Cells Flashcards
What is the basic structural and functional unit of living organisms?
The cell
All eukaryotic cells are composed of what three parts?
- Plasma Membrane
- Cytoplasm
- Nucleus
The plasma membrane has what kind of permeability?
Selective
What does the cytoplasm contain?
all the cellular contents between the plasma membrane and the nucleus. Cytosol and organelles
What contains the DNA?
The nucleus
DNA in molecules is called?
Chromosomes
Each chromosomes consists of a single molecule of ____ and associated packaging _____
DNA
Proteins
Define the plasma membrane
A phospholipid bilayer with associated integral and peripheral proteins. (he stressed the proteins were associated)
What model describes the arrangement of molecules within the plasma membrane as “a sea of phospholipids with protein icebergs floating in it?”
Fluid Mosaic Model
Why is the plasma membrane fluid?
it provides for and allows cell movement, growth, division, and sealing itself if torn.
A rigid membrane would lack mobility and a completely fluid membrane would lack structure.
What do the membrane lipids (phospholipids) do?
Allow passage of many lipid-soluble substances and a barrier to passage of charged or polar substances.
Cholesterol in the bilayer does what?
Mediates membrane fluidity, makes the lipid bilayer less fluid at normal body temperatures/ Increases membrane fluidity at lower temperatures.
Forms hydrogen bonds with heads of phospholipids and glycolipids, and fills the space between fatty acid tails.
Cholesterol is weakly_______ having a small -OH group as the only polar part.
amphipathic
What are the three things does the phospholipid bilayer consist of?
Phospholipids
Cholesterol
Glycoproteins
What are glycoproteins?
membrane proteins with a carbohydrate group attached that protrude into the extracellular fluid.
What is the glycocalyx?
the entire “sugary coating” surrounding the membrane
Membrane proteins are classified as either?
integral proteins or peripheral proteins
Integral proteins vs transmembrane proteins
Integral go well into the bilayer
Transmembrane go all the way through
Peripheral proteins go all the way through the membrane or stay on one side?
Stay on one side
What kind of channels do transmembrane proteins form? And they are also?
Ion channels
Transporters (carriers)
What are the examples of the different membrane proteins?
Ion Channels Transporters Receptors Enzymes Linkers Cell-identity markers
Name the channel: Allows specific ions to move through a water-filled pore
Ion Channel
Name the channel: Carries specific substances across the membrane by changing shape
Carrier
Name the channel: Recognizes specific ligand and alters the cell function in some way
Receptor
Name the channel: Catalyzes reaction inside or outside of the cell
Enzyme
Name the channel: Anchors filaments inside and outside of the plasma membrane, providing structural stability and shape for the cell
Linker
Name the channel: Distinguishes your cells from anyone elses (MHC)
Cell-identity marker
What are the functions of the glycocalyx?
To protect cells from enzymatic action
For cell adhesion
For cell recognition
Changes in the glycocalyx occurs in cells that are transformed into what?
Cancer cells
What kind of molecules freely pass through the plasma membrane?
small, neutrally-charged, lipid soluble substances and water.
The lipid bilayer is
- permeable to ________ uncharged molecules like oxygen, CO2, and steroids
- is impermeable to ions and large uncharged ______ molecules such as glucose
- Slightly permeable to small uncharged ______ molecules like water and urea
- nonpolar
- polar
- polar
Molecules can passively diffuse the plasma membrane if they are?
- lipid soluble
- small enough to pass through the membrane
- Assisted by carrier molecules
Examples of molecules that can passively diffuse the plasma membrane?
- O2
- CO2
- Fats
- Alcohol
What are membrane gradients?
differences of attributes of a membrane compared to the other side.
What are the three gradients talked about?
- concentration
- electrical
- electrochemical
Oxygen molecules and sodium ions are more concentrated in the ______
Carbon dioxide and potassium ions are more concentrated in the ________
Extracellular fluid
Cytosol
What are the types of gradients?
Diffusion -simple diffusion -osmosis -facilitated diffusion Activated transport -primary -secondary Bulk transport -exocytosis -endocytosis -transcytosis
What are the gradients that require energy?
Activated transport -primary -secondary Bulk transport -exocytosis -endocytosis -transcytosis
What is diffusion affected by?
- amount of substance and steepness of the concentration gradient
- Temperature
- Surface area
- Diffusion distance
What is osmosis?
Diffusion of solvent(water) through a semipermeable membrane and at least one osmotically active solute.
What is osmotic pressure?
Forced generated by the movement of water from one side to the other side.
What are examples of tonicity?
Isotonic
Hypotonic
Hypertonic
What is tonicity?
measure of the solution’s ability to change a cell’s water content by induction of osmosis.
What is facilitated diffusion?
molecules that are too big to pass through the plasma membrane or are too polar- they bind to a protein carrier on one side of the membrane and released to the other side after the transporter undergoes a change in shape.
What are solutes that move by facilitated diffusion?
glucose
fructose
galactose
some vitamins
What is active transport?
Movement against the concentration gradient
What is primary active transport?
Against the gradient and requires energy
Have sodium and potassium pumps to move solutes uphill
What is secondary active transport?
Indirectly uses the energy from active transport
the energy stored in a H+ or Na+ concentration gradient is used to drive other substances across the membrane against their concentration gradient.
What are the two types of secondary active transport mechanisms?
Antiporters - opposite directions
Symporters- same direction
What is Receptor-mediated endocytosis?
cells take up specific ligands and the particle is internalized by endocytosis
What is phagocytosis?
form of endocytosis that eats things
What is bulk-phase endocytosis (pinocytosis)?
cell dinking- plasma membrane invaginates and takes a “sip” of extracellular fluid. A digestive vacuole is formed and products of digestion are used by the cell.
What is exocytosis?
Endocytosis in reverse.
Intracellular vesicle is moved to the plasma membrane. fuses with the plasma membrane and release the contents.
Important in secretory cells, nerve cells
What is transcytosis?
uses vesicles to move substances into across and out of cell.
Mostly occurs across endothelial cells lining blood vessel where materials are moved between the blood plasma and interstitial fluid.
What are the two components of the cytoplasm?
Cytosol
Organelles
What happens in the cytosol?
- site of many chemical reactions
- energy is released by these reactions
- reactions provide building blocks for cell maintenance, structure, function, and growth
What is the cytoskeleton comprised of?
Microfilaments
Intermediate filaments
Microtubules
What does the cytoskeleton do?
Serves as structural framework, organizes the cellular contents, and provides for cellular movement.
What are the components of the nucleus?
Nuclear envelope Nuclear pore Nucleolus Genes Chromosomes
What produces both ribosomal subunits?
Nucleolus
What are long molecules of DNA combined with protein molecules?
Chromosomes
What is a complex of DNA and proteins
Chromatin
Where are amino acids assembled into new proteins?
Ribosomes
What are the two subunits of Ribosomes?
Small
Large
The large subunit of a ribosome joins the amino acids to form a?
Polypeptide chain
What does the small subunit of the ribosome do?
initiates translation, recruits the large ribosomal units, and reads the mRNA which determines the primary sequence of amino acids comprising the protein.
Which ER has ribosomes?
Rough ER
Which ER is without ribosomes?
Smooth ER
Where do dissembled ribosomes reside until needed?
Cytoplasm
What is a stack of 3-20 flattened, membrane-enclosed sacs called cisternae?
Golgi complex
What is a cisternae?
flattened membrane-enclosed sacs of the Golgi complex
What are the functions of the Golgi complex?
- Receives immature proteins from the rough ER
- Packages proteins into vesicles
- Synthesizes carbohydrates
Secretory vesicles (Golgi)
wherein the proteins will be exported from the cell by exocytosis
Membrane vesicles (Golgi)
wherein the proteins in the vesicle membrane merge with the plasma membrane
Transport vesicles (Golgi)
in which the proteins are conveyed to such structures as lysosomes or to other parts of the cells.
Self-replicating and have their own DNA
Mitochondria
Contain enzymes responsible for cellular respiration and the Krebs cycle
Mitochondria
Where do the lysosomes come from?
Golgi complex
What are functions of the lysosome?
- digest substances that enter a cell via endocytosis then transport products of digestion into the cytosol
- carryout autophagy, the digestion of worn-out organelles
- carryout autolysis, the digestion of the entire cell
What do peroxisomes do?
- Detoxify several toxic substances such as alcohol
- Abundant in the liver
- Also break down hydrogen peroxide, a biproduct of oxidation
- Self-replicating
What do Proteasomes do?
- Continuously degrade unneeded, damaged, or faulty proteins
- Found in the cytosol and the nucleus
What is theorized that some disease may result from these faulty organelles?
Proteasomes
What are vacuoles?
membranous sacs within the cytoplasm
These are formed when a part of the plasma membrane folds inward and pinches off during phagocytosis
Vacuoles
Each cylinder of the centrosome is composed of how many microtubule triplets?
9
What is the function of the centrosome?
To assemble microtubules
What is another name for a centrosome?
Microtubule organizing center
What is an example of the example of a flagella on a eukaryotic cell?
Sperm cell
What does cilia do?
Move fluids along a cell surface
What are inclusions?
Non-living components within cells, not bound by a membrane
What are the most common inclusions?
Glycogen
Lipids
Pigments
Crystals
