Nextstep 1 Bio Flashcards
A peptide bond is forms what kind of functional? And why is it so stable?
A peptide bond forms an amide linkage between the amine group of one amino acid and the carboxylic acid group of another.
Amides are stable because they show resonance stabilization.
In prokaryotes, genes can exist as operons that are transcribed into a polycistronic mRNA, containing multiple genes in a single transcript. In eukaryotes, transcripts exist only as monocistronic mRNA containing a single gene. What fundamental genetic difference is responsible for this distinction?
Eukaryotes mRNA contain a single gene because each gene contains their own transcription site.
Start codons refers to translation or transcription?
Start codons refers to translation of mRNA.
What is the definition of hybridization?
Hybridization describes the process of binding to complementary strands such as in the silencing of mRNA by miRNA
What is defined as RNA polymerization?
Polymerization is the process by which a series of nucleotides are strung together to form a single-stranded RNA strand. NOT THE JOINING OF TWO COMPLEMENTARY ONES.
If a protein is cationic at physiological pH it must have more of which amino acids and why?
If the protein is positive at neutral pH, the protein must have more amino acids that are basic than acidic.
The innate immune system includes what and what are its responses?
The innate immune system includes nonspecific immune responses. Its responses provide general protection. Inflammation is a function of the innate immune system.
The adaptive immune system includes what and what are its responses?
The adaptive immune system is directed against a particular pathogen to which the body had been exposed before. “remembering” this exposures that lead to quicker future responses. Vaccines are an example of this.
Passive immunity involves?
Passive immunity involves the transfer of one individual to another.
Which form of genetic change best explains the loss of the majority of genes from the Y chromosome?
Genetic drift. Genetic drift is a term from population gentics, and encompasses the fact that that an adult male that has only female offsprings will not pass its Y chromosome. The repeated random loss of the well-adapted Y chromosomes can result in the degeneration of the chromosome as a whole.
Researchers showed that the Y chromosome experiences a much higher mutation rate than the X chromosome. This is likely due to the fact that?
Given that sperm undergoes many divisions during gametogenesis, each cellular division makes mutations more likely in the Y chromosome.
Also, sperm develops in the testes an environment that is under unusually oxidative conditions; promoting mutations.
Finally, the X chromosome undergoes fewer total number of replications do to limited replication rounds during oogenesis, and females have crossing-over events that restore the function to damaged X chromosomes.
Stimulation of the iris dialator muscle is a result of?
Sympathetic motor neurons. Motor because are originated in the brain and sent to the muscle and sympathetic because pupil dilation is a classic response to fight-flight type of situations.
Increasing plasma concentration of aldosterone is most likely to be followed by which of the following?
B is correct. Aldosterone is released from the adrenal cortex in response to low blood pressure. Its primary function is to increase sodium reabsorption in the distal tubule and collecting duct. Aldosterone upregulates the sodium-potassium pumps along the lining of the nephron, pumping three sodium ions OUT of the nephron lining (and toward the blood) for every two potassium ions it pumps IN (toward the nephron and away from the blood). Since we have a net solute movement out of the nephron, aldosterone also increases the gradient that favors water reabsorption.
When normal human cells are grown in culture, they will divide a limited number of times – typically 50 rounds of mitosis. After this number is reached, the cells become apoptotic. This cell death is a result of:
Chromosomal telomeres shortening after each round of replication.
As cell undergoes mitosis, its telomeres, the repeating portions of DNA at the end of the chromosomes gets progressively shorter. Eventually the cell looses its telomeres entirely and is unable to reproduce. The cell then undergoes mitosis.
The process of arranging nuclear DNA in preparation for transmission to offspring is cyclical or non cyclical?
The arraging of nclear DNA otherwise known as meosis is a noncyclical process. It happens once and terminates in gamete creation (sperm or ova).
Is the growth of cell cultures cyclical or non-cyclical?
Cell culture growth occurs through mitosis which is a cyclical process.
III. Growth of cell cultures requires transformation of diploid cells into haploid cells, while genetic transmission of nuclear DNA to offspring requires transformation of haploid cells into diploid cells.
Is the above statement true or false and why?
It is false. Because the process of cell culture is a mitotic process that results in diploid cells, whereas the process described ends in haploid ones (meiosis).
What aspects separate single-crossover events from double-crossover events?
Single-crossover events affect only the ends of chromosome arms. Double-crossover events affect segments in the middle of chromosome arms.
If a compound travels more towards the positive side or negative what does it mean about the composition of the isoenzyme?
The compounds with more positive (basic) amino acids will travel the most towards the negative side. Whereas, amino acids with the most negative charge (acidic) will travel towards the positive side the most. The ones that are a combination of both will stay relatively in the middle or slightly to one side.
Cathode is what?
Cathode is where positive charges go into, which makes it the negative electrode.
Anode is what?
Anode is the where negative charges go into, making it the positive electrode.
In gel electrophoresis and galvanic cells anode and cathode differ in what ways?
In a galvanic cell, the anode is (-), and the focus is on pushing away electrons from the anode to supply power. In an electrolytic cell and gel electrophoresis, the anode is (+) and the focus is on attracting the negative ions in solution from inputted power.
CK isoforms containing M1 and M2 subunits migrate nearer the anode than do CK isoforms containing the unmodified M subunit. The region near the C-terminus of the unmodified M subunit is enriched in which of the following amino acids?
“CK M subunits are slowly converted into two modified subunits, M1 and M2, by plasma carboxypeptidases via successive cleavage of C-terminal amino acid residues.”
A is correct. The passage states that once released from tissue, the CK M subunits are converted into modified subunits M1 and M2 by successive cleavage of C-terminal amino acid residues. If the modified subunits migrate nearer the positive electrode than do unmodified subunits, then modified subunits possess a lower pI than unmodified subunits and should be enriched in lower-pI amino acids via the removal of higher-pI residues. Only choice A—lysine, asparagine, arginine—contains three higher-pI, basic residues and is the correct answer. Choices B, C, and D all contain some combination of non-basic amino acids and are incorrect.
Troponin enzymes are used as an alternative biomarker in the diagnosis of heart attack. On which muscle type does the troponin complex function in contraction?
Troponin is a complex of three proteins required for muscle contraction in skeletal and cardiac muscle, but not smooth muscle.
