Bio/Biochem Flashcards
Prokaryotes vs. Eukaryotes
Prokaryotes do NOT have membrane-bound organelles (such as ER, nucleus, etc). However, both Prokaryotes and Eukaryotes have a cell membrane and for some, a cell wall.
Describe the steps of reverse transcription
In reverse transcription: 1) single stranded RNA is used as a template to generate a complementary DNA strand. This step requires a RNA-dependent DNA Polymerase. 2) There is temporarily an RNA-DNA double helix, but the RNA strand is degraded, and the DNA strand is used as a template to generate a complementary DNA strand to form a DNA double helix. This step requires a DNA-dependent DNA Polymerase.
Megakaryocytes
Large bone marrow cells with a large nucleus that are responsible for the production of platelets necessary for normal blood clotting.
What is a key difference between viral genetics and eukaryotic genetics?
Viruses are NOT diploid, meaning they have ONE copy of a gene/allele.
What is the “fluid mosaic” model referring to
The fluid mosaic model is referring to two specific properties of the plasma membrane: 1) “Fluid” is the ability of certain molecules to travel laterally within the bilayer. 2) “Mosaic” refers to the presence of proteins and lipids/ other molecules scattered in its structure.
How do double bonds impact fluidity of plasma membrane?
More double bonds, more fluid a membrane is due to kinks.
Lytic vs. Lysogenic cycle
In the lytic cycle, the bacteriophage actively copies its genetic material, resulting in the lysing of the host cell. While, lysogenic cycle is a dormant stage, where the bacteriophage incorporates its DNA in the host genome to be activated later.
What is the impact of a stimulant, like cocaine, on glucose metabolism?
Since a stimulant such as cocaine, stimulates the CNS, it increases glucose metabolism in the brain. This effect is similar to the effect of stress!
Sympatric speciation
When reproductive isolation occurs without physical barriers
Allopatric speciation
When physical barriers cause reproductive isolation
Genetic bottleneck
When a reduction in the gene pool diversity occurs due a REDUCTION in population SIZE
Non-sense vs. missense mutation
Non-sense mutation occurs due to a premature STOP codon (UAG, UGA, UAA). Missense mutation is when one amino acid replaces another.
Adaptive radiation
When distinct species that play distinct ecological roles arise from a single ancestor
Five conditions of Hardy-Weinberg Equilibrium
- Large breeding population
- Random mating
- No immigration
- No mutations that change overall allele frequencies
- No natural selection
What direction does water move towards in osmosis?
Water moves towards greater osmotic pressure
Function of the Loop of Henle
Loop of Henle is a structure of nephrons (filtering cells in the kidney) that rely on Sodium pump to reabsorb sodium ions and make concentrated urine.
What Histone proteins are present in human nucleosomes?
H1, H2A, H3, and H4 are histones present in human nucleosomes. However, H1 is outside the bead structure of histones, because their role is to hold the DNA in place & provide stability for the structure.
What is the difference between Chromatin and nucleosomes?
Nucleosomes refers to the DNA-Histone subunits, while Chromatin is fully-packaged DNA.
How are euchromatin and heterochromatin viewed under a light microscope?
The lightly-packaged euchromatin is viewed lighter under a light microscope, while the more condensed heterochromatin is viewed darker.
What is the shape of a rate vs. pH graph for enzymes?
Parabolic- indicated that enzyme activity is optimal at a certain pH, but once the optimal pH is surpassed, the enzyme declines in function.
How is urea formed?
Urea is formed through amino acid metabolism. An enzyme called aminotransferase, replaces the amine group with a carboxyl or carbonyl group, and the free amine group becomes ammonia (NH3). Ammonia is a toxic metabolite that the liver and kidneys transfer to urea (CH4N2O) through combining it with CO2.
What direction do charged AAs travel in an isoelectric gel?
Positively charged AAs move towards cathode, while negatively charged AAs move towards anode.
Homologous Structures
Evolved from a common ancestor but now serve a different function (Ex: forelimbs of mammals such as humans, walruses, bats)
Analogous structure
Evolved individually but serve similar functions (Ex: wings of insects and bats)
What is the function of many plasma proteins in blood buffering?
Proteins with acidic or basic side chains can serve as Bronsted-Lowry bases and acids, absorbing or releasing protons, reducing shifts in pH.
What does Cholesterol do to plasma membrane at physiological temperature?
Similar to at high temperatures, increasing cholesterol at physiological temperature increases membrane rigidity.
How does glycolysis in cancerous cells differ than normal cells?
Cancer cells have a higher rate of glycolysis in comparison to normal cells because they require more energy to proliferate uncontrollably.
Why does a decrease in the number of alveoli in the lungs lead to respiratory distress?
The reduction in surface area in the lungs due to the reduction of alveoli reduces the rate at which O2 and CO2 can diffuse through lunch epithelium.
What biological processes process quicker due to surface area?
- Large number of alveolar sacs in the lungs.
- Presence of microvilli in the small intestine.
- Folding of the inner mitochondrial membrane.
When given a single-stranded DNA, how will the percent composition of the complementary bases differ from double stranded DNA?
In a single-stranded DNA, the complementary bases would not have equal % composition.
What happens when there is a deficiency in fatty acid catabolism (break down)?
There will be an abundance of fatty acids in our system, and less fatty acids can be broken down for energy production, so glucose is relied on for energy production –> less glucose in the blood because more is broken down. At a systematic level, since fatty acids are not broken down, they are stored in the liver and adipose tissue, likely leading to fatty liver disease.
What happens when Insulin is administered or injected into the bloodstream?
Think of insulin as causing the body to build up large molecules (glycogen and lipids) to store energy. Therefore, if there is enough blood sugar, then insulin would promote glycogen storage, or storage of energy in the form of lipids.
What is the function of Troponin?
Troponin is a complex of three proteins (Troponin I, C, and T) and is required for contraction of skeletal and cardiac muscles.
What travels towards the anode and cathode in electrophoresis?
The anode is positive, so negatively charged residues would migrate towards it. The cathode is negative, so positively charged residues would migrate towards it.
Difference between single & double-crossover events
In a double-crossover event, the arms of homologous chromosomes cross twice, so it involves the middle section of chromosomal arms. While single-crossover only occurs once, so it only involves the ends of chromosomal arms.
Why are mitochondrial diseases only inherited maternally?
Mitochondrial diseases are always a result of the child inheriting mitochondria from the ova (female gamete). In a fertilized egg, the mitochondria of ova predominate due to their much larger numbers compared to the mitochondria of sperm. Sperm mitochondria are also associated with ubiquitin protein which causes them to be targeted for destruction post-fertilization.
What is the function of aldosterone?
Aldosterone, released by the adrenal cortex, is released in response to low blood pressure. Its primary function is to increase sodium reabsorption in the distal tubule and collecting duct
What is internalization in the context of biological systems?
Internalization implies that it is NOT expressed on the cell membrane.
Which amino acids are most susceptible to phosphorylation?
The amino acids most prone to phsophorylation are Serine (S), Tyrosine (Y), Threonine (T) due to the presence of an OH group.
What does phosphomimetic mean?
Mimics a phosphate group, so think negatively charged at physiological pH.
Difference between innate and adaptive immunity
The innate immune system is characterized by inflammation that serves as a general response to injection or injury. Adaptive immune system protects against specific pathogens that the body has been exposed to prior.
Totipotent stem cells
Stem cells that are capable of differentiating into all embryonic and adult lineages. (Ex: Zygote)
Pluripotent stem cells
Able to differentiate into all three of the basic embryonic body layers (ectoderm, endoderm, mesoderm) (Ex: Embryonic stem cells)
Multipotent stem cells
Stem cells able to differentiate into multiple specialized cell types in a specific tissue or organ. (Ex: Mesenchymal stem cells)
What results can be inferred from a cross-sectional study?
Cross-sectional studies are observational studies at a single point in time. Only causal relationships can be concluded.
What results can be inferred from an experimental study?
Causal relationships can be inferred if experimental study is well controlled.
What happens in paralyzed patients?
The pathway is not intact and efferent signaling is interrupted. This occurs if spinal cord transection occurred (cutting and nerve damage)
What happens in spinal cord injuries?
The motor cortex is still intact so muscles can still move
What is the pathway from Central Nervous to peripheral?
Cerebral cortex –> spinal cord –> motor neurons (efferent neurons) –> skeletal muscle cells
Guanine Structure
Purine = 2 rings
Adenine Structure
Purine = 2 rings
Cytosine Structure
Pyrimidine = 1 ring
Thymine Structure
Pyrimidine = 1 ring
Uracil Structure
Pyrimidine = 1 ring
Apoenzyme
An enzyme that is devoid of its necessary cofactors and is catalytically inactive
Enzyme responsible for the last step of Glycolysis
Converting PEP to pyruvate is done by Pyruvate Kinase
What step of Citric Acid produces GTP
Conversion of succinyl-CoA to succinate
How do you determine a reversible step when given Gibbs Free Energy?
The reaction with an absolute value closest to 0 is considered reversible
Complex II in ETC
Only complex that does NOT contribute to proton gradient. Primary function is to oxidize FADH2 and reduce ubiquinone. Hypothesized to reduce production of reactive oxygen species
Ubiquinone or Coenzyme Q (CoQ)
Serves as mobile electron carrier, facilitating the transfer of electrons to Complex III & helps facilitate proton pumping, contributing to the gradient by pumping 4 protons into inter- membrane space
Why are diseases associated with splicing so rare?
Splicing is critical for survival, so mutations in core splicing machinery do not allow development of an organism
Relationship between Prokaryotic RNA polymerases and human DNA
Prokaryotic RNA Polymerases can transcribe human DNA
Acidosis
When blood pH is below a 7.35
Alkalosis or Alkaline
When blood pH is above a 7.45
What happens when people hyperventilate?
Respiratory rate increases, so more CO2 is blown off, making the blood more alkaline. Breathing into a bag and re-breathing the air helps some of that CO2 return in your system
Adrenal Medulla
Located on top of each kidney. Produces amino-acid derived hormones, norepinephrine and epinephrine
Adrenal Cortex
Located on the outer parts of the adrenal medulla. Produces corticosteroids, which are involved in stress response and circadian Rhythm,
Atrial natriuretic peptide (ANP)
Regulates fluid homeostasis
Uvula
Works with the soft palate to prevent backflow of food and liquid into nasal cavity
Epiglottis
A cartilage flap that shields the larynx from entrance of food and liquid when someone swallows
Characteristic of anomers
Anomers are a form of epimers which are diastereomers because they differ at one stereocenter only
Effects of Aldosterone secretion
When Aldoesterone is released from adrenal cortex, it triggers the reabsorption of Na+ ions and H2O into the bloodstream. To stabilize K+/Na+, as Na+ is reabsorbed into the bloodstream, K+ decreases.
