Cells and Organelles Flashcards
what are the 3 main things in a cell membrane?
phospholipids; cholesterol; proteins
what are the 2 types of membrane proteins?
integral; peripheral
_____ membranes are embedded in the core of the plasma membrane
integral
many integral proteins are _____ proteins, meaning they extend all the way through the membrane
transmembrane
integral/transmembrane proteins may function in cell _____, but most tend to transport _____ molecules across the cell membrane
signaling; large, polar (hydrophilic)
_____ membrane proteins do not extend through the entire bilayer
peripheral
what are 3 common types of peripheral membrane proteins?
receptors; adhesion proteins; recognition proteins
recognition proteins are also known as _____
glycoproteins
what is a common example of a recognition peripheral protein?
major-histocompatibility complexes (MHC molecules)
what are the 3 main factors that affect membrane fluidity?
temperature; cholesterol; the degree of phospholipid tail unsaturation
_____ particles can travel directly across the phospholipid bilayer via simple diffusion
small, uncharged, non-polar (hydrophobic)
simple diffusion is the flow of substances _____ their concentration gradient in a _____ consuming process
down; non-energy
_____ does not utilize proteins to help particles across the membrane
simple diffusion
osmosis is a type of _____
simple diffusion
_____ molecules cannot travel directly across the bilayer
large, hydrophilic
_____ describes how large, hydrophilic molecules travel across the bilayer by transmembrane proteins
facilitated transport
what are the three main types of facilitated transport (direction)?
uniport; synport; antiport
_____ move 1 molecule in 1 direction
uniporters
_____ move 2 molecules in the same (1) direction
synporters
_____ move 2 molecules in opposite (2) directions
antiporters
what are the two classes of transmembrane proteins involved with facilitated transport?
channel; carrier
_____ proteins face the extracellular and intracellular environments of the cell at the same time
channel
channel proteins are like tunnels for many _____
small, polar molecules and ions
_____ diffusion describes a type of facilitated transport of particles down their concentration gradient through a _____ protein
passive; channel
porins and ion channels are common examples of _____ diffusion
passive
_____ change their shape to facilitate the movement of molecules through the protein.
carrier proteins
_____ occurs when particles travel against their concentration gradient, which requires an energy input
active transport
active transport tends to rely upon _____ proteins
carrier
what are the 2 types of active transport?
primary; secondary
_____ active transport uses the energy released from ATP hydrolysis
primary
the Na+/K+ pump is a form of _____ active transport
primary
the Na+/K+ pump moves _____ out of the cell and _____ into the cell with the hydrolysis of 1 ATP
3 Na+; 2 K+
secondary active transport depends on _____ to generate free energy in the form of a concentration gradient
primary active transport
_____ active transport uses free energy to pump other molecules against their concentration gradient
secondary
_____ is bulk transport of large, polar (hydrophilic) molecules
cytosis
what are the 2 directions of cytosis?
endocytosis (in the cell) and exocytosis (out of the cell)
_____ is a type of endocytosis where a cell engulfs undissolved materials
phagocytosis
cellular eating
during phagocytosis, the cell membrane will project _____ to wrap around the solid
outward
phagocytosis forms _____
vacuoles (phagosomes)
_____ is a type of endocytosis where a cell engulfs dissolved materials
pinocytosis
cellular drinking
during pinocytosis, the cell membrane will _____ around the liquid
invaginate
pinocytosis forms _____
vesicles
certain non-steroidal hormones target cells via which pinocytosis mechanism?
receptor-mediated endocytosis
receptor-mediated endocytosis forms _____
vesicles
organelles are enclosed by a _____
phospholipid bilayer
membrane-bound organelles are predominately associated with which cell type?
eukaryotes
the _____ is the aqueous intracellular fluid
cytosol
the _____ is everything within the cell (fluid and organelles)
cytoplasm
what is the nucleus?
a membrane-enclosed organelle that contains most of a eukaryotic cell’s genetic material
do prokaryotes have a nucleus?
no - they have a nucleoid
the nucleus contains an aqueous _____
nucleoplasm
the nucleus has an inner and outer membrane, called the _____
nuclear envelope
what is the space between the inner and outer nuclear membranes?
perinuclear space
the _____ is a dense and fibrous network of proteins associated with the inner membrane of the nuclear envelope
nuclear lamina
the nuclear lamina is made of _____
intermediate filaments
the _____ functions to provide structural support to the nucleus; regulate DNA organization, DNA replication, and cell division
nuclear lamina
the nuclear envelope has holes called _____
nuclear pores
the _____ is a dense region in the nucleus, associated with ribosomal subunit assembly
nucleolus
is the nucleolus an organelle?
no - it is not membrane bound
ribosomal subunits contain _____ and _____
ribosomal ribonucleic acid (rRNA); proteins
eukaryotic _____ are made in the nucleus and assembled in the cytosol
ribosomal subunits
what do ribosomes do?
function in the synthesis of proteins
translation
what is the structure of a eukaryotic ribosome?
60S + 40S = 80S
what is the structure of a prokaryotic ribosome?
50S + 30S = 70S
where are ribosomes found?
freely in the cytosol or attached to the rough ER
_____ ribosomes tend to make proteins that function within the cytosol of the cell
free
ribosomes that bind to the rough ER will synthesize proteins _____
into the rough ER lumen
the rough ER is continuous with the _____, which means the ER lumen is continuous with the _____
outer nuclear membrane; perinuclear space
what happens to proteins inside the rough ER?
they are manipulated
what is a common manipulation for proteins in the rough ER?
glycosylation to make glycoproteins
what are the 2 fates of proteins that enter the lumen of the rough ER?
become a part of the cell membrane; exocytosis
the _____ synthesizes lipids and steroid hormones for export
smooth ER
in some cells (ex: liver), the _____ functions in the breakdown of toxins, and drugs
smooth ER
what is the name of the smooth ER of muscle cells that stores and releases Ca2+ ions?
sarcoplasmic reticulum
