2.1 and 2.2 Flashcards
(36 cards)
Why is the cytoskeleton important?
It is the framework of the eukaryotic cell.
It is made up of microtubules and microfilaments.
It gives the cell shape and allow materials to move.
Describe a prokaryotic cell?
No nucleus Circular DNA No membrane bound organelles Very small cells Small ribosomes
Describe a Eukaryotic cell?
Nucleus present Linear DNA Has membrane bound organelles Larger cells Larger ribosomes
What is magnification?
How much bigger the image size is than the specimen
What is resolution?
How well a microscope is able to distinguish between two objects close together
Describe a light microscope?
Uses light
Gives true colour images in 2D
Describe a laser scanning microscope?
Uses laser beams to scan specimen
Gives 3D image in fluorescent colouration
Describe a scanning electron microscope?
Scans a beam of electrons across a specimen
Gives a 3D image in black and white
Describe a transmission electron microscope?
Uses a beam of electrons
Gives a 2D image in black and white
High resolution
Only used on thin specimens
How does hydrogen bonding occur between water molecules?
A water molecule consists of two hydrogen atoms covalently bonded to one oxygen atom.
The oxygen atom has more positive protons than the hydrogen making oxygen more electronegative.
This means that it has a greater pull on the shared electrons making oxygen slightly negative and hydrogen slightly positive.
This is why water is a polar molecule.
When two H2O molecules are next to each other the slightly negative oxygen becomes attracted to the slightly positive hydrogen. This attraction form Hydrogen bonding.
What are the properties of water?
- Good solvent - The positives and negative pars of water attract to the negative and positive parts of the solute forming a solution
- High specific heat capacity - A large amount of energy is needed to raise the temperature of water (4.2kj of energy to raise the temperature of 1kg of water by 1 degree)
- High latent heat of evaporation - A large amount of heat energy is needed for water molecules to evaporate due to the hydrogen bonds (when sweat evaporates it cools skin)
- High cohesion - Water molecules stick together well beachside they’re polar. This helps water to flow making it good at transporting substances
Plus High surface tension & ice is less dense than water
What are monosaccharides?
The simplest carbohydrates
Simple single sugars
CnH2nOn
Act as a source of energy
Sweet and soluble
What are Disaccharides?
Made of two monosaccharides joined together
Sweet and soluble
When they join a condensation reaction happens forming a glycosidic bond and removing water
Broken by hydrolysis
What are Polysaccharides?
Made up of many monosaccharides joined together
Polymers of monosaccharides
Good energy store because they’re compact so don’t take up a lot of space
Less soluble in water than monosaccharides
Can be structural units
What is Starch?
The main energy storage in plants
It is a mixture of two polysaccharides of alpha glucose
Amylose - long, unbranched (1-4)
Amylopectin - Long, branched (1-4&1-6)
Starch is insoluble in water making it good for storage
What is Glycogen?
The main energy storage material in animals
Glycogen is a polysaccharide of alpha glucose (1-4& 1-6)
Has loads of branches so that stored glucose can be released quickly
Compact so good for storage
What is Cellulose?
The major component of cell walls in plants
Provides structural support for cells
Cellulose is made of long, unbranched chains of beta glucose(1-4)
When B glucose bonds it forms straight cellulose chains linked by hydrogen bonds to form microfibrils
Describe the structure of an Amino acid?
All amino acids contain Carbon, Oxygen, Hydrogen & Nitrogen
Some contain Sulphur
Have a carboxyl group (COOH) and amino group (NH2) attached to a central Carbon
Under the Carbon is a R group that is different for each amino acid
Describe a triglyceride?
Macromolecule
Lipid
Has three fatty acids joined to a glycerol
The fatty acids have hydrophobic tails making lipids insoluble
Synthesised by the formation of ester bonds during esterification
They break down when the ester bonds are broken during hydrolysis
Describe a Phospholipid?
Macromolecule
Lipid
Has two fatty acids joined to a glycerol and a phosphate group
Found in all cell membranes and make up the phospholipid bilayer
The phospholipid heads are hydrophilic and their tails are hydrophobic
The centre of the bilayer is hydrophobic so water soluble substances can’t pass through easily
Describe a Cholesterol?
Lipid
Has a hydrocarbon ring structure attached to a hydrocarbon tail
Small size and flatten shape in order to fit between the phospholipids in the membrane
Bind to the hydrophobic tails so they can pack closer together
Transported in the blood
What are proteins?
They are made from long chains of amino acids
Polymers
What are peptide bonds?
They link amino acids together to form dipeptides and polypeptides
Formed during a condensation reaction
Broken during hydrolysis
What is an organ?
An organ is made up of many tissues that all work together to do the same job
