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Flashcards in Chapter 3 Deck (82)
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1

Cell

-Structural and functional unit of life
-Basic unit of life
-Organismal functions depend on individual and collective cell functions
-Biochemical activities

2

Cell Diversity

-Over 200 different types of human cells
-Types differ in size, shape, sub-cellular components, and functions

3

General Cell (All Cells)

-All cell have some common structures and functions
-Human cells have three basic parts:
--Plasma membrane
--Cytoplasm
--Nucleus

4

Plasma Membrane

Flexible outer boundary
-lipid bilayer and proteins constantly changing fluid mosaic
-plays dynamic role in cellular activity
Separates intracellular fluid (ICF) from extracellular (ECF)
--Interstitial fluid (IF)= ECF that surrounds cells

5

Membrane Lipids
Lipid Bilayer

Phospholipids
-Phosphate heads: polar and hydrophillic (water liking)
-Fatty acid tails: nonpolar and hydrophobic (water fearing)

6

Membrane Proteins

-Allow communication with environment
-Most specialized membrane functions
2 Types
-Integral Proteins
-Peripheral Proteins

7

Integral Proteins

Firmly inserted into membrane
-Have both hydrophobic and hydrophilic
-Function as transport proteins (channels and carriers), enzymes, or receptors

8

Peripheral Proteins

-Loosely attached to integral proteins
-Include filaments on intracellular surface for membrane support
-Function as enzymes

9

6 Functions of Membrane Proteins
(Look at Diagram Cards)

-Transport
-Receptors for signal transduction
-Attachment to cytoskeleton and extracellular matrix
-Enzymatic Activity
-Intercellular Joining
-Cell-cell recognition

10

Glycocalyx

"sugar coverings" at cell surface
-lipids and proteins with attached carbohydrates (sugar groups)
-Every cell has different pattern of sugars

11

Cell Junctions
2 types
3 subtypes

Some are "free"
EX- blood cells, sperm cells
Some bond into communities
3 types:
-Tight junctions
-Desmosomes
-Gap junctions

12

Tight Junctions

Adjacent integral proteins fuse form impermeable junction encircling cell
-prevents movement

13

Desmosomes

"Rivets" or "spot-welds" that anchor cells together at plaques (thickenings on plasma membrane)
-Linker proteins between cells connect plaques
-Lends stability to cell
-Reduces possibility of tearing

14

Gap Junctions

Transmembrane proteins form pores that allow small molecules to pass from cell to cell
-for spread of ions, simple sugars, and other small molecules between cardiac or smooth muscle cells

15

Plasma Membrane

Cells currounded by interstitial fluid (IF)
-contains thousands of substances; amino acids, sugars, fatty acids, vitamins, hormones, salts, waste products
Plasma membrane allows cell to:
-obtain what is needed from IF
-Keep out what it does not need

16

Membrane Transport

Plasma membranes selectively permeable
-some molecules pass through easily; some do not
Two ways substances cross membrane
-Passive processes
-Active processes

17

Passive Processes

-No cellular energy required
-Substance move down concentration gradient
-Diffusion (2)
-Osmosis

18

Diffusion

Molecules to move down or with their concentration gradient (speed of movement is determined by molecule size and temperature
Molecule will passively diffuse through membrane if:
-lipid soluble
-small enough to pass through membrane channels
-assisted by carrier molecule

19

3 Types of Diffusion
(Look at Diagram Cards)

-Simple Diffusion
-Carrier and Channel Mediated Facilitated Diffusion
-Osmosis

20

Simple Diffusion

Nonpolar lipid-soluble (hydrophobic) substances diffuse directly through phospholipid bilayer
EX. oxygen, carbon dioxide, fat-soluble vitamins

21

Carrier-Facilitated Diffusion

Certain lipophobic molecules transported passively by;
-binding to protein carriers
-moving through water-filled channels
Transmembrane integral proteins are carriers
Used when sugars are too large for channels

22

Channel-Facilitate Diffusion

Watery channels formed by transmembrane proteins
Selectively transport ions or water
Two types:
-Leakage (always open)
-Gateway (controlled by chemical or electrical signals)

23

Osmosis

Water moves through:
-lipid bilayer
-specific water channels
Occurs when either water or solvent is too high on one side or the other than either:
-through impermeable;
osmosis occurs until equilibrium reached
-through permeable;
both solutes and water across membrane until equiilibrium reached

24

Pressures of Osmosis

Hydrostatic: back pressure of water on membrane
Osmotic: tendency of water to move into cell by osmosis

25

Importance of Osmosis
(Look at Diagram Cards)

Causes cells to swell and shrink
change in cell volume disrupts cell function, especially in neurons

26

Tonicity

Ability of solution to alter cell's water volume
3 tonics- iso, hyer, hypo

27

Isotonic

Solution with same non-penetrating solute concentration as cytosol

28

Hypertonic

Solution with higher non-penetrating solute concentration than than cytosol

29

Hypotonic

Solution with lower non-penetrating solute concentration than cytocol

30

Active Processes
2 Types

Requires ATP to move solutes across a plasma membrane because:
-Solute too large for channels
-Solute not lipid soluble
-Solute not able to move down concentration
Two types
-Active Transport
-Vesicular Transport