Tài liệu Khoa Học Tự Nhiên

Nose/mouth: filtered, warmed, humidified Pharynx Larynx: contains vocal cords Trachea: windpipe; lined with cartilage Bronchi: branches to lungs Bronchioles Alveoli: air sacs for gas exchange Mucus: traps particles Cilia: sweeps particles up to pharynx

19 trang | Chia sẻ: huyhoang44 | Ngày: 19/03/2020 | Lượt xem: 793 | Lượt tải: 0

Antigen receptors are generated by random rearrangement of DNA As lymphocytes mature in bone marrow or the thymus, they are tested for self-reactivity Some B and T cells with receptors specific for the body’s own molecules are destroyed by apoptosis, or programmed cell death The remainder are rendered nonfunctional

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Proximal tubule: secretion & reabsorption change volume and composition of filtrate Bicarbonate, NaCl, water is absorbed Descending loop of Henle: reabsorb water Ascending loop of Henle: reabsorb salt Distal tubule: K+ and NaCl levels regulated Collecting duct: filtrate becomes more concentrated; minimize water loss

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Endocrine System = Hormone-secreting cells + Tissues Endocrine glands: ductless, secrete hormones directly into body fluids Hormones: chemical signals that cause a response in target cells (receptor proteins for specific hormones) Affects 1 tissue, a few, or most tissues in body Or affect other endocrine glands (tropic hormones) Regulation by ...

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Notochord – stiff dorsal skeletal rod, forms from mesoderm Neural plate  neural tube brain and spinal cord Neurulation – forms hollow dorsal nerve chord Somites – blocks of mesoderm arranged along notochord; sign of segmentation

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In 1952, Alfred Hershey and Martha Chase used bacteriophages to show that DNA is the genetic material of T2, a virus that infects the bacterium Escherichia coli (E. coli). Bacteriophages (or phages for short) are viruses that infect bacterial cells. Phages were labeled with radioactive sulfur to detect proteins or radioactive phosphorus to detect...

113 trang | Chia sẻ: huyhoang44 | Ngày: 18/03/2020 | Lượt xem: 707 | Lượt tải: 0

In 1866, Mendel correctly argued that parents pass on to their offspring discrete “heritable factors” and stressed that the heritable factors (today called genes), retain their individuality generation after generation. A heritable feature that varies among individuals, such as flower color, is called a character. Each variant for a character,...

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Organisms reproduce their own kind, a key characteristic of life. Cell division is reproduction at the cellular level, requires the duplication of chromosomes, and sorts new sets of chromosomes into the resulting pair of daughter cells.

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Autotrophs make their own food through the process of photosynthesis, sustain themselves, and do not usually consume organic molecules derived from other organisms.

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In cellular respiration glucose is broken down to carbon dioxide and water and the cell captures some of the released energy to make ATP. Cellular respiration takes place in the mitochondria of eukaryotic cells.

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