Bio module 2-cells

Cytology

the study of cellular function and structure

Plasma membrane

forms a cells surface boundary sh. forms cells shape

Cytoplasm

the material between the plasma membrane and nucleus

parts:

• cytoskeleton

• organelles

• inclusions

• cytosol

Cytoskeleton

network of protein filaments and tubules in cytoplasm that structurally support cell

What are the main components of the cytoskeleton?

• microfilaments

• intermediate filaments

• microtubules

What function does the cytoskeleton serve?

• determines cell shape

• contributes to cell movements

• organizes content

• transports substances

Organelles

diverse structures that perform tasks for the cell

Inclusions

A nonessential cell component with no membrane that contains accumulated cell products like fats and pigments as well as viruses and bacteria

Cytosol

clear gel containing enzymes and other proteins that embeds the cell components sh. the fluid in the cell

What are the functions of the plasma membrane?

• governs interactions with other cells

• defines the boundary of the cell

• maintains chemical difference between ECF and ICF

• contributes to movement of cell components

What is the plasma membrane made up of?

a two layered lipid film with embedded proteins

Phospholipids

make up 75% of membrane lipids

Cholesterol

make up 20% of membrane lipids

Functions of membrane proteins

• receptor

• channel

• enzyme

• gated channel

• cell identifier marker

• cell adhesion molecule

Glycocalyz

a fuzzy carbohydrate coat covering cells that is made up of the sugar chains glycolipids and glycoproteins

What are the functions of the glycocalyx?

• cell adhesive

• protects plasma membrane

• identifies self-cells from foreign cells

What are the four cell surface extension types?

• microvili

• cilia

• flagellum

• pseudopods

Microvilli?

extension with finger shaped projections of the plasma membrane

functions: increases surface area for absorption and secretion

Cilia

hairlike extensions of the plasma membrane

functions: helps move things like mucus

ex. move mucus from lungs up to throat

Flagellum

extensions that resemble a long and solitary cilium sh. essentially a tail attached to a cell

function: helps cell move

Pseudopods

cytoplasm filled extensions of a cell

function: form fake arms that play a role in movement and help cells to eat

What are the functions of extensions?

• absorption

• movement

• sensory processes

• phagocytosis

Macrophages

cells that use pseudopods to engulf bacteria

What are the functions of cell junctions?

• link cells together

• attach cells to extracellular material

Tight junctions

these junctions fully encircle epithelial tissue and join it securely to adjacent cells making it difficult for substances to leak between cells

Desmosomes

holds cells together at a specific point and keeps them from pulling apart. enables tissues to resist mechanical stretching.

ex. common in skin and cardiac muscles

Gap junctions

formed by ring of proteins that surround a channel and is used for the diffusion of ions, glucose, and other solutes.

Filteration

A process in which external pressure forces fluid through a selectively permeable barrier and holds back large particles while allowing water and small particles to pass through.

sh. the passage of fluid

Simple diffusion

the net movement of particles from high to low concentration with random motion of molecules providing energy for diffusion.

ex. simple diffusion seeks to achieve balance

Osmosis

the net movement of water from lower to higher solute concentration

Tonicity

the ability of a solution to change intracellular pressure and the volume and shape of a cell

Isotonic

• extracellular fluid has an equal concentration of solutes as the intracellular fluid

• cells gain and lose water by an equal rate sh. cell does not change shape

Hypertonic

• extracellular has a higher concentration of solutes than intracellular fluid

• draws water out of cell and cell shrinks

Hypotonic

• extracellular fluid has a lower concentration of solutes than intracellular

• water enters cell and cell swells

Active transport

like facilitated diffusion, is a carrier mediated transport

What is the difference between active and passive transport?

Active transport requires ATP (energy) while passive transport does not

Vesicular transport

substances move through membranes in vesicles (resemble bubbles or sacs)

Endocytosis

brings matter into cell

Phagocytosis

A type of endocytosis that is “cell eating” and uses pseudopods to reach out and surround particles

Pinocytosis

A type of endocytosis that is “cell drinking” that starts off with the formation of dimples that cave in and pinch off as vesicles

Receptor mediated

This type of endocytosis is more selective, and the cell can take in specific molecules from the ECF through receptor proteins on plasma membrane

ex. absorption of insulin from blood

Exocytosis

exports matter from cell

How does exocytosis occur?

cell vesicle migrates to surface, fuses with plasma membrane and ruptures, releasing products from the cell