Nucleic Acids and their Functions

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  • Created by: Ellen122
  • Created on: 16-03-21 19:37
ATP
Produced by chemiosmosis in every living organism
Evolved in our Last Universal Common Ancestor (LUCA)
Proton gradients that exist in thermal vents gave rise to the origin of life approximately 3.5 billion years ago
Universal energy currency
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ATP Money Metaphor
Though of as a £10 note
Can be saved when there is sufficient energy released from a reaction (respiration)
Spent when a process (muscle contraction) requires energy
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What Does ATP Consist of?
Organic base adenine
A 5C sugar
Ribose
3 Phosphate groups linked together
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ATP and Recycling
Constatntly recycled
Has to be synthesised when it is required
An active cell requires an excess of 2 million ATP molecules per second
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Production of ATP
Involves the addition of a phosphate molecule to ADP
Requires 30.6KJmol-1 of energy
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Reactions Achieving Phosphorylation
Oxidative phosphorylation which occurs on the membranes of mitchondria during respiration
Photophosphorylation which occurs on the membranes of chloroplasts during photosynthesis
Both are endergonic reactions - require energy
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Endergonic Reaction
ADP + Pi --> ATP - 30.6KJmol-1
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Exergonic Reaction
Release of energy from a single molecule of ATP involves the hydrolysis to release a single molecule of phosphate
ATP --> ADP + Pi + 30.6KJmol-1
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Advantages of Using ATP over Glucose as a Source of Energy
ATP releases small packages of energy (30.6KJmol-1) when and where they are needed - there is little wastage. If the amount of energy in a glucose molecule was used for active transport, the waste would be release as heat. This would cause a catastrophic
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Nucleic Acids
Structure allows them to act as a digital code for all living organisms
2 types of nucliec acids include DNA and RNA
Made of repeating units called nucleotides
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Nucleotides
Consist of 3 parts joined together by condensation reactions
Organic, nitrogenous bases which can be single ringed pyrimidines (thymine, cytosine and uracil) or double ringed purines (adenine and guanine)
Phosphate (H3PO4)
Pentose sugars - ribose or deoxy
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Deoxyribonucleic Acid
Double stranded molecule
Made of 2 polynucleotides
DNA molecules may be several million base pairs long
2 strands form a double helix
Shape is held in place by the hydrogen bonds between the complementary base pairs
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Adenine and Thymine
2 hyrogen bonds are formed between them
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Guanine and Cytosine
3 hydrogen bonds are formed between them
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Double Helix
Unzips during DNA replication and transcription so that the genetic code can be read
Ring of the ladder are the bases and the sugar phosphate backbones form the uprights
Srands are described as antiparallel as they run in opposite directions
One strand ru
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Ribonucleic Acid
A single stranded polymer of nucleotides
Pentuse sugar in the sugar phosphate backbone is ribose
Thymine base found in DNA is replaced with Uracil
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Three Types of RNA
mRNA (messenger RNA0 is transcribed from the nucleus when the genetic code is read. It then travels to the ribosomes to be translated
rRNA (ribosomal RNA) is a component of ribosomes
tRNA (transfer RNA) is a small single stranded molecule that delivers th
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DNA vs RNA
DNA is double stranded, contains Thymine, and pentose sugar is deoxyribose
RNA is single stranded, contains Uracil and pentose sugar is ribose
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DNA Replication
DNA replication takes place during interphase
Each daughter cell gets an exact copy of the chromosomes
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Watson and Crick
Proposed the semi-conservative mechanism in their famous Nature paper from 1953
'It has not escaped our notice that the specific we have psotulated immediately suggests a possible copying mechanism for the genetic material'
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Protein Synthesis
Chromosomes contain thousands of genes
Genetic code within the genes determines the 1o struture of the proteins produced the cells
These may be the structural proteins that make up cells as well as the enzymes that control their chemcial reaction
Other pr
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The Triplet Code
Only 4 letters in the DNA 'alaphabet'
20 different amino acids that make up the proteins found in all living things
Each amino acids can have a geneci code a series of 3 DNA letter codes for each amino acid
This groups o 3 letters is called codon
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Codons
Provides 64 different permutations of codons, more than enough for 20 different amino acids
Genetic code is described as redundant or degenerate - some amino acids have more than one codon
Codons act as 'punctuation' for the genetic code
Analagous to capi
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Polypeptide
Each gene codes for a specific polypeptide
'One gene one protein' hypothesis needed to be modified to 'one gene one polypeptide' when proteins with quarternary structure was discovered
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Two Stages of Protein Synthesis
Necessary as the DNA is too 'valuable' to leave the nuclues
Code is copied onto a messenger RNA molecule (transcription)
mRNA then leaves the nucleus and is translated by a ribosome into a polypeptide
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Transcription
The region of the DNA copied is technically called the cistron
Thought of as the gene and codes for a certain polypeptide
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Introns and Exons
Eukaryotes have regions of DNA that code for proteins called exons
Between exons and within them are non coding regions called introns
During transcription the entire gene is copied into a pre-mRNA, which includes exons and introns
RNA splicing - endonucl
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Translation
Takes place when the large and small sub-units of a ribosome clamp onto an mRNA molecule
Amino acids will make up the completed polypeptide chain are carried to the ribosome by transfer RNA molecules
20 different tRNA molecules; one for each of the 20 ami
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Initiation
The ribosome binds to the mRNA. There are 2 reading frames in the large sub-unit so that 2 tRNA molecules a a time can be brought into the ribosome
The first tRNA binds its anticodon to the cocmplementary codon on the mRNA
A second tRNA binds in the secon
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Elongation
The ribosome then moves along the mRNA one codon at a time
The polypeptide chain grows out of the ribosome as it moves along the mRNA molecule
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Termination
Once a stop sequence is reached the polypeptide is cast off from the ribosome
More than one riosome can move along a molecule of mRNA at a time
Polysome System
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Polypeptide Chain and Golgi Body
May be modified by the golgi body
Quarternary proteins can be formed by the addition of more polypeptide chains
Proteins fold into their distinctive secondary teriary and quarternary structures after they have been translated
Non protein molecules can als
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Amino Acids and the Polypeptide Chain
Once the amino acids have been given to the polypeptide chain the tRNA molecules are activated by having their specific amino acid added so that they can be reused
This requires energy in the form of ATP
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Other cards in this set

Card 2

Front

ATP Money Metaphor

Back

Though of as a £10 note
Can be saved when there is sufficient energy released from a reaction (respiration)
Spent when a process (muscle contraction) requires energy

Card 3

Front

What Does ATP Consist of?

Back

Preview of the front of card 3

Card 4

Front

ATP and Recycling

Back

Preview of the front of card 4

Card 5

Front

Production of ATP

Back

Preview of the front of card 5
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