A&P 2.14 cell membranes & cellular transport Flashcards Preview

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Basic cell anatomy

Plasma membrane
Nucleus
Cytoplasm

1

Plasma membrane

Cell membrane and boundary, maintains its integrity,
Protein molecules embedded in the plasma membrane perform various functions

2

Nucleus

Holds the genetic code which dictates protein synthesis, thereby playing an essential role in other cell activities, namely cell transport, metabolism and growth

3

Cytoplasm

Gel-like substance, includes various organelles suspended in a watery fluid called cytosol (intercellular fluid)

4

Components of the plasma membrane

Phospholipid bilayer
Membrane proteins

5

Phospholipid bilayer

Maintains cell integrity

Made of membrane proteins and receptor molecules allow for transport of molecules, hormones, and other chemicals involved in signal transduction

Enzymes catalyze specific reactions that regulate metabolic reactions

6

Phospholipid bilayer consists of

Six main types of proteins in the cell membrane
Layer is studded with membrane proteins performing various functions

Two layers: hydrophobic (lipid) tails and hydrophilic (phosphate) heads

7

Membrane layers

Phospho head - outer - water liking

Lipid tail - inner - water hating

8

Membrane proteins

Act as channels or carriers of molecules - controls transport of water soluble molecules from one compartment to another

Bind molecules outside the cell that form connections between cells & other structures (tissue fibers or other cells)

Those that bind to support filaments within the cytoplasm maintain shape and movement

9

Membrane proteins

Glycoproteins

Are proteins in the membrane that act as markers that recognize cells or organelles

10

Functions of membrane proteins

Formation of a channel
Transporter proteins
Receptor proteins

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Membrane proteins

4

Ion channels
Carriers (transporters)
Receptors
Cell identity markers

12

Ion channels

Pores or holes through which specific ions can flow to get into or out of the cell (most ion channels are selective - one type of ion)

13

Carriers (transporters)

Selectively move a polar substance or ion from one side of the membrane to the other

14

Receptors

Cellular recognition sites, recognizes and binds a specific type of molecule ( insulin receptor)

15

Cell identity markers

Enable a cell to recognize other cells of the same kind or identify foreign cells (blood type)

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Elements defined

Substances that cannot be broken down into a simpler form by ordinary chemical means (pure)

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96 % of the human body is composed of

4 major elements:

Carbon
Oxygen
Nitrogen
Hydrogen

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Compounds

More than one element combined

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Classes of compounds

2

Inorganic

Organic

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Inorganic compound

70% +\- of our body is water (the most abundant and important compound)

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Organic compound

Presences of carbon and they are protein, carbohydrates, lipids and nucleic acids ( RNA & DNA)

Carbon hydrogen bond

22

Transport across the membrane

2 types

Passive

Active

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Passive transport

Movement of substances down a concentration gradient until equilibrium is reached,

Does not require cellular energy in the form of ATP

Particles move using energy they already have

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Three types of passive transport

Diffusion
Osmosis
Facilitated diffusion

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Diffusion

Movement of a substance by kinetic energy down a concentration gradient until equilibrium is reached

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Simple diffusion

Passive movement of a substance through the lipid bilayer of the plasma membrane

Tendency of small particles to spread out evenly within a given space

Requires a concentration gradient

Measurable concentration difference between areas

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Osmosis

Movement of WATER molecules through/across a selectively permeable membrane from an area of higher water concentration to an area of lower water concentration

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Facilitated diffusion

Passive movement of a substance down a concentration gradient aided by ion channels and carrier molecules

29

Active transport

Defined

Movement of substances against a concentration gradient
Requires cellular energy in the form of ATP