Review for short answer/essays: Important Terms…Vocabulary You will be given 5 short answer questions and YOU will choose 2 to write about. Remember these three tips: 1) Use the vocab!; 2) Define the vocab; and, 3) Give an example and relate the vocab. to the topic (i.e., put in context). The Good Vocab comparisons section below contain bullets which are ideas that will help you earn a “advanced proficient” score (10-12 on the rubric= A- to A+). AP Essay Themes: A. Cancer and the Cell Cycle: What is the cell cycle and what is cancer? Why does it occur? What does the cell do in response? B. Diet and Nutrition: What are the 6 essentials in the diet? Why are they important? How is diet related to good health? C. Mitosis v. Meiosis: Compare and contrast D. Cell Signaling: What are the steps of cell signaling? Describe and explain an example such as G-protein linked receptor; Tyrosine Kinase; Ion-gated Ligand channels. Why is cell signaling important? Good Vocab comparisons to Know: 1. Sex chromosomes and autosomes Sex chromosomes are XX (human female); XY (human male) 22 pairs of chromosomes are autosomal; and 1 pair is related to sex chromosomes (gender) Chromosomes are made of DNA and they have genes that code for specific traits 2. The chromosomes of a homologous pair You inherit 1 chromosome of each type from each parent (maternal (mom) and paternal (dad)) They find each other in meiosis 1 (prophase I and metaphase 1) to form a tetrad (2 Xs or 2 copied homologous chromosomes from mom and dad) The homologous chromosomes from each parent contain the same genes, but they may have different forms (“alleles”) of the trait; ex. Mom’s homologous chromosome #1 may have a gene for eye color that is green in shade and Dad’s homologous chromosome #1 may have a gene for eye color that is brown in shade. 3. The two sister chromatids of a single chromosome Sister chromatids are created during the S phase of Interphase, which is when DNA is replicated The replicated chromosome copy attaches to the original chromosome and looks like an “X” These copies are attached with the help of proteins, and the attachment site is called the “centromere” These sister chromatids are identical and have the same genes (codes= sequence of A, T, C, and G bases) 4. A diploid and a haploid cell A diploid cell is a somatic cell (comes from tissue/cells of the body that are not sex cells) such as liver, skin, heart, muscle, etc… A diploid cell has a 2n number of chromosomes (twice as many as the haploid number); ex. Humans have a diploid number of 46 A haploid cell is a sex cell (either sperm or egg) and it contains an “n” number of chromosomes which is half the diploid number; ex. Human sperm and egg cells have 23 chromosomes which is half of the diploid number of 46 5. A somatic cell and a gamete Somatic cells are cells of the body that are not part of the cells that make sex cells. Examples are: skin cells, heart cells, neurons (brain cells), muscle cells, liver cells, stomach cells, etc… A gamete is a sex cell such as the sperm or eggs Somatic cells divide through the process of mitosis and gametes are formed from the process of meiosis Somatic cells have a diploid number of chromosomes and gametes have a haploid number of chromosomes Two gametes come together in the process of fertilization (i.e., a sperm fertilizes as egg) to make a diploid cell 6. Mitosis and Meiosis See if you can use the textbook to label this diagram: (Mitosis is on the left and Meiosis is on the right) DNA Replication occurs in the S-phase of Interphase before either mitosis or meiosis occurs Mitosis has one complete division ( one PMAT) whereas meiosis has two complete divisions (2 PMATs) In metaphase of mitosis chromosomes line up single file (ex., 1- 46 in humans) and in meiosis metaphase I chromosomes line up in pairs (2 x 2; or 23 tetrads)…homologous chromosomes find each other Crossing over occurs in prophase I and metaphase I of meiosis; no crossing over in mitosis Mitosis creates 2 somatic cells that are diploid (same chromosome number as the original cell); Meiosis creates 4 haploid sex cells Mitosis produces cells for growth, repair or asexual reproduction (binary fission); Meiosis produces sex cells for sexual reproduction (genetic variability is a key feature; more diversity, better survival!) 7. X and Y chromosomes Sex chromosomes are XX (human female); XY (human male) X chromosome is much larger than the Y chromosome In some species the number of X chromosomes determines gender; not the possession of a Y chromosome X and Y are the sex chromosomes and sperm cells have either an X or a Y; egg cells have only X chromosomes 8. Gene and Locus A gene is a DNA code for a specific protein; a Locus is a specific location of a gene or allele on a chromosome In other words, a gene is the instructions, and a locus is the position or location of the instructions 9. An egg and a zygote An egg is a haploid sex cell or gamete produced by meiosis; a zygote is a fertilized diploid cell that will go through several mitotic divisions to produce a new diploid organism (ex., a human baby) 10. Fertilization and meiosis Fertilization is the process of two gametes (an egg and a sperm) uniting their nuclei to form a diploid cell The gametes were produced in the process of meiosis; gametes are haploid Example: human sperm has 23 chromosomes and a human egg (oocyte) has 23 chromosomes When a human sperm fertilizes a human egg, a zygote is produced with 46 chromosomes 11. Cell Cycle and Cancer The Cell Cycle is comprised of Interphase (G1 (Growth), S (DNA Synthesis), G2 (Growth)) and M (which can be either mitosis or meiosis depending on the cell type) The Cell Cycle has checkpoints in which P53, cyclins, kinases, MPF and other proteins tightly regulate the timing and accuracy of the processes If a cell is mutated (usually DNA damage) and the cell cycle becomes damaged and unregulated, then the cell will undergo apoptosis or cell suicide P53 helps regulate cell suicide, but if P53 is damaged, then the cell may become cancerous The immune system can give outside signals to the cell to commit apoptosis, but sometimes the signals are ignored, especially if P53 is damaged. This may result in a malignant cancer.
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