Cells Flashcards
Tissues:
groups of cells; similar in structure/ function
Anatomy of the Cell
Cells are not all the same
All cells share general structures
All cells have three main regions
Plasma membrane
Nucleus
Cytoplasm
The Nucleus
Control center of the cell
-Contains genetic material (DNA)
Three regions of the nucleus
Nuclear envelope (membrane)
Nucleolus
Chromatin
Nuclear envelope (membrane)
Barrier of the nucleus
Consists of a double membrane
Contains nuclear pores that allow for exchange of material with the rest of the cell
Nucleoli
Nucleus contains one or more nucleoli
Sites of ribosome assembly
Ribosomes migrate into the cytoplasm through nuclear pores
Chromatin
Composed of DNA and protein
Present when the cell is not dividing
Scattered throughout the nucleus
Condenses to form chromosomes when cell divides
Plasma Membrane
Barrier for cell contents
Double phospholipid layer
Hydrophilic heads
Hydrophobic tails
Also contains proteins, cholesterol, and glycoproteins
Plasma Membrane Specializations
Microvilli
Finger-like projections that increase surface area for absorption
Plasma Membrane Specializations
Membrane junctions
Tight junctions
Impermeable junctions
Bind cells together into leakproof sheets
Plasma Membrane Specializations
Membrane junctions
Desmosomes
Anchoring junctions that prevent cells from being pulled apart
Plasma Membrane Specializations
Membrane junctions
Gap junctions
Allow communication between cells
Cytoplasm
is the material outside the nucleus and inside the plasma membrane
Contains three major elements
Cytosol
Fluid that suspends other elements
Organelles
Metabolic machinery of the cell
―Little organs‖ that perform functions for
the cell
Inclusions
Chemical substances such as stored nutrients or cell products
Mitochondria
―”Powerhouses”of the cell
Change shape continuously
Carry out reactions where oxygen is used to break down food
Provides ATP for cellular energy
Ribosomes
Made of protein and RNA
Sites of protein synthesis
Found at two locations
Free in the cytoplasm
As part of the rough endoplasmic reticulum
Endoplasmic reticulum (ER)
Fluid-filled tubules for carrying substances
Two types of ER
Smooth endoplasmic reticulum
Rough endoplasmic reticulum
Rough endoplasmic reticulum
Studded with ribosomes
Synthesizes proteins
Smooth endoplasmic reticulum
Functions in lipid metabolism and detoxification of drugs and pesticides
Golgi apparatus
Modifies and packages proteins
Produces different types of packages
Secretory vesicles
Cell membrane components
Lysosomes
Lysosomes
Contain enzymes that digest worn-out or nonusable materials within the cell
Peroxisomes
Membranous sacs of oxidase enzymes
Detoxify harmful substances such as alcohol and formaldehyde
Break down free radicals (highly reactive chemicals)
Replicate by pinching in half
Cytoskeleton
Network of protein structures that extend
throughout the cytoplasm
Provides the cell with an internal framework
Cytoskeleton
Three different types of
elements
Microfilaments (smallest)
Intermediate filaments
Microtubules (largest)
Centrioles
Rod-shaped bodies made of microtubules
Direct the formation of mitotic spindle during cell division
Cellular Projections
- Not found in all cells
- Used for movement
-Cilia move materials across the cell surface
-Located in the respiratory system to move mucus- Flagella propel the cell
-The only flagellated cell in the human body is sperm
- Flagella propel the cell
Membrane transport—
movement of substances into and out of the cell
Two basic methods of transport
Passive transport
No energy is required
Active transport
Cell must provide metabolic energy (ATP)
Solution—
homogeneous mixture of two or more components
Solvent—
dissolving medium; typically water in the body
Solutes—
components in smaller quantities within a solution
Intracellular fluid—
nucleoplasm and cytosol
Interstitial fluid—
fluid on the exterior of the cell
Selective Permeability
-The plasma membrane allows some materials to pass while excluding others
-This permeability influences movement both into and out of the cell
Diffusion
Particles tend to distribute themselves evenly
within a solution
Movement is from high concentration to low concentration, or down a concentration gradient
Simple diffusion
An unassisted process
Solutes are lipid-soluble materials or small enough to pass through membrane pores
Osmosis
—simple diffusion of water
Highly polar water molecules easily cross the plasma membrane through aquaporins
Facilitated diffusion
Substances require a protein carrier for
passive transport
Transports lipid-insoluble and large substances
Filtration
- Water and solutes are forced through a
membrane by fluid, or hydrostatic pressure - A pressure gradient must exist
-Solute-containing fluid is pushed from a high-pressure area to a lower pressure area
Cells:
1) perform all chemical activities needed for life
2) building blocks of all living things
