health

Cells Use molecules to: Transform energy and matter Respond to the environment Reproduce themselves Lowest level that can perform all activities required for life Cell theory Cells are the fundamental units of life All organisms are composed of cells All cells are going to be derived from preexisting cells Are similar in chemical composition Concept 6.1 Microscopes and the Tools of Biochemistry are used to Study Cells Magnification: ratio of image size to real size Resolution: measure of clarity What is the minimum distance required to distinguish two points as separate Light microscopy View living cells Magnify 2000X Resolution: 200nm Electron microscopes View dead cells Magnify 2,000,000X Resolution 0.2 nm Scanning electron microscopy Surface of a specimen (3D)

Concept 11.1 Local Signaling Cells may communicate by direct contact Animal cells Gap junctions Cell junctions Plant cells Plasmodesmata between cell plants Signaling substances can pass freely between adjacent cells Cell?cell recognition Paracrine signaling Short distances One cell can secrete some chemical or molecule that can then act on neighboring cells Example growth factors Stimulate adjacent cells to grow and divide Synaptic signaling Nerve cells in brain from one cell to another mostly an electrical signal Electrical signal triggers release of neurotransmitter Long distance signaling Endocrine signaling Hormones travels in bloodstream Target cell specifically binds hormone 3 stages of cell signaling 1 reception signaling molecule will combine to receptor