DAT bio Chapter 2! 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
what proteins 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 that do not extend through the entire bilayer
peripheral
what are 3 common types of 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
what kind of 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 without the use of energy. Goes from high concentration to low concentration
A type of simple diffusino
osmosis
What molecules cannot travel directly across the bilayer
large, hydrophilic. the inside of the bi layer is hydrophobic
facilitated transport
integral proteins allow larger, hydrophilic molecules to cross the cell membrane
what are the three main types of facilitated transport (direction)?
uniport; symport; antiport
uniporters
move 1 molecule in 1 direction
symporters
move 2 molecules in the same (1) direction
antiporter
move 2 molecules in opposite (2) directions
what are the two classes of transmembrane proteins involved with facilitated transport?
channel and carrier
What are channel proteins
open tunnels that face both sides of the bi layer (facilitated transport)
carrier proteins
bind to molecule on one side and changes shape to bring it to the other side
Passive diffusion
Type of facilitated transport
performed by channel proteins
NO energy is used
just like simple diffusion but uses protien channel
Examples of passive diffusion
aqua porins for hydrophilic and ion channels for ions
two types of active transport
primary and secondary
Active transport is what
helps substances travel against their con gradient by requiring the consumption of energy by carrier protiens
sodium potassium is primary or secondary active transport
primary
primary active transport uses what
ATP hydrolysis to pump molecules against their con gradient
Secondary active transport uses what
free energy released when other molecules flow down their concentration gradient
Sodium potassium exchanges how many potassium for sodium
3 Na for 2 K
cytosis
bulk transport of large, polar (hydrophilic) moleculesrequires energy!. Active transport
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)
type of endocytosis where a cell engulfs dissolved materials
pinocytosis
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
Endocytosis
cell membrane wrapping around an extracellular (coming outside the cell membrane) substance, internalizing it into the cell as a vesicle or a vacuole (rememebr video)
organelles are enclosed by a _____.
phospholipid bilayer. Organelles are also cellular compartments
membrane-bound organelles are predominately associated with which cell type?
eukaryotes
Cytosol
aqueous intracellular fluid where the organelles reside
Cytosol + organelles
Cytoplasm
the nucleus contains an aqueous
nucleoplasm
T/F only eukaryotic cells contain membrane bound oranelles
True
What happens in the nucleus
DNA replication and transciription
What is the nuclear envelope?
“cell” membrane of the nucleus. Contains two phospholipid bilayers . One inside and one outside. In the middle lies the perinuclear space
what is the space between the inner and outer nuclear membranes?
perinuclear space
Nuclear lamina
provides structural support to the nucleus and regulates DNA and cell division.
What is the nuclear lamina made of
intermediate filaments
the _____ is a dense and fibrous network of proteins associated with the inner membrane of the nuclear envelope
nuclear lamina
the nuclear envelope has holes called _____ that allows molecules to travel in and out or the nucleus
nuclear pores
the _____ is a dense region in the nucleus, associated with ribosomal subunit assembly
nucleolus (the inner circle inside the nucleus)
is the nucleolus an organelle?
no - it is not membrane bound
ribosomal subunits are made up of 2 things
ribosomal ribonucleic acid (rRNA); proteins
eukaryotic _____ are assembled in the nucleoplasm and then exported from the nucleus to form the complete ribsome in the cytosol.
ribosomal subunits
what do ribosomes do?
make proteins
translation
Are ribosomes organelles
no… they carry out translation. They are made up of ribosomal subunits
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
free-floating ribosomes do what
tend to make proteins that function in cytosol of the cell
ribosomes embedded
in the rough endoplasmic reticulum (rough ER) do what?
make proteins that are sent out of the cell or to the
cell membrane.
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 membrane of the nuclear envelope; perinuclear space
Proteins made by the embedded ribosomes are sent where?
in the lumen (inside of the rough ER) for modifications. Afterwards they are sent out of the cell to become part of the cell membrane
Smooth ER is not continuous with other membranes T/F
TRUE
Function of smooth ER
make lipids, produce steroid hormones, and detoxify cells
What is the Golgi apparatus made of and what does it do?
Cisternae (flattened sacs)
modify and package substances.
Vesicles coming from the ER reaches what face of the Golgi apparatus?
the Cis face. Side closest to the ER of the GOLGI apparatus
Vesicles leaving the Golgi apparatus leaves from what face?
Trans face (side closest to cell membrane
Lysosomes
are membrane-bound organelles that
break down substances (through hydrolysis)
taken in through endocytosis.
what kind of enzyme does lysosomes contain
acidic digestive enzymes
Who carries out autophagy and what is it?
Lysosomes. breakdown of the cell’s own machinery for
recycling) and
Who carries out apoptosis
Lysosomes. programmed cell death
Transport vacuoles
- transport materials
between organelles.
Food vacuoles -
temporarily hold endocytosed
food, and later fuse with lysosomes.
Central vacuoles
very large in plants and
have a specialized membrane called the
tonoplast (helps maintain cell rigidity by
exerting turgor). Function in storage and
material breakdown).
Storage vacuoles -
store starches, pigments,
and toxic substances.
Contractile vacuoles
found in single-celled
organisms and works to actively pump out
excess water.
Function of the endomembrane system
group of
organelles and membranes that work together to
modify, package, and transport proteins and
lipids that are entering or exiting a cell.
the endomembrane system includes
nucleus, rough and smooth ERs, Golgi
apparatus, lysosomes, vacuoles, and cell
membrane.
Function of peroxisomes
Peroxisomes perform hydrolysis, break down
stored fatty acids, and help with detoxification.
What process generate hydrogen peroxide?
Peroxisomes breaking down stored fatty acids
What enzyme does peroxisomes contain that quickly breaks down the hydrogen peroxide into water and oxygen
catalase
Mitochondria is what
power house of the cell. Produces ATP
Chloroplasts do what and where are they found
in plants and carry out photosynthesis
What are centrosomes?
organelles found in animal cells containing a pair of centrioles
What does a cytoskeleton do?
provides structure and function
within the cytoplasm.
what are Microfilaments
smallest structure of the
cytoskeleton, and are composed of a double helix
made of two actin filaments. involved in cell movement
Function of microfilament
- Cyclosis (cytoplasmic streaming) - ‘stirring of
the cytoplasm’; organelles and vesicles travel
on microfilament “tracks”. - Cleavage furrow - during cell division, actin
microfilaments form contractile rings that split
the cell. - Muscle contraction - actin microfilaments
have directionality, allowing myosin motor
proteins to pull on them for muscle
contraction.
What are intermediate filaments?
more stable than microfilaments. Bigger than microfilaments but smaller than microtubules. Main job is structural support. Ex keratin, lamins
Microtubules
largest in size and give structural integrity to cells. hollow walls made of tubulin protein dimers. functions also in cell division, cilia, and flagella
What two motor proteins
transport cargo along microtubules.
kinesin and dynein
What helps organize microtubule extensions in eukaryotic cells?
Microtubule Organizing Centers (MTOCs)
What are centrioles
hollow cylinders made of nine
triplets of microtubules (9x3 array). Centrosomes
contain a pair of centrioles oriented at 90 degree
angles to one-another. They replicate during the S
phase of the cell cycle so that each daughter cell
after cell division has one centrosome.
What are cilia and flagella
have nine doublets of microtubules with two singles in the center 9+2.
What produces cilia and flagella
basal body
The extracellular matrix provides what
mechanical support for cells
Extracellular matrix components
proteoglycan collagen integrin fibronectin laminin basal lamina
proteoglycan (ECM)
type of glycoprotein that has a high proportion of carbohydrates
Collagen (ECM)
most common structural protein (organized into collagen fibrils)
integrin ECM
transmembrane protein that facilitates ECM adhesion and signals to cells how to respond to the extracellular environment
Fibronectin ECM
protein that connects integrin to ECM and helps with signal transduction
Laminin ECM
similar to fibronectin! influences cell differentiation, adhesion, and movement. MAJOR COMPONENT OF THE BASAL LAMINA (Which is a layer of the ECM secreted by epithelial cells
The structure of cell walls
carbohydrate based structures that act like a substitute ECM because they provide structural support to cells that either do not have ECM or have a minimal ECM
Where are carbohydrate based structures found?
plants (cellulose)
fungi (chitin)
bacteria (peptidoglycan
and archae
what is glycocalyx
glycolipid/glycoprotein coat found mainly on bacterial and animal epithelial cells. Helps with adhesion, protection, and cell recognition.
What does the cell matrix junctions connect?
The ECM and cytoskeleton
Focal adhesions
Connects the ECM to actin-based microfilaments in the cytoskeleton
hemidesmosomes
connect the ECM to the keratin intermediate filaments of the cytoskeleton.
What does cell to cell junctions connect
Connect adjacent(side by side) cells
Tight junctions (cell to cell junctions)
form water tight seals between cells to ensure substances pass through cells and not between them
Desmosomes (cell to cell junctions
provide support against mechanical stress. Connects neighboring cells using intermediate filaments
Adherens junctions (cell to cell junctions
connect the ECM to the keratin intermediate filaments of the cytoskeleton.
Gap junctions (cell to cell junction
connect the ECM to the keratin intermediate filaments of the cytoskeleton.
Two unique cell to cell junctions in plants
Middle lamella - sticky cement similar in
function to tight junctions.
2. Plasmodesmata - tunnels with tubes between
plant cells. Allows cytosol fluids to freely travel
between plant cells.
What is isotonic solutions?
extracellular and intracellular environments have the same solute concentrations.
What is hypertonic solutions?
If the solute concentration outside a cell were higher, it would be called a hypertonic environment. Here, water will leave the cell via osmosis in an attempt to reduce the solute concentration outside the cell. The loss of fluid causes the cell to shrivel.
DAT Pro-Tip: if a cell in a hypertonic environment has a cell wall (as in a plant cell), the cell membrane will dehydrate/shrink away from the cell wall in a process called plasmolysis.
Hypotonic solutions
If the solute concentration is lower outside the cell than it is inside the cell, the environment is hypotonic. In this case, water will travel via osmosis from the external environment and into the cell. In this way, an animal cell will swell and eventually burst in a process called lysis.
What is lysis
Bursting of a cell when too much water enters
