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Biology AS 3.1 - 3.4 - Coggle Diagram

- - - - Types of Carbohydrates:
        
        Monosaccharides --> single sugar monomer, all are reducing sugars --> e.g. glyceraldehyde (3C), ribose (5C), glucose (6C) --> source of energy in respiration, building blocks for polymers.
        
        Disaccharides --> a sugar formed from 2 monosaccharides joined by a glycosidic bond in a condensation reaction --> e.g. maltose (alpha glucose + alpha glucose), sucrose (alpha glucose + fructose), lactose (alpha glucose + galactose) --> sugar found in germinating seeds (maltose), mammal milk sugar (lactose), sugar stored in sugar cane (sucrose)
        
        Polysaccharides --> a polymer formed by many monosaccharides joined by glycosidic bonds in a condensation reaction --> e.g. cellulose (beta-glucose), starch (alpha-glucose in the form of amylose and amylopectin), glycogen (alpha-glucose) --> energy storage (plants - starch and animals - glycogen), structural --> cell wall
        
        3.1.1.2: Reactions
        
        A covalent bond is the sharing of 2 or more electrons between 2 atoms.
        
        The electrons can be shared equally, forming a nonpolar covalent bond or unequally (where an atom can be more electronegative) to form a polar covalent bond.
        
        When 2 monomers are close enough that their outer orbitals overlap this results in their electrons being shared and a covalent bond forming.
        
        If more monomers are added then polymerisation occurs (and / or a macromolecule forms).
        
        Condensation reaction:
        
        Also known as dehydration synthesis ("to put together while losing water")
        
        Occurs when monomers combine together by covalent bonds to form polymers (polymerisation) or macromolecules (lipids) and water is removed.
        
        Hydrolysis reaction:
        
        Hydrolysis means 'lyse' (to break) and 'hydro' (with water)
        
        In the hydrolysis of polymers, covalent bonds are broken when water is added.
        
        Covalent bonds in Organic molecules:
        
        Carbohydrates --> glycosidic --> C-O-C
        
        Proteins --> peptide --> O=C-N-H
        
        Lipids --> ester --> C-O-C=O
        
        Nucleic acids --> phosphodiester --> between phosphate molecule and 3rd sugar of deoxyribose sugar
        
        3.1.1.3: Monosaccharides:
        
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- - - - 3.4.1.2: Eukaryotic DNA
        
        Chromosomes are made of one very long, condensed DNA molecule associated with proteins (in eukaryotic cells)
        
        The main proteins present are the large positively charged globular proteins called histones, their role is to organise and condense the DNA tightly so that it fits into the nucleus.
        
        The other proteins are enzymes used in copying and repairing the DNA
        
        The tightly coiled combination of DNA and proteins is called chromatin – this is what chromatids, and therefore chromosomes, are made of
        
        During interphase (S phase) the DNA replicates to create two identical strands of DNA called chromatids, joined together by a narrow region called the centromere.
        
        The two chromatids that make up the double structure of a chromosome are known as ‘sister chromatids’
        
        It is important that the sister chromatids are identical (contain the same genes) because this is key to cell division, as one chromatid goes into one daughter cell and one goes into the other daughter cell during mitosis, ensuring the daughter cells are genetically identical.
        
        Each chromatid is made up of one very long, condensed DNA molecule, which is made up of a series of genes.
        
        The ends of the chromatids in chromosomes are ‘sealed’ with protective structures called telomeres
        
        3.4.1.3: Mitochondria & Chloroplast DNA
        
        Mitochondria:
        
        The site of aerobic respiration within eukaryotic cells, mitochondria are just visible with a light microscope
        
        Surrounded by double-membrane with the inner membrane folded to form cristae
        
        The matrix formed by the cristae contains enzymes needed for aerobic respiration, producing ATP
        
        Small circular pieces of DNA (mitochondrial DNA) and ribosomes are also found in the matrix (needed for replication).
        
        Chloroplast:
        
        Larger than mitochondria, also surrounded by a double-membrane
        
        Membrane-bound compartments called thylakoids containing chlorophyll stack to form structures called grana.
        
        Grana are joined together by lamellae (thin and flat thylakoid membranes).
        
        Chloroplasts are the site of photosynthesis:
        
        The light-dependent stage takes place in the thylakoids
        
        The light-independent stage (Calvin Cycle) takes place in the stroma.
        
        Also contain small circular pieces of DNA and ribosomes used to synthesise proteins needed in chloroplast replication and photosynthesis
        
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