Which of the following organic molecules may have up to four levels of structure?

Proteins have up to four levels of organic structure.

1.Primary structure -  the linear arrangement of amino acids.

2. Secondary structure - areas of folding or coiling within a protein.

3. Tertiary structure - the final three dimensional structure of a protein.

4. Quaternary structure - non covalent associations that bind multiple polypeptides into a single larger protein. E.g.  hemoglobin has four polymers, two alpha and two beta chains. They are non covalently bound to each other to form a single large protein - hemoglobin.

an adaptation is a change or process by which an organism takes to be better suited for its environment. for example; migration is a behavioral adaptation, this is needed because birds are not built to last extremely cold climates. there are different adaptations because there are different species needing to adjust to different things, bears don't migrate; they hibernate.

fertilization, pictured in figure 24.23a is the process in which gametes (an egg and sperm) fuse to form a zygote. the egg and sperm each contain one set of chromosomes. to ensure that the offspring has only one complete diploid set of chromosomes, only one sperm must fuse with one egg. in mammals, the egg is protected by a layer of extracellular matrix consisting mainly of glycoproteins called the zona pellucida. when a sperm binds to the zona pellucida, a series of biochemical events, called the acrosomal reactions, take place. in placental mammals, the acrosome contains digestive enzymes that initiate the degradation of the glycoprotein matrix protecting the egg and allowing the sperm plasma membrane to fuse with the egg plasma membrane, as illustrated in figure 24.23b. the fusion of these two membranes creates an opening through which the sperm nucleus is transferred into the ovum. the nuclear membranes of the egg and sperm break down and the two haploid genomes condense to form a diploid genome.

explanation: