Cell Organelles Flashcards
Cells
smallest units of life ; over 250 ; cells are very diverse
What are the 3 basic parts of cells?
Plasma membrane
Cytoplasm
Nucleus
Plasma Membrane
flexible outer boundary
Cytoplasm
intracellular fluid containing organelles
Nucleus
DNA controlling control center
Extracellular Materials
Substances found outside your cell
Interstitial fluid
cells are submersed (bathed) in this fluid
Blood plasma
fluid of blood
Cerebrospinal Fluid
fluid surrounding nervous system organs
Cellular Secretions
saliva and mucus ; external elimination of substances produced by the cell
Extracellular matrix
substance that acts as glue to hold cells together
Cytoplasm
All cellular material that is located between the plasma membrane and the nucleus
Cytosol
gel-like solution made up of water and soluble molecules such as proteins, salts, sugars, etc.
Cytoplasmic Organelles
These are divided into membranous (eukaryotes) and non membranous (prokaryotes)
Mitochondria
Called the “power plant” of cells because they produce most of cell’s energy molecules (ATP) via aerobic (oxygen-requiring) cellular respiration
- fact: mitochondria has its own DNA , all of mitochondrial DNA comes from your mom
Double Membranes
Mitochondria is enclosed by double membranes;
Cristae
The inner membrane of mitochondria has many folds, called cristae
Cristae are embedded with membrane proteins that play a role in cellular respiration
Ribosomes
- nonmembranous (no membrane around them)
- sites of protein synthesis
Membrane Bound Ribosomes
attached to membrane of endoplasmic reticulum (ER); site of synthesis of proteins to be incorporated into membranes or lysosomes, or exported from cell
Free Floating Ribosomes
free floating; site of synthesis of soluble proteins that function in cytosol or other organelles
Endoplasmic Reticulum
- folds of membrane outside the nucleus
- take MRNA that comes out of nucleus and feed it to ribosomes to produce proteins
Rough ER
External surface appears rough because it is studded with attached ribosome
Site of synthesis of proteins that will be secreted from cell
Site of synthesis of many plasma membrane proteins and phospholipids
Final protein is enclosed in vesicle and sent to Golgi apparatus for further processing
Smooth ER
- Network of looped tubules continuous with rough ER
- Enzymes found inside function to:
- Lipid metabolism; cholesterol and steroid-based hormone synthesis; making lipids for lipoproteins
-Absorption, synthesis, and transport of fats
-Detoxification of certain chemicals (drugs, pesticides, etc.)
-Converting of glycogen to free glucose
-Storage and release of calcium
Sacroplasmic Reticulum
specialized smooth ER found in skeletal and cardiac muscle cells
Golgi Apparatus
- continuation of ER
-Modifies, concentrates, and packages proteins and lipids received from rough ER
Three Steps in Golgi Apparatus
- Transport vesicles from ER fuse with cis (inner) face of Golgi
-Proteins or lipids taken inside are further modified, tagged, sorted, and packaged
- Golgi is “traffic director,” controlling which of three pathways final products will take as new transport vesicles pinch off trans (outer) face
Perixisomes (special vacuole)
Membranous sacs containing powerful detoxifying substances that neutralize toxins
- good at getting rid of hydrogen peroxide
Free radicals
toxic, highly reactive molecules that are natural by-products of cellular metabolism; can cause havoc to cell if not detoxified
- charged active particles
Oxidase and Catalase
oxidase uses oxygen to convert toxins to hydrogen peroxide (H2O2), which is itself toxic; however, peroxisome also contains catalase, which converts H2O2 to harmless water
Lysosomes
- Spherical membranous bags containing digestive enzymes (acid hydrolases)
-Considered “safe” sites because they isolate potentially harmful intracellular digestion from rest of cell
-kept in inactivated state
- can break down organelles and ingest bacteria
Autolysis
Intracellular release in injured causes cells to digest themselves
Cytoskeleton
Three Types of Proteins
Microfilaments
Intermediate filaments
Microtubules
Microfilaments
-Thinnest of all cytoskeletal elements
-Semi-flexible strands of protein actin
-Strengthens cell surface and helps to resist compression
- Some are involved in cell motility, changes in cell shape, or endocytosis and exocytosis
Microtubules
-Largest of cytoskeletal elements
- help keep organelles in place and move them around
Motor Proteins
Many substances are moved throughout cell by motor proteins, which use microtubules as tracks
Intermediate Filaments
anchor nucleus and other organelles
Centrosome
- located near nucleus
- It is a microtubule organizing center, consisting of a granular matrix and centrioles
Centrioles
a pair of barrel-shaped microtubular organelles that lie at right angles to each other
- Centrioles form the basis of cilia and flagella
Cilia
- whiplike, motile extensions on surfaces of certain cells (such as respiratory cells)
- Thousands of cilia work together in sweeping motion to move substances (example: mucus) across cell surfaces in one direction
Flagella
longer extensions that propel the whole cell (example: tail of sperm)
What are flagella and cilia made of?
Both structures are made up of microtubules synthesized by centrioles that are called basal bodies because they form the base of each cilium and flagellum
What is the cell membrane made out of?
phospholipids
what is the lipid bilayer made up of? (3)
75 percent phospholipids, 5 percent glycolipids, and 20 percent cholestrol
Function of Cholesterol in cell membrane?
increases membrane stability
Fluid Mosaic Model
Specialized membrane proteins float through the fluid membrane and constantly change shape as they like to diffuse across membrane (side to side movement)
Glycocalyx
Surface sugars form glycocalyx (determines blood type)
Cell Junctions
Membrane structures help to hold cells together through cell junctions
What are the two types of protein?
Integral and Peripheral proteins
Integral Proteins (location)
- goes through membrane
- have both hydrophobic and hydrophillic regions that allow it to stick
- function as transport proteins
Peripheral proteins
- all the way to the inside and not outside (not in middle of membrane)
- Include filaments on intracellular surface used for plasma membrane support
- function as enzymes and motor proteins
Transport Proteins
proteins that pump substances through the membrane (energy comes from ATP)
Receptor Proteins
Hormones activate specific receptors to cause reactions
Enzyme Proteins
enzymes can be attached to membrane to do things
cell to cell recognition
some glycoproteins serve as cell identification for other cells
cell to cell junctions
water tight junctions allow plasma to not leak out of skin
Three Types of Junctions
- Tight Junctions
- Desmosomes
- Gap Junctions
Tight Junction
water tight ; prevent acids and urine from leaking
Desmosomes
mediate cell-cell contact and strong adhesion.
Gap Junctions
- communication junctions that have holes to pass ions
- in heart so muscle cells know how to pump together
Diffusion
Diffusion is the net movement of anything generally from a region of higher concentration to a region of lower concentration.
- usually doesn’t take energy input
three types of passive transport
- simple diffusion
- facilitated diffusion
- osmosis diffusion
facilitated diffusion
the diffusion of solutes through transport proteins in the plasma membrane (goes through date like structures)
osmosis
water diffusion
active transport
requires energy in the form of ATP