A&P: Cellular level

Quizlet Annie Song (Class 21?)

Cell

the smallest structural and functional unit of an organism

Cell doctrine

1. All living things consist of one or more cells

2. Each cell can live independently of the rest

3. Cells can arise only from other cells

Prokaryotic and Eukaryotic

What are the 2 types of cells?

37.2 trillion

Average adult human body is made of about ____________ of cells

200

Cells can be classified into about ____________ different cell types

Reproductive cells

Gametes(sperm & egg)

Somatic cells

All other body cells

Plasma memberane

-flexible outer surface

-selective barrier

-plays key role in communication among cells and environment

Cytoplasm

Includes all cellular contents except the nucleus

-Consists of cytosine and organelles

Nucleus

-largest organelle

-contains the chromosomes (that house the DNA molecules with the genes)

fluid mosaic model

model that describes the arrangement and movement of the molecules that make up a cell membrane

-continually moving sea of fluid lipids with a mosaic of many different proteins

-some proteins float freely as icebergs, others are anchored at specific locations

Why a fluid mosaic?

Selective permeability

What's the most important property of the plasma membrane?

-Lipid-soluble substances pass

-barrier for polar substances

-some membrane proteins allow polar substances to pass and move in

What is the selective permeability of the plasma membrane?

Amphipathic

The plasma membrane is a lipid-bilayer structure composed of __________ molecules

One that have one water soluble end and another lipid-soluble end

What is an amphipathic molecule?

-phospholipid (75%)

-cholesterol (20%)

-glycolipids (5%)

Which are the amphipathic lipids of the plasma membrane?

Integral protein

-many are glycoproteins

-extend through bilayer (transmembrane)

-anchored, don't move

Peripheral protein

-attached to the polar heads

-attached to integral proteins at the inner or outer surface

protrudes into the extracellular fluid

The "glyco" portion of the glycoproteins in the membrane are oligosaccharides (sugar) and _____________________

protrudes into the extracellular fluid

The "sugar" portion of the glycolipids in the membrane ___________________

Glycocalyx

An extensive sugary coat in the outside of the membrane form by the "sugar" portions of both glycoproteins and glycolipids

unique

The pattern of the sugars in the glycocalyx is ____________to the cell

-cell can recognize one another

-WBCs can recognize a "foreign glycocalyx"

-enables cells to adhere to one another

-protects cell against digestive enzymes

-attracts a film f fluid to the surface of many cellls

What are the functions of the glycocalyx?

1. Ion Chanel

2. Carrier protein

3. Receptor protein

4. Enzyme protein

5. Linker proteins

6. Cell identify protein markers

What are the 6 membrane integral proteins?

Ion channels

Pores for one specific ion

Receptor protein

-serve as a recognition site

-it binds to one specific molecule (ligand)

carrier proteins (transporters)

Move one polar substances or ion across

Enzyme protein

Catalyzes reaction at the membrane or inside the cell

Linker proteins

Anchor membrane proteins of neighbouring cells

Cell identify protein markers

-Glycocalyx

1. Support plasma membrane

2. Anchor integral proteins

3. Participate in the intracellular movement of materials

4. Attach cells to one another

What are the functions of the peripheral proteins?

Rotate, move

Most membrane lipids and many proteins ___________ and ____________ sideways

Cholesterol

___________makes the bilayer stronger but less fluid at body's temperature

more fluid but less strong

In low temperature, cholesterol makes the membrane:

Allows interactions within the membrane including:

1. Movement of components (growth, division, secretion)

2. Formation of the cellular junctions

3. Self-healing if torn or punctured

Why is membrane fluidity important?

Non polar molecules : O2, CO2, steroid

The membrane is high permeable to:

Small uncharged molecules: (H2O, urea)

The membrane is moderately permeable to:

Ions, large uncharged molecules (glucose)

The membrane is impermeable to:

transmembrane proteins

______________ allows a variety of ions and uncharged polar molecules to pass

endocytosis and exocytosis

The proteins can pass only by:

1. Simple diffusion

2. Facilitated diffusion (channel-mediated, carrier mediated)

3. Osmosis

Passive transport across the plasma membrane

Hydrophobic

________________ substances move freely through the bilayer down their concentration gradient

Channel-mediated facilitated diffusion

-substance moves down its concentration gradient through a channel, very fast

-most membrane channels are ion channels

Carrier-mediated facilitated diffusion

An integral membrane protein undergo changes in shape to move a substance across down its concentration gradient

Osmosis

Net passive movement of water though a selective permeable membrnae

-Simple diffusion

-aquaporins

High water concentration moves to area of lower water concentration by:

hydrostatic pressure

The pressure exerted by the moved water

-forces water to move back until the same amount of water moves in each direction

Osmotic pressure

The pressure exerted by the solute particles in the solution that cannot cross the membrane

-directly proportional to the concentration of the solution

Same

The normal cell's volume remains constant because the osmotic pressure in the ECF is ______________as the osmotic pressure of the ICF

Isotonic

The solution in which the cell maintains its normal shape

Primary active transport

pumping solutes against a concentration gradient using ATP

Ex. Na-K pump

Na+/K+ ATPase

Sodium-potassium pump is also known as as:

Hydrolytic enzyme

The functioning sodium-potassium pump in the cell spends such a large amount of ATP that it is acting as a _______________ for ATP

-maintains low concentration of Na+ and high concentration of K+ within the cytosol

Function of Na/K pump

1/3

Under normal circumstances, about _________ of the total energy of the body at rest is consumed to keep the Na/K pump working

1. Osmotic stability

2. Secondary active transport

3. Bioelectricity

4. Metabolism

Why is it worthy for the body to spend so much ATP in once process?

Secondary active transport

Use electrochemical gradient across a plasma membrane as it energy source to move molecules against its concentration gradient

Symporters

Move substances in the same direction

Antiporter

Move substances in opposite directions

Endocytosis

materials move into a cell in a vesicle formed from the plasma membrane

Exocytosis

Materials are moved out of the cell by the fusion of vesicles with the plasma membrane

Energy

Transport in vesicles requires_________________

1. Receptor-mediated endocytosis

2. Phagocytosis

3. Bulk-phase endocytosis (pinochtosis)

What are the 3 types of the endocytosis?

receptor-mediated endocytosis

-highly selective, cell takes up a specific substance that binds to the membrane

-membrane in-vaginitis and forms a vesicle

-the vesicles is surrounded by lysosomes and digested

-psudopods surround the particle

-forms the phagosome

-phagosomes are surrounded by lysosomes

-particle is digested

Describe the process of phagocytosis

-macrophages

-neutrophils

What are carried out by the phagocytes?

bulk-phase endocytosis (pinocytosis)

Droplets of ECF are brought into the cell:

-membrane forms vesicles

-vesicles are surrounded by lysosomes

-contents are digested

Exocytosis

Release materials from the cell

-membrane-enclosed vesicles within the cytoplasm fuse to the membrane and release the contents into ECF

Secretory cells (hormones, enzymes, mucus, sweat), neurons (NTs)

Exocytosis is carried out by all cells, specially:

Transcytosis

Used by the cell to move substances in, across, and the out of the cell

-how nutrients are absorbed in the intestines into the blood