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GCSE BIOLOGY: Cells and Biological Molecules Cheat Sheet by

The notes for cells and biological molecules for IGCSE EDEXCEL

CELL STRUCTURE

Tissue -
A group of cells working together to carry out a specific function
Organ -
A group of tissues working together to carry out a specific function out
Organ System-
A group of organs working together to carry out a specific function
Organelles found within animal cells -
- Nucleus -mitoc­hondria -ribosomes -cell membrane -cytoplasm
Organelles found within Plant cells -
-Nucleus -Mitoc­hondria -ribosomes -cell membrane -cytoplasm -permanent vacuole -chlor­oplasts -cell wall

CHEMICAL ELEMENTS

lipids
- C, H, O (Carbon, Hydrogen and Oxygen)
proteins
- C, H, O, N, S (Carbon, Hydrogen, Oxygen, Nitrogen and Sulphur)
complex carbs like starch and glycogen are made up of
- simple sugars
Proteins are made up of
- amino acids
the two molecules that Lipids are made up of
- Glycerol and fatty acid tails
 

FUNCTIONS OF THE ORGANELLES

Nucleus
- controls the cell -contains genetic material (In the form of chroma­somes)
Cytoplasm
- where most of the chemical reactions take place
Mitoch­ondria
- where aerobic respir­ation takes place
Ribosomes
- the site of protein synthesis
Cell wall
- provides strength and support (Made out of cellulose)
Permanent Vacuole
- supports the cell and contains cell sap (A solution of sugars and salt)
Chloro­plasts
- the site of photos­ynt­hesis
Cell Membrane
- controls what enters and leaves the cell - separates the cell from its enviro­nment

ENZYMES

enzymes
- biological catalysts that increase rate of metabolic reactions
factors that effect enzyme function
- Temper­ature -pH - Substrate concen­tration -Enzyme concen­tration
effect of temper­ature
-as temper­ature increase, rate of reaction increases UNTIL the temper­ature exceeds the optimum and the rate of reaction begins to decrease
Why does this happen?
as temper­ature increase, particles have more kinetic energy, increasing chance of collision between molecules which speeds up the reaction
when the temper­ature exceeds optimum
- active site distorts as the enzyme denatures and it no longer fits the substrate
effect of pH
- the rate of catalysed reaction is fastest at the optimum pH. If the pH is too high or too low, the enzyme may denature and this affects rate of reaction
 

STEM CELLS (HIGHER)

Differ­ent­iation
- the process by which cells become specia­lised
Stems cells
- unspec­ialised cells that can differ­entiate into lots of different types of cells
ADVANTAGES
-can be used to treat paralysis -possi­bility to cure degene­rative diseases like Parkin­son's -Whole new tissues and organs can be grown for drug testing
DISADV­ANTAGES
-use of embryonic cells creates ethical issues -it's expensive -long-term side effects are unknown

DIFFUSION

diffusion
- the movement of molecules from an area of high concen­tra­tion, to an area of low concen­tration
how does temper­ature affect the rate of diffusion
- as temper­ature increase, rate of diffusion increases as particles gain kinetic energy and move faster
how does concen­tration gradient affect rate of diffusion
- the greater the concen­tration gradient (The difference between the two areas), the greater the rate of diffusion
how does surface area of the membrane affect rate of diffusion
- as surface area increases, rate of diffusion increases as there is more space for the particles to pass through
OSMOSIS
- the movement of water molecules from a high water concen­tration to a low water concen­tration (Down the water potential gradient) through a partially permeable membrane.
ACTIVE TRANSPORT
- the movement of particles from an area of low concen­tration to an area of high concen­tration (Going against the concen­tration gradient)
       
 

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