DNA

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  • Created by: LucySPG
  • Created on: 28-05-13 13:21
What is a nucleotide?
Three basic components that make up DNA
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What are the three components of a nucleotide?
A sugar called deoxyribose, a phosphate group and an organic base
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How is the deoxyribose sugar, phosphate group and organic base combined?
Condensation reaction
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What is formed when two nucleotides join together?
Dinucleotide
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What is formed when many nucleotides join together?
Polynucleotide
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What is DNA made up of?
2 strands of nucleotides
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How are the two strands of nucleotides joined together?
Hydrogen bonds formed between certain bases
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What pairs with Adenine?
Thymine
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How many hydrogen bonds pair Adenine and Thymine?
2
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What pairs with Cytosine?
Guanine
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How many hydrogen bonds pair Guanine and Cytosine>
3
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What is the structural name for a DNA molecule?
Double Helix
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What forms the structural backbone of the double helix?
Deoxyribose sugar and a phosphate group
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What is the function of DNA?
It is the hereditary material responsible for passing genetic information from cell to cell and generation to generation
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There are 4 ways in which a DNA molecule is adapted to carry out its function. Name one of these adaptations.
It is very stable and can pass from generation to generation without change
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Name another way in which DNA is adapted to carry out its function
Its two separate strands are joined only with hydrogen bonds, which allow them to separate during protein synthesis
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Name another way in which DNA is adapted to carry out its function
It is an extremely large molecule and can therefore carry an immense amount of genetic information
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Name another way in which DNA is adapted to carry out its function
By having the base pairs within the helical cylinder of the deoxyribose-phosphate backbone, the genetic information is to some extent protected from being corrupted by outside chemical and physical forces
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Describe the DNA of prokaryotic cells
Small DNA molecules, form a circle, aren't associated with protein molecules and do not have chromosomes
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Describe the DNA of Eukaryotic cells
Large DNA molecules, linear, associated with protein molecules and form chromosomes
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When do chromosomes become visible?
During cell division
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What are chromosomes made up of?
Proteins and DNA
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What is a gene?
Sections of DNA that contain the coded information for making polypeptides
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What form is the coded information in?
A specific sequence of bases
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What is formed as a result of a combination of polypeptides?
Proteins
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What is a gene made up of?
Amino acids
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How does DNA determine our nature and development?
DNA sequence determines amino acid sequence. Proteins and enzymes are formed. Enzymes enable metabolic pathways. Metabolic pathways help determine nature and development.
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How many amino acids regularly occur in proteins?
20
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What must each amino acid have?
Its own code of bases of the DNA
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How many bases are present in DNA?
4
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What is the triplet code?
The sequence of three nucleotide bases that codes for the synthesis of a specific amino acid
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There are 8 features of the triplet code. Name one of these features.
A few amino acids have only a single triplet code
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There are 8 features of the triplet code. Name another one of these features.
The remaining amino acids have between two and six triplet codes each
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There are 8 features of the triplet code. Name another one of these features.
The code is known as a 'degenerate code' because most amino acids have more than one triplet code
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There are 8 features of the triplet code. Name another one of these features.
The triplet code is always read in one particular direction along the DNA strand
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There are 8 features of the triplet code. Name another one of these features.
The start of the sequence is always the same triplet code. This codes for the amino acid methionine. If this first methionine molecule does not form a part of the final polypeptide, it is later removed.
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There are 8 features of the triplet code. Name another one of these features.
Three triplet codes do not code for any amino acids, these are called stop codes and mark the end of a polypeptide chain.
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There are 8 features of the triplet code. Name another one of these features.
The code is non-overlapping - each base in the sequence is only read once
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There are 8 features of the triplet code. Name another one of these features.
The code is universal - it is the same in all organisms
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How is the DNA in chromosomes held in position?
By proteins
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What are homologous chromosomes?
One of each pair is derived from the chromosomes provided by the mother in the egg and the other is derived from the chromosomes provided by the father in the sperm
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What is the diploid number of chromosomes?
46
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What is the haploid number of chromosomes?
23
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A homologous pair is always two chromosomes that determine the same genetic characteristics but...
determining the same genetic characteristics is not the same as being identical
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What are chromosomes made up of?
Two chromatids containing DNA
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What is an allele?
A gene that exists in more than one form
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What happens if the base sequence of an allele of a single gene is changed?
Will result in a different sequence of amino acids being coded for
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What happens if there is a different amino acid sequence?
It will lead to the production of a different polypeptide and hence a different protein
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How many stages are there in the cell cycle?
3
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Name the three stages of the cell cycle
Interphase, nuclear division and cell division
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Other cards in this set

Card 2

Front

What are the three components of a nucleotide?

Back

A sugar called deoxyribose, a phosphate group and an organic base

Card 3

Front

How is the deoxyribose sugar, phosphate group and organic base combined?

Back

Preview of the front of card 3

Card 4

Front

What is formed when two nucleotides join together?

Back

Preview of the front of card 4

Card 5

Front

What is formed when many nucleotides join together?

Back

Preview of the front of card 5
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