Chapter 3 Flashcards
Who Discovered Cells?
-Robert Hooke in 1665 -Observed cork slices -Coined the term “cells”
Schleiden and Schwann Cell Theory
Schleiden- concluded that all plant parts are made of cells Schwann- stated that all animal tissues are composed of cells
Cell Theory
-All life forms are made of one or more cells -Cells only arise from pre-existing cells -The cell is the smalled form of life
Cell Types
-Cells that connect body parts, form linings or transport gases -Cells that move organs and body parts -Cells that store nutrients -Cells that fight disease -Cells that gather info and controls body functions -Cells of reproduction
Cells that connect body parts, form linings, or transport linings
-Fibroblasts -Erythrocytes -Epithelial cells
Cells that move organs and body parts
-Skeletal muscle cell -Smooth muscle cells
Cell that stores nutrients
-Fat cell
Cell that fights disease
-Macrophage
Cell that gathers info and controls body function
-Nerve cell
Cell of reproduction
-Sperm
Plasma Membrane functions
-Boundary-separates intracellular fluid from extracellular fluid -Regulates transport of molecules into and out of the cell -Recognition molecules that identify a cell to other cells
Membrane Lipids
-75% phospholipids Lipid bilayer -5% glycolipids Lipids with polar sugar groups on outer membrane surface -20% cholesterol Increases membrane stability
Membrane Proteins
-Integral Proteins -Peripheral Proteins -Filament of Cytoskeleton
Integral Proteins
-Firmly inserted into the membrane -Often transmembrane -Usually transport proteins -Often contains pores -Can mediate attachment to cytoskeleton and extracellular matrix
Peripheral Proteins
-Loosely attached to integral proteins -Usually enzymes
Filament of Cytoskeleton
-Cytosolic -Supports membrane -Gives cells their shape
Glycocalyx
-Carbohydrate coat of cell surface Glycolipids Glycoproteins -Important in cell recognition Immune cells MHC proteins ABO blood groups
Plasma Membrane Special Features
-Microvilli -Gap Junctions -Tight Junctions
Microvilli
-Finger like projections of the cell membrane -Increase surface area of cell -Aid in absorption -Found in small intestine, kidney
Gap Junctions
-Transmembrane proteins that form pores that allow small molecules to pass from cell to cell -Found in cardiac myocytes and smooth muscle cells
Tight Junctions
-Prevent molecules from passing through layers of cells -Found in the intestines
How do molecules pass through cell membranes?
-Passive transport -Active transport
Passive Transport
-Does not require energy (ATP) -Molecules move down a concentration gradient
Active Transport
-Requires ATP -Molecules move against a concentration gradient
Simple Diffusion
-Molescules diffuse directly through phospholipid bilayer -Molecules must be small, non-polar, and lipid soluble (O2, CO2, Ureae, Alcohol) -Requires concentration gradient
Facilitated Diffusion Channel Mediated
-Molecules diffuse directly through channels down concentration down concentration gradient -Usually small polar charged molecules (Na+, K+)
Facilitated Diffusion Carrier Mediated
-Carriers have high specificity (Glucose, amino acids) -Carriers can become saturated (Tm) -Tm= transport max -Maximum level of saturation for a carrier protein
Osmosis
-Diffusion of water through a semipermeable membrane -Uses aquaporins -Travels down a concentration gradient
Isotonic solutions
-Usuallu 0.9% NaCl -5% Glucose
Hypotonic solutions
-Less than 0.9% NaCl -Less than 5% Glucose
Hypertonic solutions
-Greater than 0.9% NaCl -Greater than 5% Glucose
Osmotic Pressure
-Pressure that develops as a result of osmosis
Filtration
-Moving down a pressure gradient
Hydrostatic Pressure
-Pressure exerted by water against the plasma membrane
Plasma Membrane Potential
-Voltage resulting from separation of oppositely charged particles Regulated by -Na+K+ pump -Leaky K+ channels -Membrane Potential is usually -70 to -90 mV
Endocytosis
-Uptake of large particles or numerous particles into cells through vesicles -Form of Active Transport
Phagocytosis
-“Cell-Eating” -Engulfment of bacteria or other particles by psuedopod extension -Particle enclosed in phagosome (later combines with lysosome) -Macrophages
Pintocytosis
-“Cell-Drinking” -Engulfment of extracellular fluid and dissolved molecules (nutrients) -Intestinal cells
Exocytosis
-Moving particles out Ex: -Hormones -Neurotransmitters -Mucus
Cytoplasm
-Area between plasma membrane and nuclear membrane -Cytosol -Organelles -Inclusions
Cytosol
-Viscous jelly like substance suspending all cytoplasmic components -Mostly water
Organelles
-Little organs
Inclusions
-Cell specific -Glycogen (liver and muscle) -Lipid droplets (Adipose) -Melanin (Skin)
Mitochondria
-“Power house” of cell -Aerobic Respiration -Have their own DNA, RNA and ribosomes
Aerobic Respiration
-Process of conversion of glucose to ATP -Requires Oxygen
Ribosomes
-Sites of protein synthesis Two types -Free ribosomes -Membrane-bound (ER) ribosomes
Free ribosomes
-Synthesize cytosolic proteins
Membrane bound (ER) ribosomes
-Synthesize plasma membrane proteins, or proteins that are exported -Antibodies, hormones, neurotransmitters
Endoplasmic Reticulum
-Network of interconnected membranes, continuous with nuclear membrane
Rough ER
-Ribosomes attached -Ribosomes synthesize membrane proteins or proteins that are exported
Smooth ER
-No ribosomes, so no role in protein synthesis -Contains enzymes which play a role in lipid synthesis, steroid hormone synthesis -Detoxify drugs -Sarcoplasmic Reticulum (SR) (in muscle) regulate calcium needed for muscle contraction
Golgi Apparatus
-Modifies, sorts and packages proteins made in the ER Example: -Carbohydrate or phosphate attachment
Lysosomes
-Spherical organelles containing digestive enzymes (hydrolases) -Macrophage lysosomes digest particles (bacteria) taken in by endocytosis -Digest non-functional organelles -Digest non-functional tissue (webbing in feet-hands in fetal development)
Peroxisomes
-Spherical organelles containing enzymes -Enzymes detoxify harmful substances (alcohol, fermeldahyde) -Neutralizes free radicals such as superoxide (O2-) a byproduct of cellular respiration
Cytoskeleton
-The cell’s skeleton Made of: -Microfilaments -Intermediate filaments -Microtubules
Microfilaments
-Cell shape -Cell contraction -Reinforce the plasma membrane -Cytokinesis
Intermediate filaments
-Help cells resist tension (stretching)
Microtubules (MTs)
-Position and suspend organelles
Centrioles
-Centrioles are paired hollow tubes that anchor and organize MTs -Centrioles generate the mitotic spindle -Direct cilia and flagella formation
Nucleus
-Control center of the cell -Most cells have one nucleus Exceptions: -Skeletal muscle (multinucleate) -Red blood cells (anucleate)
Nuclear Envelope
-Double membrane -Continuous with ER
Nucleolus
-Make ribosomes
Chromatin
Contains: -DNA -Histone Proteins
Chromosome Architecture
-DNA is wound around histone proteins -During mitosis chromatin organizes into chromosomes
DNA Transcription
-DNA info encoded in mRNA
DNA Translation
-mRNA decoded to assemble polypeptides (proteins)
DNA transcription
