Unit 2 Flashcards
Cell Theory
- All living things are made up of 1
or more cells. - Cells are the smallest working
units of all living things. - All cells come from pre-existing
cells through cell division.
Cell (Def.)
A cell is the smallest unit that
is capable of performing life
functions.
Unicellular
An organism made up of one cell.
Multicellular
An organism composed of multiple cells.
Prokaryotes
Cells that do not have a nucleus or membrane-bound organelles (bacteria).
Eukaryotes
Cells that have a nucleus and organelles (ex: plants, fungi, protista, animals)
Organelles
Cell structures that have a specific
function and are surrounded by a
membrane that are found in eukaryotes
only.
Cell Wall Function
Found outside of the
cell membrane in
plant cells & bacteria
only. Contains cellulose (carb)
that provides support
(rigidity) & protection.
Cell Membrane Function
A bi-layer surrounds the cells and controls the movement in and out of cells. There is a receptor on the outside of the plasma membrane that lets things into the cell. It has phospholipids which are held together through the cholesterol bonds. The protein channel lets things in and out of the cell membrane. In plants and bacteria, it is within the cell wall.
Cytoplasm Function
The cytoplasm is a gel-like mixture inside cells and is surrounded by the cell membrane. It contains the cell structure that carries out specific jobs (ex. Mitochondrion, nucleus) and it provides a medium for chemical reactions to take place.
Nucleoid (Only Prokaryotes)
A region in the cytoplasm that contains a singular, circular chromosomal DNA. Plasmids, smaller circular DNA, are also located in the cytoplasm.
Ribosomes
Are contained on the rough ER and throughout the cytoplasm. The ribosomes make proteins. There are thousands in each cell.
Nucleus
Organelle: Contains the genetic material (DNA) within a nuclear membrane and directs the cell’s activities.
Nuclear Membrane
Organelle: Work just like the cell membrane, but they surround the nucleus, which holds the DNA. The nuclear membrane is made up of two layers and can allow certain materials into the nucleus through pores.
Chromatin
Metabolic Organelle: Is located within the nucleus and is the genetic material in the non-divided state (chromosomes). The chromatin is practically uncoiled chromosomes that contain instructions for traits and characteristics (DNA-genes).
Nucleolus
Organelle: A dark staining feature inside of the nucleus that makes ribosomes.
Rough Endoplasmic Reticulum (ER)
Organelle: Network of continuous sacs, studded with ribosomes. The rough ER is the internal delivery system of the cell that manufactures, processes, and transports proteins (made by ribosomes) for export from the cell. The rough ER continues from the nuclear envelope
Smooth Endoplasmic Reticulum (ER)
Organelle: Also continues from the nuclear membrane and is similar in appearance to the rough ER, but the smooth ER doesn’t contain ribosomes. The smooth ER produces lipids, involved in carbohydrate metabolism, and detoxification of drugs and poisons.
Golgi Apparatus
Organelle: prepares the proteins and lipids created in both the ERs for export from the cell. The golgi apparatus encloses digestive enzymes (lipase, amylase etc.) into membranes to form lysosomes (the waste removers [removes proteins, lipids, and carbs]).
Lysosome
Organelle: Created by the golgi apparatus by enclosing waste materials (protein, lipids, and carbs) with a digestive enzyme inside the membrane. It breaks down cellular waste and debris and transports undigested material to the cell membrane to be removed.
If a lysosome explodes,
the cell breaks down.
If cholesterol concentration (or levels) are high,
then things can’t be produced by the cell or exported out of the cell because the cell membrane is stiff (non-functioning).
Mitochondria
Organelle: Mitochondria generate the chemical energy needed to power the biochemical reactions of the cell. They are the site of cellular respiration, which is the use of glucose to create cell energy. They are membrane-bound organelles that have inner and outer membranes.
Active cells (like muscles) have
more mitochrondria
Animal Vacuole
Organelle: A membrane-bound organelle that is used for storage, digestion, and waste-removal. They contain a water solution.
Plant Vacuole (Central Vacuole)
Organelle: Plants contain large central vacuoles to store water and needed nutrients for the cell (generally to go through photosynthesis). Also support the shape of the cell, which is rigid due to the cell wall. Pushes the chloroplasts to the sides of the cell due to the enormity of the vacuole.
Chloroplasts
Organelles (plants and sometimes protists): An organelle used to withgo photosynthesis because the organelle contains chlorophyll. After photosynthesis, the chloroplast produces sugars (plant food) and oxygen gas.
Cilia and Flagella
Organelles (found in both prokaryotes and eukaryotes): External appendages from the cell membrane that aid in locomotion (movement) of the cell. Cilia also help to move substance past the membrane.
Centrioles
Organelles (only animal cells): Self-replicating bundles of microtubes that organize cell division.
Differences Between Prokaryotes and Eukaryotes
Prokaryotes are smaller, have a higher rate of reproduction (cell division), have free-floating DNA, have cell walls and membranes, have ribosomes, sometimes have a flagellum, and have no membrane-bound organelles. Eukaryotes have membrane-bound organelles, a nucleus, which contains the DNA, are bigger cells, are complex (multicellular), can have a cell wall, and are animals, plants, fungi, and protists (unicellular).
Differences Between Animal Cells and Plant Cells
Animal cells do not have a cell wall, chloroplasts, or a large central vacuole, but they do have a cytoskeleton for structure, centrioles for cell division, and an animal vacuole that digests material, removes waste and is there for general storage. Plant cells have chloroplasts, cell walls, and large central vacuoles because plants need the chloroplasts and large central vacuoles to go through photosynthesis and fuel the cell with enough energy and food (sugar created from photosynthesis). The plant has the cell wall to allow for a strong, rigid structure that can fit together with other cells to create chains (like a bunch of rectangles stacked on top of each other) and because of the cell wall, many plant cells are shaped the same, unlike animal cells.
Enzyme
A catalyst that generally ends with -ase. They speed up chemical reactions by lowering activation energy.
Steps in which an enzyme bonds:
- The substrate bonds to the active site
- The enzyme breaks down the reactant (substrate) to create a product
- Products are released from the active site
3a. Enzymes can continue to bond with substrates
Denaturalization
When an enzyme is not in its optimal temperature and pH range, the enzyme becomes malformed and becomes non-functioning by being harder to bond with.
Inhibitors
Replacement substrates and molecule bonding with the allosteric site. There are non-competitive and competitive inhibitors.
Each enzyme has…
an optimal temperature and pH range.
Non-competitive Inhibitors
Bind with the allosteric site on an enzyme and changes the shape of the enzyme, so that the substrate can never bond with the enzyme and create a product.
Competitive Inhibitors
Molecule gets to the active site before the substrate can bond with the enzyme. The inhibitor binds with the enzyme and prevents bonding of the substrate.
Activation Energy
Energy enzyme takes to create products with substrates.
Function of Cholesterol
Keeps the phospholipid layer from spreading out in the cell membrane. Causes rigidity in the cell membrane.
Function of a Receptor
A carb that sees what goes in the cell and tells the membrane what to let in. It is nonpolar.
Function of Protein Channel
Allows certain molecules into the cell through facilitated diffusion and protein pumps.
What are the phospholipids made of?
A polar hydrophilic phosphate head with a hydrophobic fatty acid tail.
Is cholesterol polar or non-polar?
Cholesterol is non-polar, which allows it to bond to the non-polar fatty acid tail.
Semipermeable
Cell membranes are semipermeable, meaning that they let some things into the cell, but not others.
Passive Transport
When certain molecules or elements are able to pass in and out of the cell membrane without expending energy.
Simple Diffusion
When small molecules (no more than 1-2 elements) pass through the membrane to move from a high concentration of the molecule to a low concentration of the molecule.
Facilitated Diffusion
When larger molecules like Potassium or Salt move from a high concentration of the molecule to a low concentration of the molecule with help of the protein channel. The protein channel allows the molecules in through the two protein channels.
Osmosis
The movement of liquid water through the semipermeable membrane from a high concentration to a low concentration.
Hypotonic Solution
When a high concentration of water surrounds the membrane with a lower concentration of water. The water moves from the exterior to the interior through osmosis. This can make the cell burst. The water, when it moves into the cell, will dissolve the solutes because before there was a high concentration of solutes in the cell, and a low concentration outside the cell.
Isotonic Solution
When there is an equal concentration of water inside and outside of a cell, so the water just moves both ways, in and out of the cell. The number of solutes is equal.
Hypertonic Solution
When the cell contains a higher concentration of water than the outside of the cell, so the water moves outside of the cell and the cell shrinks. There are more solutes outside the cell due to the lack of water. This can dehydrate the cell.
Active Transport
Transport in and out of the cell that requires cellular energy or ATP. It is when a low concentration of a molecule moves to a high concentration of a molecule.This is against the gradient.
Protein Pump: Sodium Potassium Pump
- Top of the protein is closed. Sodium will bind with the ion channels, then the ATP will open it. ATP gives off a phosphate, which causes ATP to create ADP (with 2 phosphates instead of 3).
- Sodium (Na+) is pumped outside the membrane where there is a higher concentration of the sodium.
- Bottom of the protein closes.
- Potassium (K+) comes into the protein and binds ith the protein. ATP releases a phosphate (now ADP) and opens the bottom of the protein.
- Closes the top of the protein.
- Potassium is pumped inside the cell.
- Repeat continuously
Endocytosis
Endo: inside (moves the molecules inside the membrane). ATP opens the membrane and takes in a substance/molecules inside the cell. A membrane will close and a vesicle will form, carrying the substance inside the cell.
Exocytosis
Exo: outside (think exoskeleton: exports molecules out of the cell). Substances/molcules will leave the cell in bulk by vesicles carrying the materials. Then, ATP causes the bonding of the vesicle to the cell membrane and opens the cell membrane to release the material.
Ligand
Within biochemistry, a ligand is defined as any molecule or atom that irreversibly binds to a receiving protein molecule, otherwise known as a receptor.
Fluid Mosaic Model
The fluid mosaic model states that lipids and proteins are embedded in the phospholipid bilayer in a mosaic-like pattern; this applies to the cell membrane. The fluid mosaic model states that amphipathic proteins (ion channels) are embedded in the phospholipid bilayer. The cell membrane is a fluid mosaic of phospholipids and proteins. Phospholipids and proteins move laterally within the membrane. The unsaturated hydrocarbon tails of the phospholipids keep membranes fluid at lower temperatures and cholesterol helps them resist changes in fluidity in the face of temperature changes. Like a mosaic, integral proteins are embedded in the lipid bilayer while peripheral proteins are attached to the membrane surface. Glycoproteins and glycolipids are also embedded on the exterior side of the plasma membrane and interact with surface molecules of other cells. This membrane structure results in selective permeability of the cell membrane, allows for cell-cell adhesion, and cell signaling.
Concentration Gradient
A concentration gradient occurs when the concentration of particles is higher in one area than another. [ie: Concentration gradient refers to the gradual change in the concentration of solutes in a solution as a function of distance through a solution].
Aquaporin
Aquaporins, also called water channels, are channel proteins that mainly transport water between the cell membrane.
Vesicle
In cell biology, a vesicle is a structure within or outside a cell, consisting of liquid or cytoplasm enclosed by a lipid bilayer. They bring in substances into a cell and export materials out of the cell in endocytosis and exocytosis.
What are the different functions of the proteins in the cell membrane?
Speed up chemical reactions and let things in and out of thee membrane through the protein channels.
How can cells recognize each other?
The glycoproteins (receptors) on the outside of the membrane receive signals from the ligands (things that send proteins messages).
