Water, Macromolecules, and Membranes
True or False: Within a cell, passive transport is the movement of molecules from a low concentration to a high concentration?
False. Movement of molecules from low to high concentration refers to active transport.
Trick- Think of a slide. Just like climbing up a slide requires more energy than sliding down, active transport requires energy while passive transport does not as it is the movement of molecules from low to high against their concentration gradient.
Which organelle houses chromosomes that store and transmit genetic information?
The nucleus.
True or False: Meiosis allows for more genetic diversity than mitosis?
True. Meiosis creates four unique haploid cells while mitosis creates two identical daughter cells. Crossing over, independent assortment, and random fertilization all contribute to the increased genetic diversity that meiosis produces.
True or False: DNA is synthesized in the 5'-->3' direction by DNA polymerases?
True.
True or False: Condensed chromatin is associated with activation of gene expression?
False. If the chromatin is condensed, it is harder to replicate, thus harder to express.
True or False: Small, uncharged molecules pass through the plasma membrane easier than large, charged molecules?
True. The interior of the phospholipid bilayer is hydrophobic, therefore smaller, nonpolar molecules will be able to pass through the membrane without transport proteins or protein channels.
An inhibitor binds to an enzyme causing a conformational shape change, thus hindering the substrate from binding to the active site. What kind of inhibition is this called?
Allosteric inhibition. If it were competitive inhibition, the inhibitor would compete with the substrate for the active site.
Two identical chromatids in a replicated chromosome are called___________?
Splicing, 5' capping, and addition of 3' Poly-A Tail are the three main steps of RNA processing. Do these occur in prokaryotes or eukaryotes?
Eukaryotes. Eukaryotes have a nucleus, so the mRNA must be processed and protected before entering the cytoplasm for translation. Also, prokaryotes usually don't have introns, so splicing does not occur.
True or False: Most of the human genome does not code for proteins?
True.
True or False: The tertiary structure of proteins is formed through hydrogen bonds between backbone atoms?
False. Formation of proteins through backbone hydrogen bonds refers to the secondary structure of proteins.
True or False: During cellular respiration, the Citric Acid Cycle (Krebs Cycle) occurs directly after glycolysis?
False. The pyruvates must be oxidized into Acetyl-CoA before entering the Citric Acid Cycle.
There are four blood types: A, B, AB, and O. Which one of these represent co-dominance?
AB. In co-dominance, both alleles are fully and equally expressed in a heterozygous individual. A person with genotype IᴬIᴮ has both A and B antigens on their red blood cells.
True or False: In prokaryotes, the binding of general transcription factors to the promoter initiates transcription by recruiting RNA polymerase?
False. The binding of general transcription factors to the promoter initiates transcription in eukaryotes. In prokaryotes, the sigma protein binds to the promoter in order to recruit RNA polymerase.
When one daughter cell receives a signal that the other does not, this is called?
Induction.
When looking at an amino acid's side chain that has no charge but contains an oxygen, what would be the classification?
Uncharged polar. Due to oxygen's high electronegativity, a partial charge is created within the molecule.
What is the order in which proteins travel through the endomembrane system?
Rough ER-->Golgi Apparatus-->secretory vesicles--> cell membrane.
The protein is made by ribosomes at the rough endoplasmic reticulum, then sent to the Golgi Apparatus where it is modified (folding, addition of phosphate group or sugar), and lastly stored in vesicles where it is sent to the membrane to be secreted via exocytosis.
Is the following a lipid-soluble or lipid-insoluble enzyme-linked receptor pathway?
Signal arrives--> Binds receptor on cell surface-->receptors are autophosphorylated-->phosphorylation cascade eventually changes gene expression
Lipid-insoluble. Because the lipid signal is insoluble, it cannot go through the cell membrane, so it binds to the receptor at the surface of the cell instead of inside of the cell.
If UUU and UUC both result in phenylalanine, and a mutation causes a part of the mRNA sequence to change from UUC to UUU, what kind of mutation would this be describing?
Silent mutation. This mutation would be recognized as "silent" as the actual protein that the anti-codon coded for did not change after the mutation.
What are the steps of Polymerase Chain Reaction?
Denaturation: The DNA template is heated to separate the double-stranded DNA into two single strands. This breaks the hydrogen bonds between the complementary bases, giving access to the individual strands for replication.
Annealing: The reaction is cooled so that short DNA primers (which are complementary to the target sequence) can bind (or "anneal") to their respective single-stranded regions on the template DNA.
Extension: The enzyme Taq polymerase (or another heat-stable polymerase) extends the primers by adding complementary nucleotides (A, T, C, G) to synthesize the new DNA strand. The polymerase moves along the DNA, building the new strand in the 5′ to 3′ direction.
Based on an image of a nucleotide, how might one determine if it contains ribose or deoxyribose?
If the 2' (on the five carbon sugar) has a hydroxyl group, the nucleotide contains ribose. If it has hydrogen, the nucleotide contains deoxyribose.
Trick- Think of "Deoxy" as deoxygenated.
Name two ways in which enzymes increase reaction rates.
Enzymes can do this by lowering the activation energy, bringing substrates together, and promoting transition state formation.
True or False: X-linked recessive traits are more common in males than females?
True. Males have one X chromosome and females have two. For males, if the recessive trait is on that X chromosome, it will be expressed. For females, the recessive trait would have to show up on both X chromosomes, resulting in a lower probability.
An abnormality on chromosome #_______ causes down syndrome?
21. Trisomy is a type of aneuploidy where there are three copies of a given chromosome instead of two. If this phenomena occurs on chromosome #21, it's called Trisomy 21 and it results in down syndrome.
Cancers often mutate the _____ gene so that the protein it encodes is nonfunctional?
p53. p53 is a tumor suppressor gene, so if it is mutated, the cell might develop a tumor.