Introduction, Evolution and Genomes-1 Flashcards
Introduction
What are prokaryotes and eukaryotes?
Prokaryotes- no nucleus. Bacteria and archaea.
Eukaryotes- nucleus, cell wall and chloroplasts. Fungus and animals.
What determines phenotypes? Give examples
Molecules determine phenotypes.
Much of our knowledge comes from studies of mutants.
E.g. mutant haemoglobin- sickle cell anemia. Mutant phospholipase- brain cells commit suicide and adult cells are full of holes, swiss cheese phenotype. Hormone leptin is missng- loss of cell signalling pathway, obese mouse.
How can sugars interchange?
Can interchange between alpha and beta, but not through rotation of -OH and -H bonds, instead dynamic interchange between alpha and beta forms via a linear form.
Sugars break and reform.
What is the main energy source for cells?
Glucose (C6H12O6).
Hexose sugar.
What is the general formula for monosaccharides?
(CH2O)n, where n=3 or more.
What is glycogen and cellulose made of?
Linked glucose residues.
Glycogen- multibranched, alpha glucose polysaccharide used for energy store in animals, fungi and bacteria.
Cellulose- single branched, beta glucose molecules linked to form fibres that give structured cell walls in plants and algae.
What is a lipid?
A water-insoluble biomolecule that is highly soluble in organic solvents such as chloroform.
How much energy do fatty acids have relative to glucose?
They have twice the energy per g.
What is a fatty acid?
Has a carboxylic acid group at one end, a methyl group on the other end and a long aliphatic (C and H) chain.
May be saturated and straight or unsaturated and kinky.
Functions: energy, structure and signalling.
Class: fatty acids, membrane lipids and steroid hormones.
Examples: palmitate, phospholipids and oestrogen.
What are membrane lipids?
E.g. phospholipids, glycolipids and cholesterol.
Structural function.
Hydrophilic head and hydrophobic tails allow a membrane to form. Water is absorbed on outer membrane.
Membranes are dynamic and not stiff.
What are steroid hormones?
E.g. oestrogen and progesterone are similar, but decorated differently by chemicals.
Two fatty acids govern how we produce eggs and both regulate the menstrual cycle.
What are amino acids?
Made up of central alpha carbon, a basic amino group (NH2), an acidic carboxylic acid group (COOH), hydrogen and side chain (R).
20 amino acids, typically found in proteins. 20 different R chains determine the properties of each amino acid.
What does altering the R side chain do?
Alters the properties of an amino acid.
E.g. serine is hydrophilic and valine is hydrophobic. -OH of the R-group in serine is soluble, but on valine the R group is insoluble (but the amino acid and carboxylic acid group are- is overall hydrophobic).
How is polarity of proteins read?
Polarity (directionality) is read from N- to C- terminus.
Amino acid residues are linked by peptide bonds to form proteins, N- and C-terminus.
What form of the protein carries out its function?
The mature form of the protein, after the primary structure (the chain of amino acid residues) folds.
What are the functions of amino acids?
Catalyse chemical reactions, communication, defence, transport, structure, control and many more.
What are nucleic acids made of? What do they do?
Nucleic acids are formed by nucleotides joined together.
Nucleic acids store genetic information and are all the information carriers of the cell.
Directionality: 5’ to 3’. First nucleotide has a free phosphate on the 5’ end and last nucleotide has a free hydroxy group on the 3’ end.
Some RNA molecules are catalytic (ribozyme function).
What is a nucleoside vs nucleotide?
Nucleoside- base and sugar.
Nucleotide- base and sugar phosphate.
How can a phylogenetic tree be built?
Gene sequences are conserved between organisms.
Data allows you to build a phylogenetic tree. This implies there is a common ancestor- 3 domains of life, all organisms are related, based on comparison of ribosomal RNA.
The data is consistent with a common evolutionary ancestor, 3.5-3.9 billion years ago.
