Core Concepts Flashcards
1
Q
What is the definition of organic?
A
Carbon containing molecules, not the oxides.
2
Q
What is the definition of inorganic?
A
No carbon in molecules.
3
Q
What is a carbohydrate?
A
Contains C,H,O.
General formula: C(H20)n
Main groups: monosaccharides, disaccharides, polysaccharides.
Functions: instant energy source, structural materials.
4
Q
What are monosaccharides?
A
Monomers.
Named according to number of carbon atoms.
(3=triose, 5=pentose, 6=hexose).
5
Q
What is pentose?
A
5 carbon sugar. (deoxyribose or ribose)
6
Q
What is hexose?
A
6 Carbon sugar (glucose). Polar molecule, soluble-so transported in solution in blood plasma. Glucose readily broken down in respiration and the energy released is used to make ATP.
7
Q
What is an isomer?
A
Same elements, different arrangements.
8
Q
Draw the structure of glucose?
A
CH2OH
|
H C——O
\ / \ /H
C C
/ H H \
HO | | OH
\ C C /
OH OH
9
Q
What is the difference between alpha and beta glucose?
A
alpha: H beta: OH
| |
OH H
10
Q
How many covalent bonds can a carbon atom form?
A
4
11
Q
What is a condensation reaction?
A
Combines monomers to form polymers- giving out water.
12
Q
What is a dissacharide?
A
Formed by a condensation reaction.
Glucose+Glucose=Maltose
Glucose+Fructose=Sucrose
Glucose+Galactose= Lactose
13
Q
What is hydrolysis?
A
Opposite of condensation. Water added to break the glycosidic bond.
14
Q
What does isotonic mean?
A
Same water potential in and out the cell, no net movement of water.
15
Q
What is a polysaccharide?
A
A large carbohydrate molecule formed by linking many monosaccharide (simple sugar) units together through glycosidic bonds (condensation reaction).
16
Q
What is Glycogen?
A
Storage polysaccharide found in animals-muscle cells and liver. Alpha glucose.
17
Q
What is starch?
A
Storage polysaccharide found in plants for respiration. Alpha glucose. (straight chain amylose-1,4 glycosidic bonds and branched amylopectin with 1,4 and 1,6 glycosidic bonds).
18
Q
What is cellulose?
A
Structural polysaccharide found in plant cell walls, beta glucose, 1,4 glycosidic bonds, every other glucose rotated 180 degrees, straight chains, H bonds holding together chains to form microfibrils-making it strong.
19
Q
What does alpha and beta glucose form?
A
Alpha forms spiral structure (helix).
Beta forms fibres (chain structure).
20
Q
What is Chitin?
A
Structural heteropolysaccharide. Similar to beta glucose (structural). Additional group to cellulose (Acetylamide side group). Polysaccharide found in insect exoskeletons- strong, waterproof and very lightweight.
21
Q
What are hydrogen bonds?
A
Opposite attract = O2 of one water molecule with H of another molecule.
22
Q
What is cohesion?
A
Attraction between water molecules- makes water molecules stick together - H bonds are strong together.
23
Q
What is Adhesion?
A
Water molecules also tend to form H bonds to other molecules that are charged or polar.
24
Q
What is water?
A
Is a solvent. It can dissolve substances that have charged or polar regions.
25
When do metabolic reactions happen most readily?
When reactions are dissolved in water.
26
What is hydrophilic?
Substances attracted to water.
27
What is hydrophobic?
Insoluble in water.
28
What are proteins made from?
C, H, O, N and some S + P.
29
What are the monomers of proteins?
Amino acids= 20 naturally occurring and 8 from diet.
30
How are 2 amino acids joined?
Joined by a condensation reaction- which forms a dipeptide. Forms a peptide bond.
31
What is the primary structure of a protein?
Order of amino acids in a ppc. Peptide bond. Coded by DNA.
32
What is the secondary structure of a protein?
Initial folding of ppc to form alpha helices of beta pleated sheets. Hydrogen bonds.
33
What is the tertiary structure of a protein?
Further folding of the ppc to give a specific 3D shape. H bonds, ionic bonds, disulphide bridges, hydrophobic interactions.
34
What is the quaternary structure of a protein?
Not all proteins have this level. More than 1 ppc bonded together e.g Hb (4ppcs) or Collagen (3ppcs). H bonds, ionic, disulphide bridges, hydrophobic interactions.
35
What is a prosthetic group?
Chemical groups which are not amino acids/made of proteins.
36
What is Haemoglobin?
4 globin molecules held together by H bonds. 4 folded ppc, 4 iron containing haem groups, compact and spherical, soluble in water, quaternary structure.
37
What is collagen?
Found in skin, bones and ligaments. Fibrous. Made from 3 identical left-handed helix ppc wound around each other to form a triple helix. In each ppc, every 3rd amino acid is glycine, 3 chains held together by H bonds, very stable, insoluble in water, collagen molecules cross link through covalent bonds to form fibres which give collagen it's great strength.
38
Fibrous Vs Globular proteins: (3D shape, solubility, amino acid sequence, function, features)
Fibrous: forms fibres, insoluble in water, 35% of amino acids are glycine, structural role found in skin, tendons, cartilage and bones, does not contain a prosthetic group.
Globular: Rolls up to form balls, soluble in water, wide range of amino acids, metabolic role- carries O2 in RBCs, contains a prosthetic group-haem.
39
What are lipids used for in the body?
Thermal insulation, cell membranes, electrical insulation of nerves, storage of energy, respire to release energy, protect vital organs, hormones and steroids.
40
What are triglycerides?
Hydrophobic and non polar, contains C,H,O. Have 1 glycerol and 3 fatty acid tails. Joined in a condensation reaction and forms 3x ester bonds and releases 3x H2O. Breaks in hydrolysis (uses 3x H2O).
41
What is an unsaturated fatty acid?
Have 1 or more C=C. Each pack as tightly together, tend to be liquids at room temperature (oils).
42
What is a saturated fatty acid?
no C=C. Each carbon has max number of H bonded, straight chains, can pack tightly together, solid at room temperature (fats).
43
What are phospholipids?
Made of 1 glycerol, 2 fatty acid tails and a phosphate group. They form cell membranes. They can prevent polar molecules crossing the membrane. They are flexible and allow lipid soluble/non-polar molecules through.
44
How does a phospholipid form a phospholipid bilayer?
Phosphate heads face water (hydrophilic). Fatty acids face away from water (hydrophobic) and turn towards eachother creating a layer that excludes water.
45
What are lipoproteins?
Proteins combined with and transport fat or other lipids in the blood plasma. (Fats can't dissolve in water).
46
What are Low Density Lipoproteins (LDL's)- in relation to diets?
A diet high in saturated fat, increases the production of LDL by the liver. These LDL normally deliver fats around the body. In excess however, these LDL's can deliver the fat to endothelial cells of arteries where it is deposited as atheroma.
47
What are High Density Lipoproteins (HDL's) - in relation to diet?
A diet high in unsaturated fat, increases the production of HDL by the liver. These HDL scavenge excess LDL and return them to the liver. This therefore reduces the rate of atherosclerosis.
48
What are enzymes?
They are biological catalysts which speed up chemical reactions without being used up in them. They are 3D globular proteins with a specific tertiary structure. They are specific- only catalyse 1 type of reaction. Their active site is complementary to the shape of their specific substrate. The active site lowers the activation energy required to start the reaction.
49
What is Activation Energy?
Extra energy required to enable a reaction to occur.
50
What is the 'Lock and Key' model?
States that the active site is a specific shape, which is perfectly complementary to the shape of it's substrate.
51
What is the 'Induced Fit' model?
Active site changes shape to allow the substrate to fully enter the active site. Substate collides with the active site. The active site moulds around the substrate and is held in position by oppositely charged groups on the amino acids in the active site. An ESC is formed. A change in the enzymes 3D shape puts strain on substrate=weakens chemical bonds=break more easily-lowering activation energy. EPC forms. Product no longer fits into active site and is released. E.g. Lysozyme.
52
What is a Catabolic reaction?
Break down/hydrolysis of larger molecules to smaller ones e.g. polypeptide-> amino acids.
53
What is an Anabolic reaction?
Larger molecules being made by the condensation of smaller molecules e.g. alpha glucose->starch.
54
What are Intracellular enzymes?
Remain inside the cells (respiratory enzymes).
55
What are Extracellular enzymes?
Secreted from cells to function (digestive enzymes).
56
What is the turnover number?
Max number of substrate molecules an enzyme can convert to product per unit of time.
57
What are enzyme inhibitors?`
Any molecule/substrate which slows rate of enzyme controlled reaction (amount of esc made).
58
What are competitive inhibitors?
Inhibitor is a similar shape to the substrate (complementary to the active site). It inhibits by binding to the active site (EIC) and competes with the normal substrate. It prevents as many esc forming=reduces ROR. Increasing the substrate concentration can reduce the effects of the inhibitor. Usually this is reversible.
59
What is a non-competitive inhibitor?
Binds to the allosteric site-often irreversible. Binding to the allosteric site causes a conformational (shape) change of the active site= active site and substrate are no longer complementary=no esc formed=no products made. An increase in substrate concentration cannot decrease the inhibitor effect as the inhibitor isn't in direct competition for the active site. The active site is permanently altered/new enzymes would have to be made. V max not reached. (e.g. Cyanide).
60
What is magnification?
The degree to which something can be viewed larger than it is.
61
What is resolution?
The shortest distance between 2 points on a specimen that can still be distinguished as separate entities.
62
How do you convert from centimeters to millimeters to micrometers to nanometers?
cm-mm (x10). mm-um (x1000). um-nm (x1000).
nm-um (/1000). um-mm (/1000). mm-cm (/10).
63
Draw and label a Mitochondria
Check notes for answer.
64
Draw and label a Chloroplast
Check notes for answer.
65
What is the difference between a prokaryotic cell and a eukaryotic cell?
Prokaryotic: cells are smaller and have no nucleus or nuclear envelope, only living prokaryotic cells are bacteria, lack of membrane bound organelles.
Eukaryotic: larger and have a nucleus bound by nuclear membranes (envelope), have membrane bound organelles.
66
What are the stages of Endosymbiosis?
1. Anaerobically respiring cell took in bacterium up by endocytosis.
2. Bacterium was not digested.
3. Bacterium respired aerobically.
4.Bacterium supplied itself and the larger cell with ATP.
5. Larger cell had a competitive advantage (aerobic respiration is more efficient than anaerobic).
6. This bacterium evolved to become the mitochondria we see today.
7. Larger cell evolved to become the heterotrophic (consume food) eukaryotic cells we see today.
67
What is the endosymbiotic theory?
Some of the organelles in eukaryotic cells were once prokaryotic cells = mitochondria, chloroplasts and prokaryotic cells are the same size, divide into 2 by binary fission, have their own circular DNA and have 70s ribosomes. Mitochondria and Chloroplasts are both double membrane bound suggesting they were previously engulfed by another organism.
68
What are viruses?
Consist of a small piece of DNA/RNA surrounded by a protein. Very small, 'live' in host cells, use host cells to reproduce, acellular (not cells)=no organelles, cytoplasm.
69
What are the stages of virus replication?
1. Virus attaches to host cells and injects genetic material.
2. Genetic material used as a code to synthesis proteins.
3. New virus particles are assembled.
4. Viruses burst out of, and destroy, host cell.
70
What is Cholesterol?
It is a lipid that fits between the phospholipid and bind to hydrophobic tails of phospholipids, causing them to pack more tightly together. It regulates membrane fluidity.
71
What are Glycolipids?
Can act as receptors for cell signaling, sites where molecules (drugs, hormones, antibodies) can bind and antigens involved in the immune system.
72
What are the factors affecting the rate of diffusion?
Surface area- larger the SA:V, greater the rate of diffusion. Conc gradient: diffusion rate will be higher when there is a greater diff in conc between 2 regions. Distance: diffusion over shorter distances occurs at a greater rate than diffusion over longer distances. Temperature: diffusion occurs faster at higher temperatures.
73
What is Fick's Law?
Rate of diffusion = (D.P.T) S A x conc difference/ distance
74
What is a Gene?
A length of DNA that codes for a polypeptide. Each gene occupies a specific place/locus on the chromosome.
75
What is the Genetic Code?
Is a triplet code (codon). A sequence of 3 nucleotide bases codes for an amino acid. Is a degenerate code- all amino acids except methionine have more than one codon.
76
Where does mRNA function and what is it's function?
Functions in the nucleus, migrates to ribosomes in cytoplasm-carries DNA sequence information to ribosomes.
77
Where does tRNA function and what is it's function?
Functions in the cytoplasm-provides linkage between mRNA and amino acids, transfers amino acids to ribosomes.
78
Where does rRNA function and what is it's function?
Functions in cytoplasm- structural component of ribosomes.
79
What is diffusion?
Movement of molecules from high conc-low conc down a conc gradient until equilibrium is reached.
80
What is facilitated diffusion?
Transport of substances across a biological membrane, from an area of high conc-low conc by means of a carrier protein.
81
What is active transport?
Movement of substances across a cell membrane against a concentration gradient (low-high), which requires ATP via carrier proteins.
82
What is Osmosis?
The net movement of water from a region of high water potential to a region of low water potential through a selectively permeable membrane.
83
What is the Fluid Mosaic Model?
Components in the cell membrane (phospholipid, cholesterol, proteins, carbohydrates) aren't static-gives cell membrane it's flexibility. Mosaic= molecules are different shapes and sizes.
84
Adaptations of Fluid Mosaic Model?
If temp drops, cholesterol can act as 'spacers' between phospholipids to stop them becoming too packed. Cholesterol can connect phospholipids to keep them from becoming too fluid in warm temps.
Extrinsic proteins can act as enzymes to speed up reactions or attach to cytoskeleton to help with cell shape.
Intrinsic proteins are involved in transport methods.
Glycoproteins and Glycolipids can identify the cell as belonging to the organism = important when fighting pathogens, also involved in cell signaling.
85
What are the proteins function (in plasma membrane)?
Channel proteins: with a hydrophilic centre to allow passage of polar molecules through.
Carrier proteins: use energy to transport substances by facilitated diffusion or active transport.
Glycoproteins: can act as receptors for cell signaling, sites where molecules (drugs, hormones, antibodies) can bind.
Extrinsic proteins: surface proteins.
86
What is the process of Transcription?
DNA helicase breaks the H bonds that hold the 2 strands together. RNA polymerase bind to the template and uses free complementary RNA nucleotides present in the nucleoplasm to form mRNA. 1 strand of mRNA leaves by the nuclear pore. RNA polymerase separates from the template when it reaches a stop codon. RNA polymerase builds a new RNA strand in the 5' to 3' direction. mRNA goes to ribosomes for activation and translation.
87
What is the process of Activation?
ATP required to form peptide bonds and join ATP and an amino acid to form activated amino acid and to join an activated amino acid and tRNA to form activated tRNA. (activated amino acid is transferred on to the tRNA to form activated tRNA).
88
What is the process of Translation?
Each ribosome consists of 2 subunits. Start codon (AUG) of mRNA attaches to the small subunit of ribosome. Large subunit has 2 sites for the attachment of tRNA. The anticodon on tRNA links up with codon on mRNA. Ribosome attaches to start codon on mRNA-Initiation. Then a 2nd activated tRNA with an anti codon complementary to the 2nd codon comes and attaches to the ribosome. It's anticodon links up with the 2nd codon on the mRNA. A ribosomal enzyme catalyses peptide bond formation between the 2 amino acids. The 1st tRNA molecule releases it's amino and and leaves the ribosome, leaving the P site vacant, the ribosome moves along the mRNA to the next codon. Another tRNA molecule brings the next amino acid into place, which will be attached to the previous one by a peptide bond-Elongation. Continues until a termination (stop) codon is reached-polypeptide is then complete.
89
What is the function of DNA?
Replication in dividing cells, carrying the genetic information for protein synthesis.
90
What is DNA?
Consists of a pentose sugar (deoxyribose), phosphate group, nitrogenous base. Very large nucleic acid macromolecule, made up of a long chain of sun-units (nucleotides). Consists of strong covalent bonds between the sugar phosphate backbone and the bases are joined by H bonds. Anti-parallel.
91
Describe DNA replication:
Bases always pair up in the same way- complementary base pairing. Replication-during interphase. Before a cell divides, the DNA strands unwind and separate. DNA helicase is used to break down the H bonds between complementary bases. Each strand makes a new partner by adding the appropriate nucleotides using DNA polymerase= now 2 double stranded DNA molecules in the nucleus. So that when the cell divides, each new nucleus contains DNA identical to the original= semi-conservative.
92
What was the Meselson and Stahl Experiment?
They cultured the bacterium (Ecoli) for several generations in a medium containing amino acids made with N15 instead of the usual N14. This N15 was incorporated into the E coli nucleotides and therefore their DNA. They extracted the bacterial DNA by breaking open the cells and put it into an ultra centrifuge. DNA settled at the bottom-N15=heavy. The N15 bacteria were washed and transferred to a medium containing normal N14 and were allowed to divide once (Gen 1). Extracted DNA and centrifuged-Middle=ruled out conservative-would produce a band showing only heavy-completely preserve both old strands. Bacteria allowed to replicate in the N14 for a 2nd Gen and the DNA was extracted and centrifuged. Band was at middle and top in equal amounts. Rules out dispersive-would always be a mixture of light and heavy in every strand and only one band would form. One parental strand is conserved-evidence for semi conservative replication.
93
Where do living organisms get their energy from?
Living organisms obtain their chemical energy from food-originally the energy in food comes from the sun.
94
What are Autotrophs?
Organisms that convert light energy from the sun to chemical energy in photosynthesis (plants and some microorganisms (some bacteria and protists)).
95
What are Heterotrophs?
Organisms that cannot use the suns energy to make food (animals and microorganisms).
96
What is a cells usable source of energy?
Adenosine triphosphate (ATP).
97
What is ADP?
Adenosine diphosphate = only 2 phosphate groups.
98
How is ATP converted to ADP?
Breaking bond between the 2nd and 3rd phosphate. ATP molecule is hydrolysed into ADP and an inorganic phosphate (Pi). ATPase catalyses this. Every mole of ATP hydrolysed releases 30.6KJ of energy. Releases energy=exergonic.
99
How does ADP and Pi combine to form ATP?
Condensation reaction. To synthesise 1 mole of ATP, an input of 30.6KJ of energy is required-endergonic. Addition of phosphate to ADP=phosphorylation.
100
Why is ATP a better energy currency than glucose?
Hydrolysis of ATP-ADP requires 1 enzyme (ATPase), whereas many enzymes are needed to release energy from glucose.
Hydrolysis of ATP-ADP involves a single step, whereas the breakdown of glucose involves many intermediates and takes longer for energy to be released.
ATP releases energy in small amounts, when and where it's needed, whereas glucose releases energy in large amounts which would be all at once.
101
What does ATP provide energy for?
Cellular activities such as active transport, metabolic processes, movement (muscle contraction), nerve transmission, secretion.
