Biology Topic 2 - Molecules and Movement

Diffusion

the net movement of particles from a region of high concentration to low concentration (passive process)

Active Transport

the uptake of molecules or ions from a region of low concentration to high concentration across a selectively permeable cell membrane (active process)

Osmosis

movement of water from area of high concentration to low concentration through a semi-permeable membrane

Turgid

cell with a lot of water

Flaccid

cell with not enough water

Where does diffusion occur?

In lungs - gas exchange in alveoli

Where does osmosis occur?

In all cells to transfer water

Where does active transport occur? (2)

In root hair cells - to absorb minerals from soil

In small intestine - in villi to absorb minerals from food into blood

Which molecules are organic and why?

Carbohydrates and lipids - they contain just C, H and O

Which molecules are inorganic and why?

Protein - it contains N and S

Monomer

smaller basic unit

Polymer

multiple monomers in a chain

Enzyme

protein that functions as a biological catalyst

Enzyme-substrate complex

when enzyme and substrate are locked in together

Denatured

active site has changed shape

What denatures the active site?

Extreme temp

Inappropriate pH

Protease —>

protein

Carbohydrase —>

carbohydrate

Lipase —>

lipids

Amylase —>

starch

Active site

The part of the enzyme to which a specific substrate can attach or fit on to

lock and key hypothesis

substrate must be specific to enzyme like a lock and key

substrate

the specific molecule or substance upon which an enzyme acts

metabolic reactions

reactions that take place in cells

What is the optimum temperature for enzymes?

37 degrees

Test for glucose - colour change

Benedict’s solution + heat - blue to green yellow (a bit)/brick red (a lot)

Test for protein - colour change

Biuret’s reagent - blue to purple

Test for lipids - colour change

Ethanol + distilled water - transparent to cloudy

Test for starch - colour change

iodine solution - orange to blue-black

What factors increase the rate of diffusion?

Large SA to V ratio

Short diffusion distance

High temperature

Steep concentration gradient

Substrate must be _______ to enzyme active site shape

complementary

Diffusion (extra details)

high to low

passive

in liquids and gases - transports solutes

Osmosis (extra details)

high to low

passive

in water only (not gases)

requires a semi-permeable membrane

Active Transport (extra details)

low to high

active

transports solutes

requires a semi-permeable membrane

Carbohydrate chemicals

C H O

Carbohydrate monomer

glucose

Carbohydrate function

main source of energy for respiration

Carbohydrate polymers

starch, glycogen, cellulose

Lipids chemicals

C H O

Lipids made of…

1 glycerol + 3 fatty acids

Lipid function

essential part of cell membranes

act as insulator

Lipid polymer

Cholesterol

Protein chemicals

C H O N S

Protein monomers

amino acids

Protein function

needed for growth and repair

protein polymer

enzymes, haemoglobin, hormones

Catalyst

Thing that speeds up reaction but does not get used up/changed in reaction