L1 Flashcards
What are all biological entities capable of autonomous existence built of?
Cells
What are the three domains of life?
Bacteria, archaea, eukarya
What are the two types of cells?
Prokaryotic and eukaryotic
Bacteria and archaea are prokaryotic
All other cells are eukaryotic
What do typical eukaryotic cells (animal and plant) consist of?
Nucleus and DNA, vacuole (plant), Golgi, rough ER and ribosomes, plasma membrane, mitochondria, chloroplasts (plant) cell wall (plant), microvilli (animal), flagellum (animal).
What does a typical prokaryotic cell contain?
Bacterial chromosome, nucleoid, ribosomes, plasma membrane, cell wall, capsule, flagella, fimbriae.
Prokaryotic cells vs eukaryotic cells - differences?
Prokaryotic - limited. Transcription and translation coupled, smaller 70S ribosomes, no endo/exo
Eukaryotic - RNA processed in nucleus and exported, larger 80S ribosomes, exo/endo of certain substances.
What do all organisms consists of?
Water and four basic classes of macromolecules.
Carbohydrates, proteins, nucleic acids (monomers covalently linked to form polymers)
lipids (phospholipid monomers and non covalently linked.
How are macromolecules built and broken down?
Connected together by condensation/dehydration reaction
Broken down by hydrolysis
What do synthesis and breakdown require
Enzymes
What are enzymes?
Specialised proteins that catalyse chemical reactions in biological systems.
What are carbohydrates used for?
Used for fuel and building materials. Sugars = energy used by cells. Sugar polymers = used by animals and plants as stores or fuel, or given structural roles. Carbohydrates are monomers and polymers of sugar.
What is polysaccharides synthesis?
Sugar polymers are synthesised by stepwise condensation reactions. Sugars are combined through dehydration reactions, water is produced as a by-product. Monosaccharides are linked together by glycosidic linkages to form polysaccharides. Different glycosidic linkages between different OH groups on reacting sugar molecules.
How are polysaccharides stored in plants and animals?
In plants as starch, composed of two distinct glucose polymers - amylose and amylopectin. Starch is stored in plasmids.
In animals as glycogen, multibranched polysaccharide of glucose, in muscle and liver cells.
What is a structural polysaccharide example?
Cellulose - glucose polysaccharides. Form microfibrils.
What is another structural polysaccharide example?
Chitin polymer made of sugars, N-acetylglucosamine. Chitin is strong and durable and can be used to make threads for stitching wounds.
What are lipids?
Lipids are characterised by their hydrophobicity, they assemble into fat droplets or bilayers.
What are triglycerides and what does there synthesis involve?
Common forms of fat, ester derived from glycerol and three fatty acids. Synthesis involves three dehydration reactions between glycerol and fatty acids.
What are phospholipids?
Glycerol linked to two fatty acids, a phosphate and hydrophilic chemical. They are both hydrophilic and phobic. They self assemble into bilayers in water.
What is cholesterol?
Sterol, found in many bio membranes, it is synthesised in the liver of animal cells. Decreases membrane fluidity, precursor for many steroid hormones.
What are proteins made of?
Amino acids which contain an amino group, carboxylic acid, central carbon atom, linked to a hydrogen atom and variable R side chains. These side chains can be polar, non-polar, acidic or basic. There are 20 different amino acids. Arrangement of amino acids give proteins they exact function, properties and structure.
What happens on protein synthesis?
Peptide bonds are formed during dehydration reactions - peptide bonds. Synthesised by ribosomes, every peptide has N and C ends. Protein synthesis - amino acids are added to the C end.
What are the four levels of protein structure?
Primary - order of AA, secondary - folding of regions into local structures, tertiary - arrangement of secondary structure into a stable protein. Quaternary - arrangement of more than one polypeptide to make a functional protein.
What are nucleic acids and nucleotides?
Nucleic acids (DNA + RNA) are the genetic material of all forms of life. A long chain of nucleotides is called a polynucleotide (RNA/DNA). The basic building blocks of nucleic acids are nucleotides.
What is a nucleotide composed of?
Pentose sugar, phosphate group, nitrogenous base.
What can the sugar be?
Deoxyribose - DNA (1 OH at 3C)
Ribose - RNA (2 OH at 2 + 3C)
What is the phosphate group?
Attached to 5’ carbon of the sugar
What are the possible nitrogenous bases.
Adenine, guanine, cytosine, thymine, uracil
How are nucleotides joined?
Successive nucleotides are joined by phosphodiester bonds (between 3’ and 5’ carbon). One end of the chain has a free 5’ end and the other end of the chain has a free 3’ end.
What is the structure of DNA?
A double helix. One strand runs in 5-3 and the other 3-5. The double helix maintains a constant width because purines always face pyrimidine in the complementary A-T and G-C base pairs. The nitrogen bases form sugar phosphate back bones held together by hydrogen bonds. G-C 3 h bonds, A-T 2 h bonds
Nucleic acids and biological information?
Each cell has a genome of DNA, encodes proteins, DNA is converted into RNA (nucleus), mRNA is converted to protein (cytoplasm)
