Unit 3- Cells 🧫

Cell

• The basic unit of all living things

• The smallest living unit of any organism

• Used for specific tasks like support, communication, movement, and the production of proteins or other cell products

Cell theory

A fundamental concept of biology that states:

1.) All living things are made up of cells

2.) Cells are the basic unit of structure and function in living things

3.) New Cells are produced from existing cells

Cell Membrane

• A thin flexible barrier that all cells are surrounded by

• Sometimes called the plasma membrane

• contains steroids, carbs, protein channels, etc.

• Found in animal and plant cells

Nucleus

• A large membrane enclosed structure that contains nearly all of the cells genetic material in the form of DNA and the coded instructions for making proteins and other important molecules

• Positively charged center of an atom consisting of protons and neutrons.

• Not found in Prokaryotic cells

Nuclear Membrane

• a double layered barrier surrounding the nucleus, separating its contents from the cytoplasm

Nucleolus

• is a small dense region of the nucleus that starts the assembly of ribosomes

Cromesomes

• are found in the nucleus: they carry the cell’s genetic info.

Eukaryotes

• Cells that enclose their DNA in nuclei (Nucleus separates the genetic material from the rest of the cell)

• Larger and more complex than Prokaryotes

• Contain dozens of structures and internal membranes and many of them are highly specialized

• Ex: Plants, Animals, Fungi

Prokaryotes

• Cells that don’t enclose their genetic information (DNA) in nuclei

• Less Complex (smaller and simpler) than Eukaryotes

• Ex: Bacteria, also the first photosynthetic organisms to appear on earth

Cytoplasm

• Portion of the cell outside the nucleus

• Holds organelles and transfers materials

• Found within the cell membrane of both prokaryotic and eukaryotic cells

Ribosome

• Small particles of RNA and protein found through the cytoplasm (in both Eukaryote and Prokaryote cells)

• Produces proteins by following coded instructions that come from DNA

• Links amino acids to form proteins

• Cells more active in protein synthesis have a larger # of ribosomes

• Found in all cells

Endoplasmic Reticulum

• An internal membrane system in eukaryotic cells

• Where lipids are synthesized, along with proteins and other materials that are exported from the cell

Rough ER

• involved in the synthesis of proteins - called the ER because of the ribosomes found on its surface

• Proteins made include those that will be released or secreted from the cell and ones that will travel to other locations in the cell

• abundant in cells that produce large amounts of portion for export

Smooth ER

• contains a collection of enzymes that perform specialized tasks like the synthesis of lipids and the detoxification of drugs

• does not have ribosomes found on its surface

• plays an important role in the synthesis of carbohydrates

Golgi Apparatus

• An organelle that modifies, sources and packages proteins, as well as other materials for storage or release of/in the cell.

• appears as a stack of flatten membranes.

• Receives proteins produced in the rough ER and shipped them to their final destinations inside or outside of the cell

Lysosome

• Small organelles filled with enzymes that breakdown lipids, carbs, and proteins into small molecules - which can then be used by the rest of the cell.

• Also involved in breaking down organelles that have outlived their usefulness or getting rid of junk/clutter in the cell

• They are mostly found in animal cells, but a few types of plant cells contain them as well

Cytoskeleton

• A network of protein filaments used by eukaryotic cells for their shape and organization

• Certain parts of it also help transport materials between different parts of the cell

• Microphone and microtubules are two of the principal protein filaments that make up the cytoskeleton

Chloroplast

• Organelles that capture the energy from sunlight and converted into chemical energy

• Two membranes surround the chloroplasts, and inside are large stacks of other membranes which contain green pigment chlorophyll

Mitochondria

• An organelle that converts the chemical energy stored in food molecules into compounds (that are more convenient for the cell to use).

• Two membranes enclose the mitochondria, its inner membrane is folded up inside the organelle

• Found in cytoplasm

Cell wall

• A strong supporting layer around a cell membrane

• Its function is to support shape and protect the cell

• Found in most prokaryotic and eukaryotic cells except for animal cells

• Provide much of the strength needed for plants to stand against the force of gravity

Lipid Bilayer

• A flexible structure that forms a strong barrier between the cells and its surroundings.

• Delivered by layer bilayer makes up the cell membrane

• Regulates what enters and leaves the cell and also protects and supports the cell

Selectively Permeable

• A concept that shows some substances can pass through the cell membrane while others cannot

• Selectively permeable membranes are also called semipermeable membranes

Organelle

Cell structures (that act as if they are specialized organs).

Vacuole

• Large sac-like membrane enclosed structures that store materials like water, salts, proteins, and carb

• Found in many eukaryotic cells

Vesicle

• A small membrane enclosed structure

• Stores and moves materials between cell organelles as well as to and from the cell surface

Centriol

• small structure near the nucleus made of proteins called tubulin

• Plays a key role in cell division

• Found in animal cells

Homeostasis

• An important process carried out by the cell membrane.

• A state of constant internal conditions that regulates the movement of molecules and other things crossing the cell membrane.

Diffusion

• The process where solute particles move from an area of high concentration to one of low concentration (with the concentration gradient) until they reach equilibrium.

Equilibrium

• When the concentration of the substance on both sides of the cell membrane is the same.

• dynamic equilibrium:

  • a state of balance between continuing processes

  • molecules are balanced on both sides of the membrane

Passive transport

• The movement of molecules across the cell membrane without the use of cellular energy

Facilitated diffusion

• The process where molecules that cannot directly diffuse across the cell membrane, (charged & large molecules) pass through special protein channels that allow them to cross the membrane.

• Pass through a membrane protein from high to low concentration

Aquaporin

• Water protein channels that allow water to pass through the cell membrane easily (because a cell’s lipid bilayer is hydrophobic).

Osmosis

• The diffusion of water through a selectively permeable membrane.

• Just like regular diffusion, except the only difference is that they are water molecules instead of solute molecules.

Isotonic

• When the concentration of solution on both sides of the cell membrane is the same

• Cell will stay the same size

• “Iso-“ = same

Hypertonic

• When the concentration of solution outside of the cell is greater than inside the cell

• Cell will shrink (When water moves out to achieve equilibrium)

• “Hyper-“ = more/a lot

Hypotonic

• When the concentration inside of the cell is more than outside of the cell

• The cell will grow larger (As water comes in to achieve equilibrium)

• “Hypo-“ = less/lower

• This type of environment is good for plant cells because it maintains cell rigidity

Osmotic pressure

• A force produced by the movement of water out of or into a cell (Osmosis)

• Can cause animal cells to shrink or swell based on the solution concentration

Active Transport

• The movement of materials against a concentration gradient (low to high concentration)

• Requires Energy

• Movement of molecules using energy in the form of (ATP)

Endocytosis

• Active/Bulk Transport

• The process of taking material into the cell by using foldings/pockets in the cell membrane to form a vesicle or vacuole within the cytoplasm.

• The cells membrane pinches in forming a vesicle to take in molecules

• cyto- = cell, so Endocytosis means “in the cell”

Phagocytosis

• A type of Endocytosis/Active and Bulk Transport (Requires a considerable amount of energy)

• A type of Endocytosis were extensions of the cytoplasm surround a particle and package it within a food vacuole. Then the cell engulfs it

• This method is used to remove/destroy damaged or foreign cells

Pinocytosis

• A type of Endocytosis/ Active or Bulk Transport

• A process where tiny pockets form along the cell membrane and fill with liquid, Then they detach to form vacuoles.

Exocytosis

• a type of Active/Bulk Transport

• A process were cells release larger molecules amounts of material

• The cell membrane fuses with the membrane of the vacouole and force the contents out of the celll

ATP

• An energy molecule made in the mitochondria of a plant, animal, and fungi cell

• In bacteria, it is made in the cytoplasm

• Used for energy to carry out active transport

• Stands for a adenosine triphosphate

• Consist of adenine, a five carbon sugar called ribose, and three phosphate groups

Photosynthesis

• meaning to “use light to put something together”

• Plants convert the energy of sunlight into chemical energy stored in the bond of carbohydrates

Heterotroph

• Organisms that obtain food by consuming other living things

Autotroph

• organisms that make their own food

Sodium Potassium Pump

• A type of active Transport

• An enzyme in the cell membrane that uses ATP energy to move sodium (NA) ions out of the cell and potassium (K) ions into the cell

• Movement against the concentration gradient

• For every cycle it moves 3 sodium out and 2 potassium in

Calorie

• lowercase c: the amount of energy needed to raise the temperature of 1 gram of water 1°C

• Uppercase C: used on food labels and is a kilo calorie or 1000 calories

Cellular Respiration

• The process of energy conversion that releases energy from food in the presence of oxygen

• Equation: 602+ C6 H12 O6 ==> 6CO2 + 6 H2O + energy

  Oxygen + glucose = carbon dioxide + water + energy

• Takes place in three stages: glycolysis, the Krebs cycle, and electron transport chain

Aerobic

• pathways of cellular respiration that require energy

• Ex: the Krebs cycle, the electron transport chain

Glycolysis

• The process were a molecule of glucose is transformed into two molecules of the three carbon compound, pyruvic acid

• The first step of cellular respiration

• Anaerobic - not needing oxygen

The Krebs Cycle

• The process were pyruvic acid is broken down into carbon dioxide, NADH, ATP, and FADH2

• The second step to cellular respiration

Electron Transport Chain

• The process where high energy electrons are transported by carrier molecules (NADH) from both the Krebs cycle and glycolysis, and FADH2 from the Krebs cycle to convert ADP into ATP

Anaerobic

• processes of cellular respiration that do not require energy or do not rely on an oxygen requiring process to run

• Ex: glycolysis

NAD+

• An electron carrier

• Nicotinamide adenine dinucleotide

Matrix

• The innermost compartment of the mitochondria and the site where the Krebs cycle reactions take place

DNA

• the complex molecule carrying the genetic instructions for development, functioning, and reproduction of all known organisms

• Found in all cells