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Flashcards in Biology: Ch. 2 Cells Deck (95)
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1

Cell

Basic functional unit of all living things

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Plasma membrane (Cell membrane)

-Bounds the cell & encloses the nucleus and cytoplasm
-Separates internal metabolic events from external environment
-Controls movement into and out of the cell
-Phospholipid bilayer

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Cytoplasm

Consists of organelles suspended in the cytosol

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Cytosol

Consists of water and dissolved substances such as proteins and nutrients

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Peripheral proteins

Attach loosely to the inner or outer surface of the protein

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Integral proteins

Extend into the membrane; amphipathic

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Transmembrane proteins

Integral proteins that span across the membrane and appear at both surfaces

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Fluid mosaic model

Mosaic nature of scattered proteins within a flexible matrix of phospholipid molecules

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Phospholipid membrane

-Selectively permeable
-Allows small, uncharged, polar molecules (H2O & CO2), hydrophobic molecules (O2 & lipid-soluble molecules) to pass

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Channel proteins

Open passageways for hydrophilic substances (polar and charged molecules)

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Ion channels

Passage of ions

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Gated channels

Ion channel in nerve and muscle cells that responds to chemical or electrical stimuli

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Porins

Allow passage of certain ions and small polar molecules

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Aquaporins

Increase passage rate of H2O molecules in kidneys and plant roots

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Carrier proteins

Binding to specific molecules (glucose) induces change of shape which transfers the molecule across

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Transport proteins

Use ATP

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Active transport

When energy is used to transport materials

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Na+-K+ pump

Uses ATP to maintain higher concentrations of Na+ and K+ on opposite sides of the membrane; active transport

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Recognition proteins

Gives each cell a unique identification which allows them to make a distinction between self and foreign; glycoprotein

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Glycoprotein

Protein with a short polysaccharide chain attached

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Adhesion proteins

-Attach cells to neighboring cells
-Provide anchors for internal filaments and tubules

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Receptor proteins

Binding sites for hormones or other trigger molecules

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Cholesterol

Distributed throughout lipid bilayer providing rigidity to the plasma membranes of animal cells; sterols provide similar function in plants

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Glycocalyx

-Carbohydrate coat covering the outer face of the cell wall (some bacteria) or plasma membrane (certain animal cells)
-Consists of various oligosaccharides attached to membrane phospholipids and proteins
-Can provide adhesive capabilities, barrier to infection, cell-to-cell recognition

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Organelles

Bodies within the cytoplasm that physically separate the various metabolic reactions

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Nucleus

-Bounded by nuclear envelope
-Contains DNA in form of chromatin
-One or more nucleoli
-Site for separation of chromosomes

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Nuclear envelope

Consists of 2 phospholipid bilayers

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Chromatin

DNA which is spread out within the nucleus as a threadlike matrix

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Chromosomes

Condensed form of chromatin when cell begins to divide; made up of two long DNA molecules and various histone molecules

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Histones

Organize the DNA into bundles (nucleosomes)