Exam 1 Flashcards
(124 cards)
1
Q
Cell
A
-basic unit of life
-Interior of cell separated from its environment
-Inside of cell chemically different from environment; accommodates the biochemistry of life
2
Q
Two types of cells
A
prokaryotes and eukaryotes
3
Q
Prokaryotic cells
A
a single-celled organism whose cell lacks a nucleus and other membrane-bound organelles
4
Q
Eukaryotic cell
A
cells that have a membrane-bound nucleus and organelles
5
Q
Prokaryotic cell structure
A
-no nucleus
-membrane bound organelles
-have plasma membrane, cytoplasm, DNA, and ribosomes, cell wall, flagella, capsule, and fimbriae
-genome is typically one large circular
molecule
-bacteria/archaea
-0.1 - 5 micrometers
6
Q
Animal cell structure
A
-larger than prokaryotic cells (10-30 micrometers)
-Contains mitochondrion, cytoskeleton, nucleolus, nucleus, free ribosomes, peroxisomes, centrioles, ribosomes, golgi apparatus, plasma membrane, ERs
7
Q
Plant cell structure
A
-similar to animal cell, except contain several additional organelles
-Contains vacuole, cell wall, ribosomes, ERs, plasma membrane, plasmodesmata, mitochondrion, nucleus, peroxisomes, chloroplasts, golgi apparatus
- 10-100 micrometers (varies due to central vacuole)
8
Q
Nucleus
A
-encloses the genetic material (DNA) and is site of RNA production (transcription)
9
Q
Nuclear envelope
A
-Separates nucleus from cytoplasm
-has two layers
-Contiguous with endoplasmic reticulum
-Two lipid bilayers with nuclear baskets
10
Q
Nuclear pores
A
Allows things to exit/enter nucleus
11
Q
Nucleolus
A
-Site of ribosomal biogenesis and assembly
-Transports to cytoplasm
12
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Nucleoplasm
A
-Region outside of the nucleolus
-Filled with chromatin (DNA packaged with proteins)
13
Q
Rough ER
A
-Ribosomes temporarily dock at rough ER surface
-Secretory proteins and proteins addressed to some organelle compartments are inserted into the lumen of the rough ER for processing (protein synthesis, folding, and processing)
-Often this processing involves the addition of sugar groups
14
Q
Smooth ER
A
-Contiguous with the rough ER
-Proteins in the lumen of the ER are further processed
-Site of steroid and lipid synthesis
-detoxification and carbohydrate metabolism
15
Q
Golgi apparatus
A
-Continues with processing and sorting of secretory proteins and proteins destined to other cellular compartments
-processes/packages proteins/lipids
16
Q
Vesicle
A
-Carried by motor proteins along cytoskeletal tracks
-Carry proteins and other materials to outside of cell
-enclosed in a membrane similar to cell’s plasma membrane
-can fuse with plasma membrane to release contents of cell
17
Q
Phagosome
A
a membrane-bound vesicle formed within a phagocyte (like a macrophage or neutrophil) when it engulfs a particle like a microbe or a dead cell through a process called phagocytosis
18
Q
Lysosome
A
-Special type of vesicle
-Contain enzymes that degrade materials such as proteins/food/particles
19
Q
Endocytosis
A
-cellular process where a cell takes in substances from its external environment by engulfing them with the cell membrane, forming a vesicle that then pinches off into the cell
-importing something into the cell
20
Q
Phagocytosis
A
-a cellular process where cells, particularly phagocytes like macrophages, dendritic cells, and neutrophils, engulf and digest large particles like bacteria and cellular debris
-crucial part of immune system
21
Q
Pinocytosis
A
the ingestion of liquid into a cell by the budding of small vesicles from the cell membrane.
22
Q
Exocytosis
A
-cellular process where cells release materials, like proteins or neurotransmitters, from their interior to the extracellular space
23
Q
Receptor mediated endocytosis
A
a cellular process where specific molecules (ligands) are internalized by binding to cell surface receptors, triggering the formation of an inward-budding vesicle
24
Q
Mitochrondria
A
-Site of cellular respiration and energy (ATP) production
-Contain double-membrane and ribosomes
-Site of steroid and heme synthesis
-Contains ribosomes (prokaryotic-like) and DNA (circular)
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Endosymbiont theory for origin of mitochondria/plastids
-Mitochondria are remnants of bacterial cells that took up residence in an ancestral eukaryotic cell
-Evidence:
--presence of circular DNA and ribosomes in mitochondria and chloroplasts
--their own double membranes
--their ability to divide independently
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Plastid
-Found in plants and red/green algae
-Site of photosynthesis
-Site of biosynthesis of fatty acid, starch, and other important biomolecules
-Also contain a separate (circular) DNA genome and prokaryotic-like ribosomes
-Have double membrane
-Remnants of photosynthetic bacterial cells that took up residence in an ancestral eukaryotic cell as a result of an additional endosymbiotic event
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Chloroplast
-essential plant organelles
-primarily responsible for photosynthesis (where light energy is converted into chemical energy in the form of sugars)
-type of plastid
-contain chlorophyll
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Actin microfilament
-responsible for cell shape, locomotion (dynamic)
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Intermediate filament
fibrous proteins: lamins
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Microtubules
-framework for movement of vesicles, chromosome segregation
-Motor proteins, like kinesin, drive movement down microtubule tracks
-Kinesin cross links the vesicle to the microtubule
-Detachment and reattachment of kinesin causes it to “walk” along microtubule
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Most common elements in biological tissues
H, C, N, O, P, S
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Covalent bond
-formed by the sharing of a pair of electrons between adjacent atoms (arises from electrostatic attraction of their nuclei for same electrons)
-Strength of single covalent bond: 50-100 kcal/mol
-Multiple covalent bonds can also occur, resulting in stronger and shorter bond
-Covalent bonds are stable under typical physiological conditions (temperature, salt, pH)
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Octet rule
-tendency for atoms in stable molecules to have eight electrons surrounding in their outermost shells surrounding the positively charged atomic nucleus
-Atoms with less than 8 electrons in their outer shell can comply with the octet rule by sharing electrons with another atom (covalent bond)
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Electronegativity
the strength with which an atom’s nucleus ‘monopolizes’ on the sharing of the electron pair in a covalent bond is a function of the atom’s electronegativity= attractive force that an atomic nucleus exerts on electrons
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Non-covalent bonds
-weaker than covalent bonds but essential for biochemical processes
-Based on electrostatic interaction between opposite charges:
--Ionic interaction
--Hydrogen bond (H-bond)
--Van der Waals interaction
--Hydrophobic interaction
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Ionic interaction
-a type of chemical bonding that involves the electrostatic attraction between oppositely charged ions (sharply different electronegativities)
-Bond energy: 3-7 kcals/mol or about 1/10 of covalent
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Simple ions
elemental, such as Na+ or Cl-
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Complex ions
-compounds of covalently bonded atoms carrying an electric charge
-R-NH3+ (Alkyl-ammonium)
-R-COO- (Carboxyl ion)
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Ion
an atom or molecule with a net electrical charge (e.g. anion/cation)
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Salt bridge (proteins)
-a strong non-covalent (ionic) interaction between oppositely charged amino acid side chains
-often between acidic (Asp or Glu) and basic (Lys or Arg) residues
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Hydrogen (H) bond
-Form between a strongly electronegative atom and a hydrogen atom covalently bonded to a different electronegative atom (N, O, F)
-Bond energy; 1-5 kcals/mol
-H-bond length is longer than covalent bonds
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Strongest H-bonds
-Linear arrangement of donor and acceptor yield strongest H-bonds
-Donor= atom with covalent bond to H-atom
-Acceptor= atom that forms H-bond with H
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Van der Waals interaction
-Transient fluctuation -> asymmetry in electron distribution around one atom induces a compensatory asymmetric electron distribution in neighboring atom
-Very low bond energy (0.5-1 kcals/mol)
-such interactions summed over the surface of large molecules can be significant
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Hydrophobic interaction
-Many biological molecules contain numerous C-H and C-C covalent bonds
-Because C and H have similar electronegativity, these covalent bonds are non-polar
--Non-polar hydrocarbons are Hydrophobic
-Non-polar compounds form weak interactions with polar water molecules, while polar molecules can form stable H-bond interactions among each other
--Polar water molecules form “cages” around non-polar molecules
--Fewer ordered water molecules caging the non-polar molecules
-bond energy strenght of 1-2 kcal/mol
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Functional groups
-Hydroxyl (-OH)
-Aldehyde (-CHO)
-Keto (>CO)
-Carboxyl (-COOH)
-Amino (-NH3)
-Phosphate (-OPO3^2-)
-Sulfhydryl (-SH)
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Macromolecules
-a large, complex molecule typically composed of smaller repeating units called monomers
-These large molecules are essential for life
-Proteins (polypeptides)
-Nucleic Acids
-Carbohydrates (polysaccharides)
-Lipids
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Monomer
a single molecule that can bond with other similar molecules to form a larger, more complex molecule called a polymer
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Polymer
a large molecule, or macromolecule, composed of repeating structural units, called monomers, connected by chemical bonds
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Monomers (macromolecules)
-Amino Acid
-Monosaccharide (sugar)
-Nucleotide
-glycerol/fatty acids
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Polymers (macromolecules)
-Polypeptide (protein)
-Polysaccharide (carbohydrate)
-Nucleic Acid
-Lipids
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Hydrolysis
-any chemical reaction in which a molecule of water breaks one or more chemical bonds
-molecule is cleaved into two by addition of water molecule
-monomer --> polymers
-BREAKS BONDS
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Condensation reaction (dehydration synthesis)
-occurs when two molecules or compounds are joined to form a larger molecule following the removal of water
-molecule of water is removed from two reactants, allowing them to form new bond
-polymer --> monomer
-CREATES BONDS
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Protein
-large biomolecules and macromolecules that comprise one or more long chains of amino acid residues
-Involved in almost every cellular process, including energy production, catalyzing reactions, cell structural, and all forms of regulation
-Proteins are NOT usually used for information storage or as energy stores
-involved in catalyzing reactions, providing structural support, and transporting molecules
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Base protein structure (neutral pH)
-H
-R group
-N-terminus (NH3+)
-C-terminus (COO-)
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Zwitterion
a molecule, like an amino acid, that has both a positive and a negative charge within the same molecule, but has a net neutral charge
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Polar (neutral) R-groups
5 groups (hydrophilic)
-Asparagine (Asn)
-Glutamine (Gln)
-Serine (Ser)
-Threonine (Thr)
-Tyrosine (Tyr)
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Polar (positively charged) R-groups
3 groups (hydrophilic)
-Arginine (Arg)
-Histidine (His)
-Lysine (Lys)
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Polar (negatively charged) R-groups
2 groups (hydrophilic)
-Aspartic Acid (Asp)
-Glutamic Acid (Glu)
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Non-polar R-groups
10 groups (hydrophobic)
-Alanine (Ala)
-Cysteine (Cys)
-Glycine (Gly)
-Isoleucine (Ile)
-Leucine (Leu)
-Methionine (Met)
-Phenylalanine (Phe)
-Proline (Pro)
-Tryptophan (Trp)
-Valine (Val)
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N and C terminus changing depending on pH
-low pH (<7):
--N-terminus: NH3+
--C-terminus: COOH
-neutral pH (7):
--N-terminus: NH3+
--C-terminus: COO-
-high pH (>7):
--N-terminus: NH2
--C-terminus: COO-
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Disulfide bridge
-strong covalent bonds that stabilize protein structures by connecting the sulfur atoms of two cysteine amino acids
-These bonds are crucial for maintaining the correct 3D shape and function of proteins
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Protein structure
-Slightly polar nature of C=O and N-H bonds adjacent to the peptide bond opens up possibility of hydrogen bonding
-4 different levels of structure (primary, secondary, tertiary, quarternary)
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Primary protein structure
-the linear sequence of amino acids that make up the polypeptide chain
-written from N-terminus to C-terminus
-dictates all subsequent levels or protein structure
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Secondary protein structure
-the local spatial arrangements of a polypeptide chain backbone, primarily stabilized by hydrogen bonds between backbone atoms
-Hydrogen bonding is essential to protein secondary structures (occurs due to polarity difference between C-terminus and N-terminus on adjacent proteins)
-A helix and B sheet
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Alpha helix (protein secondary structure)
-Right-handed (twist in clockwise direction when viewed from top)
-3.6 amino acids per turn (360 degrees)
-coiled, rod-like shape
-R-groups project outward
-Modifiers:
--Proline: alpha helix breaker
--Glycine: H=R group
-Polar side chains with H-bond acceptors/donors that compete with the main chain H-bonding interactions are less likely to be found in alpha-helices
-H from N-terminus bonds with O from C-terminus four residues away
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B sheet (protein secondary structure)
-Extended amino acid chain ~3.5 angstroms per amino acid residue
-B-sheet can be parallel/antiparallel
-Antiparallel: strands run in opposite directions, more stable (better hydrogen bond alignment, H-bonds are straight), N-terminus and C-terminus on same side
-Parallel: strands run in same direction (worse hydrogen bond alignment), N-terminus and N-terminus on same side
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Tertiary protein structure
-the overall three-dimensional shape of a single polypeptide chain
-formed by the folding and bending of the chain, driven by interactions between the amino acid side chains (R-groups) and the backbone
-Interactions between amino acid side chains, including hydrogen bonds (hydrogen atom with polar atom binds to another polar atom), ionic bonds (salt bridges form between oppositely charged side chains), disulfide bonds (two cysteines), hydrophobic interactions (non-polar cores), and van der Waals forces stabilize tertiary structure
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Quaternary protein structure
-not every protein has quaternary structure
-the arrangement of multiple polypeptide chains (subunits) in a single protein, where each subunit has its own tertiary structure
-held together by peptide bonds
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Denaturation
-disrupts tertiary and secondary structure of a protein and destroys the protein’s biological functions
-usually irreversible
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Chaperonin
-play role in protein folding and refolding inside the cell
-Proteins bind and enter chaperonin and is released after folding into appropriate shape
-consist of lid and cage
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Induced conformational change of protein
-metal binding protein/metal
-hormone receptor/hormone
-enzyme/substrate
-transcription factor/DNA
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Prion diseases
-associated with protein misfolding
-Progressive neurodegeneration associated with formation of protein aggregates
-Ex. Kuru, Mad Cow Disease, Scrapies
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Alpha carbon
a carbon atom that is directly bonded to a functional group in an organic compound
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Enzyme
-a substance produced by a living organism which acts as a catalyst to bring about a specific biochemical reaction
-catalyzes reactions in biochemical pathways (metabolism)
-Metabolism: network of biochemical pathways with reactions catalyzed by enzymes
-powerful and highly specific biological catalysts
-Most are protein, but some are RNA molecules
-facilitate formation of transition state
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Gibb's free energy
-If ΔG is negative, the reaction will proceed spontaneously (but may be very slow)
--Exergonic
-If ΔG is positive, energy has to be put into the system for the reaction to proceed
--Endergonic
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Exergonic
-releases energy as work
-ΔG < 0
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Endergonic
-absorbs energy as work
-ΔG > 0
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Kinetics
-measure of the rate at which a reaction will occur
-ΔG is a thermodynamics parameter, determines whether a reaction will occur (not how rapidly)
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Catalyst
-substance that speeds up a reaction without being permanently altered by the reaction
-Change the kinetics of a reaction, not the thermodynamics
-lowers activation energy of reaction
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Active site
-3D cleft/crevice where the enzyme and substrate interact and catalysis occurs
-Typically a small part of the enzyme
-Unique microenvironments where substrates are bound by multiple weak interactions
-Orienting substrates, physically straining substrates, adding chemical charges happens at active site
-substrate is turned into product
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Michaelis-Menten kinetics graph
-shows rate of reaction with different amounts of substrate
-Vmax: maximum initial velocity of the reaction (at high substrate concentrations)
-Km: the substrate concentration when the reaction is proceeding at half the maximal velocity, approximation of how efficiently an enzyme binds the substrate and converts it to a product
--if an enzyme has low Km, it achieves maximal catalytic efficiency at a low substrate concentration
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Competitive inhibition
-a substrate molecule is prevented from binding to the active site of an enzyme by a molecule that is very similar in structure to the substrate
-Km increases, Vmax stays the same
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Non-competitive inhibition
-an inhibitor binds to an enzyme at a site other than the active site, reducing the enzyme's activity
-Km stays the same, Vmax decreases
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Allosteric site
-a binding site on a protein that's distinct from the active site, binding of ligand results in change in enzyme’s activity/shape
-binding of regulatory molecule can cause conformational change that affects active site
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ATP
-Adenosine triphosphate
-The universal currency of free energy
--the molecule used by living organisms to store and transfer energy for various cellular processes
-ATP hydrolysis releases large amounts of free energy
--Terminal phosphate (gamma y) of ATP is often transferred to substrates to “activate” them for subsequent reactions
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Cellular membrane
-a thin, flexible barrier that separates the inside of a cell from the outside environment
-Cellular membranes play many important roles in living cells (separates the cell from its environment)
-Made primarily of phospholipids and proteins
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Lipid
-any of a class of organic compounds that are fatty acids or their derivatives and are insoluble in water but soluble in organic solvents
-include many natural oils, waxes, and steroids
-energy storage, structural support for cell membranes, hormone production, insulation, and signaling (steroids)
-Made up of hydrocarbons (C-H bonds)
-Form macromolecular aggregates in aqueous environments through hydrophobic interactions
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Types of lipids
-triglycerides
-phospholipids
-steroids (cortisol)
-cholesterol
-hydrocarbons (beta-carotene, viatmin A)
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Triglyerides
-Made up of 2 components (glycerol and 3 fatty acids)
-Fatty acids: long, hydrocarbon chain, terminates in a carboxylic acid group
-around 14 and 24 carbons (always even numbers, 16/18 is average)
-Covalent bond formed by dehydration synthesis (condensation)
-Triglycerides are nonpolar
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Glycerol
-C3H8O3
-hydrophilic
-polar
-serves as backbone of triglycerides
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Unsaturated vs Saturated fatty acid
-Unsaturated: 1 or more C=C double bonds, causes bent structure and liquid at room temperature, maintains structure and fluidity
-Saturated: no C=C double bonds, solid at room temp, makes up cell membrane, can raise LDL
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Phospholipid
-made up of glycerol, two fatty acids, and a phosphate-linked head
-One fatty acid is replaced by a phosphate-containing compound
-Gives phospholipid both hydrophobic (glycerol and fatty acid tails) and hydrophilic (phosphate and choline head) properties (amphipathic)
-Amphipathic phospholipids form lipid bilayers
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Lipid bilayer
-composed of two layers of lipid molecules, primarily phospholipids, with hydrophobic (water-repelling) tails facing inward and hydrophilic (water-attracting) heads facing outward
-provides a barrier that separates the cell's internal environment from the outside world
-amphipathic (have polar and nonpolar regions)
-have proteins and cholesterol embedded in bilayer
-fluid (determined by how strong hydrophobic interactions between adjacent fatty acid tails are and amount of saturated/unsaturated fatty acids)
-selectively permeable (only small, nonpolar molecules and hydrophobic molecules (small polar can pass through but slowly))
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Cholesterol
-Lipid
-Part of animal plasma membrane
--OH forms H-bond with head group
-Disrupts interactions between fatty acids
-consists of sterol nucleus (4 hydrocarbon rings), a hydrocarbon tail, and a hydroxyl group
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Cortisol receptor
-intracellular receptor
-Short signaling pathway
-No second messengers, no signal amplification
-Receptor (in cytoplasm, bound to a chaperone)
-Signal (cortisol) is a steroid hormone (lipid), diffuses across membrane
-Signal (cortisol) binds to receptor, releases chaperone, stimulates down stream signaling (causes response)
-Receptor free to move into nucleus (NLS)
-Receptor binds to DNA and activates transcription
-Cellular responses:
--Stress
--Activate transcription of genes whose products are involved in breaking down glucose (energy for cells)
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G protein-coupled receptors (epinephrine)
-membrane localized receptors
-Ligand binding to a G protein-coupled receptor triggers a response in cell
-5 steps: Signal perception/receptor activation, transduction, amplification, distribution, and cellular response
-Receptor: GPCR
--7TM receptor
--Initially bound to G protein (GDP-bound, inactive)
-Transducer: G protein
--Activates when signal binds, causing GDP to be exchanged for GTP (active form)
--GTP proceeds to activate another protein (Adenylyl Cyclase)
--Turns off from slow GTP hydrolyzing activity (GTPase) intrinsic to G protein
-Secondary messenger: cAMP
--produced by Adenylyl Cyclase
--activates down stream transducers (proteins such as kinases)
--amplifies the signal
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Integral protein
-span the membrane (either fully or partially)
-crucial for a variety of cellular functions, including transporting molecules across the membrane, acting as receptors, and participating in signal transduction
-have a hydrophobic region that allows them to interact with the lipid bilayer
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Peripheral protein
-do not penetrate membrane
-indirectly associated with membrane via interaction with integral protein, fatty acid head groups, or a lipid modification
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Passive transport
-molecules move down concentration gradient (high --> low) through simple diffusion (if membrane is permeable) or diffusion through a channel/carrier
-does not require input of chemical energy (ATP)
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Active transport
-molecules move against their concentration gradient (low --> high)
-requires input of chemical energy (ATP)
-two types: Primary and Secondary
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Carrier proteins
-bind substances and speed up their diffusion through the bilayer
-example: glucose transporter, Na+/K pump
-in passive transport, molecule binds in binding site of carrier protein, which triggers shape change and release of molecule through membrane
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Channel proteins
-integral membrane proteins
-specific to molecule (water, ions, sugar)
-can be gated (regulated) via ligand, voltage, or mechanical force
-example: Ca channel, Aquaporins
-concentration/electrochemical gradient is driving force
-has hydrophilic pore
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Primary active transport
-direct hydrolysis of ATP to provide energy for transport
-example: K+/Na+ pump (energy from ATP hydrolysis is used to move Na+ out and K+ in cell)
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Secondary active transport
-does not use ATP directly
-energy for transport supplied by ion concentration gradient across the membrane, established through primary active transport
-example: glucose transporter (gradient established by Na+/K+ pump drives transport of glucose into cell with Na+)
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Two cellular locations for receptors
Intracellular (found inside cell, signal must travel through membrane) and membrane (embedded in membrane, signal does not have to pass membrane)
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Ligand
molecule that binds specifically to receptor
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Kinase
-Enzymes that add phosphate group to substrates (other proteins), often provided by ATP
-Removal of phosphate group catalyzed by protein phosphatase
-Phosphorylation often regulates activity of protein
-Substrates are often -OH groups
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secondary messengers
-Synthesized in response to a primary signal
-Small molecules, not proteins
-Can diffuse within the cell, disperse and amplify the signal
-Part of signal amplification
-Activation of adenylyl cyclase produces a lot of cAMP
-Encode info through changes in their concentration
-Examples: cAMP, Ca ion, inositol triphosphate (IP3), diacylglycerol
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Protein phosphorylation
-a phosphate group is added to a specific amino acid residue on a protein molecule, altering the structural conformation of a protein, causing it to become activated, deactivated, or otherwise modifying its function
-Important component of many signaling pathways
-driven by kinases
-serine, threonine, and tyrosine are commonly phosphorylated
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protein phosphatase
-an enzyme that catalyzes the removal of a phosphate group
-Often regulates activity of protein
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Signaling by B-Adrenergic Receptor
-1 Adenylyl cyclase converts many ATP to many cAMPs
-Steps:
--1. Epinephrine binds to B2-Adrenergic Receptor in muscle and liver cells
--2. B2-Adrenergic Receptor stimulates activation of G protein
--3. Ga-GTP activates Adenylyl cyclase
--4. Adenylyl cyclase converts ATP to cAMP
--5. cAMP stimulates a kinase cascade that results in glycogen breakdown -> glucose
-Signal amplification
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Glycogen
-the storage form of glucose in animals
-Glucose is a sugar
-Fuel for cells
-Glycogen is a polymer of glucose monomers
-a1,4 straight chain between glucose monomers and a1,6 branch
-highly branched
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Phototroph
-obtain energy through sunlight
-Photosynthesis → production of sugars
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Chemotroph
-obtain energy from breaking down chemical bonds
-Oxidation of organic molecules (fuel: sugars, lipids, proteins)
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Carbohydrates
-any of a large group of organic compounds that includes sugars, starch, and cellulose, containing hydrogen and oxygen in the same ratio as water (2:1) and used as structural materials and for energy storage within living tissues
-sugars, saccharides, polysaccharides
-Provide energy for cells to metabolize and use to do work, Transport energy within complex organisms, Metabolic intermediates to make new molecules, Structural framework of RNA and RNA (ribose), Structural elements in cell walls of bacteria and plants
-4 categories: monosaccharides, disaccharides, oligosaccharides, polysaccharides
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Chiral carbon
-a carbon atom bonded to four different atoms or groups, creating a tetrahedral structure that lacks a plane of symmetry
-present in carbohydrates
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Isomer
-two or more compounds with the same formula but a different arrangement of atoms in the molecule and different properties
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Monosaccharides
-1 monomer
-Glucose, ribose, deoxyribose, glyceraldehyde
-3-9 carbons
-can exist in linear and ring forms (ring forms more stable and predominate under physiological conditions)
-a form: OH group down on first carbon
-b form: OH group up on first carbon
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Starch
-storage form of glucose in plants
-less branched than glycogen
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Cellulose
-structural element in plant cell wall
-one of most abundant molecules in nature
-adjacent parallel linear chains bond via H-bonds, adds strength
-unbranched chains of glucose monomers with B1,4 linkages (diagonal)
-compose microfibrils, which are highly organized in cell
-most animals can't digest cellulose (lack enzyme, cellulase, which degrades B-1,4 linkages between glucose monomers)
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Lactose
-disaccharide of galactose and glucose
-b1,4 linkage
-milk sugar
-degraded by b-galactosidase (enzyme that degrades B1,4 linkage between galactose and glucose) in bacteria and lactase in mammals
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Disaccharides
-2 monomers
-Sucrose (combo of glucose and fructose), lactose, maltose
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Polysaccharides
->20 monomers
-starch, cellulose, glycogen
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