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Proteins that move two molecules in the same direction across the membrane are called:

Transmembrane proteins are integral membrane proteins that completely span from one side of a biological membrane to the other and are firmly embedded in the membrane.

Worldwide, only about 35% of adults can digest lactose, the primary sugar in milk. Breakdown of lactose requires the enzyme lactase; while it is normal for all mammals to express lactase as an infant, in most species, including humans, the gene is turned off at weaning.  Thus, in most people, consumption of dairy products in adulthood is less than pleasant, a condition termed lactose intolerance.  Lactose intolerance is caused by the non-persistence of lactase expression.  The mutation that led to lactase-persistence (continued expression of lactase) is thought to have risen in frequency in pastoralist populations – those that started domesticating and farming animals.  The image below shows regions of DNA around the lactase gene in African and European populations.  The lactase persistence allele is shown in red.  Each row is an individual and the colored bars indicate areas of homozygosity – a region where both chromosomes in one person are exactly the same sequence.  These areas of homozygosity represent DNA sequences that are all inherited together without being split apart by recombination.  What is the term for this?    

Jamie has $900 in a bank account. She signs up for a one-year cell phone contract that automatically takes $50 from her account each month. The contract only lasts for one-year and Jamie does not use this account for anything else.  Use this story problem to help you answer the questions that follow.

Rewrite the following equations in simplified slope-intercept form (y = mx + b). Remember, don’t leave a 1 in front of a variable. 1. 5x + y = 5  [a]  3 points 2. -4x + 4y = 8  [b]  2 points 3. -14x – 7y = -7 [c]  1 point  

What would result if a leech had a mutation causing it to secrete low levels of anticoagulants?

In animals that display indeterminate development        

Round worms (Phylum: Nematoda) move by essentially thrashing from side to side. Segmented worms (Phylum: Annelida) are capable of much more controlled and intricate movements. What feature of annelids, missing in nematodes, allows for the annelids’ more complex locomotion?  

Trochophores, the free-swimming larvae of many mollusks, are propelled through the water by

Many mollusks feed using a rasping, tonguelike structure called the _________.