Chapter 4-

Discuss two major ways that mutation occurs

A mutation is defined as a mistake in, or damage to, the DNA strand that is not corrected and is passed on to the new cells. Mutations can occur during replication when an incorrect nucleotide or extra nucleotides bind to the parental DNA strand. Mutations can also occur if sections of the DNA strands are deleted, misplaced, or attached to the wrong chromosome.

What effect might changes in the pH of body fluids or body temperature that accompany illness have on cells?

Acidic pH and high temperatures denature proteins. By disrupting H-Bonds and other structure-stabilizing bonds, acids and high temperature cause enzymes to change shape and lose function. Ph is the cause not the effect but they cause the effect of breaking. Since enzymes catalyze metabolic reactions at only a specific pH, if the pH of body fluids is altered, enzymes will become denatured and cell metabolism will be altered. Enzymes and their associated (vitamin) coenzymes are reused in metabolic reactions. Excessive amounts of coenzymes are normally excreted.

Define cofactor

An enzyme may be inactive until it combines with a nonpro- tein component called a cofactor which helps the active site attain its appropriate shape or helps bind the enzyme to its substrate. A cofactor may be an ion of an element, such as copper, iron, or zinc, or a small organic molecule, called a coenzyme. Many coenzymes are composed of vitamin molecules or incorporate altered forms of vitamin molecules into their structures.

Distinguish between catabolism and anabolism

Anabolism uses energy to build large molecules from smaller ones. Catabolism releases energy by breaking large molecules into smaller ones.

Discuss three ways that the genetic code protects against the persistence of a mutation

Because of the importance of the DNA molecule, there are many safeguards against mutation. For instance, there are sixty-one codons that specify the twenty amino acids. If the mutation occurs in the third nucleotide of a codon, it is likely that this mutation will still yield the correct amino acid (ITS THE WOBBLE THEORY). If the mutation is in the second codon, the new sequence will generally yield a structure similar enough to the original amino acid that the effect would not be significant. There are two copies of each chromosome in an adult cell. If one chromosome is mutated, the genes of the second chromosome will usually provide enough normal "blueprints" to maintain the health of the cell. If a mutation occurs in a cell of an adult, it will probably go unnoticed because of the many normal cells around it. If the mutation occurs in the cell of an embryo or child, the results can be catastrophic because that cell may be the first, or be the parent, to many other cells as the infant grows.

How can the same molecule be both a reactant (starting material) and a product of a biochemical pathway?

Because the biochemical pathway is crossed each other.If a chemical is involved in a biochemical cycle, like the citric acid cycle, it can be a reactant and also a product. This is common in metabolic processes throughout the body, because it allows materials to be continually reused.

Give examples of a dehydration synthesis reaction and a hydrolysis reaction

Dehydration synthesis joins many simple sugar molecules to form larger molecules of glycogen. Glycerol and fatty acid molecules join to form larger fat molecules. Hydrolysis of a disaccharide yields two monosaccharide molecules. Fats are broken down into glycerol and fatty acids.

Define active site

During an enzyme-catalyzed reaction, regions of the enzyme molecule, and it temporarily combine with portions of the substrate, forming an enzyme-substrate complex.

Define DNA damage response

If the mutation to a DNA molecule occurs only on one strand, the cell uses special enzymes called repair enzymes to clip out the defective portion and rebuild it correctly.

Explain how metabolic pathways are linked and intersect

In many cases, products of one reaction are starting materials for the next. These reactions form cycles and pathways that may intersect where they share intermediate compounds. Each step may be catalyzed by an enzyme.

Discuss the relationship between a coenzyme and a vitamin

Many coenzymes are composed of vitamin molecules or incorporate altered forms of vitamin molecules into their structures.

Distinguish between dehydration synthesis and hydrolysis

OH from the end of one molecule and an -H from the end of another. The OH and H combine to form H2O, and the ends of the two molecules join by sharing the remaining oxygen atom. Hydrolysis is the opposite of dehydration synthesis. In hydrolysis, a large molecule is split apart at a certain point and a hydrogen atom is attached to one of the new molecules, while a hydroxyl group is attached to the other. Both of these processes can occur over and over until the original molecule is altered to the cell's needs. In short, dehydration synthesis dehydrates a molecule and hydrolysis rehydrates it.

Michael P. was very weak from birth, with poor muscle tone, difficulty breathing, and great fatigue. By his third month, he began having seizures. Michael's medical tests were normal except for one: his cerebrospinal fluid (the fluid that bathes the brain and spinal cord) was unusually high in glucose. Hypothesizing that the boy could not produce enough ATP, doctors tried an experimental treatment: they gave him a diet rich in certain fatty acids that caused the cellular respiration pathway to resume at the point of acetyl CoA formation. Michael rapidly improved. Explain what caused his symptoms.

The individual's cells utilize glucose as their primary and most efficient source of metabolic energy. Genetic defect caused deformation of an enzyme which was important in glycolysis. This causes an excess in glucose as evident in the question because its not breaking down (no enzyme=no glycolysis) and giving fact because glycolysis is not working it gives fat and the fat doesn't go into glycolysis it just skips it and produces in energy in an alternative way and thats why it works. With less carbohydrate available to provide glucose, the cells would make increased use of fatty acids, glycerol, and amino acids as sources of energy. Lipids and proteins can be broken down to release energy for ATP synthesis. The final process is aerobic respiration. From the breakdown glycolysis does not name a specific enzyme because its some way on the pathway of glycolysis

Distinguish among mutations, SNPs, and copy number variants

The rare distinctions in DNA sequence that affect how we look or feel are called mutations. More common genetic variants with no detectable effects are called single nucleotide polymorphisms (SNPs). Polymorphism is a term used to describe copy number variants.

Explain the importance of a rate-limiting enzyme

The rate at which a metabolic pathway functions is often determined by a regulatory enzyme that catalyzes one of its steps example would be only as good as your slwoest/ worst player

Describe how negative feedback involving a rate-limiting enzyme controls a metabolic pathway

The rate of a metabolic pathway is often determined by a regulatory enzyme responsible for one of its steps. This regulatory enzyme is present in limited quantity. Consequently, it can become saturated with substrate molecules whenever the substrate concentration increases above a certain level. Once the enzyme is saturated, increasing the number of substrate molecules will no longer affect the reaction rate. Talk about how increased final product can in turn regulate the enzayme can intern regulate the enxyme allostrectly (goes to the non active site and regulates the structures which in turn regulates the enzyme) or competitivity (competwes with the substrate thus descreasing the concentration of the final product).

A student is used to running 3 miles at a leisurely jogging pace. In a fitness class, she has to run a mile as fast as she can. Afterwards, she is winded and has sharp pains in her chest and leg muscles. What has she experienced, in terms of energy metabolism?

The student's muscles are using up oxygen rapidly, and some muscle cells revert to anaerobic respiration. Lactic acid build-up causes her pain.

Describe how an enzyme interacts with its substrate

The surface of an enzyme contains areas called active sites that will bind to a specific substrate only. When the correct substrates are attached to the active sites, the enzyme alters the shapes of the substrates in a way that promotes the reaction. All enzymes demonstrate this specificity to its substrates. To illustrate, an enzyme-substrate complex is like a "lock-and-key" model with the enzyme as the lock and the substrate as the key. Although many keys may fit the lock, only one type of key will make it work.

Three Stop Codons

UAA, UAG, UGA

In cyanide poisoning, levels of ATP in the brain plummet, but levels of lactic acid increase markedly. Explain how both effects occur.

You make lactic acid when you don't have enough oxygen. Cyanide affects the ETC you go from glycolysis (anaerobic part) to Krebs to ETC it takes o2 and turns it into water so if you block any of it, it gets back up and you make lactic acid so you can block the ETC or the kerbs you for how both effects occur.

Consider the following DNA sequence: TCGAGAATCTCGATT a. Write the sequence of the DNA strand that would be replicated from this one. b. Write the sequence of the RNA molecule that would be transcribed from the DNA strand (the one written above -- i.e. the "template" strand). c. State how many codons the sequence specifies. d. State how many amino acids the sequence specifies.

a. AGCTCTTAGAGCTAA b. UCGAGAAUCUCGAUU c. 5 d. 5

Some antibiotic drugs fight infection by interfering with DNA replication, transcription, or translation in bacteria. These processes are different enough in bacteria that the drugs do not harm us. Indicate whether each of the following effects is on replication, transcription, or translation. a. Rifampin binds to bacterial RNA polymerase. b. Streptomycin binds bacterial ribosomes, disabling them. c. Quinolone blocks an enzyme that prevents bacterial DNA from unwinding

a. Transcription b. Translation c. Replication