Sperm need significant amounts of ATP to fuel their travel through the reproductive tract. This ATP is generated via oxidative metabolism of the glucose and fructose contained in the seminal fluid.     These sugars are large polar molecules that enter sperm cells via glucose transporters or GLUTS.  One such GLUT protein is depicted in the image below.  When GLUTS recognize and bind glucose, they undergo a conformational change releasing glucose on the other side of the membrane. Due to the persistent high energy demands of the sperm cell, these sugars are continually being catabolized (broken down).  GLUTs mediate what type of transport of glucose and fructose across the membrane? ________________  Is this an active or passive process? _________________        What type of transport protein are the GLUTs described in this question? ___________________    How many transmembrane domains does this GLUT have?  _______________

In normally dividing cells, once chromosomes have been properly segregated via the steps of mitosis, the two resulting “daughter cells” separate. In animal cells (and other cell types without a cell wall) the contractile ring plays a crucial role in the process of cytokinesis. Exactly how the contractile ring is accurately positioned, so as to be located midway between the two poles (ends) of the dividing cell, is still not fully understood, although factors released from the mitotic spindle are thought to play a role.Regardless of the precise positioning mechanism, one key player in the assembly of the contractile ring is the GTP/GDP binding protein Rho. In its active form, Rho can stimulate the activity of the actin-binding protein formin and (via effects on the myosin regulatory light chain) that of myosin II. Given their respective roles, why might activation of formin and myosin II be beneficial as cells assemble a functional contractile ring structure?

Anaphase B involves the separation of spindle poles. What forces have been proposed to drive this separation? What underlying molecular mechanisms are thought to provide these forces?

Describe an experiment that shows if early mouse embryo inner cell mass cells containing mitochondrial defects die through necrosis of apoptosis.

Control female AOX female DJ-1 female A. = ROS = Antioxidants B. Control female AOX female DJ-1 female = ROS = Antioxidants Control female AOX female DJ-1 female C. = ROS = Antioxidants Using the image above, which drawing (A, B, or C) do you think predicts the amount of ROS and antioxidants the sperm cell is exposed to. ROS is represented by the yellow star and antioxidants are represented by a blue asterisk. Remember that even though all the males were genetically identical and produced a normal amount of ROS and antioxidants, their sperm can still be affected by both ROS and antioxidants from nearby cells in the female's body. O A O B Oc

Rather surprisingly, some cellular components that we know best from our study of nuclear protein traffic also appear to be involved in the process of spindle assembly. These include Ran GEF (which, as you may recall, is bound to chromatin – an association that apparently continues even when the nuclear envelope breaks down at the onset of mitosis) and importin-β. Now think back to the process of nuclear protein import. To which form of Ran (Ran-GDP or Ran-GTP) does importin-β bind and what is the significance of that interaction with respect to the efficiency of delivery of import “cargo” to the nucleus? To which form of Ran (Ran-GDP or Ran-GTP) do exportins bind and what is the significance of that interaction with respect to the efficiency of delivery of export “cargo” to the cytoplasm?

Fruit flies (Drosophila melanogaster) are a common model organism in genetics labs. A somatic cell in D. melanogaster has 2n = 8. How many chromosomes will a D. melanogaster female gamete contain?

Explain: The cell has  ----- Chromatides during g2.     -------    Chromatides during a phase and.      _________Chromatides during metaphase .

Select the incorrect statement: O A. Transcription produces an mRNA of a gene that leaves the nucleus. O B. A hydrophobic hormone-receptor complex may increase the expression of a specific protein by stimulating the transcription of more of that protein's MRNA. OC Protein synthesis is a two-phase process that includes transcription and translation. O D, In the process of transcription, the entire chromosome is copied by RNA polymerase.

The seed of the castor bean (Ricinus communis) contains large amounts of ricin, a deadly poison for animals, including humans. One of the two subunits of this toxin is a lectin that binds terminal N-acetylgalactosamine residues on glycoproteins on the surface of eukaryotic cells, allowing the other subunit to enter the cell and kill it by preventing proteins from being made. Select the possible antidotes that could prevent or reverse ricin-mediated entry of the toxin. a high concentration of N-acetylgalactosamine an oligosaccharide with the same structure as that recognized by ricin a compound that prevents synthesis of extracellular glycoproteins a compound that activates enzymes that break down glycogen into glucose an enzyme that degrades lipopolysaccharides