds in the substrate.
What factors affect enzyme activity?
Temperature, Enzyme concentration, inhibitors, substrate, concentration, pH
How do you answer exam questions that use the word describe?
Describe the pattern, outline the pattern in all parts of the graph, reference specific data points.
How do you answer exam questions that use the word explain?
Make a point, Use a linking word like therefore, Follow with scientific explanation
What does increasing temperature mean for an enzyme?
An increase in kinetic energy, this means the enzyme and substrate spell collide, more frequently, and more enzyme substrate complexes will form.
What happens when the temperature is too high and goes above and enzymes optimum temperature?
The enzyme begins to denature, this means the active site is no longer complimentary to the substrate. (Due to the change in tertiary structure, because the H bonds and ionic bonds have been broken down). This means fewer ES complexes can be formed.
how do you measure how well an enzyme is working?
Measure the rate of chemical reaction
What are the two ways to measure rate of reaction?
Measure how quickly reactants are used up, or measure how quickly products are formed
what is the formula for rate of reaction?
rate of reaction= changing amount of reactant or product/ time taken for change
how do you figure out the rate of reaction for a curved graph?
Draw a tangent, make a triangle from it, take the concentration off of the time
How do you workout rate of reaction for a straight line graph?
Draw a triangle, take away the concentration shown from the time
What happens if an enzyme does not have the optimum pH?
The intermolecular bonds (H and ionic bonds) in the proteins tertiary structure are disrupted. Discord is the active site to change shape so it’s no longer complimentary to the substrate. No E S. Complexes
What is substrate Concentration?
The amount of substrate present that can be turned into product in a given volume
How is substrate concentration often measured?
Molarity
What are inhibitors?
Chemicals that slow or stop an enzyme from working
What are the two types of inhibitors?
Competitive and non-competitive inhibitors
What does a competitive inhibitor do?
it binds to the enzymes active site and slows down the process, it has a similar shape/tertiary structure to the substrate. Eight forms and inhibitors enzyme complex and stops. Enzyme substrate complex is being formed.
how can you overcome competitive inhibitors?
Is a higher substrate concentration makes it more likely that the substrate will enter an active site rather than a competitive inhibitor
What will the graph look like when a line showing a reaction with a competitive inhibitor, and without one looks like?
The line without a competitive inhibitor will be higher than that of the one with an inhibitor however, they were both finish at the same point
What is a noncompetitive inhibitor?
The shape of the active site changes because the non-competitive inhibitors bound to an allosteric site, preventing enzyme substrate complexes.
What are the features of a noncompetitive inhibitor?
it has a different shape to the substrate and instead binds to an allosteric site. Binding to the enzyme changes the shape meaning, enzyme substrate complex is cannot be formed. The rate of reaction slows.
what will the graph showing a line without noncompetitive inhibitor, and with one look like?
The line without the noncompetitive inhibitor will be continuously higher than that of the noncompetitive inhibitor, the line with the noncompetitive inhibitor will never reach as high as that without it as no more substrates can bind with the active site as it’s changed shape.
What are the three things cell division is needed for?
Growth, repair of all the damage tissue and reproduction
What kind of cell division is for growth and repair of all the damage tissue?
Mitosis
What kind of cell division is needed for reproduction?
Meiosis
What are the key features of mitosis?
The chromosome number is maintained, two genetically, identical daughter cells are made, it’s used for growth, repair, and during asexual reproduction
What are the four phases of mitosis?
Prophase, metaphase, anaphase, telophase
What is the stage of the cell cycle that comes before mitosis?
Interphase
what is the additional phase of cell division that occurs after the complete nuclear division?
Cytokinesis, the splitting of the cytoplasm
What happens during interphase?
genetic material in the cell doubles
What happens during prophase?
The chromatin condense and become shorter to form chromosomes
During prophase, what does each chromosome consist of?
two sister chromatids join together at the centrometre
What happens to the nuclear membrane during prophase?
It breaks down
What happens during metaphase?
The chromosomes move to form a line in the centre of the cell
What happens during anaphase?
The sister chromatids are pulled apart by the centimetre, by spindle fibres
What happens during telophase?
After being pulled apart, the daughter chromosomes arrive at opposite poles of the cell as microtubules shorten, then the chromatids decoil
What happens to the nuclear membrane in telophase?
it reforms
How can you tell if a cell is in mitosis?
The chromosomes will be visible
During what phase do spindle fibres develop from the centrioles?
Prophase
what are the three stages interphase can be divided into?
G1, first gap, S synthesis, G2 second gap
what is G1 in interphase?
Cell grows in size produces new proteins
What is S in interphase?
DNA replication
What is G2 in interphase?
Cell grows in size, new proteins and organelles are produced
What does G0, represent in the cell cycle?
oppose in the cell cycle, it can be temporary, such some stem cells may pause cycling if there are no gross factors, it can also be permanent, e.g. mature specialise cells lose their ability to cycle and divide.
when studying mitosis, why am I you choose to look at a bone marrow cell rather than a neuron?
because they are stem cells, and therefore divide more quickly and
mature, specialised cells do not reproduce
What is the longest stage of the cell cycle?
Interphase
How do you workout the time a cell spent in a certain phase of the cell cycle?
Time spent in phase= % cells in phase x Length of the cell cycle/ 100
What are all cells in the body programmed to do?
Die
how many times will the cell in the body divided before death?
Around 20 to 50
What might cause a cell to not die?
damaged DNA can cause a sound not to die when it’s programmed to. The cell deaf given enough nutrients will just continue to divide to form tumours
what is cancer?
Uncontrolled growth and division of cells
What are oncogenes?
The genes that stimulate a cell to divide
what are tumour suppressor genes?
They maintain normal rate of cell division
what happens if there is a mutation in the DNA which damages the oncogenes and tumour suppressant genes?
The cell will continue to divide without dying
What are tumours?
growth of abnormal cells consistently expanding in size, they can develop in any organ of the body
what are the most common organs to have cancer?
Lungs, prostate, breast, ovaries, large in testing, stomach, oesophagus, pancreas
What’s the difference between a benign and malignant tumour?
Benign tumours are contained within a membrane, they cannot spread and grow slightly. Malignant tumours are not contained within a membrane, meaning they can spread and grow quickly. However, both can damage organs, cause blockages or obstructions and damage/exert pressure onto other organs.
What is meta stasis?
Malignant, tumours, invading neighbouring tissues, including blood vessels, the cancer cells travel through the blood and lymph to other organs.
Secondary tumours form in these organs
what are the challenges of chemotherapy?
The cancer drugs disrupt the cell cycle of normal cells as well as cancer cells
why does chemotherapy cause hair loss?
Because chemotherapy targets, fast, growing cells, hair follicle cells, have a cell cycle of 12. Five hours and two muscles is seven hours so they are both fast growing.
What are the two types of membranes?
Plasma and cell membranes
What is a plasma membrane?
All membranes around and inside a cell
What is a cell membrane in comparison to a plasma membrane?
The plasma membrane that surrounds cells and Form is a boundary between the cell cytoplasm and the environment
What is the phospholipid bilayer made up of?
hydrophobic fatty acid tails on the inside, and a hydrophilic phosphate head on the outside.
what can diffuse through the phospholipid bilayer of the cell membrane?
Nonpolar, lipidsoluble, and a very small molecules.
what cannot go through the phospholipid bilayer of the cell membrane and has to find another route?
Polar/charged, water soluble, large molecules cannot
What are the different things that make up the cell membrane?
Phospholipids, cholesterol, intrinsic, protein, extrinsic, protein, glycolipid, glycoprotein
What are intrinsic proteins?
These are proteins that span both layers of the phospholipid bilayer, they can actors channel or carrier proteins to transport, water, soluble molecules.
what are extrinsic protein?
found on only one side of the bilayer, they can function as receptors on the outside, enzymes and catalyse chemical reactions on the inside. They also offer a mechanical support.
What are Glyco proteins?
A protein with a polysaccharide chain, extending outwards. Involved in cell recognition (antigens) and immune responses. They can also be receptors for hormones in neurotransmitters. They stabilise the membrane.
What are glycolipids?
A carbohydrate covalently bonded to a lipid. They actors recognising sites and help solve adhere to each other.
They maintain stability of the membrane.
What is cholesterol?
A very hydrophobic molecule found in the phospholipid bilayer, it holds the phospholipids closer together, it prevents loss of water and dissolved irons from the cell.
It regulates stability and fluidity of the membrane and resist the effect of temperature changes
What is the fluid mosaic model?
A model of the cell membrane showing that the individual phospholipid molecules move relative to one another, so the membrane is constantly changing shape, it also has proteins, Glyco proteins, glycolipids and cholesterol that are interspersed between the phospholipids.
What are the three types of transport across membranes?
Diffusion, facilitated diffusion, osmosis
What is diffusion?
The net movement of molecules or ions from a region, where they’re in a high concentration to one in a lower concentration until evenly distributed.
What factors affect diffusion?
Concentration gradient (bigger concentration difference= Quicker diffusion) diffusion difference, temperature, surface area, humidity (with water)
what is flicks law?
surface area x concentration gradient/ diffusion pathway.
What is facilitated diffusion?
When molecules after you specific intrinsic proteins to get into the cell as they can’t get in through the phospholipid bilayer
What does channel proteins do?
transport ionic substances (e.g. sodium irons) they are selective and will only open in the presence of a specific ion or molecule.
What are carrier proteins?
Intrinsic proteins that transport water soluble molecules (e.g. glucose) it changes, tertiary structure with a particular molecule binds, releasing it to the other side of the membrane.
