Topic 1B: More biological molecules

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What does DNA stand for?
Deoxyribonucleic acid
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What does RNA stand for?
Ribonucleic acid
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What 3 components make up a nucleotide structure?
Phosphate group, pentose sugar and nitrogen containing organic base
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What is the chain of phosphates and sugars called?
The sugar-phosphate backbone
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What is the bond that is formed between a phosphate group and the sugar in a polynucleotide structure?
A phosphodiester bond
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How is a phosphodiester bond formed (in a polynucleotide structure)?
Condensation reaction
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What does a 'double helix structure' mean in DNA?
It means that a DNA molecule is formed from two seperate strands which wind around together to form a spiral
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Why are DNA moleules really long and coiled up tightly?
So lots of genetic information can fit in a small space
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What are the 3 components of a DNA nucleotide structure?
A phosphate group, deoxyribose sugar and a base (A T C G)
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What are the 4 possible bases in DNA? (FULL names pls)
Adenine, Thymine, Cytosine and Guanine
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What is the bond formed between two bases on two DNA polynucleotide strands?
Hydrogen bonds
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What is complementary base pairing?
When each base can only join with one particular partner
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What does adenine always pair with (in DNA)?
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What does Guanine always pair with?
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How many hydrogen bonds from between C and G?
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How many hydrogen bonds form between A and T?
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Two polynucleotide strands are anti-parallel. What does this mean?
They run in opposite directions
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Give the 4 ways that the structure of RNA differs from DNA
1: sugar in RNA is ribose (not deoxyribose) 2: Uracil replaces thymine as a base 3: Nucleotides form a single polynucleotide strand (not a double) 4: RNA is a lot shorter than DNA
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What do ribosomes make?
RNA and proteins
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Why did people not think DNA was the carrier of the genetic code back in the day?
It has a relatively simple chemical composition
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Why did scientists think that proteins carried the genetic code?
They are more chemically varied
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What is semi-conservative replication?
Replication of DNA in which half of the new molecules of DNA are from the original piece of DNA
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What does semi-conservative replication ensure?
That there's genetic continuity between generations of cells
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What enzyme breaks the hydrogen bonds in DNA replication?
DNA helicase
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How does the helix unwind to form two single stands in DNA repliction?
DNA helicase breaks the hydrogen bonds between base pairs on the two polynuclotide DNA strands
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What enzyme joins the newly formed nucleotides together in DNA replication?
DNA polymerase
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What type of reaction joins the nucleotides together in DNA replication?
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What is each end of the DNA strand called?
The 3' (three prime) or 5' (five prime)
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In what direction does DNA polymerase move down the template strand?
3' to 5' direction
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What experiment proved DNA is replicated using semi conservative replication?
Meselson and Stahl's experiment
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Name the two enzymes involved in DNA replication
DNA helicase and DNA polymerase
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Describe the first stage of DNA replication, in which two strands of DNA are seperated
The DNA helicase breaks hydrogen bonds between bases on the two polynucleotide DNA strands. This caused the double helix to unwind
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Describe the second stage of DNA replication, where the single strands act as templates
Complementary base pairing means free floating nucleotides are attracted to their bases on each original template strand
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Describe the third stage of DNA replication, where two new molecules of DNA are formed.
Condensation reactions join the nucleotides of the new strand together. This is catylsed by the enzyme DNA polymerase. Hydrogen bonds form between bases.
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Why is energy important to animal and plant cells?
They need it for biological processes
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What are the 3 components of an ATP molecule?
Adenine, ribose sugar & three phosphate groups
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What does ATP stand for?
Adenosine triphosphate
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Where is the energy in ATP stored?
In high energy bonds between the phosphate groups
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What is ATP broken down into?
ADP (adenosine diphosphate) and Pi (inorganic phosphate)
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By what reaction is ATP broken down?
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What enzyme catalyses the breaking down of ATP?
ATP hydrolase
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What is phosphorylation?
When inorganic phosphate is added to another compound (it often makes the compound more reactive)
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How can inorganic phosphate (released by the breakdown of ATP) be used?
It can be added to another compound, which makes the compound more reactive
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What enzyme reforms ATP by the addition of ADP and Pi?
ATP synthase
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What type of reaction is the reformation of ATP from ADP and Pi?
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Give an example of a process during which the reformation of ATP from ADP and Pi takes place
Respiration and photosynthesis
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ATP hydrolysis can be 'coupled' to other energy-requiring reactions in the cell. What does this mean?
The energy released form the formation of ADP and Pi can be used directly to make the coupled reaction happen, rather than it being lost as heat
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Give 4 functions of water, inside and outside of cells
1:Water is a metabolite in lots of metabolic reactions (hydrolysis and condensation) 2: water is a solvent and most metabolic reactions take place in solution 3: helps with temperature control 4: water molecules are cohesive
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What properties of water mean it helps with temperature control?
It has a high latent heat of vaporisation and a high specific heat capacity
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Why is it important that water is cohesive (they stick together) in organisms?
It helps water transport in plants (as well as other organisms)
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Why is water classed as a polar molecule?
It has a slight negative charge on one side and a slight positive charge on the other
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Why does hydrogen have a slight positive charge in water?
The electrons are pulled towards the oxygen atom
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What element is slightly negatively charged in water?
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What are hydrogen bonds?
Weak bonds between a slightly positively charged hydrogen atom in one molecule and a slightly negatively charged atom in another
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Why do hydrogen bonds form in water?
Slightly positively charged oxygen atom attracts the slightly positively charged hydrogen atoms in another water molecule
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List as many properties of water as you can (there are 5)
Important metabolite, good solvent, high latent heat of vaporisation, can buffer (resist) changes in temp, very cohesive
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What is a metabolite?
A substance involved in a metabolic reaction
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Why is water needed in metabollic reactions?
Hydrolysis requires a molecule of water to break a bond and a molecule of water is released during condensation.
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Why does water surround charged particles?
It is partially negatively charged on one side and partially positively charged on the other, so one side will be attracted to the charged particle
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What is a solvent?
A substance capable of dissolving another substance
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Why is water being a good solvent important for living organisms?
It means that they can take up useful substances dissolved in water and these dissolved substances can be transported around the organisms body
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Water has a high latent of vaporisation. What does this mean?
Lots of heat is required to change it from a liquid to a gas
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Why is high latent heat of vaporisation useful for living organisms?
It means they can use water loss through evaporation to cool down without losing too much water
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How does sweat cool down organisms?
When water (sweat) evaporates it carries heat energy from a surface, which cools the surface and helps lower temperature
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What is specific heat capacity?
The energy needed to raise the temperature of 1 gram of a substance by 1 degrees.
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What feature of water gives it a high specific heat capacity?
The hydrogen bonds
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How is water having a high specific heat capacity beneficial to living organisms?
It helps them remain at a constant internal body temperature
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What is cohesion?
The attraction between molecules of the same type (e.g. water molecules)
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Why are water molecules cohesive?
They're polar
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Why is cohesion between water molecules important in plants?
Strong cohesion between water molecules allows water to travel in columns in the xylem tissue inside plants. Substances are transported around plants this way.
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Why does water have a high surface tension when it comes into contact with air?
Water molecules are strongly cohesive (right wording??)
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What is an ion?
An atom that has an electric charge
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What is an inorganic ion?
It is (mainly) an ion that doesn't contain carbon
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Where do inorganic ions occur?
In solution, in the cytoplasm of cells and in the body fluids of organisms
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What determines an ion's specific role?
Its specific propeties
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What happens to the Fe2+ ion in haemaglobin when it binds to oxygen?
It becomes Fe3+ until its released
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Name the ion that affects Ph
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What does adding more H+ do to the pH of a solution?
Makes it more acidic (lower pH basically)
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Where do you find phosphate ions?
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What type of ion is involved in moving glucose and amino acids across cell membranes?
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What is the name of the process which moves glucose and amino acids across cell membranes?
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Other cards in this set

Card 2


What does RNA stand for?


Ribonucleic acid

Card 3


What 3 components make up a nucleotide structure?


Preview of the front of card 3

Card 4


What is the chain of phosphates and sugars called?


Preview of the front of card 4

Card 5


What is the bond that is formed between a phosphate group and the sugar in a polynucleotide structure?


Preview of the front of card 5
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