Biology

Part II: Sections VI-X (573 Pages; 2017 Edition)

(Emphasis is on Biochemistry and Molecular Cell Biology)


At the beginning of each of the 10 sections in the Biology Review Books is a page listing the "Top 10 Section Goals" for that particular section. After reading the text in each section and completing the accompanying MCAT-style passages, we feel that you will have a better conceptual understanding of the material important to the Biological and Biochemical Foundations of Living Syetems (formerly Biological Sciences) section of the MCAT.

Section VI: Structure and Function in Cells and Viruses

Top 10 Section Goals

  1. Be familiar with the basic biological molecules of cells and viruses. The four general classes of biological molecules are amino acids, nucleic acids, carbohydrates, and lipids. Be able to recognize their basic differences and know their functional significance.

  2. Know the 20 standard amino acids that are used to synthesize proteins. Be able to associate amino acid names with structures, especially the 5 amino acids (Asp, Glu, Lys, Arg, & His) that can have charged polar side chains.

  3. Understand the difference between mitosis and meiosis at the cellular level. Know the different stages of the cell cycle and how they relate to one another. Be able to describe the chromosome number and ploidy level at any stage of mitosis or meiosis.

  4. Be familiar with the different types of membrane transport processes. Have a feel for the differences between simple diffusion, facilitated diffusion, active transport, and bulk transport. Be aware of symports, antiports, uniports, and membrane charge balance.

  5. Be familiar with the different organelles in a eukaryotic cell. Be aware of how they relate to one another within their cellular environment. Know their general structural characteristics (e.g., single membrane, double membrane, contains DNA, etc.).

  6. Be familiar with the functions of eukaryotic organelles. For each of the major organelles in a eukaryotic cell, be able to define its function in general terms. Are they involved in metabolism? Cellular packaging and sorting? Replication? Protein synthesis?

  7. Know where the different metabolic processes occur in a cell. The general metabolic reactions of glycolysis, Krebs cycle, electron transport, and oxidative phosphorylation are common to eukaryotes and prokaryotes. Where do they occur in each cell?

  8. Know the general differences between Gram-negative and Gram-positive bacteria. Bacterial cells, for the most part, can be divided into Gram- negative and Gram-positive cells. It is important to have a feel for the structural differences between the two cell types.

  9. Be familiar with the reproductive cycle of a virus. The biological diversity within viruses is enormous. Just have a general idea of the strategy that an enveloped and a non-enveloped virus uses when taking over a host cell.

  10. Know the general differences between eukaryotes, prokaryotes, and viruses. Just as it is important to know which galaxy our solar system is located in, it also important to know the basic differences between eukaryotic cells, prokaryotic cells, and viruses.

Passages and Solutions

Section VI includes 15 MCAT-style passages with detailed solutions. Passage topics are centered around information important to the structure and function in cells and viruses. Also included are 15 MCAT-style free standing questions with just the letter choice indicating the best answer.


Section VII: Metabolic Components

Top 10 Section Goals

  1. Be familiar with the concept of transition states. It is important to understand the difference between the activation energy of an uncatalyzed reaction and that of a catalyzed reaction.

  2. Understand how to read a Michaelis-Menten graph. Don't worry about the algebra involved in deriving the Michaelis-Menten equation. Instead, be able to understand the components of that equation in relationship to its graphical form.

  3. Understand how to read a Lineweaver-Burk graph. Be able to interconvert between the Michaelis-Menten graph and the Lineweaver-Burk graph. Be sure you understand the meaning of the different parameters.

  4. Be familiar with the concept of enzyme inhibition. Enzyme inhibition is a favorite topic in biology. Know the difference between a competitive and a non-competitive inhibitor and how they function in the presence or absence of substrate.

  5. Understand the basics of the chymotrypsin mechanism. The details of this mechanism have been on the MCAT before. Those who took this exam needed only a basic understanding of enzymatic mechanisms. Keep track of your electrons!

  6. Be aware that not all enzymes are composed of amino acids. At one time, it was thought that all enzymes were proteins. This is no longer the case, because RNA has been shown to have enzymatic activity. Just be aware of this recent discovery.

  7. Be familiar with the concept of molecular evolution. On occasion, the MCAT has had a few questions concerning evolution. Be aware of the terms convergent evolution and divergent evolution.

  8. Know the basic components and functions of the molecule ATP. ATP is the energy currency of the cell. We will encounter this metabolic component throughout our entire review session. Know its components and understand its uses in metabolism.

  9. Know the basic components and functions of the coenzymes NAD and FAD. NAD and FAD are both coenzymes. They are not enzymes. A coenzyme helps an enzyme function properly. NAD and FAD are probably the two best known coenzymes.

  10. Be familiar with coenzyme A and its uses in metabolism. Coenzyme A is another important coenzyme, especially in the Krebs cycle and in fatty acid metabolism. Have some understanding of where this molecule is used in the cell and why.

Passages and Solutions

Section VII includes 15 MCAT-style passages with detailed solutions. Passage topics are centered around information important to metabolic components. Also included are 15 MCAT-style free standing questions with just the letter choice indicating the best answer.


Section VIII: Metabolic Pathways

Top 10 Section Goals

  1. Understand the general concepts behind the glycolytic pathway. Glycolysis is one of the pathways central to metabolism. You should have a basic understanding of how it operates, what it generates, and how it is tied in with the Krebs cycle.

  2. Be familiar with the common types of sugars that can be metabolized. Sugars other than glucose can be used for metabolism. Sucrose, lactose, fructose, and galactose are but a few sugars that are commonly metabolized by a wide variety of organisms.

  3. Be able to link the concepts of glycolysis with the Krebs cycle. Once the commitment to aerobic respiration is made, pyruvate is converted to acetyl-CoA which then enters the Krebs cycle. This link unites glycolysis and the Krebs cycle and is important.

  4. Understand the importance of the coenzymes NADH & FADH2. NADH is generated in both glycolysis and the Krebs cycle. FADH2 is generated in the Krebs cycle. Understand how these reducing components are important for the generation of ATP.

  5. Know how the electron transport chain operates. It is important to have an understanding of how electrons flow from NADH and FADH2 down the electron transport chain to oxygen, the ultimate electron acceptor.

  6. Understand the chemiosmotic hypothesis and the concept of a proton gradient. Understand how a proton gradient is generated, and how it leads to the eventual synthesis of ATP in oxidative phosphorylation. Be familiar with inhibitors and how they work.

  7. Be familiar with the general concepts of the pentose phosphate pathway. Do not memorize the structures of the pentose phosphate pathway. Just understand why this pathway is important. Many of its components are also found in the Calvin cycle.

  8. Understand the relationship between glycolysis & gluconeogenesis. Be aware that gluconeogenesis is not the complete reverse of glycolysis. There are irreversible steps which must be bypassed. Know the importance of gluconeogenesis in metabolism.

  9. Know the concepts involved in the beta-oxidation pathway. Fatty acid oxidation is important in metabolism. There are many classic biochemical reactions in this pathway that illustrate the importance of understanding organic chemistry.

  10. Be familiar with the urea cycle and its relationship to the liver & kidney. Be aware of the cells in the body that can generate urea and the concept behind transamination reactions. Understand how nitrogenous wastes are removed from the body and in what form.

Passages and Solutions

Section VIII includes 15 MCAT-style passages with detailed solutions. Passage topics are centered around information important to metabolic pathways. Also included are 15 MCAT-style free standing questions with just the letter choice indicating the best answer.


Section IX: Genetic Information

Top 10 Section Goals

  1. Be familiar with the transmission of genetic traits. Understand how genetic traits are transmitted from one generation to the next. Think of meiosis in this context, especially genetic recombination.

  2. Be familiar with the work of Mendel. Trace the pioneering work of Gregor Mendel and his garden peas. Understand how to use a Punnett square, and be able to obtain simple ratios of genetic events.

  3. Understand the concept of genetic loci and alleles. A locus (plural, loci) is the position of a gene on a genetic map. An allele is simply one of two or more alternate forms of a single gene at a given locus.

  4. Know how to read a pedigree and find simple outcome probabilities. Don't get lost in the details of difficult pedigrees. At most, be able to take a pedigree back to three generations. Be able to follow the lineages of the individuals.

  5. Be familiar with the concept of genetic mutants and replica plating. Know what is meant by a biochemical pathway, and how mutations in a particular enzyme might affect that pathway. How are mutants isolated, if they cannot grow in a minimal medium?

  6. Understand the importance of nucleic acids. Be familiar with the base pairing rules established by Watson and Crick. Know how to determine the base composition of a given piece of DNA.

  7. Be familiar with the Meselson-Stahl experiment. The Meselson-Stahl experiment is a classic experiment in molecular biology. It proved that DNA replicates semiconservatively, as proposed by Watson and Crick.

  8. Be familiar with the general process of DNA replication. Don't get lost in all the enzymes involved in DNA replication. Just have a simple understanding of the overall process, and feel comfortable with some of the names and structures.

  9. Understand how the polymerase chain reaction works. The discovery of the polymerase chain reaction ranks among the greatest scientific discoveries of the 20th century. There have been many articles on this process, and it is certain to be on the MCAT.

  10. Be able to relate the discussions of this section with genetic expression. Besides DNA replication, there is also DNA transcription and mRNA translation. Once a cell divides, it must synthesize proteins in order to survive. You will need to understand this process.

Passages and Solutions

Section IX includes 15 MCAT-style passages with detailed solutions. Passage topics are centered around information important to genetic information. Also included are 15 MCAT-style free standing questions with just the letter choice indicating the best answer.


Section X: Expression of Genetic Information

Top 10 Section Goals

  1. Understand the differences between RNA & DNA polymerase. RNA polymerase is used to transcribe DNA into RNA language. DNA polymerase replicates DNA before cellular division. Understand these functions and how they apply to the cell.

  2. Be familiar with the concept of a transcription promoter. RNA polymerase does not begin transcription just anyplace on the DNA helix. There are specific addresses that tell the polymerase where to bind. Understand the basics of these functions.

  3. Know the differences between eukaryotic & prokaryotic RNA processing. Eukaryotic RNA must undergo extensive processing in the nucleus before it can be used in the cytosol for protein synthesis. Prokaryotic RNA is used immediately and is not processed.

  4. Be able to read the genetic code. DNA codons on the coding strand are the same as the mRNA codons. DNA codons on the template strand are the same as the anticodons on tRNA (except for replacement of Us and Ts).

  5. Have a feel for transcription & translation in eukaryotes & prokaryotes. In prokaryotes, transcription and translation are tightly coupled. In eukaryotes, transcription and translation are separated both in space and in time. Understand this important distinction.

  6. Be familiar with the actual process of transcription. You should have a firm grasp of tRNA activation and subsequent binding of the activated tRNAs to the P-site and A-site on the ribosome. Understand translocation and protein synthesis.

  7. Understand the lactose operon and how regulation is achieved. The lactose operon ties in all of these aspects of transcription and translation discussed so far. It is an excellent example of how a bacterial cell regulates its need for a particular metabolite.

  8. Understand the basic tools involved in genetic engineering. Probably the most important genetic engineering tools are the restriction endonucleases. Do not memorize their recognition sequences. Instead, know the basics of how they function.

  9. Be able to read autoradiographs from polyacrylamide gels. Understand the process of gel electrophoresis and why it is that bands are read from the bottom of the gel to the top of the gel. Be familiar with the Sanger dideoxy sequencing method.

  10. Be familiar with the process of cloning foreign DNA into plasmids. This is the core of genetic engineering. Understand how to remove a seqment of foreign DNA, open up a plasmid, insert that foreign DNA into the plasmid, and then express the gene of interest.

Passages and Solutions

Section X includes 15 MCAT-style passages with detailed solutions. Passage topics are centered around information important to the expression of genetic information. Also included are 15 MCAT-style free standing questions with just the letter choice indicating the best answer.

Two Full Diagnostics

At the end of Book II are two full diagnostics, each with 10 passages, free standing questions, and detailed solutions.

SAMPLE PASSAGE




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