Molecules and Membranes
True or False: Diffusion is when solutes (small molecules) move FROM HIGH concentration TO LOW concentration
TRUE.
Which organelle houses chromosomes that store and transmit genetic information?
The nucleus.
True or False: DNA is synthesized in the 5'-->3' direction by DNA polymerases?
True.
True or False: A missense mutation changes an amino acid codon to a codon for a different amino acid.
TRUE. Other types of mutations:
Silent-Changes an amino acid codon to a different codon that still codes for the same amino acid
Nonsense-Changes an amino acid codon to a stop codon
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: Passive transport REQUIRES ENERGY input?
FALSE. Movement of molecules by Passive transport from high to low concentration DOES NOT REQUIRE energy. Active transport from low to high concentration DOES REQUIRE energy.
Trick- Think of a slide. Just like climbing up a slide requires more energy than sliding down, active transport requires energy as it is the movement of molecules from low to high against their concentration gradient. To go down the slide from high to low in Passive Transport doesn't require energy.
An inhibitor binds to an enzyme outside of its active site, 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.
True or False: In MEIOSIS, each daughter cell will be GENETICALLY IDENTICAL (have the same number of chromosomes) as the parent cell?
FALSE. Meiosis creates four unique haploid cells (gametes) while mitosis creates two identical daughter cells.
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: A constitutive gene is one that is ALWAYS expressed
TRUE.
True or False: A POLAR covalent bond shares electrons UNEQUALLY between atoms.
TRUE. POLAR covalent bonds share electrons unequally creating a partial positive and partial negative charge on atoms involved.
The Citric Acid Cycle (Krebs Cycle) produces what two reduced electron carriers in cellular respiration?
1. NADH
2. FADH2
This is the main role of the Citric Acid Cycle, to produce reduced electron carriers to power the ETC and ATP synthesis.
Name and define two types of Cell-Cell junctions.
Tight Junctions-Membrane proteins of adjacent cells that "stitch" membranes of two cells together; creates a "seal" between cells in a tissue layer
Desmosomes-Membrane proteins that link intermediate cytoskeletal filaments in adjacent cells to resist shearing and pulling forces
Gap Junctions-Direct protein connections between cells that form channels that ions and small molecules can pass through.
Plasmodesmata-Gaps in plant cell walls that connect plasma membranes, cytoplasms, and smooth ERs of two 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.
Name two differences between plant and animal cells:
1. Lysosomes are ONLY found in Animals
2. Chloroplasts are ONLY found in Plants
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.
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 on the Rough ER, then sent to the Golgi Apparatus where it is processed, sorted and packaged, and finally sent to the membrane to be secreted via exocytosis in Secretory Vesicles at the Cell Membrane.
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.
Name the types of bonds that connect the following:
1. Amino Acids
2. Nucleotides
Amino Acids are connected via peptide bonds
Nucleotides are connected by phosphodiester linkages (bonds)
Name a major functional role of Carbohydrates in the cell.
The three roles for Carbohydrates we've discussed are: Energy Storage, Structural Support, and Cell Identity
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.
Name and define the two ways that Meiosis generates genetic diversity.
Crossing Over-Produces new combinations of alleles within a chromosome that were not present in either parent.
Independent Assortment-Maternal and paternal chromosomes separate independently from one another in meiosis I; Produces new sets of alleles across different chromosomes
Name and Define the 4 types of Chromosomal Mutations.
Deletion-Loss of a large segment of a chromosome
Inversion-Segment of a chromosome is broken, flipped, and rejoined
Duplication-A chromosome has an additional copy of a segment
Translocation-One part of a chromosome attaches to a completely different chromosome
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.