Chapter 3/4: Cells & Membranes Flashcards
Cell
The smallest unit of life
Cell: self-contained structure capable of:
1) Replication
2) Maintenance
Cell theory
1) Everything living thing is composed of one or more cells
2) Cells come from pre-existing cells
Cells are Small (Usually)
1) Unknown until microscopes were available (mid-1600s)
2) Some cells are quite large though
Surface are-to-volume ratio definition
1) As an object gets larger, its surface area increases more slowly than its volume
2) Cells must be able to interact with the environment (exchange materials)
Two types of cells
1) Prokaryotes
2) Eukaryotes
Prokaryotes
Small and relatively simple (domain Bacteria and Archaea), single-celled organisms
Eukaryotes
Typically larger and have organelles (domain Eukarya; plant and animal cells), single or multicellular organism
Plasma membrane
Phospholipid bilayer separating extracellular (outside) from intracellular (inside)
1. Necessary for homeostasis
2. Selectively permeable
3. Used in communication, and interaction with other cells
DNA
Found in nucleoid
Cytosol
Liquid inside the plasma membrane
Ribosome
RNA/protein structures used for protein synthesis
Prokaryotes (Optional structures)
1) Cell wall: (structure/protection)
2) Capsule: (defense) prevent dehydration, recognition
3) Flagella (movement)
4) Pili (attachment/transfer of materials)
5) Cytoskeleton (structure)
Eukaryotes
Compartmentalize by developing distinctive parts, eukaryotic cells isolate functions into distinct organelles
Origins of Eukaryotes
1) Endosymbiosis
2) Invagination
Endosymbiosis
Absorption of one prokaryote by another forms a symbiotic relationship
Photosynthesis makes
More energy available and similar size, independent DNA, and fission
Invagination
Plasma membrane folded in on itself making a pocket’s that become specialized
The nucleus contains genetic materials (DNA)
Chromosome that contain genes (Instruction)
Nucleolus
Responsible for producing rRNA
Nuclear envelope
Double membrane that covers the nucleus and controls access
Ribosome
Sites of protein construction
Free ribosome float in
The cytosol
Bound ribosomes are attached to
The endoplasmic reticulum and making it rough or bumpy
Mitochondria and chloroplasts
Have their own ribosomes
Rough Endoplasmic Reticulum (RER)
Bound ribosomes and production with modification of proteins
Smooth Endoplasmic Reticulum (SER)
No bound ribosomes
Metabolic processes
Synthesis of lipids, modification of drugs/poisons
Alcoholics/drug addicts have more
Smooth ER than non-users
Large in cells that produce, what?
Hormones
Golgi apparatus (body):
Transport hub (warehouse and shipping center of the cell
Golgi apparatus receives
Transport vesicles (bubbles of membrane holding some material)
Golgi apparatus modifies and produces some, what?
Molecules
Golgi apparatus produces, what?
Transport vesicles
Lysosomes
Bag of digestive enzymes
Lysosomes used to
Digest/recycle macromolecules, phagocytosis like cellular eating
Autophagy
Recycling of cellular material
Vacuoles
Compartments filled with aqueous solutions (large vesicles)
Eukaryotic storage
Waste, toxins, or distasteful substances
Eukaryotic structure
Central vacuoles (plants)
Eukaryotic digestion
Food Vacuoles
Eukaryotic regulation
Contractile vacuoles
Contractile vacuoles
Maintain water balance
Mitochondria
Energy conversion (from chemical bonds into ATP) via cellular respiration
Mitochondria have double-layered of what?
Organelle
Mitochondria density and size vary with
Cell type
Plastids
Specialized group of plant organelles
Chloroplast
For photosynthesis, green color from chlorophyll and similar to mitochondria with double membrane design
Cytoskeleton
A fiber network extending across the cytoplasm key to cell organization, movement
Composed of 3 fiber types
1) Microtubules
2) Microfilarments
3) Intermediate filaments
Cilia
Short, numerous structures hair like
In multicellular organisms can help move, what?
Extracellular material
Flagella
Longer structure, often single or in pairs used to propel the organism
Extracellular structure
1) Outside the plasma membrane: Extracellular
2) Inside the plasma membrane: Intracellular
Plant cell walls
1) Provide a rigid frame of support, shape
2) Protect contents of cell
Animal cells do not have walls
1) Extracellular matrix containing collagen (proteins) & proteoglycans (sugars)
2) Provide adhesion, protection, communication, movement, & certain physical properties
Plasma membrane
Separates the intracellular from the extracellular
Selective permeability
Allows some substances to cross but not others (regardless of size)
1) This allows the inside of the cell to be different from the outside
2) Necessary to get nutrient in and waste out
Phospholipids have both
Hydrophilic and hydrophobic regions and form a bilayer sandwich
Fluid mosaic model
Not a solid, inflexible barrier
Cholesterol helps
Stabilize and maintain membrane flexibility at normal temperatures and surface proteins move freely
Receptors
Receive extracellular information
Recognition
Identification (typically of non-self cells)
Carbohydrate chains also are used for
Cell recognition
Transport
Allow large molecules to enter/exit the cell
Enzymes
Enhance reactions on the inner or outer membrane surface
Passive transport
Requires no energy; dependent on molecular motion
Active transport
Requires energy; independent of molecular motion
Diffusion
The movement of molecules from areas of higher concentration to areas of lower concentration (moving down a concentration gradient)
Solute
The molecule (particle) of interest must be dissolved in a liquid or gas
Solvent
The liquid or gas that the solute is dissolved in
Types of diffusion
1) Simple
2) Facilitated
Simple diffusion
Unassisted movement (either no barrier or crossing membrane alone)
Facilitated diffusion
Assisted (non-energy requiring) movement across a membrane (generally using a transport protein)
Osmosis
A specific type of diffusion only referring to the movement of water across a semi-permeable membrane
Tonicity
The concentration of extracellular to intracellular solutions
Hypertonic
Higher solute concentration
Hypotonic
Lower solute concentration
Isotonic
Inside and outside are equal
Primary active transport
Use ATP directly to move molecules across a membrane
Secondary active transport
Use indirect energy to move molecules across a membrane
Molecules too large to move through the membrane enter/exit via, what?
Endocytosis or exocytosis
Bubbles of membrane containing
Material too large or otherwise incapable of physically crossing the membrane
