Module 2 Cells Review

Cell

smallest basic unit of life

comprised of organelles

Cell membrane

Separates cell from environment around it and helps regulate homeostasis

Phospholipid Bilayer

Composed of tightly packed phospholipids that controls what can go in or out of the cell

Characteristics of Phospholipid Bilayer

Center is hydrophobic while the phosphate heads on the outside are hydrophilic.

What can go through the phospholipid bilayer? Why?

Substances that are small and nonpolar (not electrically charged)

The phospholipids are tightly packed so large items can not pass, and the hydrophobic center rejects anything with a large charge.

What is an example of a substance that can pass through? Can not?

Oxygen and carbon dioxide are small and nonpolar so they can. Water is a large molecule and polar so it may not.

amphipathic

Consisting of both hydrophilic and hydrophobic parts

How do plant cells stabilize the cell membrane?

Plants have a cell wall around the membrane which “boxes” it in

What are the 2 ways animal cells stabilize the cell membrane?

Animal cells can use sticky substances to glue the phospholipids together, thus stabilizing the membrane. ex: cholesterol

They can also anchor down the cell membrane to the ECM (extra cellular matrix) or to internal membranes.

Aquaporin

Any protein that allows water transfer into the cell

What are the three major types of cell?

Bacterial, Plant and Animal Cells

What type of cell is the smallest?

Bacterial Cell

Nucleus

holds linear chromosomal DNA within cell and controls cell activity

Ribosomes

Site of protein synthesis

Lysosomes

ONLY FOUND IN ANIMAL CELLS

contains proteins capable of breaking down macromolecules (proteins, lipids, carbohydrates, and nucleic acids)

Mitochondria

site of cellular respiration and energy production (ATP)

Cell Wall

ONLY FOUND IN PLANT CELLS

gives cell structure

Chloroplasts

ONLY FOUND IN PLANT CELLS

produce energy through photosynthesis

Smooth Endoplasmic Reticulum

network of membranes inside a cell that produce the lipids found in the cell membrane and detoxifies poisons (ex: growing tolerance of alcohol)

Rough Endoplasmic Reticulum

network of membranes inside a cell that houses ribosomes

Golgi Apparatus

Transport + modifies vesicles

Endocytosis

Process where macromolecules are let into the cell

Exocytosis

Process where matter is forced out of the cell

ex: pancreatic cells make insulin but don’t use it, so the insulin and forced out and transferred to other places within the cell

Hypotonic Solution

Solution with a lower concentration of solutes

Hypertonic Solution

Solution with a higher concentration of solutes

Isotonic Solution

Solution has an equal concentration of solute

Membrane receptors

Integral proteins that communicate with the outside environment and lock themselves through the entire cell membrane.

Signal transduction

The process where the signal from the ligand is spread throughout the cell, triggering an intercellular response.

Ligands

Signaling molecules that ionically bond to another molecule.

Ligand-receptor complex

Formed when ligands bind to membrane receptors, initiating signal transduction.

Locke and Key Model

The concept that each specific receptor can only bind to a few types or often one kind of ligand.

Induced Fit Model

The idea that ligands and receptors can change conformations to fit each other.

Ligand-gated Ion Channels

Ion channels with a hydrophilic center that open in response to the bonding of a ligand, allowing polar molecules to pass through the cell membrane and trigger an intracellular response.

G-protein Coupled Receptors (GPCRs)

The largest known class of membrane receptors, consisting of 7 transmembrane alpha helices and interacting with G proteins.

G proteins

Proteins that bind GTP and GDP, playing a role in signal transduction.

Heterotrimeric proteins

Proteins with three subunits (alpha, beta, and gamma) that are attached to the cell membrane by lipid anchors.

GTP and GDP

Guanosine triphosphate and guanosine diphosphate, respectively, which bind to G proteins.

Target protein

A protein in the membrane that is regulated or affected by the alpha, beta, and gamma subunits of a G protein.

Second messengers

Molecules, such as ions or enzymes, produced by target proteins that transmit signals throughout the cell.

Hydrolysis

The process of breaking down a molecule, such as GTP, by adding a water molecule, resulting in the release of energy and the formation of GDP.

Enzyme-Linked Receptors

A group of membrane receptors that have enzymatic activity and play a role in signal transduction.