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study guide exam II
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Question | Answer | |
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1) What are the 2 types of cell division? What cell type(s) use each one? For what purpose(s)? | Mitosis and Meiosis are the two types of cell division. Mitosis is the division of somatic cells for growth and repair of specific tissues and the body as a whole. Meiosis is the division of reproductive cells for the production of gametes (sperm in mal | |
What is chromatin? What are chromosomes? Why do cells need both? | Chromatin is uncondensed (open, accessible) DNA, while chromosomes are condensed (inaccessible) DNA. DNA needs to be accessible to regulatory proteins for protein synthesis and duplication when a cell is not dividing, but needs to be condensed during cel | |
are genes? What role(s) do genes play in the characteristics (traits) of a cell or individual? | Genes are segments of DNA that encode for a specific protein(s). Since proteins are the “work horses” of a cell or individual, their activity determines the characteristics of that cell or individual. The more active the gene, the more of a particular p | |
How many chromosomes are in a somatic cell? Where did they come from? | There are 23 pairs of homologous chromosomes (46 chromosomes) in a somatic cell. One set of chromosomes (23 chromosomes) comes from a sperm (dad) and the other set of chromosomes (23 chromosomes) comes from an egg (mom).There are 23 pairs of homolo | |
What are homologous chromosomes? What are different forms of the same gene called? | Homologous chromosomes are non-identical chromosomes of the same type. They have the same genes in the same locations (loci) on the chromosome, but the genes are present in different forms. Genes which encode for the same protein, but with slight variat | |
are the 2 general types of chromosomes? What does each type of chromosome provide an individual? | The two general types of chromosomes are autosomal chromosomes and sex chromosomes. Autosomal chromosomes (chromosomes 1 – 22) determine most of the inherited characteristics of a person, while the sex chromosomes (X and Y) determine the sex of an indivi | |
How are chromosomes viewed? What can be learned from viewing chromosomes? | Chromosomes are viewed by condensing, staining and arranging them in order, a process known as karyotyping. Irregularities in chromosome shape, size and number can be observed to determine if a person will be (has been) born with a disorder. In particul | |
What is the cell cycle? What are the 2 major parts of the cell cycle? What occurs during each part? | The cell cycle includes the events that need to occur for a cell to reproduce itself. The two major divisions of the cell cycle are interphase and cell division. During interphase the cell grows by duplicating everything, including its organelles and DN | |
What are the 3 parts of interphase? What occurs during S phase? | Interphase is composed of three sequential parts: Gap1 (G1), S phase and Gap 2 (G2). It is only during S phase that a cell duplicates (replicates) its DNA so that each chromosome has 2 sister chromatids. | |
What are the 2 parts of cell division? What occurs during each part? | Cell division can be divided into two overlapping parts: mitosis and cytokinesis. During mitosis a cell separates its chromosomes (division of the nucleus), while during cytokinesis the cell itself divides into two cells (division of the cytoplasm). | |
How are the different phases of the cell cycle identified? What is observed for each phase? | The phases of the cell cycle can be identified by looking at what is happening to the chromosomes. | During interphase the chromosomes are uncondensed and appear as a bunch of thin strands. During prophase the chromosomes condense into a pile of thick structures, each looking like the letter X or H. During metaphase the condensed chromosomes are lined |
If cells can divide by mitosis, why is meiosis necessary? What is different between mitosis and meiosis? | Meiosis is necessary to reduce the number of chromosomes in half so that during fertilization, when the chromosomes from the two gametes combine, the number of chromosomes in the zygote remains correct | Mitosis uses one cell division to form two diploid daughter cells (somatic cells) that are identical to the parent cell to be used for growth and repair, while meiosis uses two cell divisions to form four haploid daughter cells (sex cells) that have half |
What is provided during meiosis that is not provided during mitosis? When do they occur? | Meiosis provides opportunities for genetic variability to be inserted into the genome. These occur at synapsis during prophase I by crossing over, when homologous chromosomes are paired during metaphase I by independent assortment and during fertilizatio | |
15) What is spermatogenesis and oogenesis? What is provided at the end of each process? | Spermatogenesis is the production of sperm by meiosis in males to provide 4 spermatozoa from each primary spermatocyte. Oogenesis is the production of eggs by meiosis in females to provide 1 egg (ovum) from each primary oocyte. | |
16) What is a nondisjunction? When do they occur? What can occur because of a nondisjunction? | A nondisjunction is the improper separation of chromosomes during meiosis. They can occur by the improper separation of homologous chromosomes during anaphase I or by the improper separation of sister chromatids during anaphase II. The presence of a non | |
17) What are the syndromes presented in class? How do they occur? | Down syndrome is one of the only common syndromes that occur by a nondisjunction of an autosomal chromosome, caused by the presence of an extra chromosome 21 (trisomy 21).Turner syndrome occurs by the loss of an X or Y chromosome, producing a female w | Klinefelter syndrome occurs by the presence of an extra X chromosome, producing a male with two X chromosomes (XXY).Jacobs syndrome occurs by the presence of an extra Y chromosome, producing a male with two Y chromosomes (XYY). This can only occur du |
18) What are stem cells? How do they differ from other cells of the body? | Stem cells are unspecialized cells that can differentiate into different types of cells. Other body cells have already differentiated into a particular cell type (muscle cell, nerve cell) and so can not go back to the undifferentiated state to become a d | |
are the 3 major types of stem cells? Where are they obtained? | The 3 major types of stem cells are embryonic stem cells, adult stem cells and umbilical cord stem cells.Embryonic stem cells are obtained from embryos (blastocysts) created by in vitro fertilization. Embryonic stem cells are the most undifferentiate | Adult stem cells are obtained from adult tissues (bone marrow, skin, liver). Adult stem cells are partially differentiated and can only form cells from their particular lineage.Umbilical cord stem cells are obtained from the fetal blood that resides |
What are the 4 phases of mitosis and meiosis? Write the phases in order from prophase to telophase. | The phases of mitosis (meiosis) include: prophase, metaphase, anaphase, and telophase. |