2.3 and 2.4 Flashcards

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1
Q

What is a nucleotide?

A

A biological molecule made from

  • Pentose sugar
  • A nitrogenous base
  • A phosphate group
It contains the elements
Carbon
Hydrogen
Oxygen 
Nitrogen 
And Phosphorus 

They are monomers that make up DNA

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2
Q

What is the difference between RNA and DNA?

A

RNA has the bases A,U,C or G
and has a ribose sugar

DNA has the bases A,T,C or G
and has a deoxyribose sugar

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3
Q

What is a purine?

A

It contains two carbon-nitrogen rings joined together

They are Adenine and Guanine

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4
Q

What is a pyrimidine?

A

It contains only one Carbon-Nitrogen ring

Is smaller than a purine base

They are Cytosine and Thymine

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5
Q

What is the names of all the bases?

A
Adenine
Guanine
Cytosine
Thymine
Uracil
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6
Q

What is the structure of DNA?

A

Double helix shape

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7
Q

What do nucleotides help regulate?

A

Metabolic pathways

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8
Q

Where is DNA found?

A

Nucleus

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9
Q

Explain protein synthesis?

A

Transcription: A section of DNA unwinds (catalysed by DNA helicase) and acts as a template. The section is then copied to make mRNA (catalysed by RNA polymerase). The mRNA then leaves the nucleus and enter the cytoplasm where it is held by a ribosome. The instruction will be complimentary to the DNA strand with Thymine being replaced by Uracil.

Translation: In the cytoplasm, tRNA picks up amino acids. One end of tRNA carries one amino acid and the other end has a triplet code sequence that is complimentary to the codon on mRNA (known as anti codon). Once the mRNA is in the cytoplasm and attached to a ribosome, it is read by tRNA. tRNA molecules line up against mRNA.

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10
Q

What are DNA strands made up of?

A

Polynucleotides

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11
Q

Why do the bases have specific pairs?

A

A purine must always pair with a pyrimidine to give equal sized rings on the double helix

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12
Q

What is a phosphorylated nucleotide?

A

A nucleotide with added phosphate groups

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13
Q

What is the structure of ADP?

A

It contains the base adenine, the sugar ribose and two phosphate groups

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14
Q

What is the structure of ATP?

A

It contains the base adenine, the sugar ribose and three phosphate groups

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15
Q

What process is used to add phosphate groups to a molecule?

A

Phosphorylation

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16
Q

Explain the synthesis and breakdown of polynucleotides?

A

Nucleotides join together between the phosphate group of one and the sugar of another, forming a phosphodiester bond.

They are broken down in to nucleotides by breaking the phosphodiester bonds

17
Q

What is an enzyme?

A

Globular proteins

Biological catalysts that speed up metabolic reactions in living organisms

18
Q

Describe the lock and key analogy

A

It describes the fact that only a specific substrate will fit the active site of an enzyme

19
Q

Describe the induced fit theory

A

It states that the active site is not rigid but is flexible allowing the shape to change slightly when a substate renters but then returns to its original shape once the product is released

20
Q

How does temperature affect enzyme activity?

A

The rise in temperature makes the enzyme molecule vibrate more increasing the rate of reaction

If the temp goes above a certain level then the vibration breaks some of the bond holding the enzyme’s tertiary structure

This changes the shape of the active site

The substrate can therefore no longer fit

When the enzyme is denatured there is no reaction

At this point the enzyme is denatured

21
Q

How does pH affect enzyme activity?

A

Small changes of the pH, either side of the optimum pH slows the rate of reaction as the shape of the active is disrupted.

If the normal optimum pH is restored the shape of the active site is restored

At extremes of the pH the active site may permanently change

When the enzyme is denatured it cannot change the reaction

22
Q

How does substate concentration affect enzyme activity?

A

If there is no substrate present then no reaction can take place

As the substate is added, the concentration increases so the rate of reaction increases

As the concentration of substate is increased even further the reaction will reach its maximum rate

23
Q

How does enzyme concentration affect enzyme activity?

A

As the enzyme concentration increases, more active sites become available

Therefore there’s more successful collisions between enzymes and substrates

If substrate concentration increases then the rate of reaction increases until maximum rate

If the enzyme concentration is increased further it will have no effect on the rate of reaction

This is beachside all active sites have been used

Enzyme concentration is no longer the limiting factor

24
Q

What is the function of catalase?

A

It is a enzyme that works inside cells to catalyse the breakdown of Hydrogen Peroxide to harmless oxygen and water