Biological Molecules 2

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  • Created by: jackjj9
  • Created on: 20-11-16 12:31
What kind of substance is water?
Polar
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Which side of water is delta negative?
Oxygen
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Which side of water is delta positive?
Hydrogen
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What causes water's polarity?
Electronegativity
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What kind of bonds form between H2O molecules?
Hydrogen bonds (as O is one of three most electronegative elements)
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Why is water called a metabolite?
Because it is needed in many metabolic (essential to life) reactions
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What 5 things make water essential to life?
Surface tension. Cohesion. Solvent. High latent heat of vaporisation. High SHC.
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What is Specific Heat Capacity (SHC)?
The amount of energy required to heat 1g of substance by 1 degree celcius
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Why is water having a high SHC an advantage?
It means that it takes lots of energy to heat so it a stable environment for aquatic organisms. It also keeps our blood at a relatively constant temperature so enzymes do not become dentaured
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What is latent heat?
The amount of energy required to change a substance from one state to another - e.g. liquid to gas.
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Why is water having a high latent heat of vaporisation advantageous?
It provides a cooling effect, without an organism losing too much water
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How does water provide a cooling effect?
It requires lots of energy to break the H-bonds meaning that not much energy is left to actually raise the temperature of the body as the water evaporates from the skin.
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How is water cohesive?
The polarity of water means that molecules are attracted to one another
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What is cohesion?
When identical molecules are attracted to one another
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What is adhesion?
When 2 different molecules are attracted to each other
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Give an example of when water being cohesive and adhesive is advantageous
When drawing water up a xylem vessel, in capillary action
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Why does water have a good surface tension?
The molecules on the top (where it meets the air) are not surrounded by like molecules on all sides so are attracted to each other with H-bonds to a greater degree than other molecules
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Why is having surface tension good?
Insects such as mosquitoes can walk on water. Sweat forms beads on the skin.
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Why is water a good solvent?
Its polarity means that the delta negative O is attracted to cations, surrounding them entirely. The delta positive hydrogen is attracted to anions of ionic substances, completely surrounding them.
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When is a substance completely dissolved?
When all of the ions are surrounded by oppositely charged sides of a solvent molecule
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Why is the fact that water is the best solvent on earth good?
Most reactions happen in solution or in the cytoplasm of cells
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What is the generally accepted theory of DNA replication called?
Semi- Conservative DNA replication
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What are the 2 enzymes that are involved in DNA replication?
DNA helicase and DNA polymerase
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Why is it called Semi-Conservative theory?
1 strand of the DNA is kept and a new strand is added onto it each generation so half (Semi) of the DNA is the same between 2 generations.
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What does DNA helicase do?
Break the hydrogen bonds between the complementary base pairs, "unzipping" the DNA
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What does DNA polymerase do?
Attaches complimentary base pairs to the original strand of DNA
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Explain why 2 DNA polymerase enzymes work in opposite directions
DNA has antiparallel strands. The nucelotides are arranged in different orders. DNA polymerase has a specific shaped active site for the substrate. Only substrates with this shape will bind to the active site of DNA polymerase.
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Which scientists helped to validate the semi-conservative replication theory?
Meselson and Stahl
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What did Meselson and Stahl do?
Grew bacteria on mediums containing different isotopes of N and then floated the DNA is CsCl(l). Heavier/more dense DNA will sink futher.
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What part of the DNA contains nitrogen?
Nitrogenous bases
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What is the function of DNA?
To code for a polypeptide
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Name 2 nucleic acids
DNA and RNA
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What is the monomer of DNA?
Nucleotides
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What are the three components of a single nucleotide of DNA?
Phosphate, deoxyribose sugar and a nitrogenous base
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What is the complimentary base pairing rule?
A-T and G-C
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What is the bond between a phosphate group and a pentose sugar in the backbone of a nucleic acid called?
Phosphodiester bond
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Why can DNA not leave the nucleus?
It is too big to fit through the nuclear pores
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What are ribosomes made of?
RNA and proteins
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Give the 3 types of RNA
mRNA, tRNA and ribosomal RNA
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Give three differences between RNA and DNA
RNA is shorter - coding for only 1 gene. RNA contains U instead of T. It has a ribose sugar, not deoxyribose. RNA is single stranded
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Give 2 similarities betweeen RNA and DNA
Both have the bases A, C and G. Both consist of nucleotides
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What kind of reaction joins nucleotides together to form phosphodiester bonds, resulting in a polynucleotide chain?
Condensation
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What type of bonds hold together the complimentary base pairs?
Hydrogen bonds
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How many hydrogen bonds are there between adenine and thymine in DNA?
2
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How many hydrogen bonds are there between cytosine and guanine in DNA?
3
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Which of the bases are pyrimidines?
Thymine, cytosine and uracil
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What do the pyrimidines, thymine and cytosine join to?
Purines
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What are the two purines in DNA bases?
Guanine and adenine
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Which is bigger, pyrimidines or purines?
Purines
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Why are purines bigger than pyrimidines?
They contain a 2-ring structure, whereas pyrimidines only contain a 1-ring structure
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How many complimentary base pairs are there between one full turn of DNA?
10
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Why are there 10 base pairs between each turn on DNA?
The pyrimidines hydrogen bond to the purines to form a three-ring structure
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What kind of molecule is ATP?
A nucleotide derivative
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What does ATP stand for?
Adenosine triphosphate
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What does ADP stand for?
Adenosine diphosphate
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Which organelle produces ATP?
Mitochondria
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Give three things we need energy for...
Active transport. Muscle transport. (Protein) synthesis. Cell replication. DNA replication
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What are the three components of ATP?
Adenine, ribose sugar and 3 phosphate groups
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What is the order of the phosphate groups, starting with furthest away from the ribose sugar?
Gamma - Beta - Alpha
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Which bond between the phosphate groups is broken first?
Gamma and Beta
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What type of reaction breaks this bond?
Hydrolysis
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What does ATP split into, after the gamma-beta bond has been hydrolysed?
ADP and Pi (Pi = inorganic phosphate)
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What enzyme catalyses the hydrolysing of the bonds in ATP?
ATP hydrolase
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Which enzyme catalyses the condensation reaction, adding Pi back onto ADP?
ATP synthase
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When is ATP resynthesised?
During photosynthesis and respiration
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What are the 4 inorganic that are needed for the exam?
Iron, Sodium, Hydrogen and Phosphorous (phosphate)
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What is an inorganic ion?
A charged particle that does not contain carbon
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Where are Fe2+ cations found?
There is one in the centre of each polypeptide that makes up haemoglobin on the RBCs
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What does Fe2+ allow?
It allows oxygen to bind to it, creating oxyhaemoglobin and allow RBCs to carry oxygen in the blood
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What does Fe2+ temporarily become when oxygen binds to it and why?
Fe3+ because it has been oxidised (lost an electron)
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What does the concentration of H+ cations effect?
pH
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If there is a high concentration of H+ ions, what is the pH?
Low - Acidic
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Why is pH important?
It effects all enzyme-controlled substances and an extremity can cause the ionic and hydrogen bonds in the tertiary structure to break, therefore the active site shape is lost
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What is a negative ion called?
Anion
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Which two molecules need help to pass through the cell-surface membrane?
Glucose and amino acids
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Which ion helps to get glucose and amino acids across the cell-surface membrane?
Na+ (Sodium cations)
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What is this process called?
Cotransport
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What is cotransport?
Using the concentration gradient of one substance to move another substance against its concentration gradient
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Why are phosphate anions important?
They are found on many molecules including phospholipids and nucleotides
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How many polypeptides make up haemoglobin?
4
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Other cards in this set

Card 2

Front

Which side of water is delta negative?

Back

Oxygen

Card 3

Front

Which side of water is delta positive?

Back

Preview of the front of card 3

Card 4

Front

What causes water's polarity?

Back

Preview of the front of card 4

Card 5

Front

What kind of bonds form between H2O molecules?

Back

Preview of the front of card 5
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