In these tissues the cilia have the defensive function of sweeping mucous and foreign substances that enter the airways. In cells of the phagocytic defense system, like macrophages, cytoskeleton is responsible for the plasma membrane projections that engulf the external material to be interiorized and attacked by the cell. Differences: lysosomes have digestive enzymes hydrolases that break substances to be digested into small molecules; peroxisomes contain enzymes that degrade mainly long-chained fatty acids and amino acids and that inactivate toxic agents including ethanol; within peroxisomes there is the enzyme catalase, responsible for the oxidation of organic compounds by hydrogen peroxide H2O2 and, when this substance is in excess, by the degradation of the peroxide into water and molecular oxygen. The cell theory is one of the basic theories of Biology. There are other polymers of glucose, like glycogen and starch. With the osmotic action of the vacuole the cytosol becomes hypertonic in relation to the exterior and more water enters the cell.
What are the main structures within the cell nucleus? Ans: Bacteria possess many enzymes whose rate of synthesis depends on the availability of external food molecules. What are its main functions? What is mass transportation across the cell membrane? Thus, when lactose is absent the lac operon lactose operon repressor prevents synthesis of enzymes that metabolize lactose. Concentration gradient is the difference of concentration of a substance between two regions. But it is not impossible that evolutionary distant species, like rat and oat, bears similar karyotypes and the same total number of chromosomes. The virus is considered the only alive beings that do not have cells. What are the chemical substances that compose the plasma membrane? What are the properties of that organelle that enable it to the task? According to the position of the primary constriction the chromosomes are classified as telocentric, acrocentric, submetacentric or metacentric.
The remodelation of the osseous tissue, the function of acrosomes in sperm cells and the elimination of the tadpole tail are examples of biological processes in which lysosomic enzymes are key factors. The most accepted hypothesis asserts that the more simple cell, the prokaryotic cell, appeared early in evolution than the more complex eukaryotic cell. The phospholipds, amphipathic molecules, are regularly organized in the membrane according to their polarity: two layers of phospholipids form the lipid bilayer with the polar part of the phospholipids pointing to the exterior of the layer and the non polar phospholipid chains in the interior. Sex chromosomes are also called allosomes the other chromosomes that are not sex chromosomes are called autosomes. What are the three main types of passive transport? Since the vacuolar solution is hypertonic in comparison to cytosol it attracts water then increasing the cytosol concentration. What are its main constituents in animal cells? What is the other name given to the secondary constriction? It is possible to apply in the solution another pressure in the contrary way to the osmotic pressure, like the hydrostatic pressure of the liquid or the atmospheric pressure.
What is the molecule responsible for the absorption of photic energy for photosynthesis? It consist of a Purine rich nucleotide sequence b Pyrimidine rich nucleotide sequence c Uracil containing nucleotide sequence d None of above 35 Which of the following is the initiation codon? Concentration gradient is the difference of concentration of a substance between two regions. Cell Nucleus Review — Image Diversity: nucleolus Of which structures is the nuclear membrane composed? This description with further explanations is kown as the fluid mosaic model about the structure of the cell membrane. The most accepted hypothesis asserts that the more simple cell, the prokaryotic cell, appeared early in evolution than the more complex eukaryotic cell. How is that situation possible? One of the main examples of facilitated transport is the entrance of glucose from the blood into cells. Ans: The overlapping genes are two or more genes in which part or complete gene is co-extensive with part of another.
They are not considered cell organelles. Microtubules are made of consecutive dimers of the protein tubulin each dimer has an alpha and a beta tubulin associated. As the name indicates, the cytoskeleton is responsible for the supporting of the normal shape of the cell; it also acts as a facilitator for substance transport across the cell and for the movement of cellular organelles. This description with further explanations is kown as the fluid mosaic model about the structure of the cell membrane. What are the properties of that organelle that enable it to the task? Are euchromatin and heterochromatin part of chromosomes? Lipid membranes do not form only the outer cover of cells. Which of the following factors facilitates the initiation codon? Active transport is made by specific membrane proteins.
The eukaryotic cell can be divided into two main portions: the cell membrane that separates the intracellular space from the outer space phisically delimiting the cell; the cytoplasm, the interior portion filled with cytosol the aqueous fluid inside the cell ; and the nucleus, the membrane-delimited internal region that contains the genetic material. Likewise mitochondria, chloroplasts have two boundary membranes and many internal membranous sacs. How are chromosomes classified in relation to the position of their centromere? Osmosis also is the main process for maintenance of the flaccid, turgid or plasmolytic states of plant cells. What is deplasmolysis of plant cells? It is made of an extensive network of fibers dispersed in the cytoplasm and anchored in the plasma membrane. What is the outcome of the process? Cell Nucleus Review — Image Diversity: karyotype 102. Cell Membrane Review — Image Diversity: pynocitosis phagocytosis 66.
One nucleus can have one or more nucleolus. The cell membrane is formed of lipids, proteins and carbohydrates. The previous question paper section at the end will help you in understanding the pattern of different exams. Without saturation of transport proteins and under same concentration gradient how can the speed of simple diffusion be compared to the speed of facilitated diffusion? Cell Nucleus Review — Image Diversity: centromere 98. The lac operon occurs in Escherichia coli at ca.
Cell Structure Review — Image Diversity: mitochondria 30 :: Why can mitochondria be considered the power plants of the aerobic cells? To which component of the cell structure that membrane is contiguous? Hemolysis destruction of red blood cells by entrance of water, the hydric regulation in plants and the entrance of water in the xylem of vascular plants are all examples of biological phenomena caused by osmosis. In this situation the cell membrane retracts and detaches from the cell wall. The sodium-potassium pump is the transport protein that maintains the concentration gradient of these ions between the intra and the extracellular spaces. Nevertheless the karyotypes of two normal individuals of the same species and of the same sex are always identical. Withered plant cells are those that shrank due to loss of water by evaporation without enough replacement. Cell organelles, such as the Golgi complex, mitochondria, chloroplasts, lysosomes, the endoplasmic reticula and the nucleus, are delimited by membranes too. Microtubules participate in cell division, they are constituents of cilia and flagella and they also form the centrioles.
Cell secretion is the elimination to the exterior of substances produced by the cell for example, hormones, mucous, sweat, etc. How do the amoeboid movements occur? Heterophagic intracellular digestion is the breaking into smaller substances of external substances engulfed in the cell by pinocytosis or phagocytosis. The plant cell wall the covering of the cell external to the cell membrane is made of cellulose, a polymer of glucose. Ans: It is because more than one codon can code for the same amino acid. Cell Membrane Review — Image Diversity: plasmolysed cell flaccid cell turgid cell 71. One nucleus can have one or more nucleolus.