Ch3 Cellular Form and Function Flashcards
Cells shapes and sizes ___
Cells shapes and sizes VARIES
Most human cell sizes are ___ µm (micrometer) in diameter.
Most human cell sizes are 10-15 µm (micrometer) in diameter.
Egg cells (very large) are ___ in diameter
Egg cells (very large) are 100 µm in diameter
Muscle cells can be ___ cm long
Muscle cells can be 30 cm long
Nerve cells can be ___ meter(s) long
Nerve cells can be 1 meter long
Cell growth ____ volume more than surface area
Cell growth INCREASES volume more than surface area
Plasma (cell) membrane is _____ ______, surrounds ____ and ______ entry/exit - on perimeter of the cell
Plasma (cell) membrane is SELECTIVELY PERMEABLE, surrounds CELL, and REGULATES entry/exit - on perimeter of the cell
The cytoplasm is the ___ ____ of the cells
The cytoplasm is the INNER CONTENTS of the cells
What are the 3 things located in the cytoplasm?
- Organelles
- Cytoskeleton
- Cytosol (intracellular fluid, ICF)
98% of molecules in plasma membrane are ____.
The other 2% are ____.
98% of molecules in plasma membrane are LIPIDS (mostly phospholipids).
The other 2% are PROTEINS.
What 3 things can phospholipids be?
- Amphiphilic
- Hydrophilic
- Hydrophobic
How are amphiphilic molecules arranged?
In bilayer
What way do hydrophilic phosphate heads face?
Towards the water
Where are hydrophobic tails directed towards?
Towards the center
What way do phospholipids drift from place to place?
Laterally
What keeps membrane fluid in phospholipids?
Movement
What 2 other lipids are molecules in the plasma membrane?
- Cholesterol
- Glycolipids
What are glycolipids?
1/2 sugar and 1/2 lipids - contribute to glycocalyx
What are the 2 membrane proteins?
- Transmembrane proteins
- Peripheral proteins
What are transmembrane proteins?
Proteins that cross over from one side to other side in membrane (go from ECF to ICF).
What are peripheral proteins?
Proteins that are between the plasma membrane and the ICF.
- adhere to face of membrane
- usually tethered to cytoskeleton
What are the functions of the membrane protein?
- Receptors - receives and binds to something (hormone, neurotransmitter, etc)
- Second messenger systems - receptors & enzymes working together - signaling for a change to occur inside the cells
- Enzyme - breaks things down
- Ions channels
(Channel protein - gate constantly open and allows solutes to pass into and out of cell & gated channel - gate that opens and closes to allow solutes through only at a certain time, something has to happen to let it through)
- Carriers - transmembrane proteins that bind to glucose, electrolytes, and other solutes & transfer them to other side of membrane (some carriers, called pumps, consume ATP in process)
- Cell - identity marker - identifies cell for who it is (distinguishes body’s own cells from foreign cells, example: kidney donation line up closely to receiver?)
- Cell-adhesion molecule (CAM) - help link cells together
What are second messenger systems?
Receptors and enzymes working together in a way that they create a second messenger system and it’s a way of signaling for a change to occur inside the cell
What are glycocalyx?
Unique fuzzy coat external to plasma membrane
- carbohydrate moieties of membrane glycoproteins and glycolipids
- unique (except identical twins)
What are the functions of glycocalyx?
- Protections
- Immunity/defense
- Transplant compatibility
- Cell adhesion
- Embryonic development
- Fertilization
What are membrane extensions?
Microvilli
- numerous and small (1-2 µm)
- increases cell’s surface area
What do microvilli specialize in?
Cells specialized in absorption
What are microvilli called when they are very dense?
“Brush border”
What are cilia? How long are they?
Hairlike processes 7-10 µm long
Where are motile cilia located?
In respiratory tract, uterine tubes, brain’s ventricles, efferent ductules of testes
- beat in waves, sweep substances
- power strokes, recovery strokes
What is axoneme?
The core of cilia - structural basis for cilary movement
What are microtubules?
“Tent poles” of cilia
What is the structure of microtubules?
9+2
What do microtubules form inside the cell?
Form basal body inside the cell
What do dynein arms do?
They “crawl” up adjacent microtubules, bending cilia
What is a flagella and what is it’s structure?
Tail of sperm - only functional flagellum
-whiplike structure with axoneme identical to cilium
What are pseudopods?
Extensions that change
The plasma membrane is…
Selectively permeable - controls which things enter/leave cells
Does passive transport require ATP?
No.
What are the types of passive transport?
- Filtration
- Simple diffusion
3A. Carrier-mediated facilitated diffusion
Does active transport require ATP?
Yes
What are the types of active transport?
3B. Carrier-mediated (active) transport
- Vesicular transport
What is filtration?
Particles driven through a selectively permeable membrane by hydrostatic pressure
ex) filtration through capillary walls
What is simple diffusion?
Net movement of particles from HIGH to LOW concentration
- due to constant, spontaneous motion
- movement “down the concentration gradient”
What factors affect diffusion rate through membrane?
- Temperature: high temp, high motion of particles
- Molecular weight: larger molecules move slower
- Steepness of concentrated gradient: high difference, high rate
- Membrane surface area: high area, high rate
- Membrane permeability: high permeability, high rate
Diffusion through lipid bilayer
Smaller & nonpolar most easily
Ex) O2, CO2, & NO
Diffusion through channel proteins
Larger & more polar molecules
Ex) glucose, ions
Cells control permeability by…
Regulating number of channel proteins or by opening and closing gates
What is osmosis?
Flow of water through selectively permeable membrane
-from side with more water to side with less water
What are aquaporins?
Channel proteins that can increase rate of osmosis
What is osmotic pressure?
Amount of hydrostatic pressure required to stop osmosis
-reverse osmosis
What is tonicity?
The ability of a solution to affect the fluid volume and pressure in a cell
Describe hypotonic solution
- lower concentration of nonpermeating solutes
- thus higher water concentration
- cells in this solution absorb water (even lyse!)
Describe hypertonic solution?
- has higher concentration of nonpermeating solutes
- thus lower water concentration
- cells in this solution lose water & shrivel
What are isotonic solutions?
Concentrations in cell = ICF
What is carrier-mediated transport?
Proteins that carry solutes across cell membrane
What are the carriers of of carrier-mediated transport?
- Uniport - 1 solute at a time
- Symport - 2 solutes simultaneously, same direction
- Antiport - 2 solutes simultanously, opposite direction
Solute binds to a ___ ____ on carrier protein
Solute binds to a RECEPTOR SITE on carrier protein
What are the types of carrier-mediated transport?
- Facilitated diffusion
- Active transport
What is facilitated diffusion?
- Solute through a membrane down its concentration gradient
- no ATP consumed
What is active transport?
- Carrier-mediated transport of solution through membrane up (against) it’s concentration gradient
- uses ATP
What is vesicular transport?
- Transport of large particles or fluid droplets through membrane in vesicles or membrane
- uses ATP
What is exocytosis?
Vesicular transport out of cell
What is endocytosis?
Vesicular transport into the cells
What are the 3 types of endocytosis?
- Phagocytosis
- Pinocytosis
- Receptor-mediated endocytosis
Describe phagocytosis, pinocytosis, and receptor-mediated endocytosis.
- Phagocytosis - engulfing large particles (eg. pathogens)
- Pinocytosis - taking in fluid droplets
- Receptor-mediated endocytosis - taking in specific molecules
What does exocytosis do?
- Secretes material (cells get rid of waste)
- Replaces membrane removed by endocytosis
What is the cell interior?
Cytoplasm
What are the structures in the cytoplasm?
- Cytoskeleton
- Organelles
- Inclusions
** all embedded in a clear gelatinous cytosol
What is a cytoskeleton?
Protein filaments and tubules (in the cytoplasm of living cells) that helps maintain shape and internal organization
What is the cytoskeleton composed of?
- Microfilaments - of protein actin
- Intermediate filaments
- Microtubules - of protein tubulin
Describe microfilaments
Microfilaments - of protein actin
- supports membrane & microvilli
- produces cell movement
Describe intermediate filaments
Tight junctions
Describe microtubules
Microtubules - of protein tubulin
- hold organelles in place, maintain cell shape
- inside cilia, flagellum
- move cargo
Be able to locate things in this picture
Describe a nucleus
- Largest organelle
- usually one, few cells anuclear or multinucleate
Describe nuclear envelope
Membranes that surround nucleus; nuclear pores
Define nucleolus
Ribosome synthesis (reponsible for making ribosomes)
What does the endoplasmic reticulum (ER) consist of?
Rough ER & Smooth ER
Describe Rough ER
Cisternae (system of tunnels interconnected) covered with ribosomes
- continuous with outer membrane of nuclear envelope
- function: protein synthesis
Describe smooth ER
Smooth because no ribosomes in it
- cisternae seem continuous with rough ER
- function: steroids (+ other lipids) synthesis
detoxifies alcohol, drugs
Define ribosomes
Small granules of protein & RNA
-“read” coded genetic messages (messenger RNA), assemble amino acids into proteins
Describe golgi complex
System of cisternae; function: synthesize carbohydrates and modify proteins
- receives newly synthesized proteins from rough ER
- packages proteins into membrane-bound golgi vesicles
- some become lysosomes
- some become secretory vesicles
Describe lysosomes
Catabolic enzyme bound in membrane
“cleaner uppers”
Functions:
- intracellular hydrolytic digestion
- autophagy - digestion of worn out organelles
- autolysis - “cell suicide” = programmed cell death
- (glucose mobilization - in liver cells, lysosomes break down glycogen)
Describe peroxisomes
Resemble lysosomes but use different enzymes
- use O2 to oxidize organic molecules
- neutralize free radicals, detoxify alcohol
- break down fatty acids into acetyl groups for midochondrial use (ATP synthesis)
- hydrogen peroxide (H2O2) produced buy catalase breaks that down
- in all cells but abundant in liver and kidney
What are proteasomes?
Protein disposal
Describe mitochondria
Synthesizes ATP
-double unit membrane
- inter folds= cristae (enzymes necessary to produce ATP)
- matrix contains ribosomes, enzymes for ATP synthesis, and small circular DNA molecule = mitochondrial DNA
- “powerhouses”
- energy extracted from organic molecules (glucose), transferred to ATP
Describe centrioles
- composed of microtubules
- organizes chromosomes during cell division
- form basal body of cilium or flagellum
What are inclusions?
Stored cellular products
-disease markings
Why should we care about Zellweger syndrome?
Hereditary genetic disorder that affect peroxisomes (organelles found in almost all body cells). It disturbs cellular function and causes serious problems soon after birth. Newborns can have brain, liver and kidney problems, as well as difficulty feeding or moving. There is no cure or treatment. Peroxisomes are responsible for many important cell processes, including energy metabolism, which means that Zellweger syndrome can severely impact the body
