Nucleotides and Nucleic acids Flashcards
What is a nucleotide made of?
-A pentose sugar- A nitrogenous base- A phosphate group
What elements are nucleotides made up of?
-Carbon-Oxygen-Hydrogen-Nitrogen-Phosphate
Why are nucleotides important?
-They’re the monomers that make up DNA and RNA
What is DNA used for?
-To store genetic infomation, the instructions used to grow and develop.
What is RNA used for?
-To make proteins from instructions in DNA
What are ATP and ADP?
-Special types of nucleotides that are used to store and transport energy in cells
What is ribose and what is it used in?
-A sugar that is used in RNA instead of deoxyribose
What are the four phosphate groups in DNA?
-Adenine, Guanine, Cytosine, Thymine
How do the phosphate groups in DNA pair?
- Adenine and Thymine
- Cytosine and Guanine
What type of bases are adenine and guanine?
Purine
What type of bases are cytosine and thymine?
Pyrimidine
What pentose sugar is used in DNA?
Deoxyribose
What does a purine base contain?
- Two carbon-nitrogen rings joined together
What does a pyrimidine base contain?
- One carbon-nitrogen ring, making it a smaller base than purine
What are the bases in RNA?
-Adenine, Uracil, Cytosine and Guanine
What is a molecule of DNA made up of?
- Two polynucleotide chains
What is a molecule of RNA made up of?
- A single polynucleotide chain
How do you phosphorylate a nucleotide?
Add one or more phosphate groups to it
What type of nucleotides are ATP and ADP?
Phosphorylated
What does ADP contain?
-The base adenine, the sugar ribose, and two phosphate groups
What does ATP contain?
-The base adenine, the sugar ribose and three phosphate groups
How is ATP synthesised?
- From ADP and an inorganic phosphate group, using energy from an energy-releasing reaction e.g. the breakdown of glucose in respiration
- ATP is phosphorylated and a phosphate bond is formed
What do nucleotides join together to form?
Polynucleotides
How are polynucleotides formed?
- Nucleotides join up between the phosphate group of one nucleotide and the sugar of another
- A phosphodiester bond is formed
What does a phosphodiester bond consist of?
-The phosphate group and two ester bonds
What is the chain of sugars and phosphates known as?
The sugar phosphate backbone
What do 2 polynucleotide strands join together to form?
A double helix
What bonds joint the two polynucleotide strands together?
Hydrogen bonds between the bases
Complementary base pairing
Each base only joining to it’s specific partner
How many hydrogen bonds form between A and T
2
How many hydrogen bonds form between C and G
3
How can DNA be purified?
Using a precipitate reaction
When does DNA copy itself?
Before cell division
Semi conservative replication
The copying of DNA so that half of the strands in each new DNA is made of original peices of DNA, new molecule contains half new DNA half old
Why is DNA replication so accurate?
To ensure that genetic infomation is conserved each time the DNA in the cell is replicated
Stage one of semi conservative replication
- DNA helicase breaks the hydrogen bonds between the two polynucleotide DNA strands
- The helix unzips to form two single strands
Stage two of semi conservative replication
- Each original single strand acts as a template for a new strand
- Free-floating DNA nucleotides joint the exposed bases on each original strand by complementary base pairing
Stage three of semi conservative replication
- The nucleotides of the new strands are joined together by DNA polymerase
- This forms the sugar phosphate backbone
- Hydrogen bonds form between the bases on the original and new strand
- Strands twist to form a double helix
