Exam 1 Flashcards
describe the chemical composition of the plasma membrane and relate it to membrane functions
phospholipid bilayer with hydrophobic interior and hydrophilic exterior act as a barrier to separate intracellular fluid from extracellular fluid (hydrophilic phosphate heads near the fluid) and holds cell together
membrane proteins act as selective barrier
cell theory
cell is structural and functional unit of life
structure = function
cells arise from pre-existing cells
plasma membrane
flexible outer boundary that acts as active barrier between intracellular and extracellular fluids; controls what enters and leaves the cell
membrane proteins
allow cell communication with environment and most have specialized functions
two types of membrane proteins
integral and peripheral
integral membrane proteins structure and function
firmly inserted into plasma membrane and most span the membrane
hydrophobic region interact w/lipid tails
hydrophilic region interacts w/water
function as transport proteins, enzymes, and receptors
peripheral proteins structure and function
loosely attached to surface of phospholipid bilayer and include filaments on extracellular surface for plasma membrane support
function as enzymes, motor proteins for shape changes during cell division/muscle contraction, and cell-to-cell connections
glycalyx structure and function
sugars (carbohydrates) sticking out of cell surface creating a pattern unique to each cell
biological markers for cell-to-cell recognition; allows immune system to recognize “self” vs foreigner
cytoplasm
cellular material located between plasma membrane and nucleus: cytosol, inclusions, and organelles
cytosol
gel-like solution made up of water and soluble molecules (proteins, salts, sugars)
inclusions
insoluble molecules that vary w/cell type
examples of inclusions
glycogen, granules, pigments, lipid droplets, vacuoles, crystals
cytoplasmic organelles
metabolic machinery of cell; can be membranous or non-membranous
membranous organelles
mitochondria, ER, golgi, peroxisomes, lysosomes
non-membranous organelles
ribosomes, cytoskeleton, centrioles
mitochondria structure/function
Structure: double membrane; inner membrane = cristae imbedded with membrane proteins inner membrane; contain own DNA, RNA, and ribosomes
Function: produce most of cells ATP via aerobic resp.
capable of cellular division (fission)
ribosomes structure/function
non-membranous organelles made up of protein and ribosomal RNA (rRNA); can be either free or membrane-bound (attached to rough ER)
PROTEIN SYNTHESIS!!! free ribosomes= synthesis of soluble proteins functioning in cytosol; membrane bound= synthesis of intramembrane proteins, lysosome proteins, and proteins to be exported from the cell
rough endoplasmic reticulum structure/function
series of parallel, interconnected cisterns continuous with the outer membrane; contains ribosomes
synthesize/modify proteins; package in vesicles to be sent to golgi
what types of molecules are synthesized in the rough ER
proteins that will be secreted from the cell
plasma membrane proteins and phospholipids
structure/funciton smooth ER
network of looped tubules continuous w/rough ER; contains enzymes w/in its plasma membrane
Enzymes w/in smooth ER perform:
- Lipid metabolism; cholesterol and steroid-based hormone synthesis; making
lipids for lipoproteins
- Absorption, synthesis, and transport of fats
- Detoxification of certain chemicals (drugs, pesticides, etc.)
- Converting of glycogen to free glucose
- Storage and release of calcium
Sarcoplasmic reticulum
specialized smooth ER found in skeletal and
cardiac muscle cells
golgi apparatis structure/function
Stacked and flattened membranous cistern sacs
Modifies, concentrates, and packages proteins and lipids received from rough ER
three steps of golgi protein packaging
- Transport vesicles from ER fuse with cis (inner) face of Golgi
- Proteins or lipids taken inside are further modified, tagged, sorted, and packaged
- Golgi is “traffic director,” controlling which of three pathways final products will
take as new transport vesicles pinch off trans (outer) face
three possible pathways of final transport vesicle from the golgi
– Pathway A: Secretory vesicles containing proteins to be used outside of cell
fuse with plasma membrane and exocytosis contents
– Pathway B: Vesicles containing lipids or transmembrane proteins fuse with
plasma membrane or organelle membrane, inserting contents directly into
destination membrane
– Pathway C: Lysosomes containing digestive enzymes remain in cell, holding
contents in vesicle until needed
peroxisomes structure/function
Membranous sacs containing powerful detoxifying substances that neutralize toxins and play a role in breakdown and synthesis of fatty acids
free radicals
toxic, highly reactive molecules that are natural by-products of
cellular metabolism; can cause havoc to cell if not detoxified
lysosomes structure/function
Spherical membranous bags containing digestive enzymes (acid hydrolases)
– Considered “safe” sites because they isolate potentially harmful intracellular
digestion from rest of cell
– Digest ingested bacteria, viruses, and toxins
– Degrade nonfunctional organelles
– Metabolic functions: break down and release glycogen; break down and release Ca2+
from bone
– Intracellular release in injured causes cells to digest themselves (autolysis)
cytoskeleton structure and function
Elaborate network of rods that run throughout cytosol; can be either Microfilaments, Intermediate filaments, or Microtubules
rods link to to other strucutres via proteins; cell movement
Microfilaments structure/function
Thinnest of all cytoskeletal elements made of semi-flexible strands of protein actin
strengthen cell surface and can be involved in cell motility, changes in cell shape, or endocytosis and exocytosis
Intermediate filaments structure/function
Size is in between microfilaments and microtubules
Tough, insoluble, ropelike protein fibers composed of tetramer (4) fibrils twisted together, resulting in one strong fiber
Help cell resist pulling forces; act as internal guy-wires
