Biology Revision

Movement Respiration Sensitivity Growth Reproduction Equilibrium Excretion Nutrition

• all living things are made up of cells

• cells are the smallest and most basic unit of life

• all cells come from pre-exisiting cells

membrane cytosol ribosomes DNA

Single loop of DNA (circular)

Multiple strand of linear DNA

controls what can and cannot enter the cell

contains salts, nutrients, and molecules (its fluid)

cytosol and all organelles (not nucleus) make the cytoplasm

double membrane, protect and confine DNA which codes for proteins

Site of ribosome production

rRNA and proteins, subunits makes proteins

Synthesises and modifies proteins

Production of lipids

Protein sorting, modifying and packaging

breaks down cell waste and toxins

2 membrane, site of aerobic cellular respiration, producing ATP

• contains its own DNA and ribosomes

double membrane, site of photosynthesis, own DNA and ribosomes

water and solute storage, turgor pressure of cell

sturdy border outside plasma membrane and provides strength and structure

membrane bound sac that transports substances in/out of cell or stores them

Protein filament, maintaining shape and transporting vesicles around cell

Glucose + oxygen -> carbon dioxide + water + energy C6H12O6 + 6O2 -> 6CO2 + 6H2O + 36 ATP

Carbon dioxide + water -> glucose + oxygen 6CO2 + 6H2O -> C6H12O6 + 6O2

Occurs in chloroplasts Green pigment chlorophyll in chloroplast absorbs light to energise reactions Glucose produced is used to build cell walls and carry out metabolic reaction Excessive glucose stored in seeds as starch

Material exchange can occur efficiently due to high surface area to volume ratio Distance to travel within cell is smaller so transport of molecules is faster

larger - more exposed area

Made of (phospho)lipids and is selectively permeable to seperate intra and extracellular environment

Proteins, carbohydrates and cholesterol

Glycerol and phosphate group

negatively charged

Hydrophilic - loves water - polar

fatty acids

Hydrophobic - hates water - non-polar

uncharged

Because they are amphipathic - contain both hydrophobic and hydrophilic components

Transport - channels and pumps control what enters/exits cell Adhesion - Stick to other cells, extracellular matrix or cytoskeleton Catalysis - speeds up chemical reaction with proteins (enzymes) Communication - signals and regonise cells and molecules

Integral - permanent part of membrane Transmembrane - Integral proteins which span entire bilayer Peripheral - temporal attached to membrane

In chains which extend outside of the cell Rooted in membrane to lipids (glyco) or proteins (glyco)

Signalling and Communication with cell Recognition of self or non-self molecules

Lipid steroid embedded between fatty acid tails of phospholipid bilayer in animal cells

Regulates membrane fluidity

• If hot keeps molecules bound together (phospholipids)

• If cold disrupts fatty acid tails, stopping phospholipids from being a solid boundary

Molecules in membrane are not static/ not held in one place Different molecules embedded in membrane Moves laterally (side to side)

Movement of particles down a concentration gradient

• from area of high concentration to area of low concentration

• non-polar

• uncharged

• hydrophobic

• small molecules (uncharged)

Kinetic energy causes molecules to randomly move and bounce off each other, eventually leading to even particle distribution

• because of this higher temperatures = faster diffusion

thing being dissolved

Thing being dissolved into

When concentration gradient is steeper

passive movement of molecules down the concentration gradient through a membrane bound protein (protein channel or carrier protein) Allows larger/polar molecules to pass through membrane STILL A PASSIVE PROCESS

Pores/holes in the membrane which let specific substances through

Binds to substance being transported and undergoes conformational change to push substance down concentration gradient through membrane

• returns to its original shape once the molecule is transported

Diffusion of water from area of low solute (high solvent) concentration to area of high solute (low solvent) concentration

Can diffuse because of their small size

Aquaporins

High solute concentration (water moves in)

Equal solute concentration (no net movement of water)

Low solute concentration (water moves out)

Lysed - Too much water moves in and cell swells and bursts

Transporting substances across the membrane using energy

Against

Energy (ATP) Membrane proteins - pumps and carriers

• Binding - binds to specific protein pump

• Conformational change - energy released when bond is broken between 2nd and 3rd phosphate ions when ATP becomes ADP + P

• Release - pushed through protein and into other side of membrane

Movement of groups of molecules across plasma membrane using vesicles

1. Vesicular transport - vesicle containing secretory products transported to plasma membrane

2. Fusion - membranes of vesicle and cell fuse

3. Release - Secretory products released from vesicle and leave cell

Because membrane is fluid and fuses with vesicle When the vesicle fuses, it adds phospholipids and makes SA slightly bigger

• contents of vesicle released from the cell

Phospholipids are added to membrane

• Transport into the cell

If invaded, a lysosome cans enter and digest invader

1. Fold - membrane folds inwards and forms cavity that fills with extracellular fluid and target molecules

2. Trap - folds in on itself until 2 ends meet and fuse

3. Bud - Vesicle (endosome) pinches off from membrane

Phospholipids are removed from membrane

Endocytosis of solid material or food particles

Endocytosis of liquid or dissolved substances

• growth and development

• maintenance and repair

• reproduction

2 genetically identical copies of a cell

1. DNA unclouded and replicated

2. Cell elongates and DNA duplicate move to opposite sides

3. Cytokinesis - pinches inwards and creates a septum

4. New wall and membrane formed down middle

5. seperate and 2 genetically identical cells are formed

plasmids replicate Independently therefore aren't distributed evenly

Cell synthesises the DNA, proteins and organelles required for growth/replication

chromatin threads not chromosomes

• Increase in cytosol volume

• Synthesising proteins for DNA replication

• Replicating its organelles At the end, cell either proceeds to S or exits cell cycle and enters G0 phase

• cells which don't need to replicate rest here

A cell which is dormant and can re-enter the cell cycle

A cell which is fully specialised and no longer replicates - remains in G0 indefinitely

replicates DNA

• 1 chromosome becomes 2 genetically identical sister chromatids

• centromere holds them together

• increase of volume in cytosol

• synthesis proteins to prepare for mitosis

• Prophase

• Metaphase

• Anaphase

• Telophase

Condensation of chromatin so chromosomes become visible Centrioles move to opposite poles Spindle fibres begin to form Nuclear membrane breaks down

• Spindle fibres are fully formed and attach to each chromosomes centromere

• The fibres guide chromosomes to line up at equator of cell

• spindle fibres contract and splits centromere

• sister chromatids pulled to opposite ends of cell

• spindle fibres disintegrate

• a cleavage furrow forms (animals)

• a cell plate forms (plants)

Cytoplasm divides and and organelles evenly distribute before separating into daughter cells

Checks if

• Cell has grown to correct size

• DNA has been damaged

• If there is sufficient nutrients for mitosis

checks if

• DNA replicated properly in S phase

• Cell has enough resources for mitosis

checks if

• Spindle fibres have formed and formed correctly

• Chromosomes are lined up in correct location

Mitochondrial (internal) Death Receptor (external)

Mitochondria - then releases cytochrome C to bind with proteins

Death signalling molecules are recognised by death receptor proteins on a cells surface (generally released by immune cells)

Molecules then bind to death receptor surface protein