Level of organization of cells

Atoms

Building blocks of cells

Cells

Building block of tissue

cytology

Study of cells

Sex Cells

sperm cells in males, oocyte cells in females.

Somatic cells

all other cells in the body.

What is the Cell is surrounded by

“watery medium” (Extracellular fluid (ECF))

Cytoplasm is made up of

cytosol (liquid/ICF)

organelles (little organs) - intracellular structures

Cell Membrane functions

Physical isolation

Sensitivity

Regulates exchange with environment

Structural support

Phospholipid Bilayer

Two layers of phospholipids with two hydrophobic tails and a hydrophilic head. Tails bind together away from H2O.

Where can H2O and Solutes pass through?

gates or pores

Integral proteins

span the membrane (transmembrane) one or more times.

Peripheral proteins

proteins attached only on inside or outside surface. Not inserted into the membrane.

Anchoring Proteins (stabilizers)

anchors membrane to the cytoskeleton (inside), anchors cell to another cell (outside).

Recognition proteins (recognizers)

immune cells use proteins on outside of membrane to identify “normal” or “abnormal” cells.

Enzymes

these catalyze reactions in (ECF) outside or inside (cytosol).

Reception proteins

molecules called ligands, come into contract with these reception proteins which triggers changes in the cells.

insulin (ligand)

binds to a receptor which causes cell to increase absorption of glucose.

Carrier proteins

binds solutes (ions such as sodium, calcium) and carries them across the membrane. These motions require ATP (energy sources) to carry/transport ions.

Channels

some integral proteins (transmembrane) form a passage through the membrane which allows H2O and small ions to pass

Leak channels

allow H2O and ions to pass at all times (rate may vary) No gates.

Lubrication

lubricates and protects cell membrane from physical and chemical injury.

Anchoring and locomotion

anchors some cells to form tissue, allows others to move.

Specificity in binding

glycoproteins and glycolipids can act as receptors.

Recognition

Enables the immune system to recognize and attack foreign antigens. Allows immune system cells to determine “friend” from “foe”.

Determines compatability

for blood transfusions and organ transplants.

Blood types

A, B, AB, O

What is Blood Type is determined by

presence/absence of glycolipids on “red blood cells”

Impermeable Permeability

nothing passes through the membrane.

Freely permeable membrane

everything passes through the membrane.

Selectively permeable membrane

Cell determines what will pass through the membrane.

What is Membrane transport is classified by

Energy Utilization or Mechanism of action (Passive or Active Transport).

Passive Transport

No energy is used as molecule is transported across membrane.

Active Transport

Energy is required to transport molecule across membrane.

Diffusion

Passive, molecules/ions in solution tend to become evenly distributed by floating around bumping into each other with random movement, this causes molecules/ions to become evenly distributed in a container (body).

Osmosis

the “diffusion” of H2O through protein leak channels across a membrane.

Where will H2O always move?

toward the area with the greatest salt/carbohydrate/solute concentration.

Tonicity

various osmotic solutions have an affect on cells; used to describe the solute in the outside (ECF) solution.

hypotonic solution

If solution outside cell (ECF) has lower concentration as inside of cell, then H2O will go/move from outside to inside. cell expands, may burst “hemolysis”

Isotonic solution

If solution outside cell (ECF) has same “solute” concentration as inside of cell, then no movement of water. No change

hypertonic” “solution

If solution outside cell (ECF) has higher concentration as inside of cell, then H2O will move from inside to outside. cell shrivels, dehydrates “crenation”

cotransport

can carry two substances/molecules at same time into or out of cell

countertransport

carries one substance in while carrying another substance out of the cell

three specific types of CMT (Carrier Mediated Transport)

Facilitated Diffusion

Primary Active Transport

Secondary Active Transpor

Facilitated diffusion

passive (no energy) ion/compound binds to a receptor which moves it from higher concentration to lower

Active Transport (Primary Active Transport)

ATP is directly used to transport molecules across cell membrane, so this is NOT dependent on concentration.

Secondary Active Transport

Tno INITIAL direct coupling of ATP. One molecule(s) goes from high concentration to low concentration; however later in order to maintain homeostasis the cell may have to expend some ATP to remove excess molecules from inside.

Vesicular Transport

materials are moved in/out of cell by “vesicles”, which are small membranous sacs that “form” or fuse with cell membrane. Large volumes are carried out this way so also called “bulk transport”.

Endocytosis

molecules are transported into the cell, receptor mediated endocytosis,pinocytosis, phagocytosis

Exocytosis

waste/molecules are transported out of cell; opposite of endocytosis

receptor mediated endocytosis

ligands (molecules) bind to receptors on outside of the cell membrane sending a signal to the cell.

pinocytosis

“cell drinking”; a groove forms on the cell membrane allowing ECF to be trapped into a vesicle.

phagocytosis

“cell eating”; A solid object (bacteria, toxin) is encountered by the cell membrane.

Non-membranous organelles

don’t have a membrane; thus they are always in touch with cytosol. Examples: cytoskeleton, microvilli, centrioles, cilia, ribosomes

Membranous organelles

organelles surrounded by lipid membrane.

Examples: ER, golgi, lysosomes, mitochondria.

Cytoplasm

comprised of:

Cytosol (fluid) and

Organelles that cytosol surrounds.

Cytoskeleton

internal protein framework; Comprised of:

1.Microfilaments

2. Intermediate fibers

3. Thick filaments

4. Microtubules

5. Centrioles

6. Cilia

Microfilaments

(less than 6 nm in diameter); most fragile of all filaments, primarily found in the peripheral parts of the cell; made up of actin which can interact with myosin to produce movement.

Microfilament Functions:

a. Anchors cytoskeleton to cell membrane

b. Provides strength

c. Alters cell shape

d. Ties cells together

e. Produces movement; actin interacts with myosin

f. Forms terminal web which is a layer of microfilaments just inside of

plasma membrane that forms a layer or lining

Intermediate filament

(7 nm to 11 nm in diameter); collagen is an example of this filament

Intermediate filament functions

a. Provides strength to maintain cell shape

b. Stabilizes the position of organelles

c. Stabilizes cell with respect to other cells.

d. Moves materials throughout cytoplasm

Microtubules

(25 nm in diameter); largest of the filaments that make up cytoskeleton; made up of protein tubulin

Microtubules functions

a. Primary component of cytoskeleton

b. Important in cell division

c. Provides strength

d. Moves organelles

e. Found in centrioles and cilia

Centrioles

made up of short microtubules, 9 + 0 array; means 9 groups, with 3 in each group (triplets) (total 27); no center group

Cilia

made up of microtubules; 9 + 2 array; means it has 9 groups, with 2 microtubules (doublets) in each group (total 18); the groups surround 2 in center;

Thick filaments

only appear in muscle (smooth, cardiac and skeletal); allow the muscle to contract

Microvilli

small finger like projections that increase surface area; allow for absorption and secretion to occur; provides approximately 600 times the amount of surface area over other cells.

Flagella

like cilia but larger; moves the cell around like a propeller on a boat; only found on the sperm in the human body.

Ribosomes

organelles that manufacture proteins;

-consists of large and small ribosomal subunit

-contains rRNA

-can be free floating or fixed in place

Proteasome

removes and breaks down damaged or abnormally folded proteins;

-proteins to be destroyed are marked/tagged with ubiquitin tag and are exposed to proteases which break peptide bonds.

Endoplasmic Reticulum

synthesizes protein, carbohydrates and lipids

- stores synthesized molecules

- transports molecules from place to place

- detoxification of drugs and toxins

- forms hollow chambers called cisternae

-folds proteins into their proper shape which are then transferred to the golgi for modifications

Smooth ER (SER)

Does NOT have ribosomes;

Makes cholesterol, steroid sex hormones

Rough ER (RER)

-HAS ribosomes

-this is where protein receives its secondary and tertiary structures then transports to the Golgi

-Moves proteins to golgi with transport vesicles

Golgi apparatus

has 5-6 flattened membranes that looks like stack of dinner plates called cisternae, lies close to nucleus, forms secretory vesicles

Transport vesicles

fuse with cell membrane of golgi’s forming face and release proteins into cisternae

Small vesicles

can move proteins from one cisternae to the next until it reaches the maturing face.

Lysosomes

contains digestive enzymes that will connect with membranes of vesicles and break down macromolecules of bacteria or own cell; responsible for autolysis of injured cells (breaks cells down)

Lipase

proteins which digests lipids

Carbohydrases

proteins which digests carbohydrates/sugars

Proteases

proteins which digests proteins

Nuclease

proteins which digests nucleic acids

Lysosome

may fuse with an organelle that’s old/damaged and enzymes break down organelle or with vesicle containing solid (bacteria) that needs to be destroyed.

Peroxisomes

smaller than lysosomescontain H2O2 hydrogen peroxide; carries enzymes that neutralize toxins by oxidation. Metabolizes fatty acids.

Mitochondria

power house of the cell; forms ATP (energy) contains matrix and cristae

Matrix

is fluid part of mitochondria

cristae

folds are in the inner membrane

TCA cycle - (tricarboxylic acid cycle)

Krebs or citric acid cycle. This cycle breaks down pyruvic acid in presence of oxygen (aerobic mechanism) to form ATP out of ADP.

Nucleus

largest most recognizable organelle inside the cell

nuclear envelope

a doubled layered membrane which separates the nucleus from cytoplasm.

perinuclear space

area between the doubled layered membrane

nuclear pores

are passageways in the envelope which allows communication w/ cytoplasm and allow ions to pass. Each nuclear pore has a regulatory protein that allow some proteins and RNA into or out of the nucleus.

Nucleoplasm

the fluid contents of nucleus.

Nuclear matrix

network of filaments that provides structural support.

Nucleoli

Organelle inside of nucleus which synthesizes mRNA; made of up:

RNA, proteins called histones and enzymes.

DNA

is coiled around small barrels called “histones”; DNA and the histones together are known as the nucleosome

chromatin

loosely coiled forming a tangle of fine filaments

kinetochore

is a protein structure where microtubules attach themselves to the chromosome

centromere

a region of DNA found in the middle of a chromosome where the two sister chromatids come in contact.

Nucleosomes

may be loosely coiled forming tangles called chromatin if cell is NOT ready to divied

chromosomes

Nucleosomes may be very tight or supercoiled if cell is ready to divide

gene

the portion/section of DNA needed to make one specific protein.