Chapter 3 Flashcards
Cytology
Study of cells
Cell Composition
Plasma membrane, Cytoplasm organelles, and Nucleus
Cell Membrane Functions
- Physical isolation
- Regulation of exchange
- Sensitivity (Changes in concentration of pH, hormones, and neurotransmitters)
- Structural Support
Cell Membrane Composition
Phospholipid bi-layer, Proteins, Glycoproteins, and Cholesterol
Phospholipid Bi-layer
Hydrophobic tails, hydrophilic heads, gives stability.
Types of Membrane Proteins
- Integral - Part of membrane structure.
- Peripheral - Bound to inner to outer surface, easily separated
Membrane Protein Functions
- Anchoring Proteins
- Recognition proteins (identification tags)
- Enzymes
- Receptor Proteins (Bind to ions and hormones)
- Carrier Proteins
- Channels (Pores)
Glycocalyx
Membrane carbohydrate; sugar coating cell.
1. Lubrication and Protection
2. Anchoring and Locomotion
3. Specificity in binding
4. Recognition
Cytoplasm
- Cytosol - Intracellular fluid, water, solutes
- Organelles - Functional structures
- Inclusions - Insoluble, storage
Organelles
Nonmebraneous - In cytosol
Membraneous - Separated from cytosol by plasma membrane
Cytoskeleton
Cell skeleton.
1. microfilaments: anchor, movement
2. Intermediate filaments: strengthen; stabilize organelles
3. Microtubules: monorail; cell division apparatus; from organelles
Microvilli
Finger-like extensions of the cell membrane which increase surface area.
Centrioles
Two bundles of microtubules; Active in cell division
Cilia
Extension of the cell membrane; contains microtubules; active in movement of substances of cell surface. (Flagellum)
Ribosomes
Small, darkly stained structures; contain rRNA; site of protein synthesis.
1. Free ribosomes: Found in the cytoplasm
2. Fixed ribosomes: Attached to the ER
Proteasomes
Contain protein digesting enzymes; breakdown and recycle damaged or abnormal intracellular proteins
Endoplasmic Reticulum
Series of membrane bound interconected channels, tubes, and chambers.
Intracellular communication and transport system.
Types of ER
- Rough ER: Associated with ribosomes, protein synthesis, and sends transport vesicles to golgi apparatus.
- Smooth ER: No ribosomes; synthesis and storage of: lipids, glycogen, steroid hormones, phospholipds, and cholesterol; detoxification.
Golgi Apparatus
Stack fo membrane bound discs that modifies and packages secretion, renews and modifies the cell membrane, and packages special enzymes used in cytosol
Lysosomes
Made by the gogli apparatus; breakdown metabolic watse products; digest or destroy worn out parts, pathoegens, and suicide bags (autolysis)
Peroxisomes
Enzymes which neutralize free radicals; protective; self-replicating
Mitochondria
Holds enzymes for aerobic respiration (Produce energy.)
The Nucleus
Separated from cytoplasm by nucelar envelope; contains genetic material; directs the activites of the cell.
Parts of the Nucleus
Nuclear Envelope - Very porous; movement of ions and small molecules
Nucleolus - Darker area within nucleous; site of ribosome production; contains RNA, enzymes, and proteins called histones.
DNA
Nucleic Acid with Base Pairs. i.e. ACGT –> TGCA. Genetic Code; instructions for making proteins. DNA winds around histones to produce a nucelosome.
Histones
Regulate and package DNA
Chromatin
Nucleosomes: DNA & Histones; Loosely organized
Chromosomes
Packages chromatin for cell division; only visible during cell division; 23 pairs.
Triplet Code
A sequence of 3 bases of DNA that codes for an amino acid
Gene
Segment of DNA that codes for a protein.
Flow of Information
DNA –> RNA –> Protein
Transcription
DNA –> mRNA
Codon
Three base mRNA sequence
Translation
RNA –> Protein
Anticodon
3 bases of tRNA complimentary to codon on mRNA
Permeability
The ability for substances to pass through the cell membrane
Passive Transport
Does not use energy (ATP)
Active Transport
Uses energy (ATP)
Diffusion
Net movement of a substance from an area of high concentration to low concentration
Concentration Gradient
Difference in concentration; more movement in one direction than the other
Factors influencing diffusion
- Distance
- Molecule Size
- Temperature
- Gradient Size (greater gradient, quicker diffusion)
- Electrical forces (opposite attracts; similar repel)
Simple Diffusion
Lipids, Gases, Toxins (Passive)
Channel Mediated Diffusion
Passes through a channel; Water and special Ions (Passive)
Facillitated Diffusion
Uses a carrier protein; Amino Acids and Carbohydrates (Passive)
Osmosis
Diffusion of water across a selectively permeable membrane in response to solute differences (Water moves with the gradient: More Water –> Less Water.
Membrane is permeable to the Solvent (Water) but not the Solute
Osmotic Pressure
Force with which pure water moves into that solution as a result of its solute concentration
Hydrostatic Pressure
Opposes osmotic pressure
Hypotonic
Less solute than what is in the cell
(higher water concentration: more dilute)
Isotonic
Same solute concentration as inside the cell
Hypertonic
More solute than what is in the cell. (less water concentration, more concentrated.)
Tonicity
Refers to the concentration of the interstitial fluid.
Carrier Mediated Transport
Binding and transporting specific substances or ions by integral proteins.
1. Cotransport: two substances move together
2. Counter-transport: two substances move in opposite directions; in and out of cell
Facilitated Diffusion
Compounds to be transported bind to a receptor site on a carrier protein
Active Transport
Consumes ATP; goes against the gradient (high –> low)
1. Ion Pump
2. Secondary Active Transport
Vesicular Transport
Material moves into or out of cells in membranous vesicles
1. Endocytosis: Movement into the cell (Pincytosis, Phagocytosis)
2. Exocytosis: Injection of materials out of the cell
Pinocytosis
Endocytosis: ingestion of liquid into the cell (Cell drinking)
Phagocytosis
Endocytosis: Ingestion of other cells by white blood cells
Mitosis
Process of cell division in somatic (body) cells where one cell produces two identical daughter cells.
Cytokinesis
Division of cytoplasm
Interphase
Cell performs normal functions; prepares to divide; DNA replication.
Prophase
Prepares further for cell division; chromatin –> Chromosomes; spindle forms, nuclear membrane disassembles
Metaphase
Chromosomes line up in center of the cell
Anaphase
Anaphase: Daughter chromosomes separate
Telophase
Telophase: Reverse of Prophase; Chromosomes –> Chromatin; Spindle disassembles, nuclear membrane forms; Cytokinesis occurs
Mitotic Rate
The longer the life expectancy of the cell, the slower the mitotic rate
Cancer
Abnormal cell division produces tumors or neoplasms
1. Benign
2. Malignant (invasive)
Differentiation
Results from inactivation of particular genes; Produces populations of cells with limited capabilities; Differentiated cells form tissues
Stem Cells
Cells which habe not been differentiated
