Exam #9 Flashcards
When a lipid hormone binds to an intracellular receptor, what occurs?
Acts as a transcription factor
Lipid hormones are small and nonpolar, and can diffuse through the cell membrane. If they bind to a cytosolic or nuclear intracellular receptor, it will translocate to the nucleus (if it is not already bound to DNA) and activate gene transcription as a transcription factor.
All of the following are composed of a polymer EXCEPT for one. Which one is the EXCEPTION?
A: Uracil B: Trypsin C: A plasmid D: Glycogen E: Chitin
A: Uracil
All other answer choices are polymers
Which of the following occurs when two amino acids form a peptide bond?
When one amino acid bonds to another (formation of a peptide bond), water is released as a product
A sample of enzymes is competitively inhibited. What will be the effect on reaction rate as more substrate is added?
The the rate of catalysis will linearly increase until the active sites begin to saturate
- cause the substrate will outcompete the competitive inhibitor
In which of the following ways do C4 and CAM plants differ from C3 plants?
In C4 and CAM plants, CO2 is initially fixed into a four carbon molecule
It’s not just C4 plants that fix into a four carbon molecule. Both CAM and C4 plants fix into a four carbon oxaloacetate, which converts into four carbon malic acid (or malate). C4 differs from CAM based on how the malic acid separated. C4 separates based on location in the plant leaf, whereas CAM separates temporally (meaning time – when the process occurs)
A scientist activates a sample containing proteins via phosphorylation. She wants to add an enzyme to deactivate the sample without destroying it. Which type of enzyme should she use?
A: Phosphorylase B: Protein kinase C: Phosphatase D: Protease E: Nuclease
C: Phosphatase
A: Phosphorylase
Incorrect. A phosphorylase is an enzyme that adds phosphate to a substance.
B: Protein kinase
Incorrect. Kinases add phosphate to their substrate.
C: Phosphatase
Correct. A phosphatase is an enzyme which cleaves phosphate off of a substrate.
D: Protease
Incorrect. Proteases are enzymes that break down proteins. The scientist in the question only wants to deactivate the phosphorylated protein (not destroy it).
E: Nuclease
Incorrect. A nuclease is a category of digestive enzyme that splits nucleic acids into individual nucleotides.
A diploid organism has a haploid chromosome number n=15. How many chromatids would you expect to find during metaphase II of meiosis in one of the daughter cells?
A . 15
B. 30
C. 60
D. 120
B. 30
If haploid number (n) is equal to 15, the diploid (2n) number is equal to 30.
Before meiosis, the DNA is duplicated, and occupied sister chromatids attach to each other by the centromere. Remember that sister chromatids that are still attached are only referred to as a single chromosome.
Before meiosis begins but after replication, the cell still has chromosome number 2n = 30, but chromatid number = 60.
After meiosis I, homologous chromosomes are separated, but sister chromatids are still attached.
Each haploid daughter cell is chromosome number n = 15, and chromatid number = 30 (sister chromatids still attached).
Metaphase II occurs during meiosis II, before the daughter cells have been divided again. Therefore, each daughter cell contains 15 chromosomes and 30 chromatids.
In eukaryotes, FADH2 is produced where?
Mitochondrial matrix
Which of the following mechanisms is used to turn off the expression of a gene?
DNA methylation
In DNA methylation, methyl groups are added to individual bases in DNA to repress their transcription. This is a form of EPIGENETIC CONTROL
, where gene expression is varied without a change in DNA sequence. DNA methylation is also used in X-inactivation (where one copy of the two X chromosomes in female mammals is inactivated).
Which of the following is a characteristic of exergonic reactions?
A: Receive a net input of energy from the environment
B: Are nonspontaneous reactions
C: Require an enzyme in order to react
D: Are used in ATP hydrolysis to drive endergonic processes
E: Do not require activation energy
D: Are used in ATP hydrolysis to drive endergonic processes
EXERGONIC = ENERGY BEING RELEASED
ATP hydrolysis is an overall exergonic process. It can be coupled with endergonic reactions (nonspontaneous) to create a coupled reaction with an overall net negative free energy (making the overall process exergonic, and therefore spontaneous and easier to occur). Put simply, we can use ATP hydrolysis (exergonic) to drive energetically unfavorable reactions (endergonic).
Which of the following molecules is correctly linked with its direct catabolic process?
A: Glucose – gluconeogenesis B: Fatty acids – beta oxidation C: Steroids – urea cycle D: Amino acids – glycolysis E: Triglycerides – glycogenolysis
B: Fatty acids – beta oxidation
[pay attention to the question, it specifies “catabolic”]
- gluconeogenesis is a anabolic rxn
A: Glucose – gluconeogenesis
Incorrect. Gluconeogenesis is the formation of glucose from noncarbohydrate precursors. This is an anabolic process.
B: Fatty acids – beta oxidation
Correct. Beta oxidation is the catabolic process in which fatty acids are broken down. Beta oxidation occurs in the mitochondria and produces acetyl CoA which enters the Krebs cycle, as well as NADH and FADH2.
C: Steroids – urea cycle
Incorrect. The urea cycle is used to dispose of toxic ammonia produced from amino acid catabolism.
D: Amino acids – glycolysis
Incorrect. Glycolysis is the catabolic process that breaks down glucose.
E: Triglycerides – glycogenolysis
Incorrect. Glycogenolysis is the catabolic process that breaks down glycogen to glucose.
Regarding the lymphatic system, all of the following are true EXCEPT one. Which one is the EXCEPTION?
A: Contains valves which ensure unidirectional lymph flow
B: Most white blood cells in lymph are neutrophils
C: Lymph is propelled by contraction of smooth muscle as well as skeletal muscle
D: Connects into the blood circulatory system
E: Controls interstitial-fluid levels
B: Most white blood cells in lymph are neutrophils
*The most abundant WBC in the lymphatic system is
B and T Lymphocytes
Which of the following correctly describes the passage of air to the lungs?
“President Lincoln Took Becky Back After she cheated on him”
Pharynx → larynx → trachea → bronchi → bronchioles → alveoli
A new drug is being tested to subdue an overactive sympathetic nervous system. It is injected at the site of release of post-ganglionic nerves. What substance does this drug most likely inhibit?
Norepinephrine
Post-ganglionic nerves of the sympathetic nervous system release norepinephrine and epinephrine onto adrenergic receptors, which stimulate sympathetic nervous system effects (commonly summarized as ‘fight or flight’).
If a person has circulating anti-A and anti-B antibodies but no antibodies to Rhesus factor (Rh), what is their blood type?
Type O+
If the same person does not have antibodies to Rhesus factor (Rh), this indicates that the individual has Rh antigen on their blood cells, and therefore would not produce antibodies against it. The (+) designation of the blood type indicates Rh positive.
