Examples of polar body in the following topics:
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- This second cell is called a polar body and usually dies.
- If the secondary oocyte is fertilized, the cell continues through the meiosis II, completing meiosis, producing a second polar body and a fertilized egg containing all 46 chromosomes of a human being, half of them coming from the sperm.
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- Tissues, in turn, collaborate to create organs (body structures with a distinct function).
- Organs (groups of tissues working together) perform specific functions, such as carrying oxygen throughout the body, removing wastes, delivering nutrients to every cell, and cooling the body.
- For example, an organism needs to regulate body temperature through a process known as thermoregulation.
- Organisms that live in cold climates, such as the polar bear , have body structures that help them withstand low temperatures and conserve body heat.
- Polar bears (Ursus maritimus) and other mammals living in ice-covered regions maintain their body temperature by generating heat and reducing heat loss through thick fur and a dense layer of fat under their skin.
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- Polar bears and seals live and swim in a subfreezing environment, yet they maintain a constant, warm, body temperature.
- Endotherms use their circulatory systems to help maintain body temperature.
- For example, vasodilation brings more blood and heat to the body surface, facilitating radiation and evaporative heat loss, which helps to cool the body.
- Ecothermic animals use changes in their behavior to help regulate body temperature.
- Describe some of the changes animals use in order to maintain body temperature
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- Hydrophobic, or water-hating molecules, tend to be non-polar.
- They interact with other non-polar molecules in chemical reactions, but generally do not interact with polar molecules.
- The hydrophilic regions of the phospholipids tend to form hydrogen bonds with water and other polar molecules on both the exterior and interior of the cell.
- This recognition function is very important to cells, as it allows the immune system to differentiate between body cells (called "self") and foreign cells or tissues (called "non-self").
- In an aqueous solution, phospholipids tend to arrange themselves with their polar heads facing outward and their hydrophobic tails facing inward.
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- As the outer layer of your skin separates your body from its environment, the plasma membrane separates the inner contents of a cell from its exterior environment.
- A single phospholipid molecule consists of a polar phosphate "head," which is hydrophilic, and a non-polar lipid "tail," which is hydrophobic.
- The polar heads contact the fluid inside and outside of the cell .
- In the case of the plasma membrane, only relatively small, non-polar materials can move through the lipid bilayer (remember, the lipid tails of the membrane are nonpolar).
- The polar heads contact the fluid inside and outside of the cell.
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- Hagfishes are entirely marine and are found in oceans around the world, except for the polar regions.
- Hagfish can also twist their bodies into a knot to gain a mechanical advantage while feeding and are notorious for eating carcasses from the inside out.
- The skeleton of a hagfish is composed of cartilage, which includes a cartilaginous notochord that runs the length of the body.
- This notochord provides support to the hagfish's body.
- They are distributed worldwide, except for the tropics and polar regions.
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- Water's polarity is responsible for many of its properties including its attractiveness to other molecules.
- One of water's important properties is that it is composed of polar molecules.
- The two hydrogen atoms and one oxygen atom within water molecules (H2O) form polar covalent bonds.
- As a result of water's polarity, each water molecule attracts other water molecules because of the opposite charges between them, forming hydrogen bonds.
- A polar substance that interacts readily with or dissolves in water is referred to as hydrophilic (hydro- = "water"; -philic = "loving").
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- Water's polarity makes it an excellent solvent for other polar molecules and ions.
- A polar molecule with partially-positive and negative charges, it readily dissolves ions and polar molecules.
- Water is therefore referred to as a solvent: a substance capable of dissolving other polar molecules and ionic compounds.
- When ionic compounds are added to water, individual ions interact with the polar regions of the water molecules during the dissociation process, disrupting their ionic bonds.
- Since many biomolecules are either polar or charged, water readily dissolves these hydrophilic compounds.
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- However, these materials are ions or polar molecules that are repelled by the hydrophobic parts of the cell membrane.
- Passage through the channel allows polar compounds to avoid the nonpolar central layer of the plasma membrane that would otherwise slow or prevent their entry into the cell.
- Glucose, water, salts, ions, and amino acids needed by the body are filtered in one part of the kidney.
- Because there are only a finite number of carrier proteins for glucose, if more glucose is present than the proteins can handle, the excess is not transported; it is excreted from the body in the urine.
- A different group of carrier proteins called glucose transport proteins, or GLUTs, are involved in transporting glucose and other hexose sugars through plasma membranes within the body.
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- The ectoderm develops into the outer epithelial covering of the body surface and the central nervous system.
- Deuterostomes undergo radial cleavage where the cleavage axes are either parallel or perpendicular to the polar axis, resulting in the alignment of the cells between the two poles.
- Acoelomates have no body cavity.
- Eucoelomates have a body cavity within the mesoderm, called a coelom, which is lined with mesoderm.
- Pseudocoelomates also have a body cavity, but it is sandwiched between the endoderm and mesoderm.