Term
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Definition
- Provide shape and structure
- Protect from physical stress
- Protect from osmotic stress (reduces the rate that water can move in an out of the cell).
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Term
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Definition
Bacillus (elongated): Streptobacillus (chains).
Coccus (round): Streptococcus (cahins), staphylococcus (clusters), diplococcus (pairs).
Spirillum (short spiral)
Spirochaete (long spiral) |
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Term
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Definition
| Present in bacterial cell walls. Consists of disacharides made from NAM-NAG. Gram positive bacteria have a thick layer of peptidoglycan and gram negative bacteria have a thin layer of peptidoglycan and an outer membrane (gram - bacteria also possess a toxin, lipopolysaccharide, in their outer membrane that is released if the bacteria dies). |
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Term
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Definition
| Do not contain peptidoglycan but sometimes contain a similar component known as psuedo-peptidoglycan. Many possess a crystalline protein wall known as an "s-layer". |
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Term
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Definition
Thick external layer of carbohydrates in bacteria. Divided into two types: Slime layer (disorganized, loosely attached) and capsule (highly organized, tightly attached).
The glycocalyx prevents dehydration of the cell, aids invasion of the host (since it's sticky), inhibits phagocytosis of bacterium, and allos many bacteria to congregate together as "biofilm". |
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Term
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Definition
| External bacterial appendages that are short, tubular, and numerous. Function in adherence and only stick to certain surfaces. |
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Term
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Definition
| External bacterial appendages that are long and are used for DNA transfer (conjugation). Their are only one or two per cell. |
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Term
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Definition
| External bacterial appendages that are long and are used for locomotion. The filament is composed of the protein "flagellin". |
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Term
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Definition
Movement in response to stimula.
+ Taxis: Movement towards stimulus.
- Taxis: Movement away from stimulus. |
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Term
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Definition
| If present, is composed of silica or calcium carbonate (often referred to as shells). |
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Term
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Definition
| Mainly composed of chitin (a strong and flexible aminosugar). |
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Term
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Definition
| Are multilayered and complex. Are held together by pectin in the middle lamella. Primary cell wall contains cellulose at a 90-degrees to the direction of cell growth. Sencondary cell wall contains cellulose at carious orientations. After growth is complete, lignin is added to 1° and 2° cell walls for hardness. To allow for communication plant cell walls are perforated by plasmodesmata. |
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Term
| Disadvantages of cell walls |
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Definition
Increases difficulty of growth and division.
Requires lots of nutrients and energy.
Makes cell rigid. |
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Term
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Definition
Do not have a cell wall but are surrounded by a gel-like collection of proteins and carbohydrated known as the extracellular matrix (ECM).
The ECM holds cells together and stabilizes tissues and organs. The proteins that connect the ECM are called integrids. |
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Term
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Definition
Points were animal cells are in contact with one another.
Three Types:
Anchoring Junctions.
Tight Junctions.
Gap Junctions. |
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Term
| Anchoring Junctions (Desmosomes) |
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Definition
| Links the keratin fibres of adjacent cell cytoskeletons and resists physical stress. |
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Term
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Definition
| A continuous serios of proteins that holds adjacent membranes in contact. Prevents leakage between cells. |
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Term
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Definition
| Composed of the protein connexin that is organized to form tube between cells (called a connexon). Allows fro cell-to-cell communication. |
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Term
| Strategies for Life Without a Cell Wall |
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Definition
Cells live in a isotonic environment (Marine)
Cells create isotonic environment (body fluids)
Regulation of water content (kidneys) |
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Term
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Definition
| Used to regulate water content in fresh-water protists. Vacuole collects excess water and then contracts to expell it outside the cell. |
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