If green plant cells are incubated in the presence of CO2 molecules containing radioactive carbon atoms, the fate of the carbon atoms can be followed. In an experiment, radioactive CO2 was given for 1 minute to plant cells, and then the cells were examined after 1, 5, 10, 20, and 30 minutes. The following molecules were labeled with radioactive carbon at some point(s): glucose, glyceraldehyde 3-phosphate, glycine (an amino acid), 3-phosphoglycerate, ribulose 1,5-bisphosphate, and sucrose. List these molecules in the order in which they first become labeled.

Explanation:                          

The glycine, among other amino acids, helps to improve chlorophyll production and promotes the process of photosynthesis.

Calvin cycle

During the carbon fixation phase, a CO² molecule combinate with a ribulose 1,5-bisphosphate to form 6-carbonated molecules, which will divide into two 3-phosphoglycerate molecules.

During the reduction phase, NADPH donates its electrons to reduce 3-phosphoglycerate molecules, and turn them into glyceraldehyde 3-phosphate.

During the regeneration phase, a glyceraldehyde 3-phosphate molecule leaves the cycle and goes to the cytosol to form glucose. This step can be done when three CO² enter the cycle and produce six glyceraldehyde 3-phosphate molecules. One of them leaves the cycle to form glucose, while the other five are recycled.

Cytosol:  

Once in the cytosol, glyceraldehyde 3-phosphate molecules are used to form glucose and fructose. These two molecules are the monosaccharides that form the sucrose.          

Once sucrose is formed, it is transported from the photosynthetic tissues to different parts of the plant by the phloem.

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: