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28 terms

Biology Unit 2

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Diffusion
when molecules move from an area of high concentration to an area of low concentration
Cell Wall
a relitivly inflexible structure that surrounds the plasma membrane
Nucleolus
located in the nucleus and produces tiny cell particles that are involved in protein synthesis called RIBOSOMES
Mitochondia
organelles in which food molecules are broken down to release energy
Chloroplasts
transform light energy into useable chemical energy and store it in food molecules
Nucleus
contains the cell's DNA and manages the cell's functions
Cell/Plasma Membrane
a boundry between the cell and its external environment
Cytoplasm
clear fluid in eukaryotic cells surrounding the nucleus and other organelles
Endoplasmic Reticulum (ER)
folded, complex system of membranes forming a type of transport system in the cytoplasm of eukaryotic cells
Golgi Appartus vacuole
membrane sacs that receive, chemically modify, and repackage proteins into forms the cell can use, expel, or keep stored
lysosome
membrane-bound organelles containing enzymes that digest food particles, viruses and bacteria, worn-out cell parts, and sometimes the cell itself
Lipids
organic compounds commonly called fats and oils; insoluble in water, lipids are the major components of membranes surrounding all living cells
ribosomes
eukaryotic organelles that are involved in protein synthesis
Osmosis
the diffusion of water molecules through a selectively permeable membrane form an area of higher concentration to and area of lower water concentration
What was Darwin's theory of Natural Selection?
heritable variation+competition+selective pressure=natural selection
enzymes
proteins that accelerate chemical reactions but do not change themselves in the reaction; enzymes enable molecules to undergo chemical change, forming new subatnaces called products
eukaryotes
cell having a true nucleus and membrane-bound internal organelles
prokaryotes
cell lacking a true nucleus or membrane-bound internal organelles
chromosome
cell structure that caries the genetic material
centromere
cell structure that joins two sister chromatids of a chromosome.
mitosis
cell division during which chromosomes are equally distributed to the two identical daughter cells that are formed; results in growth
spindle(fibers)
thin fiber structure that forms between the two poles or centioles during prophase and shortens during anaphanse, pulling the sister chromatids apart
active transport
process requiring energy by which cells move materials against a concentraton gradient
passive transport
in cells, movement across cell membranes requiring no expenditure of energy by the cell; ex. diffusion and osmosis
facilitated diffusion
passive transport of materials, such as sugars and amino acids, across the plasma membrane by way of transport proteins
exocytosis
active transport process by which materials are expelled or secreted from a cell
hypotonic solution
in cells, solution in which the concentration of dissolved materials is lower in the solution surrounding the sell than the concentration inside the cell, which will swell and possibly burst as water enters the cell by osmosis
isotonic solution
solution in cells which disolved materials and water occur in the same concentration as inside the cell