Final answer:
Prior to fertilization, an oocyte has 23 chromosomes and is haploid with one copy of each gene. Upon fertilization, it combines with a sperm to form a zygote with 46 chromosomes, which is diploid having two copies of each gene.
Step-by-step explanation:
Prior to fertilization, human oocytes are in their secondary oocyte stage, which is haploid. This means that they contain 23 chromosomes, which is half the number of chromosomes found in a diploid somatic cell. During ovulation, the secondary oocyte is released from the ovary into the fallopian tube. If fertilization occurs, the secondary oocyte completes meiosis and becomes a mature ovum, which then combines with a sperm to form a diploid zygote. The zygote has two complete sets of chromosomes, one from each parent, totaling 46. Regarding DNA copies, the oocyte, being haploid prior to fertilization, contains one copy of each gene. After fertilization, the zygote has two copies of each gene, one from the mother and one from the father.
The unequal distribution of cytoplasm during oogenesis ensures that the resulting ovum has enough cytoplasmic resources to support early embryonic development until implantation occurs. The cytoplasm in the egg includes vital nutrients and cellular organelles that are crucial for the developing embryo.