AP Biology Mitosis and Meiosis Review Sheet PDF

Preview

Summary

This is a review of Mitosis and Meiosis...

Description

AP Biology Mitosis and Meiosis Review Sheet Cell Cycle: the life of a cell. Important roles of cycle: ➔ Reproduction- amoeba dividing into two cells, each constituting an individual organism ➔ Growth and Development- fertilized egg gives rise to two-celled sand dollar embryo ➔ Tissue renewal- dividing cells in bone marrow continuously make new blood cells Interphase Cycles: ★ G1 rapid growth and producing/copying organelles. ★ S DNA is replicated ★ G2 Growth and final preparation for division. Important Vocab Words ❏ Allele- any of several forms of a gene, usually arising through mutation, that are responsible for hereditary variation. ❏ Gene- the basic physical unit of heredity ❏ Chromatin- is the entire complex of DNA and proteins that makes up chromosomes. When a cell is not dividing ❏ Chromatid- is the duplicated chromosome. ❏ Chromosome- DNA molecules in a cell. ❏ Cytokinesis- the division of the cytoplasm. ❏ Centromere-A centromere is a region containing specific DNA sequences where the chromatid is attached more closely to its sister chromatid (represented by the narrow “waist”). ❏ Daughter cells- are identical copies of their parent cells, produced during Mitosis. ❏ Gamete: A haploid reproductive cell, such as an egg or sperm. Gametes unite during sexual reproduction to produce a diploid zygote. ❏ Genome- all the DNA in a cell. ❏ Haploid- contains a single set of chromosomes. Produced during meiosis (n). Example) Gametes cell ❏ Diploid- contains two sets of chromosomes. Produced during mitosis(2n). Example) Somatic cell. ❏ When images of the chromosomes are arranged in pairs, starting with the longest chromosomes, the resulting ordered display is called a karyotype.

❏ Mitosis, the division of the genetic material in the nucleus, is usually followed immediately by cytokinesis, the division of the cytoplasm. ❏ Meiosis is the variation of cell division that produces gametes, which yields non identical daughter cells that have only one set of chromosomes, half as many chromosomes as the the parent cells. ❏ Mitotic Spindle- a structure consisting of fibers made of microtubules and associated proteins ❏ Zygote-a diploid cell resulting from the fusion of two haploid gametes; a fertilized ovum. Mitosis Checkpoints: G1 “restriction point” in animal cells; continues on to G2 if go, will usually complete cycle; exits cell cycle and enters G0, a nondividing state, if no go; regulated by the activity of cyclin-Cdk protein complexes G2 MPF triggers cell’s passage past G2 checkpoint into M phase if all chromosomes have been replicated M irreversible anaphase stage entered only if all sister chromatids correctly attached to spindle microtubules. ❖ Protein kinases are enzymes that activate or inactivate other proteins by phosphorylating them. Particular protein kinases give the go-ahead signals at the G1 and G2 checkpoints. ❖ Cyclin+CDK produces MPF and then Mitosis occurs ❖ MPF (maturation-promoting factor) triggers the cell’s passage past the G2 checkpoint into M phase. For example, MPF causes phosphorylation of various proteins of the nuclear lamina, which promotes fragmentation of the nuclear envelope during prometaphase of mitosis. ❖ Growth factors are proteins released by certain cells that stimulate other cells to divide. Fibroblasts have PDGF (platelet-derived growth factor) receptors on their plasma membranes. The binding of PDGF molecules to these receptor tyrosine, kinases triggers a signal transduction pathway that allows the cells to pass the G1 checkpoint and divide. Breakdown of nucleus- the nucleus is broken down in between prophase and metaphase (prometaphase). The nucleus begin to reform during telophase. Movement of chromosomes during anaphase Variation in amount of DNA in a cell during different phases. The cells DNA is duplicated during Interphase specifically in S phases.

Density-dependent inhibition is a phenomenon in which crowded cells stop dividing. The bindings of a cell-surface protein to its counterpart on an adjoining cell sends a growth-inhibiting signal to both cells, preventing them from moving forward in the cell cycle, even in the presence of growth factors. Moreover, in a phenomenon known as anchorage dependence, most cells must be attached to a substratum, such as the extracellular matrix of a tissue, in order to divide. Anchorage is probably signaled to the cell cycle control system via pathways involving plasma membrane proteins and elements of the cytoskeleton linked to them. Cancer cells do not follow these behaviors M phase or Mitosis: ★ Prophase- The DNA condenses and organize and the classic chromosomes appears ★ Metaphase- where the chromosomes align along the center of the cells. ★ Anaphase- where the chromosomes separate, pulled apart by kinetochore microtubules. ★ Telophase- nuclear membrane reappear around the two sets of chromosomes. Meiosis 1: Prophase- Synapsis and crossing over occurs. ➔ synapsis: The pairing and physical connection of duplicated homologous chromosomes during prophase I of meiosis ➔ crossing over: The reciprocal exchange of genetic material between nonsister chromatids during prophase I of meiosis ➔ chiasmata: The X-shaped, microscopically visible region where crossing over has occurred earlier in prophase I between homologous non sister chromatids. Chiasmata become visible after synapsis ends, with the two homologs remaining associated due to sister chromatid cohesion. ➔ Homologous chromosomes: A pair of chromosomes of the same length, centromere position, and staining pattern that possess genes for the same characters at corresponding loci. Metaphase- the homologous chromosomes align along the center of the cell Anaphase- the homologous chromosomes separate. Telophase and Cytokinesis- two haploid daughter cells are created

Meiosis 2: Prophase- interphase does not occur before prophase II and both of the two daughter cells go through Meiosis 2. Metaphase- the sister chromatids align along the center. Anaphase- the sister chromatids separate Telophase and Cytokinesis- four daughter cells, each with ½ as many chromosomes as their parent cell. Each daughter cell is genetically distinct from the others and from the parent cell. Independent Assortment- formation of random combinations of chromosomes in meiosis and of genes on different pairs of homologous chromosomes by the passage according to the laws of probability of one of each diploid pair of homologous chromosomes into each gamete independently of each other pair....