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48 Cards in this Set

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  • Back
Organisms
-single-celled, such as most prokaryotes and protists
-muti-celled, such as plants, animals, and most fungi
Light Microscopes
-can be used to explore the structures and functions of cells
Magnification
-an increase in the specimen's apparent size
Resolving Power
-the ability of an optical instrument to show two objects as separate
Cell Theory
-all living things are composed of cells
-all cells come from other cells
Electron Microscope
-EM
-uses a beam of electrons, which results in better resolving power than the light microscope
-can magnify up to 100,000 times
-can distinguish between objects 0.2 nanometers apart
Scanning Electron Microscope
-examines cell surfaces
Transmission Electron Microscope
-TEM
-useful for internal details of cells
Prokaryotic Cells
-bacteria and archaea
-older than eukaryotic cells
-appeared about 3.5 billion years ago
Eukaryotic Cells
-plants, fungi, and animals
-the region between the nucleus and plasma membrane is the cytoplasm
Plasma Membrane
-all cells are bound by a thin plasma membrane
Ribosomes
-tiny structures that build proteins
-all cells have DNA and ribosomes
Prokaryotes
-smaller than eukaryotic cells
-lack internal structures surrounded by membranes
-lack a nucleus
-have a rigid cell wall
Eukaryotes
-have organelles
-most important organelle is the nucleus which houses most of the DNA
-the region between the nucleus and plasma membrane is the cytoplasm
Organelles
-membrane-bound structures that perform specific functions
Cytoplasm
-the region between the nucleus and plasma membrane
-consists of various organelles suspended in fluid
Plant Cells
-protective cell walls
-chloroplasts
Chloroplasts
-convert light energy to the chemical energy of food
Plasma Membrane
-separates the living cell from its nonliving surroundings
-composed mostly of lipids (phospholipids) and proteins
-fluid mosaic
Phospholipids
-form a two-layered membrane, the phospholipid bilayer
Phospholipid Bilayer
-a two-layered membrane formed by phospholipids
-most have specific proteins embedded in them (help regulate traffic across the membrane and perform other functions)
Fluid Mosaic
-molecules can move freely past one another
-diversity of proteins in the membrane
Plant Cells
-rigid cell walls surrounding the membrane
-walls are made of cellulose, protect the cells, maintain cell shape, and keep the cells from absorbing too much water
Animal Cells
-lack cell walls
-have an extracellular matrix
-surfaces of most animal cells have cell junctions
Extracellular Matrix
-helps hold cells together in tissues
-protects and supports them
Cell Junctions
-structures that connect to other cells
Nucleus
-chief executive of the cell
-genes in nucleus store information necessary to produce proteins
-proteins do most of the work of the cell
-bordered by a double membrane called the nuclear envelope
-pores in the envelope allow materials to move between the nucleus and cytoplasm
contains a nucleolus
Nucleolus
-where ribosomes are made
Chromatin
-fibers formed by long DNA molecules and associated proteins that are stored in the nucleus
-each long chromatin fiber constitutes one chromosome
-number of chromosomes in a cell depends on the species
Ribosomes
-responsible for protein synthesis
-components are made in the nucleolus but assembled in the cytoplasm
-may assemble proteins suspended in the fluid of the cytoplasm or attached to the outside of an organelle called the endoplasmic reticulum
Protein Production
-DNA directs protein production by transferring its coded information into messenger RNA (mRNA)
-mRNA exits the nucleus through pores in the nuclear envelope
-a ribosome moves along the mRNA translating the genetic message into a protein with a specific amino acid sequence
Endomembrane System
-formed by many membraneous organelles are interconnected either directly or through the transfer of membrane segments between them
Endoplasmic Reticulum (ER)
-one of the main manufacturing facilities in a cell
-produces an enormous variety of molecules
-composed of smooth and rough ER
Rough ER
-"rough" is due to ribosomes that stud the outside of the ER membrane
-ribosomes produce membrane proteins and secretory proteins
-after it synthesizes a molecule, it packages the molecule into transport vesicles
Smooth ER
-lacks surface ribosomes
-produces lipids, including steroids
-helps liver cells detoxify circulating drugs
Golgi Apparatus
-works in partnership with the ER
-receives, refines, stores, and distributes chemical products of the cells
Lysosome
-a sac of digestive enzymes found in animal cells
-enzymes in a lysosome can break down large molecules such as proteins, polysaccharides, fats, and nucleic acids
-have several types of digestive functions:
-many cells engulf nutrients in tiny cytoplasmic sacs called food vacuoles
-these food vacuoles fuse with lysosomes, exposing food to enzymes to digest the food
-small molecules from digestion leave the lysosome and nourish the cell

-can destroy harmful bacteria
-can break down damaged organelles
Vacuoles
-membraneous sacs that bud from the ER, Golgi, and Plasma Membrane
-contractile vacuoles of protists pump out excess water in the cell
Central Vacuoles
-exist in plant cells
-store nutrients
-absorb water
-may contain pigments or poisons
Chloroplasts
-cells require a constant energy supply to perform the work of life
-the organelles that perform photosynthesis
-three major compartments: the space between the two membranes, the stroma, and the space within grana
Photosynthesis
-most of the living world runs on the energy provided by photosynthesis
-the conversion of light energy from the sun to the chemical energy of sugar
Stroma
-a thick fluid within the chloroplast
Grana
-the structures that trap light energy and convert it to chemical energy
Mitochondria
-the sites of cellular respiration, which produce ATP from the energy of food molecules
-found in almost all eukaryotic cells
-contains its own DNA (along with chloroplasts)
Cytoskeleton
-a network of fibers extending throughout the cytoplasm
-provides mechanical support to the cell
-maintains its shape
-contains several types of fibers made from different proteins: microtubules
-dynamic
-changes in the cytoskeleton contribute to the amoeboid motion of an amoeba
Microtubules
-straight and hollow
-guide the movement of organelles and chromosomes
Flagella
-aid in movement
-propel the cell in a whiplike motion
-has the same basic structure as cilia
Cilia
-aid in movement
-have the same basic structure as flagella
-move in a coordinated back-and-forth motion
-may extend from nonmoving cells
-in the trachea, help sweep mucus out of the lungs