A&P CH 3: Cellular level of organization

Cell membrane: 4

• “Plasma membrane”; Creates barrier between in+out

• phospholipid bilayer (“tail to tail”);

• amphipathic molecule

• Contains cholesterol (flexibility), various proteins, unsaturated fatty acids

ICF: 1

• Intracellular fluid, fluid inside the cells

ECF: 1

• Extracellular fluid, fluid outside the cell, in the vessels

IF: 1

• Interstitial fluid, fluid between cells, not vessels

Integral proteins: 2

• A membrane protein; goes all the way through membrane

  • Ex: Channel proteins create channel for certain substances to go thru membrane

Receptor proteins: 1

• allow ligands to bind to cell

Ligands: 2

• binds to cell, plugging into a receptor

• hormones, other molecules

Glycoproteins: 3

• protein with carbohydrate attached

• create ID marker for cell

• Type of recognition protein

Peripheral proteins: 2

• found on only 1 side of membrane

• Ex: “G” proteins deliver a signal inside membrane when hormone binds to receptor

Selectively permeability: 1

• only allow certain substances to cross membrane without help (usually due to hydrophobic nature of fatty acid tail blocking water soluble substances)

Things that can cross membrane easily: 2

• oxygen, CO2, other lipids, alcohol

• non polar substances

Things that need assistance to cross membrane: 2

• polar, water soluble molecules

• glucose, amino acids, electrolytes (polar ions)

Passive transport: 3

• doesn’t require ATP in order to cross membrane

• Diffusion

  • Osmosis

Diffusion: 3

• movement of particles from an area of high concentration to low concentration

  • Moves down concentration gradient

• Passive transport

Simple diffusion: 4

• automatically happens

• O2 and CO2

• non polar molecules

• Passive transport

Facilitated diffusion: 5

• NO energy needed

• molecule needs special pathway across membrane

• glucose (large + polar), Na⁺ (polar)

• Carrier protein: more selective

• Channel protein: less selective

Osmosis (4)

• diffusion of water through semipermeable membrane

• a barrier prevents solutes from diffusing down their gradient

• If barrier is permeable to water, water will go to where solutes are to equalize solution

• Passive transport

• solutes “pull” water towards them

Isotonic: 3

• relating to movement of water molecules

• Both solutions have equal concentrations

• In anatomy, refers to .9% salinity (for homeostasis)

Hypertonic: 4

• 1 solution is more concentrated than other

• cells crenates (water flows out of cell and looks crushed) in these solutions

• Interstitial fluid outside cell more concentrated than fluid inside cell

• think dehydration

Hypotonic: 3

• 1 solution is less concentrated than other

• cells swell and lyse (swells and bursts) in hypotonic conditions

• Interstitial fluid outside cell is less concentrated than fluid inside cell

Active transport: 2

• requires energy (ATP) to move substances across membrane (against concentration gradient)

• Know 3: endocytosis, Na/K pump, exocytosis

Na/K pump: (4)

• cell uses ATP to pump 3 sodium ions out and 2 potassium’s in (3:2 ratio)

  • Sodium (Na) goes against concentration gradient

• Outside of membrane is more positively charged than inside

  • Establishes electrical concentration

Endocytosis: 4

• cell engulfs something it wants to ingest into membrane bubble (vesicle)

  • Phagocytosis: cell eating (macrophages); relatively nonselective; larger particles

  • Pinocytosis: cell drinking (thyroid cells); smaller particles

  • Receptor mediated endocytosis: quite selective

Exocytosis: (2)

• cell expels product; opposite of endocytosis

• vesicles is formed and fuses with cell membrane and releases content into extracellular fluid (ECF)

Organelles: 2

• each have unique function

• little membrane-enclosed bodies in cell

Cytosol: 2

• gel-like fluid substances inside cells

• biochemical reactions take place

Cytoplasm: 1

• everything in cell except nucleus (organelles and cytosol)

Cytoskeleton: 4

• consists of protein structure; has role in motility, reproduction, & transport of substances; all polymers of protein subunits

  • Microtubules (biggest): thickest, holds organelle in place; made of tubulin

  • Intermediate filaments (medium): keratin/collagen - strength

  • Microfilaments (smallest): actin - mechanical support & flexibility

Microtubules: 3

• Centrioles: form the mitotic spindle during cell division, guides DNA where to move

• Cilia: made of microtubules that help move substances along outer membrane

• Flagella: “tail” of male sperm; for movement

Endoplasmic Reticulum (ER): 3

• systems of channels connected to nuclear membrane

• transport, synthesis; “assembly line”

• Rough & smooth

Rough ER: 2

• contains ribosomes: site of protein synthesis; (next to nucleus)

• receives new proteins & modifies them if necessary

Smooth ER: 3

• NO ribosomes; synthesis of lipids (phospholipids, steroid hormones) and carbs (glycerides)

• stores and regulates cellular calcium

• can breakdown certain toxins

Golgi Apparatus: 3

• sorts, modifies, and packages products from ER

• “UPS”

• Transport vesicles: carry products to & from golgi apparatus

Lysosomes: 3

• contains enzymes that breakdown and digest unnecessary cellular components

  • Autography: cell digesting own structures

  • Apoptosis: damaged/unhealthy cells can be triggered to release all lysosomes to self digest entire cell “programmed cell death”

• contain acid: hydrolase that breakdown worn-out parts of cell

Mitochondria: 2

• produce majority of cell’s energy (ATP) by cellular respiration; powerhouse

• has double membrane (inner & outer)

Structure of Mitochondria: 4

• Mitochondrial matrix:

  • most inner part: is site for Krebs cycle (waste product: CO2)

• Inner membrane: site of electron transport chain:

  • uses oxygen to finalize creation of ATP

Cellular respiration: 3

• Glycolysis: break 6 carbon glucose molecule into 2 3 carbon (pyruvate) pyruvic acid molecule

• Citric acid cycle: 2 3 carbon pyruvic acid molecules enter mitochondria & 2 more ATP

• Oxidative phosphorylation: high energy electrons are made; involves electron transport chain

Peroxisomes: main 2

• present in liver for detoxifying; breaks down hydrogen peroxide

• transfer harmful hydrogen atoms from reactive oxygen species (ROS) molecules

  • They are other peroxides and free radicals that have free electrons that oxidize and harm other things

• gets rid of free radicals; contains oxidases (oxidize organic substances)

• These create H2O2 in the process of neutralizing free radicals… enzyme, make it into O2 & water

Nucleus structure: 4

Nucleus: control center; stores genetic info (DNA: “blueprint”; used to build proteins)

Nuclear envelope: double bilayer of phospholipids that creates wall of nucleus

Nucleolus: region of nucleus that makes RNA; ball in very middle of nucleus

Chromatin: threads of DNA wrapped around histone proteins

Chromatin/Chromosome/sister chromatids: 3

• Chromatin: threads of DNA wrapped around histone proteins (4 ? nucleosomes wrapped by DNA)

• Chromosome: densely packed, condensed chromatin that can be more safely delivered to daughter cell during cell division

• Sister Chromatids: original copy and new copy when DNA is replicated

DNA (Deoxyribose Nucleic Acid): 4

• double stranded sequence of nucleotides coiling around each other in double helix

• must be copied before a cell can divide

• To be copied: 2 DNA strands “unzip” by DNA enzyme helicase and new complimentary strand is built on old strand by DNA Polymerase

• proteins made by ribosomes outside nucleus

Protein synthesis: 5

• Transcription: copy of gene made by mRNA and sent out into cytoplasm to ribosomes

• Translation: ribosomes read code made by mRNA and assembles amino acids into a polypeptide chain

  • tRNA: brings matching amino acid to ribosomes to add to chain

• Processing: RER & golgi apparatus make necessary modification to finish making protein

  • Adenine - Thymine ; Guanine - Cytosine

Codon:

• each 3 base sequences codes for a specific amino acid to be added next on protein being made

Somatic cells: 4

• most of our body cells (except germ cells); undergo regular cell division (mitosis)

  • Exceptions: gametes, erythrocytes, neurons, some muscle cells

• Are diploids: contain 2 copies of each of our 23 chromosomes (homologous pair)

  • 1 copy from both mom and dad

Cell Cycle: 3

• Interphase: protein of cell life NOT dividing

• Mitosis: division of genetic material (nucleus)

• Cytokinesis: division of all rest parts of cell into 2 new, identical daughter cells

Interphase: 4

G1 phase: new baby cell is growing

• G0: resting cell (happens for cells that DONT divide again (neurons)

S phase: matured enough cells, sister chromatids are made; DNA is copied

G2 phase: cell grows again

Mitosis: 4

Prophase: “before”; nuclear envelope’s gone; chromatin are condensing into chromosomes; centrioles separate & form mitotic spindle

Metaphase: chromosomes line up across middle of spindle

Anaphase: pulling apart of sister chromatids; sister chromatids separated by spindle (fibers); centromeres split

Telophase: chromosomes “arrive” at each pole and begin decondensing; nuclear envelope reforms; mitotic spindle breaks down

Cytokinesis: 1

• cytoplasm & cell membrane split into 2 (diploid, daughter) complete cells

Rate of division: 7

• normally; cell division balances cell loss

• Increases cell division:

  • internal factors (maturation promoting factor)

  • extracellular chemical factors (growth factors)

• Decreases cell division:

  • repressor genes (faulty repressor cause cancers)

  • worn out telomeres (terminal DNA segments)

Slower mitotic rate means: 3

longer cell life

• muscle and neuron cells rarely divide

• exposed cells (skin, digestive tract) live only days/hours

Abnormal cell division: 4

• cancer: illness that disrupts cellular control; begins when cells are dividing rapidly

  • tumor is cancerous when this happens

• oncogenes: mutated genes that cause cancer + produces malignant cells

• cancer stages (develops in stages): abnormal cell, primary tumor, metastasis, secondary tumor

• tumor (neoplasm): enlarged mass of cells, abnormal growth & division

Malignant & benign: 2

• malignant: invasive; spread to tissue around it (metastasis)

• benign: contained, may not be life threat

Differentiation: 3

• cells can become different things and specialize throughout life

• this depends on which genes are active/inactive

• they specialize to form tissues by turning off all unneeded genes

Stem cells: 5

• Totipotent: cell of embryo that can become anything

• Pluripotent: can become any individual tissue

• Multipotent: can become any type of cell within a certain “lineage” (RBCs & WBCs)

• Oligopotent: can become a few different types of cell types within a set category (limited, few)

• Unipotent: can be more of same thing that already is (one)

Transcription factor: 1

• class of proteins that bind to specific genes on DNA molecule & either promote/inhibit their transcription

Stem cells are…

• valuable in therapeutic applications

Gene: 1

• functional length of DNA that provides specific genetic information necessary to build a protein

Glycolipid:

• ID marker for cells; found on cell membrane

• Lipid with carbohydrate attached

Pluripotent

• Pluripotent: can become any individual tissue

Multipotent:

• Multipotent: can become any type of cell within a certain “lineage” (RBCs & WBCs)

Oligopotent:

• Oligopotent: can become a few different types of cell types within a set category (limited, few)

Unipotent:

• Unipotent: can be more of same thing that already is (one)

Totipotent:

• Totipotent: cell of embryo that can become anything