Cells Flashcards
fundamental organizing principle of biology and it says the following: * The cell is the smallest unit of life * Cells make up all living things * New cells can arise only from preexisting cells
Cell theory
▪ Structurally simple
▪ Typically smaller
▪ Lack membrane-bound organelles
▪ Include bacteria and Archaea
prokaryote cell
▪ Structurally complex
▪ Typically larger
▪ Have membrane-bound organelles
▪ Found in plants, animals, fungi, protist
Eukaryote Cell
As a cell gets larger, its surface area increases far more slowly than its volume
Surface to volume ratio
(height × width × number of sides) Volume 2 216
(height × width × length) Surface-to-volume ratio 1 216
(surface area:volume) 6:1 1:1
▪ Most eukaryotic and prokaryotic cells are typically measured in micrometers (μm), which equal 10–6 meters
▪ They can be seen through either light or electron microscopes ▪ Micrographs are the photographs taken with the microscope
cell size
makes up part of the cell membrane
Phospholipid bilayer, cholesterol, carbohydrates (gives quality of fluid mosaic)
Functions of the Plasma membrane
- Maintainsn structural integrity of the cell
- Selectively permeable as it regulates movement of substances into and out of the cell
- Glycoproteins provide recognition between cells
- Receptors provide communication between cells
- Cell adhesion molecules stick cells together to form tissues and organs
Types of movement across the plasma membrane
- PASSIVE TRANSPORT
▪ Movement across the membrane that doesn’t require energy - Simple diffusion, facilitated diffusion, osmosis
- ACTIVE TRANSPORT
▪ Movement across the membrane that requires energy
Simple Diffusion
- Movement of a substance following a concentration gradient, from high concentration to low concentration
- End result is an equal distribution of the substance in the two areas
- Eliminatestheconcentrationgradient
Facilitated diffusion
- Movement of a substance from a region of higher concentration to a region of lower concentration with the aid of a membrane protein
- To cross a cell membrane, water-soluble substances need to be assisted or “facilitated” by carrier proteins
Osmosis
- Movement of water across a selectively permeable membrane from a region of higher water concentration to a region of lower water concentration
▪ The water molecules move to dilute the solution
Active Transport
- Movement from a region of lower to higher concentration with the aid of a carrier protein and energy, typically ATP
Endocytosis
- A region of the plasma membrane engulfs the substance to be ingested and then pinches off from the rest of the membrane, enclosing the substance in a vesicle, which travels through the cytoplasm
▪ Applies to large molecules, single-celled organisms, and droplets of fluid containing dissolved substances
Types of endocytosis
- Phagocytosis (cell eating): large particles or bacteria
- Pinocytosis (cell drinking): droplets of fluid
Exocytosis
- Large molecules are enclosed in membrane-bound vesicles, which travel to plasma membranes, where they are released to the outside
organelles that have membranes
- Nucleus
- Endoplasmic reticulum
- Golgi apparatus
- Lysosomes
- Mitochondrion
Endoplasmic reticulum
- An extensive network of channels connected to the plasma membrane, the nuclear envelope, and certain organelles
- Two types of endoplasmic reticulum:
▪ Rough endoplasmic reticulum (RER) - Contains ribosomes that guide the production of cell products
▪ Smooth endoplasmic reticulum (SER)
* Lacks ribosomes
* Involved in the production of phospholipids and detoxification
▪ Golgi complex
- A series of interconnected, flattened membranous sacs
- Proteins are packaged in vesicles and transferred to the Golgi complex for processing and packaging
Mitochondria
- Sites of cellular respiration, providing cell with energy through the breakdown of glucose to produce ATP
▪ Double-membrane organelle
▪ Contain inner foldings, called cristae
cytoskeleton
▪ Network that provides shape and support for the cell
▪ Composed of thick microtubules, intermediate
filaments, and thin microfilaments
- Centriole: a microtubule-organizing center located near the nucleus
- Microtubules and microfilaments disassemble and reassemble, while intermediate filaments tend to be more permanent
Microtubules
- Maid Of The Protein Tubulin
- Responsible for the structure and movement of cilia and flagella
Cilia
are numerous short extensions in a cell that move back and forth
Flagella
are larger than cilia and move in an undulating manner
Microfilaments
- Madeoftheproteinactin
- Function in muscle contraction
- Form a band that pinches cell in two during cell division
Intermediate Filaments
- Protein composition varies from one type of cell to another
- Diverse group of ropelike fibers that maintain cell shape and anchor organelles
Cellular respiration and fermentation
▪ Cell metabolism includes all of the chemical reactions that take place in a cell
* Organized into metabolic pathways
▪ Each pathway contains a series of steps
▪ Specific enzymes speed up each step of the pathway
▪ May be catabolic or anabolic
▪ Both are catabolic pathways that generate cellular energy
* Complex molecules are broken down into simpler compounds
* Energy is released
the result of cellular respiration requires oxygen to break down sugar and produce these
c02 h20 and energy (atp)
Four phases of glycolysis
- Glycolysis
- Transition reaction
- Citric Acid cycle
- Electron transport
Phase 1: Glycolysis
- Occurs in the cytoplasm
- Splits glucose into two pyruvate molecules
- Generates a net gain of two ATP and two NADH molecules
- Does not require oxygen
Phase 2: Transition reaction
- Occurs within the mitochondria
- Removes carbon as CO2 from each pyruvate
- Generates an acetyl CoA molecule and NADH molecule from each pyruvate broken down
Phase 3: Citric acid cycle
- Occurs within the mitochondria
- Acetyl CoA enters the citric acid cycle
- Produces two ATP, two FADH2, and six NADH molecules and releases CO2 as a waste product
Phase 4: Transport chain
- Occurs across the inner membrane of the
mitochondria - Requires oxygen
- Electrons from FADH2 and NADH are transferred from one protein to another, until they reach oxygen
- Releases energy that results in 32 ATP molecules
Fermentation
▪ Breakdown of glucose without oxygen
* Takes place entirely in the cytoplasm
* Is very inefficient, compared with cellular respiration, resulting in only two ATP
* Lactic acid fermentation takes place in the human body in muscles during strenuous exercise when the oxygen supply runs low
