Biology 151 - Exam 2 Questions And Answers

Large numbers of ribosomes are present in cells that produce which of the following molecules? - ANS proteins What is an incorrect statement about the synthesis of polypeptides (proteins)? - ANS The synthesis of proteins is a catabolic process. What are constituents of the nucleus? - ANS Pores, envelope or membrane, chromosomes, chromatin Tissues that are metabolically active and utilize large amounts of energy would be rich in _____. - ANS mitochondria. What is important for allowing large, charged molecules to pass through the membrane? - ANS membrane proteins What are some true statements regarding active transport? - ANS - It requires energy - It is an active process in which molecules move from a region of lower concentration to one of higher concentration - It requires integral proteins - It is necessary to maintain solute gradients across a membrane What are some true statements about plasma membranes? - ANS - They are composed of phospholipids - They have both integral and peripheral proteins - They are composed of two leaflets of phospholipids - They function to separate the extracellular and intracellular environment Of the following molecules, which passes through a lipid bilayer most readily (easily)? a. carbon dioxide b. glucose c. K+ d. arginine e. RNA - ANS a. carbon dioxide What is true about about passive diffusion? - ANS - Passive diffusion is the process by which molecules move from an area of high concentration to an area of low concentration - Passive diffusion is a spontaneous process - Passive diffusion will occur so long as the membrane is freely permeable to the solute - Passive diffusion requires no energy The release of insulin from pancreatic cells occurs by _____. - ANS exocytosis. Facilitated diffusion across a biological membrane requires _____ and moves a substance _____ its concentration gradient. - ANS transport proteins.....down/with The idea that all living things are composed of cells that all come from pre-existing cells defines _____. - ANS cell theory. Suppose two compartments within a cell are separated by a semipermeable membrane. Compartment A has a higher solute concentration than compartment B. Compartment A is _____ to compartment B, and water will move via osmosis into _____. - ANS hypertonic; compartment A As cell size increases, the: - ANS volume increases faster than the surface area. Muscle cells make different proteins than nerve cells because they have different sequences of DNA (true/false). - ANS false Which type of protein does DNA wrap around so that it can be packaged in a cell? - ANS Histones Which one of the following correctly lists the components necessary for eukaryotic transcription? - ANS RNA polymerase, general transcription factors, DNA, and RNA nucleotides A template DNA strand contains the sequence 5'-ATGCTGAC-3'. The corresponding sequence in the RNA transcript is: - ANS 5'-GUCAGCAU-3' What are some of the molecules make during the process of transcription? - ANS mRNA, tRNA, rRNA In transcription, the energy to attach each successive ribonucleotide to the growing RNA chain comes from: - ANS cleavage of the high-energy phosphate bonds of the incoming nucleotide. A template DNA strand contains the sequence 3'-ATGCTGAC-5'. This strand is transcribed: - ANS from left to right. What would happen if an enhancer sequence were mutated so that its binding partner was always bound and recruiting the RNA polymerase complex? - ANS Transcription would occur continuously. In eukaryotes, activator proteins bind to _____ ; generalized transcription factors bind to _____. - ANS enhancers; promoters The type of RNA that physically interacts with a ribosome, providing the sequence information for a specific protein, is abbreviated: - ANS mRNA Transcription starts at a _____ and ends at a _____. - ANS promoter; terminator An intron is: - ANS an RNA sequence that is removed during the processing of an RNA molecules in the nucleus. Alternative splicing allows for: - ANS different polypeptides to be made from a single gene. RNA processing occurs in: - ANS eukaryotes only. Proteins that do not refold properly after being heated generally require the assistance of which one of the following types of molecules in cells? - ANS chaperones When a peptide bond is created between two amino acids: - ANS the carboxyl group of the first amino acid is joined to the amino group of the second. Assuming A-U and G-C pairing between the anticodon and the codon, what anticodon in tRNA^Met would pair with the codon 5'-AUG-3'? - ANS 5'-CAU-3' An mRNA molecule has a sequence 5'-CAGAUCUAAUGCUUAUCGGAU-3' - ANS 3 In what order does a charged tRNA move through the site of a ribosome? - ANS The tRNA binds with the A site, then is moved to the P site, then the E site as the ribosome shifts. The integrity of a biomembrane would have to be disrupted in order to remove what types of membrane proteins? - ANS - peripheral membrane proteins - lipid anchored proteins DNA wraps around histone and other proteins to form _____. - ANS chromatin. The multi-subunit protein structure which relays messages from specific activator and repressor proteins to RNA polymerase is known as the _____. - ANS mediator. When RNA functions as a biological catalytic, we call it a _____. - ANS ribozyme.