Chapter 6
What are prokaryotic and eukaryotic cells?
Prokaryotic cells (bacteria/archaea) are small, simple, and lack a nucleus or membrane-bound organelles, featuring circular DNA in a nucleoid region.
Eukaryotic cells (animals/plants/fungi) are larger, complex, and possess a nucleus containing linear DNA and membrane-bound organelles like mitochondria
What are the three types of intercellular junctions?
Tight junctions: 2 cells are fused to form watertight seal
Desmosomes: “rivets” that fasten cells into strong sheets
Gap junctions: channels through which ions, sugar, small molecules can pass
Why are membranes selectively permeable?
The membrane is selectively permeable to maintain homeostasis, allowing essential nutrients to enter, metabolic waste to leave, and protecting the cell by blocking harmful substances. It is structured as a phospholipid bilayer with a hydrophobic interior, letting only small, non-polar molecules pass freely while using transport proteins for others. (according to Google)
How water will move if a cell is placed in an hypertonic solution?
When a cell is placed in a hypertonic solution, water moves out of the cell into the surrounding solution via osmosis. This occurs because the solution has a higher solute concentration (lower water concentration) than the cell’s interior, causing the cell to shrink, shrivel, and potentially die.
Speak on the endoplasmic reticulum
Network of membranes and sacs
Types:
Rough ER: ribosomes on surface
Function: package proteins for secretion, send transport vesicles to Golgi, make replacement membrane
Smooth ER: no ribosomes on surface
Function: synthesize lipids, metabolize carbs, detox drugs & poisons, store Ca2+
What is the purpose of the cell wall?
Protect plant, maintain shape and composed of cellulose which is evidently different than cellulite. Who knew?
Tell me about extracellular matrix ECM NOW!
Outside plasma membrane
Composed of glycoproteins (ex. collagen)
Function: Strengthens tissues and transmits external signals to cell
What is the role of phospholipids in the cell membrane?
Phospholipids are the primary structural components of cell membranes, forming a flexible, self-sealing lipid bilayer that acts as a selective permeability barrier, separating the cell's internal environment from the outside
How water will move if a cell is placed in an hypotonic solution?
When a cell is placed in a hypotonic solution, water moves into the cell through osmosis. This occurs because the solute concentration is lower outside the cell, causing water to travel down its concentration gradient (from higher water potential outside to lower water potential inside). This process makes the cell swell and potentially burst.
Speak on the Golgi Apparatus
Function: synthesis & packaging of materials (small molecules) for transport (in vesicles); produce lysosomes
Series of flattened membrane sacs (cisternae)
Cis face: receives vesicles
Trans face: ships vesicles
What is Plasmodesmata?
Never heard of this a day in my life but channels between cells to allow passage of molecules
What in the hell are cilia and flagella?
Flagella: long and few; propel through water
Cilia: short and numerous; locomotion or move fluids
Have “9+2 pattern” of microtubules
What is the role of proteins in the cell membrane?
Membrane proteins are crucial for cell survival, acting as transport channels, signal receptors, enzymes, and structural anchors.
How are electrochemical gradients are formed?
Electrochemical gradients are formed by the uneven distribution of ions across a membrane, driven by active transport (using ATP). This creates both a chemical gradient (concentration difference) and an electrical gradient (charge difference/voltage) These gradients act as a "battery" storing energy.
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What on earth are lysosomes?
Function: intracellular digestion; recycle cell’s materials; programmed cell death (apoptosis)
Contains hydrolytic enzymes
Central vacuoles, Chloroplasts, Cell wall of cellulose,Plasmodesmata are only in WHAT kind of cells?
Plant cells
What is a ribosome?
Function: protein synthesis
Composed of rRNA + protein
Large subunit + small subunit
Types:
Free ribosomes: float in cytosol, produce proteins used within cell
2. Bound ribosomes: attached to ER, make proteins for export from cell
What is the role of carbohydrates is in the cell membrane?
Carbohydrates in the cell membrane (found exclusively on the exterior surface) function primarily as markers for cell-to-cell recognition and adhesion, allowing the immune system to distinguish "self" from "non-self". They attach to proteins or lipids to form glycoconjugates (glycoproteins/glycolipids) that provide protection, aid signaling, and form the [glycocalyx].
What are the two types of endocytosis? (I don't even know what endocytosis is but here we are and apparently there are two types.
Phagocytosis:
“cellular eating” - solids
AND
Pinocytosis:
“cellular drinking” - fluids
And what the hell are vacuoles?
Function: storage of materials (food, water, minerals, pigments, poisons)
Membrane-bound vesicles
Eg. food vacuoles, contractile vacuoles
Plants: large central vacuole -- stores water, ions
Which kind of cell contains Lysosomes, Centrioles, Flagella, cilia, Desmosomes, tight and gap junctions, Extracellular matrix (ECM)?
ANIMAL
What is the nucleolus?
Function: control center of cell
Contains DNA
Surrounded by double membrane (nuclear envelope)
Continuous with the rough ER
Nuclear pores: control what enters/leaves nucleus
Chromatin: complex of DNA + proteins; makes up chromosomes
Nucleolus: region where ribosomal subunits are formed
How water will move if a cell is placed in an isotonic solution?
When a cell is placed in an isotonic solution, water moves in and out of the cell at equal rates, resulting in no net flow of water. The concentration of solutes outside and inside the cell is equal, causing the cell to maintain its volume and shape (no swelling or shrinking)
What the hell is osmoregulation?
Control solute & water balance
Contractile vacuole: “bilge pump” forces out fresh water as it enters by osmosis
Eg. paramecium caudatum – freshwater protist
Speak on the mitochondra
Function: site of cellular respiration
Double membrane: outer and inner membrane
Cristae: folds of inner membrane; contains enzymes for ATP production; increased surface area to ↑ ATP made
Matrix: fluid-filled inner compartment