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Flashcards in Cellular Physiology Deck (69)
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1

Elements

Definition

  • the material or matter fundamental to cells.

Characteristics

  • most common elements are oxygen, carbon, hydrogen and nitrogen
  • composed of atoms

2

Atoms

Definition

  • small clusters of protons (positive), electrons (negative) and neutrons (no charge)

Characteristics

  • central nucleus and a surrounding field containing protons and neutrons
  • electrons circulate at different energy levels
    • first level has 2 electrons
    • second level has 8 electrons
  • do not have a full outer level and are therefore unstable until bonds are formed and the outer levels are full

3

Ionic Bonds

Definition

  • formed through the gain or loss of an outer electron between one or more electrons

 Characteristics

  • ionic bonds are released when the compound is dissolved in water, resulting in ions which carry an electric charge
  • an ion is attracted to another ion of opposite charge
  • an atom that gains one or more electrons acquires a negative charge and is called an anion
  • an atom that loses one or more electrons acquires a positive charge and is called a cation

4

Covalent Bonds

Definition

  • formed when electrons are shared and each atom fills its outer electron level

Characteristics

  • acids and bases are compounds which share electrons

5

Hydrogen Bonds

Definition

  • covalent bonds with hydrogen as a component

Example

  • water has both covalent and hydrogen bonds, with the oxygen attracting the hydrogen electron more strongly, causing the hydrogen atoms to be slightly positive and the oxygen atom to be slightly negative.  This causes a strong attraction between molecules, leading to surface tension.

6

Phosphate Bonds

Definition

  • unique chemical bonds which store energy
  • high phosphate bonds are between phosphate groups and adenosine monophosphate (AMP)

Characteristics

  • ADP is formed by the first phosphate bond between AMP and phosphate
  • ATP is formed by the second phosphate bond between two phosphates and AMP

7

Carbohydrates

Definition

  • sugars and starches

​Characteristics

  • complex carbohydrates are starches, which must first be broken down into simple sugars for cellular uptake
  • sugars are primarily used or stored as cellular fuel

8

Proteins

Definition

  • the structural and communication ingredients of the body made from amino acids

Characteristics

  • 20 known amino acids
  • diversity of proteins is due to the length and organization of the amino acid chains
  • structural proteins provide structure, support, strength, and tension (ex. collagen, keratin, and elastin)
  • Functional proteins are mobile and chemically active in biological processes including cellular communication (ex. transmitters, hormones, antibodies, enzymes, and contractile muscle

9

Lipids

 Classifications

  1. triglycerides
  2. phospholipids
  3. steroids

Characteristics of Triglycerides

  • comprised of a glycerol and three fatty acid chains
  • the major source of stored energy for the body

Characteristics of Phospholipids

  • bipolar lipids comprised of two fatty acid chains
  • unique in that the phosphorus polar end attracts water and ions
  • major component of the cell membrane of most cells

Characteristics of Steroids

  • lipids which are structurally related as rings, not chains
  • vary greatly in function and structure
  • cholesterol is the primary steroid lipid and is the base for steroid hormones such as testosterone, estrogen, aldosterone, and cortisol

10

Nucleic Acids

Definition

  • the most complex molecules in the body

​Classifications

  1. deoxyribonucleic acid (DNA)
  2. ribonucleic acid (RNA)

Characteristics of DNA

  • located in the nucleus
  • responsible for cell division and protein synthesis
  • genes for identical cell replication and new cell production is stored in DNA

Characteristics of RNA

  • located outside of the cell nucleus
  • carries out the orders from DNA for protein synthesis

11

Cell Membrane

Basic Structure

  • double layer of phospholipids with embedded specialized structures
    • channels
    • carriers
    • pumps
    • exchangers
    • receptors
    • effectors

Characteristics

  • semipermeable due to the basic structure of phospholipids and embedded proteins
  • a barrier to easy movement of water and water soluble substances
  • lipids move freely through membrane

Function

  • to control or regulate the intracellular environment

12

Bi-Polar Phospholipid Layer

Structure

  • only two molecules thick
    • hydrophilic - water soluble molecules
    • hydrophobic - repellant to water
      • two hydrophobic molecules face each other

Characteristics

  • due to the polarity and lipid structure, the membrane is not normally permeable to numerous substances such as ions, glucose, and urea

13

Protein Channels

Structure

  • embedded in the lipid layer
  • have gates which block the pathway between the intracellular and extracellular environment

​Function

  • provide pathways through the phospholipid layer
  • the gates must open to allow substances or enzymes into the cell

Characteristics

  • very selective - due in part to diameter and electrical charge
  • gates are controlled by either an electrical charge (voltage gating) or activation through cell communication (ligand gating)

14

Protein Carriers

Structure

  • a solid pathway from the intracellular to extracellular environment

Function

  • bind with substances and trasnport them from one side of the cell membrane to the other

Characteristics

  • very selective - due in part to the chemical structure of the transported substance

15

Ion Pumps

Characteristics

  • most important pump is the sodium-potassium pump
  • uses energy to move sodium to the outside of the cell in exchange for potassium movement into the cell

16

Receptors

Definitions

  • carbohydrate protein compounds are receptors for hormones and transmitters
  • specialized to receive stimuli and initiate a cellular response, such as an enzyme or an effector withi the membrane

Classifications

  1. Functional receptors
  • extend to the outer surface of of the cell
  1. Provisional receptors
  • located within the cell membrane and must surface before they are functional

Characteristics

  • type and number of receptors varies greatly depending on the particular cell
  • may be activated or blocked
    • an agonist effect occurs when the transmitter or chemical interacts with the particular molecular structure of receptors and initiates a response
    • an antagonist effect occurs when the transmitter or chemical occupies the receptors but blocks the agonist and response

17

Cytoplasm

Components

1.  Cytosol

  • intracellular viscous fluid in which elements are dissolved and suspended
  • different than the extracellular fluid - this is maintained by the cellular membrane

2.  Organelles

  • mitochondria
  • ribosomes
  • endoplasmic reticulum
  • golgi apparatus
  • lysosomes
  • peroxisomes
  • cytoskeleton

18

Mitochondria

Functions

  • manufacture ATP
  • enzymes within the mitochondria break down glucose and capture the released energy to form ATP

Characteristics

  • supply 95% of the cell's energy
  • density of mitochondria vary depending on the cell
  • require oxygen (aerobic cellular respiration)

19

Ribosomes

Function

  • synthesize proteins for cell function

Structure

  • tiny granules of proteins and RNA

Characteristics

  • fairly specific, depending on the cell and particular function

20

Endoplasmic Reticulum

Structure

  • an extensive network of parallel membranes which form cisternae (fluid filled cavities)
  • two types: rough and smooth
  • Rough ER has proteins on its surface
  • Smooth ER contains enzymes

Function

  • Rough ER produces proteins which are transported to the Golgi apparatus
  • Smooth ER produces lipids, including the cell's membrane phospholipids and can have specialized functions depending on the cell
  • synthesis of steroid-based hormones
  • synthesis of enzymes
  • absorption and transport of fats
  • synthesis and storage of glycogen
  • detoxification and metabolism

 

21

Golgi Apparatus

Structure

  • a group of membranous sacs near the nucleus

Function

  • modifies and transports specific proteins, such as glycoproteins and secretory enzymes

​Characteristics

  • the presence of the Golgi apparatus is a strong indicator tha tthe cell is currently active

22

Lysosomes

Structure

  • membranous sacs which contain hydrolytic (digestive) enzymes

​Function

  • digestion of particles harmful to the cell (bacteria, viruses, toxins)
  • digestion of worn-out particles
  • metabolism (such as breakdown of glycogen and release of thyroid hormone)
  • breakdown of bone

23

Peroxisomes

Structure

  • membranous sacs which contain enzymes

Function

  • enzymes called peroxidases detoxify harmful or toxic substances (such as alcohol and oxygen-free radicals - a waste product of cellular metabolism)

24

Cytoskeleton

Structure

  • internal scaffolding composed of
    • microfilaments
    • intermediate filaments
    • microtubules

25

Nucleus

Function

  • contains genetic information to direct and regulate the cell
  • cells which have complex activities have more than one nucleus
  • provides information for protein synthesis and genetic reproduction

26

Diffusion

Definition

  • the movement of substances from an area of high concentration to an area of low concentration

Classifications

  1. simple diffusion - movement of molecules through the cell membrane or protein channels
  2. facilitated diffusion - involves carrier proteins which move substances accross the membrane

Characteristics

  • energy is not requried for either type of diffusion
  • diffusion of lipid soluble substances is more rapid than water soluble substances
  •  

27

Active Transport

Definition

  • substances that move from a lower to higher concentration gradient - against the concentration gradient

Characteristics

  • requires ATP
  • can be achieved through protein carriers, pumps, and exchangers

28

Sodium-Potassium Pump

Function

  • maintains the concentration gradients of sodium and potassium
  • transports sodium ions out of the cell and potassium ions into the cell

​Characteristics

  • the pump is activated when sodium and potassium ions bind to the receptors
  • both ions are moved against their concentration gradient
  • affects cellular ion concentrations and electrical charge
  • more sodium than potassium is transported out, therefore there is a net loss of positive charge within the cell - with each exchange through the pump, 3 positive ions move out and only 2 positive ions move into the cell

29

Filtration

Definition

  • movement of water and solutes across the cell membrane
  • dependent on hydrostatic and osmotic pressures
  • water moves accross the membrane to achieve equilibrium between these pressures

30

Metabolism

Definition

  • reactions which change the complexity and size of molecules

Classifications

  1. Anabolism - larger molecules and structures are created
  2. Catabolism - conversion of complex, larger molecules to simple, building blocks 
    • vitamin dependent
    • aerobic
  3. Cellular Respiration - the group of reactions in which glucose, fatty avids, and amino acids are broken down and the energy released is captured to form ATP

Characteristics

  • nutrients are taken into the body primarily through digestion and the intestinal tract, are broken down into organic compounds and then transported to tissue cells
  • within the cells, nutrients are either build into cellular molecules or broken down by catabolic pathways to acetyl CoA for energy
  • glucose is initially broken down into pyruvic acid and then acetyl CoA before they can enter the citric acid or Krebs cycle
  • Acetyl CoA enters the mitochondria for catabolism