NATS 1610 Lecture Notes - S Phase, Microvillus, Chromatin
Document Summary
The living body begins at fertilization when one sperm fertilizes an egg: fertilization enables the combination of dna from 2 parents (creating genetic diversity, the fertilizes egg zygote cleaves to increase cell numbers. Cells divide instead of growing larger to limit their surface area to volume ratios (sa/vol ratio: cells get around this problem by: dividing, getting thinner, forming microvilli, storing nutrients. During the s phase: duplication of dna (one dna molecule into 2) Chromosome structure and terminology called turns: one duplicated chromosome, consists of 2 joined replicated dna molecules. Both chromatids are identical: still called one chromosome. Even though its consists of 2 sister chromatids. Because the chromatids are still joined to each other: when joined sister chromatids separate during cell division (mitosis, each sister becomes a separate chromosome (because they are no longer joined, each is now an unduplicated chromosome. Karyotype gives portrait of the chromosomes in a cell (pg 391 figure 20. 3)