Topic 1 Bio last Flashcards
(67 cards)
1
Q
What is a monomer?
A
- The smaller units from which larger molcules are made
2
Q
What is a polymer?
A
- Molecules made from a large number of monomers joined together
3
Q
3 EGs of monomers and polymers
A
Monomers:
- Monosaccharides
- Amino acids
- Nucelotides
Polymers:
- Polysaccharides
- Proteins
- Polynucleotides
4
Q
What is a condensation reaction?
A
- The joining of two molecules together with the formation of a new chemical bond whilst eliminating a molecule of water.
5
Q
What is a hydrolysis reaction?
A
- breakage of a chemical bond between two molecules and involves the addition of a molecule of water.
6
Q
What 3 monosaccharides do you need to know?
A
- Glucose
- Fructose
- Galactose
7
Q
What are isomers?
A
- The same molecular formula but a different structure/arrangement
8
Q
What are disaccharides?
A
- Formed by the condensation reaction of 2 monosaccharides via a glycosidic bond
9
Q
What are the isomers of glucose?
A
- Alpha and beta glucose (HOH and OHH)
10
Q
What are polysaccharides?
A
- Formed by the condensation of many glucose monomers
11
Q
What is the structure of amylose?
A
- unbranched helical polymer of alpha glucose
- gets its helical structure from the bond angles of glycosidic bonds.
12
Q
What is the structure of amylopectin?
A
- A long, unbranched polymer of alpha glucose, similar to glycogen
13
Q
How does starch’s structure relate to its function?
A
- Starch is compact due to its helical structure of amylose so lots of glucose can be stored in a small space.
- Many branches in amylopectine which increases the points
where enzymes can act. - Insoluble
14
Q
What is the structure of glycogen?
A
- Similar to amylopectin
15
Q
What is the structure of cellulose?
A
- Long, unbranches chains of beta glucose (straight chain)
- These chains run in parallel to each other and are linked by hyrdogen bonds to form microfibrils
- Many microfibrils are arranged in parallel groups called fibres/
16
Q
Reducing sugars test?
A
- Benedicts solution, heat, coloured brick red precipitate forms
17
Q
Non-reducing test?
A
- Benedicts test doesn;t form brick red precipitate
- Use HCl acid and heat in a water bath that has been brought to a boil and then sodium hydrogencarbonate to neutralise.
- Repeat benedict’s test again to form a brick red colour.
18
Q
Test for starch?
A
- Iodine dissolved in Potassium iodide solution
- Solution changes from orange to blue black.
19
Q
What is the main role of triglycerides in plants and animals?
A
- Act mainly as energy stores in plants and animals
20
Q
How are triglycerides formed?
A
- Condensation reaction of one molecule of glycerol and three fatty acid molecules via an ester bond
21
Q
Saturated vs unsaturated fatty acids
A
Saturated: Fatty acid contains no C-C double carbon bonds
Unsaturated: Fatty acid contains C-C double bonds
22
Q
What is the structure of phospholipids?
A
- Same structure as triglycerides, except that one fatty acid has been replaced by a phosphate group
23
Q
How are triglycerides, phospholipids related to function
A
Triglycerides:
- Energy storage
- Insoluble so cells dont burst or shrink
Phospholipids:
- Make up the bilayer of cell membrane, controlling what enters or leaves a cell/organelle
- Hydrophobic barrier at the centre of the bilayer
- Glycolopids are formed for cell regonition by combination of lipids and carbs.
24
Q
Emulsion test
A
- Shake some of the sample with ethanol
- Filter the liquid into a test tube of water, leaving any solids behind
- Positive result would be lipid with a white emulsion
25
What are amino acid structures?
- Same R group
- Different carboxyl group
- Different amine group
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What are the bonds formed between amino acids?
- Peptide bonds
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primary structure of protein
Sequence of amino acids
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Secondary structure of amino acids
- Hydrogen bonds form between the amino acids in the chain such as alpha helix and beta pleated sheet
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Teritary structure
- Further folding of alpha helix and beta pleated sheet including hydrogen bonds, ionic bonds and disulphide bridges.
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What is the quaternary structure?
- A number of polypeptide chains joined together ( 2 or more)
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Biuret Solution test
Blue to purple
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What are enzymes?
- Proteins that act as biological catalysts by lowering the activation energy, minimum amoutn of energy for reaction to happen.
33
What is the induced fit model?
- When the lock and key happens, the enzyme and substrate alter their shape slightly
- Weakens specific bonds in the substrate needing to be broken, which lowers the activation energy required for the reaction to happen, increasing rate of reaction.
34
3 factors that affect enzyme activity
(temperature, ph, substrate concentration)
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What are competitive inhibitors?
- Molecules with similar shape to the substrate that fit into the enzyme's active site to form an enzyme-inhibitor complex, preventing the substrate from binding.
36
What are non-competitive inhibitors?
- Work by binding to enzyme in a place other than the active site.
- Changes tertiary structure of the adctive site meaning no complementary binding.
- Can't be reversed
- No competition happens
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Function of DNA and RNA?
- DNA holds genetic information in all living cells
- RNA transfers genetic information from DNA to ribosomes.
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DNA structure
- Phosphate
- Pentose (Deoxyribose)
- Base
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RNA structure
- Phosphate
- Ribose
- Either A,U,C,G
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How do nucleotides join together?
- Nucleotides join by a condensation reaction between the phopshate group of one nucleotide and pentose sugar of another
- Forms a phosphodiester bond between two nucelotides
41
What direction are DNA strands?
- antiparallel
42
History of DNA?
- Some argued that DNA was too simple to carry the genetic code.
- Some argued that genetic information must be carried by proteins, which are more chemically varied.
- 1953 experiments showed that DNA was the true carrier of genetic code after Watson and Circk determined the sturtcure of DNA.
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DNA structure relation to function?
- Two DNA polynucleotide strands are only joined together by weak H bonds, meaning that strands can separate during DNA replication
- Base pairs are protected by sugar-phosphate backbone
- Large molecule so carries losts of genetic information
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RNA structure relation to function
- Much shorter than DNA
- mRNA - Genetic info from DNA to ribosomes
- tRNA: involved in protein synthesis
- rRNA: makes up part of the ribosome structure
45
Why does DNA replicate itself before mitosis and meiosis?
- To ensure all the daughter cells produced have the genetic information to produce all the enzymes and other proteins they need.
46
What does semi conservative replication mean
- Each of the two new DNA molecules has 1 strand from the original molecule and 1 strand of new material.
47
What is the process of DNA replication?
1) DNA helicase breaks hydrogen bonds between bases on the two strands of DNA. The DNA double helix begins to unwind.
2) Original strands act as template
for a new strand. Free DNA nucleotides are attracted to complementary bases.
3) DNA polymerase catalyses condensation reaction which join the nucleotides of the new strands together by phosphodiester bonds.
48
How did Watson and Crick prove the semi-conservative theory?
- Through the Meselson and Stahl Experiment.
- This was where bacteria were grown on a medium containing heavy 15N nitrogen and the bacteria incorporated nitrogen from the medium into their DNA and is ultracentrifuged to obtain a heavy band of DNA.
- Bacteria is transferred to a medium containing lighter 14N nitrogen and are allowed to replicate once and are ultracentrifuged, obtaining an intermediate density band of DNA
- Bacteria replicates once more in the lighter 14N medium and the DNA is ultracentrifuged, obtaining both light and intermediate density DNA.
49
2 other models of DNA?
- Conservative (New material would consist of only old DNA)
- Dispersive (Original DNA would be cut up into sections leaving you with new DNA molecules with new and original material) (Can't just have intermediate density DNA)
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ATP
Adenosine triphosphate
51
Why is there lots of energy in phosphate bonds?
- Low activation energy so little energy needed to be put in to break these bonds and are easily broken/
- Lots of energy released when these bonds are broken.
52
What enzyme catalyses ATP synthesis?
- ATP synthase
53
What happens when ATP is formed in the body?
- ATP diffuses to the part of the cell that requires energy and is hydrolysed into ADP and Pi
54
What enzyme catalyses ATP hydrolysis?
- ATP hydrolase
55
Outline ATP as an energy source
- ATP is an immediate source of energy
- ATP releases energy is smaller, more manageable quantities
55
Why is water a good metabolite?
- Because many metabolic reactions are either condensation or hydrolysis reactions involving water
56
Why is water a good solvent?
- Water is a polar molecule so can therefore interact with charged ions or polar molecules.
57
Why does water have a relatively high specific heat capacity?
- Due to hydrogen bonding, it takes a lot of energy to change the temperature of water
58
Why does water have a large latent heat of vaporisation?
- It takes a lot of energy to break hydrogen bonds and change liquid water into a gas
59
What is cohesion?
Water forming hydrogen bonds with itself
60
What is adhesion?
Water forms hydrogen bonds with other materials
61
What are inorganic ions?
- Ions that don't contain carbon
62
What is the role of hydrogen ions?
- Concentration of H ions determines pH
- Higher = lower pH
- pH affects enzymes
63
What is the role of iron ions?
- Haemoglobin contains Fe2+ at its centre which binds to oxygen to temporarily become Fe3+
64
What is the role of sodium ions?
- Co transporter across cell membranes (sodium-glucose)
- Active transport (sodium potassium pump)
- Nerve impulse transmission
65
What is the role of phosphate ions?
- Bonds between phosphate groups store energy in ATP
- Phosphate allows DNA and RNA nucleotides to join to form polynucleotides
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