BIOL 1030H Study Guide - Winter 2018, Comprehensive Midterm Notes - Gene, Dna, Meiosis
BIOL 1030H
MIDTERM EXAM
STUDY GUIDE
Fall 2018
Introduction To Cells
●All organisms are made of either a single cell or an ensemble of cells.
Essential features of cells
1. A plasma membrane that creates a distinct boundary separating the cell interior from the
external environment
2. The ability to harness materials and energy from the environment.
3. The ability to store and transmit information
Cells are defined by membranes
●Membranes:
○ Separate the inside of the cell from the outside.
○Surround many internal structures.
Cell membranes are dynamic
●Lipids associated with each other by weak interactions called van der Waals forces
●Membrane lipids are able to move in the membrane (membrane is fluid) • Individual fatty
acid chains are also able to flex or bend.
● Fluidity depends on the fatty acids present (e.g., double bonds, and the length of the
tails).
Saturated vs. Unsaturated
●Saturated fatty acid chains lack double bonds, resulting in phospholipids with a straight
structure that favors tight packing.
●Unsaturated fatty acids have one or more double bonds that introduce kinks in the
phospholipids, reducing the tightness of packing
Plasma membrane
●Characteristics
○ Feature of all cells.
○Defines the cell boundary
○Separates internal contents from the surrounding environment
● Critical for homeostasis
○ Maintenance of a constant internal environment
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Plasma membranes are selectively permeable
● Certain items can move freely, while others only under certain conditions; others cannot
●Reasons for limited permeability
○Lipid bilayer is hydrophobic – prevents ion movement
○Many macromolecules are too large
○ Gasses, lipids, small polar molecules can cross
● Selective permeability is key to maintaining homeostasis
Active transport is movement against a concentration gradient
●Passive transport works only when the concentration gradient is in the right direction.
●Examples:
○Nutrients: higher on the outside to lower on the inside
○ Waste: higher on the inside and lower on the outside
●Two kinds of active transport:
○Primary Active Transport
○Secondary Active Transport
Cell junctions
●Cells are organized into tissues, organs and organ systems
●Nearby cells often adhere, interact and communicate with each other via physical contact
at cell junctions
●Categories of cell junctions (based on task):
○Adherens junctions; Desmosomes; Hemidesmosomes
○Tight junctions
○Gap junctions/Plasmodesmata (plants)
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
All organisms are made of either a single cell or an ensemble of cells. A plasma membrane that creates a distinct boundary separating the cell interior from the external environment. The ability to harness materials and energy from the environment. 2: the ability to store and transmit information. Separate the inside of the cell from the outside. Lipids associated with each other by weak interactions called van der waals forces. Membrane lipids are able to move in the membrane (membrane is fluid) individual fatty acid chains are also able to flex or bend. Fluidity depends on the fatty acids present (e. g. , double bonds, and the length of the tails). Saturated fatty acid chains lack double bonds, resulting in phospholipids with a straight structure that favors tight packing. Unsaturated fatty acids have one or more double bonds that introduce kinks in the phospholipids, reducing the tightness of packing. Separates internal contents from the surrounding environment.