These proteins open and close the membrane. | | 11 CORRECT | | What did Robert Hooke use to study this organism? | | | A) | light microscope | | | B) | electron microscope | | | C) | cork chamber | | | D) | DNA analysis | | | | | | Feedback: Robert Hooke used a primitive light microscope to observe organisms such as this flea, as well as cork, which led him to the notion of cells. | | 12 CORRECT | | What does this depict? | | | A) | cytoskeleton | | | B) | fluid mosaic model | | | C) | impermeable membrane | | | D) | genetic material | | | | | | Feedback: Phospholipids in the plasma membrane create a fluid environment in which other molecules can float, allowing selective permeability.
These shapes fitting together to form enzyme-substrate complexes is very important in many processes. For example, in the process of DNA replication, DNA helicase must have the correct shape in order to separate the DNA strands and DNA polymerase must have the correct shape so that free nucleotides can join to their complimentary base pair on sugar phosphate backbone to create new strands of DNA. It is also important for the nucleotides to join together with their complimentary base pair, which is more shapes fitting together to form DNA. It is also important that antigens and antibodies fit together. When a bacteria enters the body it has antigens on its surface that are recognised by the white blood cells.
Consider the following DNA sequence found on a different portion of the coding strand of Henry's CYP2C9 gene: TTACCGAGA a. What would be the sequence of the template strand on this portion of the gene? b. How many triplet codes does this DNA sequence contain? c. What would be the sequence of the mRNA after this sequence is transcribed?
There are many models of enzymes, such as the lock and key model, which explores the structure of the enzyme and its ability to bind with a substrate molecule which is specific and complementary. There is also the induced fit model which explored the ability of enzyme molecules to change shape slightly enabling it to fit and bind to substrate molecules which must be complementary and specific. The importance of enzyme and substrate molecules to fit together, is the formation of the products which may enable many vital reactions to occur within cells and organisms. Enzymes are in important in digestion and the replication of DNA. Within digestion lactose within milk is broken down by the enzyme lactase, without lactose having a complimentary specific shape to it lactase enzyme, some people are lactose intolerant.
Microscopic and molecular studies of cells focus on both multi-celled and single-celled organisms, and recognizing the similarities and differences of cells is the heart of Cytology (Ellis-Christensen, 2009). Microscopic examination helps identify different types of cells. By looking at the molecular biology that forms a cell helps to further the describing and identification of cells. All fields of biology depend on the understanding of cellular structure. An example of this is the field of genetics, which exists because we now understand cell structure and its components.
There are many molecules within cells and organisms that must have complimentary shapes that fit together in order for them to carry out their function. One type of molecule for which this is extremely important is enzymes. There are two models that demonstrate how this may work, the first of which is the lock and key model in which the substrate and enzyme binding site have complimentary shapes so that the substrate or subtrates fit perfectly into the enzyme, which joins or separates them. The second model, the induced fit model, is similar, however the enzyme moulds its shape to match the substrate. There are many processes in which it is important that these shapes fit, for example DNA helicase, RNA polymerase and DNA polymerase must all have the correct shape in order for DNA strands to separate, mRNA to form and DNA to then rejoin during polypeptide synthesis.
This is known as the lock and key model. There is also an induced fit model, which states that the model is not quite as rigid as the lock and key model states. In this model the enzyme may not have an active site that is perfectly complementary to the substrate, but when the substrate collides with the enzyme active site its shape is altered to fit the substrate and make a complex. Enzymes are proteins, the structure of the protein are very important as it give the protein a particular 3-D shape which gives the active site it’s specific shape. The protein structure consists of primary, secondary, tertiary and quaternary structure.
They help to increase the rate of chemical reactions. Enzymes are most often proteins. Enzymes are highly specific in terms of the reactions that they catalyze. In other words, they are highly specific to the substrates that they will act upon. In this lab we will investigate how amylase acts on starch, lipase on lipids, and trypsin on protein.
Enzymes are proteins folded into complex shapes that allow smaller specific molecules to fit into them like a lock and key. The place where the substrate molecules fit is called the active site; chemical reactions occur at the active site. Catalase is found in all cells and protects them from a dangerous waste chemical called Hydrogen Peroxide. It breaks the hydrogen peroxide down to water and oxygen The substrate (hydrogen peroxide) and the catalase molecules are continuously on the move. Every so often they will collide so that the substrate molecule(s) fits into the enzyme's active site.
Key developments in Molecular Genetics: Past, present and future 29. 8. 2013 2045 words Key developments in Molecular Genetics: Past, present, future. Introduction Molecular Genetics is a theoretical science that studies the nucleic acids, structure and function of genes, the products of genes and generally speaking all processes at a molecular level. This discipline is one of the most important sciences from the point of the description of any living system because the inception of each living organism is based on genetic information that determines the anatomic structure of each organism and on substances that play an important role in biochemical and physiological processes.