The plasma membrane allows some molecular species to enter and excludes others. it is therefore referred to as a(n) membrane.

permeable
semipermeable
cell
osmosis

You have just sequenced a new protein found in mice and observe that sulfur-containing cysteine residues occur at regular intervals. what is the significance of this finding? it will be important to include cysteine in the diet of the mice. cysteine residues are required for the formation of α helices and β pleated sheets. cysteine residues are involved in disulfide bridges that form tertiary structure. cysteine causes bends, or angles, to occur in the tertiary structure of proteins.

16. which of the following accurately describes a step within transcription? a. dna polymerase uses one strand of rna as a template to put together nucleotides. b. the dna strand is used as a template for which a complementary rna strand can be produced. c. the rna strand forms a template by which dna can be built. d. the rna strand is produced within the cytoplasm.

Fill in the blank 1. digestion occurs in the small intestine through the action of enzymes. 2. urea, excess water, and other waste materials are eliminated in a water fluid called 3. can cause infections by injecting dna or rna into hosts. 4. the human immune system produces in response to a vaccine, which later can bind to and destroy a pathogen if it invades. 5. are structures that link bone to bone at a joint 6. in the heart, blood flows from the right atrium to the right ventricle, where it is pumped to the the words i can use are: lymphocytes gliding pivot gas urine absorption dermis fulcrum lungs chemical viruses capillary vertebrae esophagus tendons antibodies synapses ligaments kidneys pathogens