Download Chapter 3- Cellular Level of Organization

Chapter 3- Cellular Level
of Organization
Plasma Membrane
F(x):
 1. Physical Isolation
 conditions inside & outside the cell constant to preserve homeostasis
 2. Regulation of Exchange with the Environment
 controls the entry of ions & nutrients, the elimination of wastes, & the release of secretions
 3. Sensitivity to the Environment
 contains variety of receptors that allow the cell to recognize & respond to specific molecules in its
environment
 4. Structural Support
 specialized connections b/w plasma membrane or b/w membrane & extracellular materials
Phospholipid Bilayer
 Regulate movement of molecules in/out, semi-permeable
 Hydrophilic phosphate heads & Hydrophobic lipid tails
Cholesterol: large steroid/lipid
-helps maintain structure
Membrane Proteins:
 Anchoring- attach plasma membrane to other structures & stabilize its position
 Recognition- allows immune system cells to recognize “self” vs “nonself”
 Enzymes- catalyze reactions in cytosol or extracellular fluid
 Receptors- sensitive to extracellular molecules > ligands
 Carrier- binds solutes & transport them across membrane (some require ATP)
 Channels- movement of H2O & small solutes
Membrane Carbs:
 Proteoglycans
 Glycoproteins
 Glycolipids
 Make up layer called Glycocalyx
 F(x):
 lubrication & protection
 Anchoring & locomotion
 Specificity in binding-alters property of cell’s surface
 Recognition- “self” vs “nonself”
Organelles
 Outline sheet
 Section 3-2 : Read pages 68-77
Organelles
 Cytoplasm- contains cytosol & organelles
 Nucleus- control of metabolism, storage & processing of genetic information, control of
protein synthesis
 Rough ER- modifies & packages newly synthesized proteins
 Ribosomes- protein synthesis
 Smooth ER- synthesizes lipids & carbohydrates
 Golgi body with vesicles- modifies & packages secretions for release through exocytosis,
renews or modifies the plasma membrane, packages special enzymes within vesicles for
use in the cytoplasm
 Lysosome- intracellular removal of damaged organelles or pathogens
 Peroxisome- catabolism of fats & other organic compounds, neutralization of toxic
compounds generated in the process
 Proteasomes- breakdown & recycling of damaged or abnormal intracellular proteins
 Mitochondria- produces 95% of ATP required by the cell
 Centrioles- found during cell division, form spindle apparatus
 Cilia- move fluids/secretions across the cell surface
Cytoskeleton- metabolic organization, internal protein framework, gives cytoplasm strength &
flexibility
 Microfilaments- anchor cytoskeleton to integral proteins of plasma membrane,
determines consistency of cytoplasm, movement of cell
 Intermediate filaments- strengthen cell & help maintain its shape, stabilize the positions of
organelles, stabilize position of cell to surrounding cells
 Microtubules- cell strength & rigidity, position of organelles, assist in movement, spindle
apparatus, structural components
 Thick filaments- composed of myosin, interact with actin filaments to produce powerful
contractions
Nucleus
 Controls metabolism, storage, & processing of
genetic info, control of protein synthesis
 Contains DNA & enzymes to control cellular
activities
 Genetic code: DNA set of instructions
 3 letter word = codon > specific amino acid chains
 DNA > RNA > proteins
 The Inner Life of the Cell
Diffusion- passive transport
 Movement of molecules from areas of
high concentration to low
 Down concentration gradient
 Through phospholipids/ channel
proteins
Osmosis- diffusion of water
 Isotonic- equal
 Hypotonic- salt outside is less = cell bursts (lysis)
 Hypertonic- more salt outside = water leaves = crenation (shrinking)
Carrier Mediated Transport (passive/active)
 Transportation of ions & organic substrates
 Characteristics:
 Specificity: only bind to certain things
 Saturation: limits to rate
 Regulation: hormones
 1. Facilitated Transport- passive
 Large polar molecules & ions move across
membrane
 2. Active- requires E
 Ion pumps- exchange pumps ex: Na/K
 Passive vs. Active Transport
Vesicular Transport- ATP required
 1. Endocytosis- take in using vesicles
 Receptor mediated target molecules
 Pinocytosis-liquid
 Phagocytosis- solids
 2. Exocytosis secretion, hormones/vesicles
Facilitated Diffusion vs Active Transport
 Similarities:
 Differences:
 Carrier proteins
 FD- w concentration gradient
 Transport large molecules/ions
 AT- against conc. Gradient
 AT- requires E, FD doesn’t
Transmembrane Potential
 Charges are separated creating a potential difference
 Unequal charge across plasma membrane is transmembrane potential
 Resting potential= -10mV to -100mV, depending on cell
 Minus sign signifies inside of plasma membrane contains an excess of – charges
compared with outside
 Creates potential E
Cell Cycle
 Interphase- cell increases in mass, doubles its
cytoplasm & duplicates its DNA
 G1- cytoplasm doubles
 S- DNA is copied
 G2- proteins/enzymes required for cell division are
made
 Mitosis
 Prophase- chromosomes condense
 Metaphase- chromosomes line up in middle
 Anaphase- separation
 Telophase- condense
 Cytokinesis- division into 2 daughter cells
 Late anaphase > telophase
 Marks end of cell division
Cell Cycle and Mitosis
Regulation of Cell cycle
 Proteins & enzymes are responsible
 1. Cyclins- family of proteins that increase and decrease in
number during cell cycle, bind to kinases to activate them
 M cyclins- during mitosis
 S cyclins- during interphase
 2. Kinases- Cdk (cyclin dependent kinases)-family of enzymes
that drive the cell cycle, active only when bound to cyclin
 When damage is found, the checkpoint uses a signal
mechanism either to stall the cell cycle until repairs are made
or, if repairs cannot be made, to target the cell for
destruction via apoptosis
Cancer
 Uncontrolled cell division- tumor growth
 Proto-oncogenes- naturally occurring, normally promote cell division when on
 Oncogene- mutated form, permanently spin cell cycle
 Tumor Suppressor Genes- naturally occurring, stop cell cycle
Formation of Cancer
Cancer Video
 Starts with a mutation
 Genetic, virus, environment (smoking, radiation, UV)
 Cell becomes non-functional, not density dependent, and does not stick together = primary
tumor
 Angiogenesis- formation of blood supply
 Benign-doesn’t spread
 Malignant- will spread
 Uses blood or lymphatic system to spread = Metastasis =secondary tumor
Cell Differentiation
 Development of specific cellular features
 All cells throughout the body contain the same set of chromosomes &
genes, but a different set of genes has been turned off
 All have 46 chromosomes
 Liver cells don’t have genes for production of insulin turned on
 Stem cells- undifferentiated and can become many cell types