Cells and Genomes
THE UNIVERSAL FEATURES OF CELLS ON EARTH
TERMS TO LEARN
· amino acid
· DNA replication
· messenger RNA (mRNA)
· plasma membrane
· ribonucleic acid (RNA)
· ribosomal RNA (rRNA)
· transfer RNA (tRNA)
Match each definition below with its term from the list above.
1. The selective barrier composed of a lipid bilayer and embedded proteins that surrounds a living cell.
2. A protein that catalyzes a specific chemical reaction.
3. Copying of one strand of DNA into a complementary RNA sequence by the enzyme RNA polymerase.
4. Process by which the sequence of nucleotides in an mRNA molecule directs the incorporation of amino acids into protein.
5. Region of DNA that controls a discrete hereditary characteristic of an organism, usually corresponding to a single protein or RNA.
6. RNA molecule that specifies the amino acid sequence of a protein.
7. Organic molecule containing both an amino group and a carboxyl group. Those in which the amino and carboxyl groups are linked to the same carbon atom serve as the building blocks of proteins.
8. The total genetic information carried by a cell or an organism (or the DNA molecules that carry this information).
Decide whether each of these statements is true or false, and then explain why.
· Genes and their encoded proteins are co-linear; that is, the order of amino acids in proteins is the same as the order of the codons in the RNA and DNA.
· DNA and RNA use the same four-letter alphabet.
· 'Life' is easy to recognize but difficult to define. The dictionary defines life as "The state or quality that distinguishes living beings or organisms from dead ones and from inorganic matter, characterized chiefly by metabolism, growth, and the ability to reproduce and respond to stimuli." Biology textbooks usually elaborate slightly; for example, according to a popular text, living things
1. Are highly organized compared with natural inanimate objects.
2. Display homeostasis, maintaining a relatively constant internal environ- ment.
3. Reproduce themselves.
4. Grow and develop from simple beginnings.
5. Take energy and matter from the environment and transform it.
6. Respond to stimuli.
7. Show adaptation to their environment.
· Score a car, a cactus, and yourself with respect to these seven…