Cells and Biological Molecules Flashcards
What is a cell? What do they do?
cells are the fundamental unit of all living things
on earth
- they take nutrients and free energy from surroundings and make copies of themselves
What are the universal features of all cells on Earth?
all cells are surrounded by a plasma membrane
- made up of lipid molecules arranged in a bilayer
cell exchange molecules with their surroundings
- including sugars, amino acids, peptides, ions
cells are able to communicate
- via extracellular signalling molecule binding to a receptor, initiating intracellular signalling proteins then effectors
all cells store their hereditary information as DNA
- genetic information
gene expression
- the DNA fragment corresponding to one protein is a gene
cells translate RNA into protein in the same way/process
What are the properties/features of eukaryotic cells?
rough and smooth endoplasmic reticulum mitochondrion cell membrane ribosomes = 80S lysosomes golgi apparatus cytoplasm nucleus = membrane bound
What are cells made up of?
- simplest component
sugars - form polysaccharides fatty acids - form fats, lipids and membranes amino acids - form proteins nucleotides - form nucleic acids = DNA, RNA
What is homeostasis?
the ability or tendency of an organism or cell to maintain internal equilibrium by adjusting its physiological processes
What are the different types of homeostasis?
chemical - molecules in cells or blood
cellular - maintenance of sub-cellular structures; proper distribution of organelle
systemic - blood pressure, water balance, temperature
populations - changes in prey and predator population
biosphere - global cycles between atmosphere, oceans, rocks, and living organisms
What is the meaning of life as a ‘pattern of flux’?
it means all constituents of living matter, functional or structural are in steady state of rapid flux
- molecules are constantly being replaced by the same molecules = structure stays the same
How have cells evolved from a common ancestor?
cells have evolved from a common ancestor and split into three main domains
- bacteria
- archaea
- eukaryotes
What are biological molecules? What is the function of small molecules?
biological molecules are carbon based except for some small inorganic molecules
small molecules play two roles
- are the building blocks for macromolecules
- have their own specific function
What is the function of carbohydrates?
energy storage
fuel
metabolite
structural element
What are monosaccharides? disaccharides? polysaccharides? oligosaccharides?
monosaccharides
- can be ketone or aldehyde based = ketoses and aldoses
- have chiral centres therefore have enantiomers
disaccharides
- formed by a condensation reaction (releases water) between two monosaccharides
polysaccharides
- formed by many monosaccharide molecules joined together
oligosaccharides
- polymer consisting of a small number of monosaccharides (different monosaccharides)
- blood groups
What are the different types protein structure? What is the primary structure?
primary, secondary, tertiary and quaternary structure
primary structure
- covalent bonds forming a polymer = order of amino acid residues joined by peptide bonds
peptide bond between amino acid is a type of covalent bond
What is the secondary structure?
regular folded form, often stabilised by hydrogen bonds
- alpha helices and beta sheets
What is the tertiary structure?
overall 3D structure = more folding and twisting
- stabilised by hydrogen bonds, hydrophobic forces, hydrophilic forces, disulphide bonds, ionic bonds and Van Der Waals forces
What is the quaternary structure?
organisation of polypeptide chains/macromolecules into assemblies, often stabilised by ionic bonds
- several polypeptide chains can make up a protein
What is the structure of nucleotides? What do they form?
consists of
- a nitrogenous base
- a sugar = ribose (RNA) or deoxyribose (DNA)
- phosphate molecule
nucleotides can join up to form nucleic acids
- DNA or RNA
- DNA is more stable due to the oxygen difference
What are the functions of nucleotides?
energy unit - ATP
second messenger - cAMP
involved in RNA synthesis - AMP
What are fats? What is their function?
fats are glycerol esters of fatty acids
- act predominately as food reserves = for energy
What are triglycerides and phospholipids?
triglycerides
- made up of glycerol and 3 fatty acid chains
phospholipids
- made up of glycerol, 2 fatty acid chains and a phosphate group
- form phospholipid bilayer, micelles, liposomes
What is cholesterol? What is its function? What is its affect on the plasma membrane?
cholesterol is a steroid
- can intercalate (insert) into the membrane by having its OH group interact with the polar lipid head and its steroid scaffold with the fatty acid
- decreases fluidity and increases flexibility of the membrane
- decreases the membrane permeability for water soluble molecules
