Early geneticists wondered how only four nucleotides can specify the sequence of 20 amino acids in proteins. They hypothesized that there must be a code that linked the nucleotide sequence in a gene to the amino acid sequence in a protein. Each nucleotide code is called a codon. Today we know that there is a genetic code in which __________ nucleotide(s) code(s) for each amino acid.

A. 1
B. 3
C. 2
D. 4


B. 3

Biology & Microbiology

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Organs strung together functionally and usually structurally form

(a) organs. (b) systems. (c) tissues. (d) organelles.

Biology & Microbiology

Chestnut blight _____

a. altered the species composition of eastern forests b. was caused by an introduced fungal pathogen c. was spread by wind-dispersed spores d. all of the above

Biology & Microbiology

If phospholipids form a spherical structure when placed in water, then which of the following is the most logical

conclusion about those phospholipid molecules? a. They form a bilayer. b. They are cone-shaped. c. They are not amphipathic. d. They have two hydrophilic ends. e. They contain two fatty acid chains

Biology & Microbiology

If a person turns their ankle, how would one determine if damage to the tissue in the ankle has occurred?

a. The ankle is red. b. The ankle is red, swollen, and warm to the touch. c. The ankle is very warm to the touch. d. The ankle swells.

Biology & Microbiology