Chapter 3/4: The Living Units Flashcards
What changes the function of a cell?
the shape
What does the plasma membrane do?
- physical barrier
- selective permeability
- communication
- cell-to-cell recognition
What is the plasma membrane made of?
phospholipids
True or False: phospholipid heads are hydrophilic
True
What is hydrophilic?
polar molecule attracted to water
Is the lipid tail hydrophobic or hydrophilic?
hydrophobic
How many layers does the plasma membrane have?
2 (bilayer)
Which type of heads (hydrophobic or hydrophilic) face out?
hydrophilic
What are plasma membranes made of?
lipids, proteins, and carbohydrates
What are the functions of integral proteins?
transport, signal transduction, enzymatic activity, and cell-to-cell interactions
What do carriers and channels do?
transport small molecules across membranes
What do receptors do?
sense interior and exterior environment
What do enzymes do?
perform chemical reactions
What are the functions of membrane carbohydrates?
- lubricate, cushion and protect cell
- reinforce membrane integrity
- can act as recognition factors (cell-to-cell interactions and pathogen recognition)
What can chains of sugars attach to?
- lipids (glycolipids)
- proteins (glycoproteins)
What are lipid rafts?
many kinds of phospholipids with different properties
- some form stiffer or more flexible membranes
- some form thicker or thinner membranes
What is selectively (referring to plasma membrane)?
permits free passage of some materials and restricts passage of others
What is passive transport?
move substance without using cellular energy
Can passive transport use a protein channel?
yes
What is active transport?
move substance using cellular energy (ATP)
What is diffusion?
material moves from high to low concentration; down concentration gradient
What is simple diffusion?
non-polar and lipids voluble substances defuse directly through the lipid bilayer
What are some example of molecules that can diffuse through simple diffusion?
oxygen, carbon dioxide, fat-soluble vitamins, some water
True or false: lipiphobic can pass using facilitated diffusion
false
What is channel-mediated?
acts as a pore in the plasma membrane
What is an example of channel-mediated?
leak and gated channels
What is carrier-mediated?
changes shape as it binds substrate, envelops it, and releases
What is osmosis?
defined specifically as movement of water across a selectively permeable membrane
How does water diffuses through plasma membrane?
Simple diffusion
channel-mediated facilitated diffusion
What causes water to have a change in net movement across the plasma membrane?
solute concentration
Water moves to dilute or concentrate the solute?
dilute the solute
What is osmolarity?
measure of solute concentration in water
What will happen if the membrane is permeable to the solute and water?
diffusion
What will happen of the membrane is impermeable to the solute and permeable to water?
osmosis
Tonic
concentration
Two types of active transport
active transport
vestibular transport
What do the two active transports have in common?
both use ATP to move solutes across a cell membrane
Why do these processes need to use energy?
to go against the concentration gradient
How does it differ from passive processes?
needs ATP
What does active transport require?
carrier proteins (solute pumps)
What does primary use as energy?
hydrolysis of ATP
What is hydrolysis of ATP?
using energy to break down; decomposition
What does primary transport cause?
shape change in transport protien
What is the function of primary transport?
“pumps” solutes (ions) across membrane against gradient
What is Na+/K+ pump?
- in all plasma membranes
- primary & secondary active transport
-maintains electrochemical gradient- neuron and muscle cell function
What does secondary transport depend on?
an ion gradient created by primary active transport
What is secondary transport?
energy stored in ionic gradients is used indirectly to drive cotransport of the other solute
How else can cells move materials in and out of the cell?
endocytosis & exocytosis
endo
enter
exo
exit
True or false: endocytosis and exocytosis is a form of active transport
true
What are some of the larger cellular items that get transported?
extracellular solutes, cellular debris, pathogens, cellular waste products
What does endocytosis do?
bringing materials into the cell
What are the major forms of endocytosis?
phagocytosis, pinocytosis, receptor-mediated endocytosis
What does phagocytosis do?
eat bacteria, cellular debris, and foreign material
Is pinocytosis selective about what enters the cell?
yes
Tru or false: receptor-mediated endocytosis is not selective
false
What are the receptors binding to in receptor-mediated endocytosis?
enzymes and insulin
What does exocytosis do?
releases cellular products and waste out of the cell
What gets released during exocytosis?
proteins and carbohydrates, hormones, neurotransmitters, muscles, and wastes
What is the function of the smooth ER?
the site of steroid and lipid synthesis, lipid metabolism, drug detoxification, and Ca+ storage
What makes up the cytoskeleton?
microfilaments, intermediate filaments, and microtubules
What are microfilaments?
strands made up of spherical protein subunits called actin
What are intermediate filaments?
tough, insoluble protein fibers constructed like woven ropes composed of tetramer fibrils
What are microtubules?
hollow tubes of spherical proteins subunits called tubulin
How do lysosomes work?
use hydraulic enzymes to digest substances
Where are lysosomes most abundant?
in phagocytes
How do peroxisomes work?
use molecular oxygen to detoxify harmful substances
Where are peroxisomes most numerous?
in the kidneys and liver
What do centrioles do?
aid in organizing microtubules network, form spindles and asters during cell division
