exam 5 (chapter 6,7) Flashcards
- Maintains essential differences between intracellular and extracellular environment
- Phospholipid bilayer and proteins
- Together, the lipid bilayer and proteins are semi-permeable
Plasma Membrane
Impermeable to water soluble molecules, fluid and soft
Phospholipid Bilayer
- Mediate passage of water-soluble molecules
- Some function as enzymes
- Some function as signal transducers
- Control interactions between cells of a multicellular organism
Proteins
-Proteins may move laterally (they do not flip-flop)
-Hypothesis: Proteins from 2 different cells will mix
-Experiment: Combine mouse cell and a human cell and follow the protein ‘markers’
Results: Proteins mixed
Fluid-Mosaic Model
Fluidity of phospholipid membrane depends on what 2 things?
Temperature, phospholipid composition
a. Transport
b. Enzymatic activity
c. Signal transduction
d. Cell-Cell Recognition
e. Intercellular joining
f. Attachment of cytoskeleton and extracellular matrix (ECM)
Functions of Membrane Proteins
Undergo conformation change
Carriers
Form pores across membrane, solutes pass quickly when pores are open
Channels
Movement of molecules down their concentration gradient
Simple Diffusion
Diffusion of water (occurs directly through the membrane or via protein channels called aquaporins)
Osmosis
Move concentration gradients across the membrane
- Na+-K+ ATPase (sodium potassium pump)
- H+ pumps (proton pump)
Ion Pumps
Transport out of a cell
Exocytosis
Transport into a cell
Endocytosis
A liquid that is a homogeneous mixture of 2 or more substances
Solution
The dissolving agent or the liquid in greatest abundance in the solution (example: water)
Solvent
The substance being dissolved
Solute
Water moves out of the cell
-The surrounding solution has greater amount of solutes
Hypertonic Solution
Water moves into the cell
-The surround solution has a lower amount of solutes
Hypotonic Solution
There is no movement of water
-The surrounding solution has an equal concentration of solutes compared to the inside of the cell
Isotonic Solution
The smallest structure alive
- Regulate their internal environment
- Gives rise to new ones
- Produce movement
- Take in energy and release waste products
Cell
Regulates flow of molecules into and out of the cell, surrounds all cells
Plasma Membrane
Fluid inside cell
Cytosol
Protein synthesis
Ribosomes
Has a unique set of chemicals (pH, enzymes, other proteins), different metabolic function
Organelles
- Contains genetic material (DNA)
- Components:
1. nucleolus
2. nuclear membrane
3. chromatin
Nucleus
Site of ribosome production
Nucleolus
The complex and DNA and associated proteins
Chromatin
When a cell gets ready to divide, the chromatin coils tightly
Chromosome
Covered with ribosomes, functions in protein synthesis
Rough ER
Functions in lipid metabolism, synthesis of cholesterol and steroid hormones
Smooth ER
Vesicles transport proteins to golgi
Transitional ER
- Modifies proteins and lipids from ER
- Sorts proteins and lipids for final destinations
- Packages and exports proteins and lipids in vesicles
- In plant cells, manufactures polysaccharides
Golgi Apparatus
- Controlled intracellular digestion of macromolecules
- pH=5
- Only found in animal cells
Lysosomes
Stores water, only found in plant cells
Vacuole
- Energy factories
- Site of cellular respiration (turns glucose into ATP)
- Number in a cell correlates with cell’s energy demand
- Has its own DNA
- Found in plant and animal cells
- Maternally inherited in humans
Mitochondria
Evolutionary origins of mitochondria and chloroplasts
Evidence:
-Own genome ribosomes
-2 membranes
-Arise only by growth and division of existing mitochondria or chloroplasts
-Division not timed with nuclear division
Endosymbiont Theory
Some ?? have specialized membranes that perform metabolic functions
-Are usually unfolding of the plasma membrane
prokaryotes
= colored form
Example: orange of carrots, red of tomatoes, red of peppers
Can see when chlorophyll exits the leaves of trees in fall
Chromoplast
=green form
Chloroplast
=white form
example: holds starch in potatoes
Leucoplast
- Produces hydrogen peroxide as a biproduct
- Breaks down fatty acids, alcohol
- Found in plant and animal cells
Peroxisome
Cytoplasmic streaming, cell division (cleavage furrow formation)
Microfilaments
Maintenance of cell shape (tension-bearing elements), anchorage of nucleus and certain other organelles
Intermediate Filaments
Chromosome movements in cell division, cell motility (as in cilia or flagella), organelle movement
Microtubules
Located in the centrosome, only in animal cells, microtubule-organizing center
-When the cell divides, fibers help move the chromosomes into the new cells
Centrioles
- Protects the cells
- Provides shape
- Prevents uptake of excess water
- Holds the plant up against gravity
- Composed of cellulose
- Some protists, fungi, and prokaryotes also have them of different construction
- Only found in plant cells
Cell Wall
Connect the cytosol of adjacent cells
Plasmodesmata
Make a waterproof seal
Example: skin, intestines
Only in animal cells
Tight Junctions
Forms tissues, only in animal cells
Desmosome
Similar to plasmodesmata in plants (communication between cells), only in animal cells
Gap Junctions
What is structure is found in all cells?
ribosomes
Flow of lipids and membranes
- Nuclear envelope
- ER
- golgi
- lysosomes
- vesicles
- vacuoles
Endomembrane System
- Regulation of water inside a cell
- Organsims that live in a hypertonic or hypotonic environment must have ways to control solute concentrations and water balance
- Contractile vacuoles moves water out of cell
Osmoregulation
Description of cell structure and function?
Plant and animal cells carry out cellular respiration, producing ATP
Fluid or air-filled cavity or sac
Vesicle
The movement of a substance from high to low concentration
Diffusion
The movement of a substance across a cell membrane against its concentration gradient
Active Transport
The diffusion of a substance across a biological membrane with no expenditure of energy
Passive Transport
The ability of a surrounding solution to cause a cell to gain or lose water
Tonicity
