DNA

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What are the monomers of DNA called?
Mononucleotides
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What three structures are mononucleotides composed of?
Phosphate Group, Deoxyribose Pentose Sugar, Organic Nitrogenous Base
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What is the bond between the phosphate group and deoxyribose called?
(covalent) Phosphoester
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What is the bond between two mononucleotides called?
(covalent) Phosphodiester
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What are the four bases called?
Adenine, Thymine, Guanine, Cytosine
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What are the complementary base pairs?
Adenine with Thymine, Cytosine with Guanine
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What bonds join the two bases together?
Hydrogen
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How many hydrogen bonds are there between Adenine and Thymine?
2
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How many hydrogen bonds are there between Guanine and Cytosine?
3
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What are the two types of base called?
Purines and Pyrimidines
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Which bases are the purines?
Adenine and Guanine
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Which bases are the pyrimidines?
Cytosine and Thymine
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What is different in the structure of a purine and a pyrimidine?
Purines are bigger (double ring hexagonal and pentagonal structure) and pyrimidines are smaller (single hexagonal ring)
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Why pair a purine with a pyrimidine?
To keep the length the same all the way down the double helix
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How are the two DNA strands arranged in the double helix?
Antiparallel
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What are the two strands called?
5'3' strand and the 3'5' strand (upside down)
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What is a triplet?
A group of three bases
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What is the function of a triplet?
To code for an amino acid
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What is a gene?
A section of DNA that codes for a particular polypeptide
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What is an intron?
A section within a gene that does not code for amino acids
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What is an exon?
A section within a gene that codes for an amino acid
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What is a cistron?
A gene
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What is junk or nonsense DNA?
DNA between genes that does not code for amino acids but codes for which genes are expressed
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What a locus?
The postition of the gene on the chromosome (the same in everyone)
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What is the base triplet hypothesis?
The idea that three bases code for one amino acids; there are 20 amino acids and for 1 or 2 bases to code for one aa there would not be enough to make 20 aa
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What does the base triplet hypothesis give rise to?
The idea that there is more than one code for some amino acids
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What is the start code?
TAC
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What are the stop codes?
ATT, ATC, ACC
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What is similar about the codes that code for the same amino acid?
They usually start with the same two letters
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What are the adaptations of the DNA molecule?
It is stable, large and made up of 2 strands joined together with hydrogen bonds
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Why must the DNA molecule be stable?
To pass information throgh the generations without change
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Why must the DNA molecule be large?
It carries a large amount of information
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Why does the DNA molecule have 2 strands joined together with hydrogen bonds?
So that they can be easily separated during DNA replication
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What are three features of the DNA code?
It is degenerate, universal, and non-overlapping
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What is meant by the code being degenerate?
It contains more information than necassary
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What is meant by the code being universal?
It is the same in all organisms
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What is meant by the code being non-overlapping?
EAch triplet is only read once, increasing the flexibility of the code and speed of decoding
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What is meant by a gene mutation?
A change in the arrangement of the nucleotide bases
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What is meant by a point mutation?
A change in one of the organic bases (an addition, deletion or substitution)
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How could a change in the DNA base lead to the formation of non functional proteins?
The wrong amino acid would be formed changing the primary therefore secondary, tertiary and quaternary structure of the protein
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Why do many mutations not change the polypeptides formed?
They may occur in introns or junk DNA
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Why may the protein remain unaffected if a mutation occurs in an exon?
The code is degenerate
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How can mutations be useful?
They are the raw material of evolution
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What is sickle cell anaemia?
An inherited disease where the person has abnormal haemoglobin causing the RBCs to become curved and sickled in shape
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What is sickle cell anaemia caused by?
A substitution point mutation (CTC to CAC, glutamic acid to valine)
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What is the advantage of sickle cell anaemia?
It gives resistance to malaria as the parasite cannot survive in the sickle shaped RBCs
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What were the three proposed methods of DNA replication?
Conservative, Semi-Conservative and Dispersive
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What is meant by conservative replication?
One of the new daughter cells has the complete original double helix whilst the other has a completely new double helix
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What is meant by semi-conservative replication?
Each new daughter cell has one strand of the parental DNA and one new strand
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What is meant by dispersive replication?
Each strand in each daughter cell has some parental and some new DNA
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Which method of DNA replication was proven correct?
Semi conservative
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Other cards in this set

Card 2

Front

What three structures are mononucleotides composed of?

Back

Phosphate Group, Deoxyribose Pentose Sugar, Organic Nitrogenous Base

Card 3

Front

What is the bond between the phosphate group and deoxyribose called?

Back

Preview of the front of card 3

Card 4

Front

What is the bond between two mononucleotides called?

Back

Preview of the front of card 4

Card 5

Front

What are the four bases called?

Back

Preview of the front of card 5
View more cards

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