Membranes

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  • Created by: Katy1234
  • Created on: 05-02-16 18:43
Name a role of the Plasma Membrane
Separates the cell components from the external environment
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Name a role of the Plasma Membrane
Regulates transport in and out of the cell
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Name a role of the Plasma Membrane
can contain enzymes involved in various metabolic reactions
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Name a role of the Plasma Membrane
some have antigens on them that helps them to be recognized as " self" by the immune system
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Name a role of the Plasma Membrane
Can release chemical signals
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Name a role of the Plasma Membrane
Can contain receptors for chemical signals
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Name a role of the Plasma Membrane
Site of chemical reactions
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State the 2 regions of the Phospholipid Bilayer
Hydrophillic region and Hydrphobic region
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How thick are membranes?
7-10 nm thick
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How is a white blood cell differentiated?
has more antigens on plasma membranes
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How is a muscle cell differentiated?
has more mitochondria on the inner membrane
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How is a chloroplast differentiated?
Inner membrane has more chlorphyll
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How is a growing sheet differentiated?
The inner membrane will have more chlorophyll
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what is cholesterol's role in plasma membranes?
provides the plasma membrane with mechanical stability
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What are channel proteins?
Used for for cell recognition. require energy to transport molecules across the membrane. molecules that are too big to pass through the membranes directly use the protein
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What are carrier proteins?
allow movement of substances across membrane. actively move substances across the membrane. ATP energy is used. they change shape to move the substances
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What are receptor sites?
Hormones can bind to the receptor sites, creating a cell response. cell metabolism can be controlled through these receptor sites
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What are Glyco Proteins and Glycolipids?
found on the surface of the phospholipid bi-layer. Bind to proteins held within the membrane. they can be involved in cell signaling that they are "self" so they are recognized by the immune system
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What are Enzymes and Co-Enzymes?
They are bound to membranes. There is always a set number of enzymes that can bind to a membrane. They are used in this way for both photosynthesis and respiration
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What effect does high temperatures have on membrane permeability?
Phospholipids become less tightly packed (Disaggregated). Temperatures above 55 degrees cause the protein structure to denature. Increases the diffusion rate of molecules.
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What effect does low temperatures have on membranes?
Saturated fatty acids become compressed. Unsaturated fatty acids in the phospholipid bi-layer become compressed and kinks in their tails push adjacent phospholipid molecules away. maintains the membrane fluidity
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What effect does Ethanol has on membranes?
causes the phosopholipids to move out of place so large gaps form in the membrane allowing the contents of the cell to leak out. its dissolves cholesterol and can lead to denaturing in membrane proteins
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what are the 3 ways molecules can move across a cell membrane?
Passive diffusion, Facilitated diffusion and active transport
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Describe passive diffusion
Does not require ATP. Works due to kinetic energy. molecules move from a high concentration to a low concentration. Does not require carrier or channel proteins. o2, co2 and steroid hormones pass through passive diffusion
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describe facilitated diffusion
molecules go from high to a low concentration. does not need ATP. use channel proteins such as aquaparin ( lets water through). allows for small molecules such as water to pass through
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describe active transport
use carrier proteins which help carry larger and ions across membranes. shapes to fit the molecule they carry. they carry specfic molecules in a one way direction. require ATY
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describe active transport
Require ATP. Carry molecules against the concentration gradient. they carry specific molecules (shaped to fit different molecules) in a one way direction. Use carrier proteins which carry larger molecules and ions across the mebrane
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What are factors affecting diffusion?
Temperature, concentration gradient, string/moving, surface area ( more space for reaction to take place), distance/ thickness, size of molecule
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what is the equation for water potential?
water potential= solute potential + pressure potential
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Define osmosis
the net movement of water across a partial permeable membrane from a region of higher to a lower water potential
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Solutions with a low water concentration is said to have a ........ water potential
low
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Solutions with a high water concentration is said to have a ........ water potential
High
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What happens if a animal cell is placed in a solution of higher water potential (PURE WATER)?
water moves in by osmosis down a water potential gradient. cell becomes CYTOLYSED
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What happens if a plant cell is placed in a solution of higher water potential (PURE WATER)?
water moves in by osmosis down a water potential gradient. cell becomes TURGID
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What happens if a animal cell is placed in a solution of lower water potential (CONCENTRATED SUGAR SOLUTION)?
water moves out by osmosis down a water potential gradient. cell becomes CRENATED
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What happens if a plant cell is placed in a solution of lower water potential (CONCENTRATED SUGAR SOLUTION)?
water moves out by osmosis down a water potential gradient. cell becomes PLASMOLYSED
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What does bulk transport do?
allows materials that are to large to pass the plasma membrane to be transported
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What happens in Endocytosis?
A section of the plasma membrane surrounds and encloses the particles and brings them into the cell inside a vesicle
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What happens in Exocytosis?
A vesicle containing molecules moves towards and fuses with the plasma membrane
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give an example of Endocytosis
Phagocytosis
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give an example of Exocytosis
Synapses
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Regulates transport in and out of the cell

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