natural science
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cell biology
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eukaryotic cells
prokaryotic cells
a type of cell that have a true nucleus, DNA in nucleus and membrane-bound organelles. (bigger and more complex) e.g. plant, animal cells, fungi, protists
A type of cell that does not have a true nucleus, membrane-bound organelles and free DNA. (simpler and older) e.g. Bacteria, algae
organelles
plasms
cytoplasm- everything in the cell apart from the nucleus
cytosol- the fluid everything sits in
cytosol+organelles=cytoplasm
Protoplasm- everything in the cell including the nucleus.
nucleus
structure
function
largest organelle
chromatin (dark patches
spherical
surrounded by nuclear envelope
two fluid filed membranes
nuclear pores
contains genetic material
chromatin consists of DNA and proteins
contains instructions for making protein
nucleolus
structure
functions
located inside nucleus
makes RNA and ribosomes
Endoplasmic reticulum (SER/RER)
Structure
function
consist of flattened membrane-bound sacs - cisternae which are continuous with the outer nuclear membrane
smooth ER and rough ER
SER- involved in making carbs, lipids and steroids
RER- transport proteins made on attached ribosomes
golgi body/apparatus
structure
stack of membrane-bound flattened sacs
function
receives protein from the ER
modifies them e.g. adds sugar
packages proteins into vesicles to be transported inside cell or to the outside
mitochondria
structure
function
2 membranes separated by a fluid filled space
inner membrane is folded to form cristae
central part is the matrix
site where ATP is produced during respiration
higher concentrations in metabolically active cells e.g. muscle, liver, sperm
where most respiration reactions happen
lysosome
structure
function
spherical sacs surrounded by a single membrane
contains digestive enzymes which break down materials
e.g. specialised lysosome (acrosome) in head of sperm cells helps penetrate the egg
cell membrane
structure
function
composed of a phospholipid bilayer with embedded proteins
selectively permeable to ions and organic molecules and regulates the movement of substances in and out of cells
Centrioles
structure
function
small protein tubes of microtubules
form fibers in cell division known as spindles which separate chromosomes
ribosomes
structure
function
very small organelles in the cytoplasm and bound to rough ER
consist of 2 subunits
site of protein synthesis (the process in which cells make proteins) which acts as an assembly line to use mRNA to assemble proteins
biological molecules
Carbohydrates
living organisms need carbohydrates - to act as a source of energy e.g. sugars, starch, glycogen - to play a structural role in plant cell walls e.g. cellulose
Glucose
isomers are molecules with the same molecular formula as each other, but with the atoms connected in a different way
β glucose 
α glucose
large chain of monomers is called a polysaccharide
plants form starch
aniamls form glycogen
valuable storage molecules that can be broken down into monosaccharides when energy is required
pair of monomers is called a disaccharide
glucose + galactose --> lactose
glucose + fructose --> sucrose
Glucose + glucose --> maltose
When combined in pairs, monosaccharides form disaccharides, forming a Glycosidic bond
single is called a monosaccharide
part of nucleotides
source of energy in respiration
building blocks for polysaccharides
formula e.g. glucose
soluble substances
monomer is a saccharide
protein
protein structure
quaternary
two or more polypeptide chains in tertiary form combined to form complexes joined by bonds similar to those in tertiary structure
Tertiary
the folding on the alpha helix to form very specific 3D shapes, maintained by bonds
secondary: beta pleated sheet
less common. formed by hydrogen bonding between the peptide bonds in the polypeptide chain
secondary: alpha helix
most common secondary form, formed by hydrogen bonding between the peptide bonds in the polypeptide chain
primary
the type, number and sequence of amino acids in a polypeptide chain, linked by peptide bonds only
polymerization through condensation to form peptide bonds
20 different amino acids -- usually R group varies
chain of amino acids is a polypeptide (simplest form of protein)
made of amino acid monomers
Proteins are made of C, H and O in addition to Nitrogen.
Some can also contain sulphur and phosphorus, but always look out for the nitrogen.
nucleic acids
RNA - ribonucleic acid
URACIL
ADENINE
GUANINE
CYTOSINE
DNA - deoxyribonucleic acid
double strands
GUANINE + CYTOSINE - triple bond
ADENINE + THYMINE - double bond
made of nucleotide monomers
1 nucleotide is made from -
1 phosphate - up the side
1 base - up the side
1 pentose sugar - in the middle
polymers are DNA and RNA
lipids
phospholipid
'head' is the hydrophilic phosphate group
the 'tail' is the hydrophobic fatty acids
formed when 2 fatty acids and a phosphate group join to a glycerol
monomer is called a glycerol -- when condensation reaction occurs, ester bonds are formed to form glycerides e.g. triglycerides (3 fatty acids and 1 glycerol)
used for water proofing, insulation and protection
source of energy
contribute to the flexibility of cell membranes
made of carbon, hydrogen and oxygen plus phosphorus as phosphate in phospholipids (not in set ratio(