Stuff Flashcards
Using a water molecule as an example, explain and describe the following terms:
a) Molecule (2 marks)
b) Chemical bond (2 marks)
c) Polarity (2 marks)
d) Emergent properties (4 marks)
A) molecule (2)
Molecules are group of 2 or more molecules that are bonded together by chemical bonds. A water molecule consists of 2 hydrogen atoms and one oxygen atom united chemically in a fixed proportion. Oxygen has 6 valence electrons, whereas hydrogen has 1, this allows hydrogen. When many molecules are together, they form the water we see and drink day to day. It helps support life on Earth.
B) Chemical bond (2)
A chemical bond is an attraction between atoms or ions that holds them together to form a chemical compound. The chemical bond is covalent and hydrogen bonds that occur between the atoms within the water molecule.
These chemical bonds make water have high surface tension.
C) polarity (2)
Oxygen is more electronegative than hydrogen, so it will pull the electrons, making the water molecule polar. This polarity makes it a good solvent, and a good medium to perform chemical reactions needed in most cells. Emergent properties are when separate elements have their own properties but when they come, they form one molecule, that molecule has different properties (new properties emerge) e.g. oxygen is a gas and hydrogen is a gas, but they can come together to make liquid water at room temperature.
D)emergent properties (4)
Emergent properties are when separate elements have their own properties but when they come, they form one molecule,
that molecule has different properties (new properties emerge) e.g. oxygen is a gas and hydrogen is a gas, but they can come
together to make liquid water at room temperature. These emergent properties include water cohesion forces, which help it stick together as one. It is a great temperature buffer, thus helping to create specific conditions for certain creatures to
survive
Miller Experiment
The Miller experiment attempted to mimic early earth conditions to determine whether inorganic life could give rise to organic life. Water in a flask was heated to form water vapour and to mimic the early oceans. Another flask was a synthetic atmosphere which contained a mixture of gases such as nitrogen, ammonia, methane and carbon dioxide. Using sparks from nearby electrodes to mimic the lightning and UV light, Miller found various organic molecules such as amino acids and hydrocarbons had been produced in condensed water that had formed after the reaction. This is the main premise of the Primordial soup theory, that organic molecules were produced due to the reducing atmospheric conditions, the mixture of gases and lightning and UV light present in the early earth environment and
accumulated in early seas.
Explain the difference between the two structures of chromatin and the process of acetylation
which alters chromatin structure (10 marks
All cells in the human body have the same genome and DNA but different proteins which leads to differential gene expression. To regulate the gene expression eukaryotes, modify the structure of their chromatin. They make modifications to the proteins called the histone inside the chromatin or the DNA structure and then by doing that they control transcription. There are two types of chromatins. Hetero chromatin> which is a highly packed DNA region and has low transcriptional activity. Eu-chromatin> which is a lightly packed DNA region and has high transcriptional activity. The histone proteins are made up of amino acids as any other protein is and we know that amino acids are linked by peptide
bonds and when the peptide bonds are multiple, they are called polypeptides. The polypeptide bond in the histone proteins’ tails can be chemically modified by cellular enzymes. The process of modifying these enzymes is called histone acetylation (which is the addition of an acetyl group(COCH3). This histone acetylation loosens the heterochromatin and makes it a euchromatin thus making it accessible to the RNA polymerase(replication preparation by enzymes) this allows high transcriptional
activity
