Chapter Three: Cell Biology Flashcards
What are the four functions of the cell?
- metabolism and energy use
- synthesis of molecules
- communication
- reproduction and inheritance
Is the outside of the plasma membrane positively or negatively charged?
positively
combinations of carbohydrates and lipids (glycolipids) and proteins (glycoproteins) on outer surface
Glycocalyx
amount of this determines the fluid nature of the membrane
cholesterol
this has a bilayer; is amphipathic, and has polar heads with nonpolar tails
phospholipids
allows cells to identify one another or other molecules
- distinguish between self and foreign cells
- recognition of oocyte by sperm cell
- intercellular communication
Marker Proteins:
Glycoproteins and Glycolipids
extend deep into membrane, often extending from one surface to the other and can form channels through the membrane
Integral/Intrinsic membrane proteins
attached to integral proteins or to polar heads of phospholipids at either the inner or outer surfaces of the lipid bilayer
Peripheral/Extrinsic Membrane Proteins
What are the six types of membrane proteins?
- markers
- attachment points
- channels
- receptors
- enzymes
- carriers
may attach cells to other cells or to extracellular molecules
- sometimes allow communication due to contact with intracellular molecules
- important in signal transduction
Attachment Proteins
leaky/non-gated ion channels always open (responsible for the permeability of the plasma membrane to ions when the plasma membrane is at rest) gated ion channels can be opened or closed by certain stimuli
Channel Proteins
open in response to small molecules that bind to proteins or glycoproteins
Ligand gated ion channel
open when there is a change in charge across the plasma membrane
voltage-gated ion channel
Hydrophobic regions face outward toward hydrophobic part of plasma membrane, hydrophobic regions face inward and line the tunnel, allow movement of materials through the plasma membrane
Transport Proteins
What are the three types of transport proteins?
- Channel Proteins
- Carrier Proteins
- ATP-powered pumps
these are also called transporters
- integral proteins move ions from one side of membrane to another
Carrier proteins
The three steps of carrier proteins?
- specific molecule enters the carrier
- molecule attaches to binding site in the carrier
- protein changes shape to transport to the other side, resumes original shape after transport
What are the three types of carrier proteins?
- uniporters
- symporters
- antiporters
what type of carrier protein moves one particle?
uniporters
what type of carrier protein moves two particles in the same direction at the same time?
symporters
what type of carrier protein moves two particles in opposite directions are the same time?
antiporters
requires ATP
- the use of energy allows the cell to accumulate substances by transporting against their concentration gradient
- Hydrolysis of ATP releases energy to change shape of carrier and move substance across membrane
ATP-Powered Transport
- proteins or glycoproteins in membranes with an exposed receptor site
- ligand can attach only to cells with that specific receptor
- may open channels or activate intracellular signals that alter cell function
Receptor Proteins
some act to catalyze reactions at outer/inner surface of plasma membrane
EX: surface cells of small intestine produce these that digest dipeptides
Enzymes
passage of materials through plasma membrane is regulated and some molecules can pass through; others cannot
selective permeability
movement of solutes from an area of high concentration to an area of low concentration
Diffusion
diffusion of water across a selectively permeable membrane in response to different solute concentrations on either side
osmosis
force required to prevent water from moving across a membrane by osmosis; a measure of the tendency of a solution to take in water by osmosis
osmotic pressure
isotonic
same solute concentration in solution (cell neither shrinks nor swells)
hypertonic
higher concentration of solutes in solution outside cell (cell shrinks)
Hypatonic
cell swells
- move large, water-soluble molecules or electrically charged molecules across the plasma membrane
- amino acids and glucose in, manufactures proteins out
- passive transport
Facilitated Diffusion
- active transport of one ion to extracellular space allows another molecule to enter the cell by co-transport
- ions or molecules move in same (symport) or different (antiport) direction
Secondary Active Transport
- active transport
- internalization of substances by formation of a vesicle
- accumulated vesicle secretions expelled from the cell
- types: (phagocytosis, pinocytosis, receptor-mediated endocytosis)
Vesicular Transport
supports the cell but also has to allow for movements like changes in cell shape and movements of cilia
Cytoskeleton
hollow, made of tubular proteins (internal scaffold, transport of vesicles, cell division)
microtubules
actin (structure, support for microvilli, contractility, movement)
microfilaments
mechanical strength
intermediate filaments
has attached ribosomes, proteins produced and modified, embedded in plasma membrane or secreted from the cell
rough ER
no attached ribosomes, manufactures lipids detoxification
smooth ER
- composed of flattened membrane sacs stacked on each other
- modifies, packages, and distributes proteins and lipids for secretion or internal use
- substances packages into transport vesicles
Golgi Apparatus
fuse with endocytosed vesicles, contain hydrolytic enzymes, digest material ingested by the cell or non-functional organelles
Lysosomes
contain enzymes to break down fatty acids and amino acids, hydrogen peroxide is a byproduct of-product of breakdown, catalase breaks down hydrogen peroxide into water and O2
Peroxisomes
- cellular material outside nucleus but inside the plasma membrane
- composed of cytosol, cytoskeleton, cytoplasmic inclusions, organelles
- cytosol: fluid portion
Cytoplasm
- appendages projecting from cell surfaces
- capable of movement
- moves materials over the cell surfaces
Cilia
- membrane-bound organelle consisting of nucleoplasm surrounded by a nuclear envelope containing nuclear pores
- most of the DNA in a cell is located here
- Nucleolus: dense region within the nucleus where ribosomes are manufactured
- membrane-bound organelle consisting of nucleoplasm surrounded by a nuclear envelope containing nuclear pores
- most of the DNA in a cell is located here
Nucleus
- major site of ATP synthesis
- increase in number when cell energy requirements increase
- contains DNA that codes for some of the proteins needed for production
Mitochondria
- located in centrosome: specialized zone near nucleus
- center of microtubule formation
- before cel division, centrioles divide, move to ends of cells and organize spindle fibers
Centrioles and Spindle Fibers
similar to cilia but longer, usually only one per cell, move the cell by beating in wave-like fashion
EX: sperm cell
Flagella
extension of plasma membrane, increase the cell surface area, normally many on each cell, smaller than cilia, does not move
Microvilli
- sites of protein synthesis
- composed of a large and a small subunit
- types: free and attached (to ER)
Ribosomes
proteins fold to form a barrel-like structure with enzymatic regions on the inside surface that break down and recycle proteins in cell
Proteasomes
Name the four molecules that form the plasma membrane:
- Carbohydrates
- Cholesterol
- Proteins
- Phospholipids
Cadherin and integrin are examples of _________ proteins
attachment
Transport proteins are __________ proteins
integral
3 Characteristics that pertain to transport proteins:
- Saturation
- Specificity
- Competition
What are the two types of molecules that form the majority of the plasma membrane?
Proteins and phospholipids
The transmembrane proteins with pores without gates that allow ions to pass through the membrane are called ion _____________ _____________
leak channels
What are the three types of substances that require vesicles for transport across the cell membrane?
- Non-lipid soluble molecules
- Large molecules
- Small pieces of matter
As the concentration gradient of a diffusing substance decreases, the rate of diffusion _________
decreases
The sugar concentration in your glass of ice tea is very high at the bottom and low at the top. This concentration distribution is an example of a(n)….
concentration gradient
The diffusion of water across a plasma membrane is an example of…
osmosis
Large, non-lipid-soluble molecules and small pieces of matter are transported across the cell membrane by…
vesicles
The measurement of a fluid’s resistance to flow is referred to as its….
viscosity or fluidity
The force required to prevent water from moving across a cell membrane is called ________ pressure
osmotic
The diffusion of water across a semi-permeable membrane is…..
osmosis
Large molecules move across cell membrane with the help or assistance of protein carriers. This type of transport is generally called….
Mediated Transport
When a molecule diffuses across a membrane via a transporter protein and metabolic energy is not expended, this is called…
Facilitated Diffusion
The sodium-potassium pump is an example of _____________ transport
active
Pinocytosis and phagocytosis are both forms of….
Endocytosis
The uptake of material through the plasma membrane by the formation of a vesicle is called…
facilitated diffusion
This viscous fluid of the cell, containing cytoskeleton and cytoplasmic inclusions, is knows as the…
cytosol
What is an important function of the cytoskeleton?
Movement of cell organelles
Which component of the cytoskeleton produces the internal scaffolding of the cell, is involved in cell division and is a component of the centrioles and spindle fibers?
Microtubules
The process in which the cell membrane forms a vesicle to draw substances into the cell is referred to as…
Endocytosis
What is cytosol?
The fluid portion of the cytoplasm containing the cytoskeleton
Microtubules are hollow tubes primary made of protein units called…
tubulin
How does RNA leave the nucleus?
Through nuclear pores
Organelles that synthesize proteins are….
ribosomes
Organs like the liver and kidney cells contain cells that are active in detoxification. These cells contain a large number of….
peroxisomes
What is a proteasome?
a barrel-like structure in the cell that breaks down and recycles proteins
The organelle composed f a short cylinder of nine triplets of microtubules is a…
centriole
Which enzyme splices together Okazaki fragments?
DNA ligase
The kinetochore is a _______ structure
DNA
a protein structure that forms on a chromatid during cell division and allows it to attach to a spindle fiber on a chromosome
Kinetochore
