Biology; membranes and enzymes

Meaning of the compartmentalization and its advantages.

Under compartmentalization is meant, that the cell is divided into "rooms" to allow different conditions for  each compartment. Examples: cytosol, membranes, organelles.

plasmatic and non-plasmatic phases

Plasmatic: water and proteins, thicker

Non-plasmatic: watery, not many or even none proteins

organelles with two, one and no membranes

Double membrane: nucleus, mitochondria, plastids

Single membrane: Golgi apparatus, vacuole, vesicles, endoplasmic reticulum (rough and smooth), lysosomes

No membrane: ribosomes, nucleolus, cytoskeleton -> composed of proteins and nucleic acids

1: channel, pump or carrier

2: integral protein

3: peripheral protein

4: phospholipid

5: phosphate group / hydrophilic side of phospholipids

6: non-polar tails of phospholipid / hydrophobic end on phospholipids

7: phospholipid bilayer = membrane

definition of fluid mosaic for biological membranes

Fluid because the molecules can move freely, mosaic because of the diversity of molecules.

process of simple diffusion

solutes from the side with higher concentration to the side with lower concentration of the membrane

process of facilitated diffusion

solutes pass through the membrane with the help of channel proteins

process of active transport

molecules are pumped from the side with lower concentration to the side with higher concentration → process requires energy from ATP

process of exocytosis and endocytosis

endocytosis: cell membrane buds inwards creating a pouch and fills with solutes / pouch grows, closes and separates from the membrane / outer solutes now in vesicle inside the cell

exocytosis: molecules to be exported packed in a pouch moving towards the cell membrane / membrane and vesicle fusing / content spilled out outside

examples for transport types (simple diffusion, etc.)

simple diffusion: fatty acids

facilitated diffusion: H₂O

active transport: K⁺

exocytosis / endocytosis: proteins, particles

definition of phagocytosis

Cellular eating: particle is taken into the cell through endocytosis → in a vesicle, fuses with a lysosome → smaller cell broken down

examples: white blood cells, enzymes

definition metabolism

total of chemical reactions in an organism both inside and in between the cells

definition activation energy

certain amount of energy needed to start a chemical reaction, it lowers some kind of barrier around the cell to make it more likely for the reaction to take place

definition active site and induced fit

active site: site of an enzyme (pouch) with the right shape and chemistry (right amino acids in the right places) for the substrate

induced fit: the active site changes slightly to the substrate

steps of an enzyme catalyzing a reaction

substrate binds to the active site / induced fit started by substrate → catalyzing the reaction / products released from active site / new substrate binds the enzyme

(enzymes are reusable)

5 factors affecting the activity of the enzymes

• product concentration (own product binds enzyme in case of overproduction)

• availability of cofactors (cofactors = chemical compounds; low availability → low activity)

• substrate concentration (fewer substrates → fewer substrates, fewer products)

• temperature (best activity around body temperature → 36.5°C)

• pH (preferred pH range)

2 ways of the cell changing its concentration

increased enzyme concentration → more products

increased rate of breaking down enzymes (high → low)

2 enzymes with their substrates and products

lactase → lactose → glucose + galactose

amylase → starch → maltose

2 ways of inhibitors inhibiting enzymes

binding the enzyme outside its active site, altering the active site

substrate imposter blocking the active site from “real” substrate