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The Cell and Cell Membrane (Types of Active Transport (Co-transport…
The Cell and Cell Membrane
Cell Fractionation
A technique used to study cell structure and function
Takes cells apart and separates major organelles and cell structures from each other
Done by a Centrifuge
Spins test tubes holding cell mixture
Low Speed- Large Organelles
High Speed- smaller organelles
Allows researchers to separate and research specific cell components in bulk
Membrane Structure
Fluid Mosaic Model
Groups of proteins in long lasting areas
carry out common functions
Model changes
held together by hydrophobic interactions
Peripheral Proteins
loosely bound to the membrane surface and can be touching integral proteins
Both Proteins are held in place by the cytoskeleton
Integral Proteins
Inside the hydrophobic interior of the bilayer
mostly trans-membrane proteins
consists of nonpolar amino acids 20-30
Prokaryote vs. Eukaryote
Prokaryote
Unicellular
no membrane bound organelles
no nucleus (nucleoid)
smaller in size
Eukaryote
multi-cellular
membrane bound organelles
Larger
Nucleus
Microscope Types and Function
Electron Microscope (EM)
Resolution of .002nm
Focuses a beam of electrons through specimen or its surface
Light Microscope (LM)
Light passed through specimen and then lens
Magnifies up to1,000x the specimen size
Scanning Electron Microscope (SEM)
can see topography (3D) imaging
uses electron beam
Transmission Electron Microscope (TEM)
displays pattern of transmitted electrons (2D)
Electron beam on small section
Microscopes are important for Cytology- the study of cell structure
Surface/Volume Area
Metabolic Requirements set limits on cell size
More Surface Area is needed but not volume
Certain cells need more surface area than others
nerve
intestinal
More surface area allows for more molecules to cross the membranes
Microvilli- long thin projections of cell surface area
increase surface area without increasing volume
6:1:6 ratio
Membrane Protein Functions
Signal Transduction
A membrane protein that binds to a specific shape (hormone, signal molecule)
Cell-Cell Recognition
Glycoproteins are like IDS that membrane proteins recognize
Enzymatic Activity
Protein with enzyme that carries out metabolic processes
Intracellular Joining
Cells join, Tight,gap, or desmosomes
Transport
provides a channel for a solute to enter the membrane
Attachment to the cytoskeleton and ECM
Microfilaments noncovalently bonded help form shape of cell and stabilizes proteins
Diffusion
movement of particles spread out into available space
Diffuses from where it is more concentrated to less concentrated
equal on either side of the membrane
much of the exchange across the membrane occurs through diffusion (cellular respiration)
Concentration Gradient
Area which the density of the substance increases/decreases
Diffuses along own concentration gradient regardless of other molecules in the mixture
Represents potential energy
Passive Transport
Diffusion across a biological membrane
Cell expends no energy
Types of Active Transport
Requires energy to transport across the membrane
Transport Proteins
Move solutes against the concentration gradient
Channel Proteins
Allow solutes to diffuse down their concentration gradients over transfer against another concentration gradient
Sodium-Potassium Pump
Trades Na for K through the plasma membrane
Co-transport
Active Transport led by a concentration gradient
a transport protein that diffuses solute down while diffusing another solute up
Co-Transport helped find medical treatments
Exocytosis
Cell secretes molecules by fusing with plasma membrane vesicles
Endocytosis
Cell takes in molecules and forms new vesicles from the plasma membrane
Phagocytosis
Cell Eating
Pinocytosis
Cell Drinking
Receptor Mediated Endocytosis
Bulk Quantities of substances
Cell Organelles
Plasma Membrane
Membrane that encloses the cell
Ribosomes
Make up proteins
Free in cytosol or attached to ER or nuclear envelope
Bound make proteins or inserted into membrane
Free ribosomes function in cytosol
Nucleus
Nucleolus
Helps produce ribosomes
Cell can have one or more nucleoli
Chromatin
Made up of DNA and proteins
Visible in mitosis as individual chromosomes
Nuclear Envelope
Double membrane that holds the nucleus
Porous and also has the ER
Nuclear Lamina
Protein filaments in a net shape (on the nuclear side minus where the pores are)
Golgi Apparatus
Helps with synthesis, modification, sorting, and secretion of cell products
flattened membranous sacs (cisternae)
Endoplasmic Reticulum
Rough ER
Network of sacs and tubes (membrane synthesis, metabolic process)
Smooth ER
Not ribosome studded
.
Cytoskeleton
Intermediate Filaments
Microtubules
Microfilaments
Microvilli
Help to increase cell surfaces area without increasing the volume ( long thin projections )
Peroxisome
Metabolic Functions - makes H and peroxide and converts it to water
Centrosome
Houses the centrioles
Microtubules start here
Mitochondria
Cellular Respiration and ATP generator
Theorized to have been a separate prokaryote that was taken in by a eukaryote
Flagellum
Helps move cell
Made up of microtubules
Extends from the plasma membrane
