CA TONE zoo 2105 CEL L BIOLOGY Attempt all questions. 1.Conside r the way living things are or anized.Descr ibe levels of the organizati on starting from atoms (5marks) coll ergan c - urgar system 2.Describe a)what an organism's genom e is, b)what chromoso mes are, c)wha t sister chromatids are, d)what homol gous chromosome s are , and e) how each of us obtains our homo log ous chromos omes (5marks) 3.Name the human body part that can be utilized to illustrate mitosis phases Explain. (2marks) 4. Telophase is the e rever se of prophase . Elucidate the sta temen t. (4m arks) 5.State three characteristics of viruse s that exempt them from the cell theory . 3 marks) 6.Giv the correct seq uenc e of step:s in cell fractionati on. (5 mar ks) 7. Explain the significance of polar amin o acids for membran proteins.(3marks) 8. Explain why Lysos omes are known as sui cide bags (3marks)

1. The levels of organization in living things start from atoms, which combine to form molecules. Molecules form organelles, which are specialized structures within cells. Cells are the basic unit of life, and similar cells form tissues. Tissues combine to form organs, and different organs work together in organ systems. Finally, multiple organ systems make up an organism. <br /><br /> 2. a) An organism's genome is the complete set of DNA, including all of its b) Chromosomes are structures that contain DNA and proteins, carrying genetic information. c) Sister chromatids are identical copies of a chromosome formed during DNA replication, joined at the centromere. d) Homologous chromosomes are pairs of chromosomes in a diploid organism that have the same structure and carry genes for the same traits, but may have different alleles. e) Each person obtains their homologous chromosomes, one from each parent, during fertilization. <br /><br /> 3. The human body part that can be used to illustrate the phases of mitosis is the bone marrow, where blood cells are constantly being produced through mitosis. <br /><br /> 4. Telophase is considered the reverse of prophase because it involves the reversal of the processes that occur in prophase. In prophase, chromosomes condense and become visible, the nuclear envelope breaks down, and the mitotic spindle forms. In telophase, chromosomes reach the poles of the cell, decondense back into chromatin, the nuclear envelope re-forms around each set of chromosomes, and the spindle apparatus disassembles. <br /><br /> 5. Three characteristics of viruses that exempt them from the cell theory are: viruses are not made up of cells, they cannot carry out metabolic processes on their own, and they cannot reproduce without a host cell. <br /><br /> 6. The correct sequence of steps in cell fractionation is: a) Homogenization, where cells are broken up; b) Centrifugation, where cell components are separated based on density; c) Collection of fractions, where specific components are isolated; d) Analysis, where the properties of the isolated components are studied. <br /><br /> 7. Polar amino acids are significant for membrane proteins because they have side chains that are hydrophilic at one end and hydrophobic at the other, allowing them to span the hydrophobic core of the membrane while interacting with the aqueous environment on either side. <br /><br /> 8. Lysosomes are known as "suicide bags" because they contain digestive enzymes that can break down cellular components. If a lysosome breaks open, these enzymes can cause the cell to self-destruct, a process known as autodigestion or programmed cell death (apoptosis).