Nucleic Acids - 13/11/23 Flashcards
What are the two types of Nucleic Acids?
- DNA
- RNA
What do DNA and RNA both carry?
Information
Where is DNA and RNA found?
In all living cells
What does DNA stand for?
Deoxyribonucleic Acid
What does RNA stand for?
Ribonucleic Acid
What are the monomers of DNA and RNA?
Nucleotides
What is a mononucleotide?
Only one nucleotide
What is a Nucleotide made of?
- A phosphate group
- A nitrogen containing organic base
- A pentose sugar (5 carbon atom)
In DNA, what is the sugar making it up?
Deoxyribose
In RNA, what is the sugar making it up?
Ribose
What do the pentose, organic base and phosphate group join together by?
Condensation reaction
What is the polymer of nucleotides?
DNA/RNA (polynucleotides)
How does a polynucleotide structure occur? [3]
- Nucleotides join by condensation reaction
- Between deoxyribose sugar at one nucleotide and the phosphate group of another
- This continues bonding
What is the bond between a polynucleotide?
Phosphodiester bond
What is the chain of phosphate and sugars known as?
The sugar-phosphate backbone
How many bases are there?
5
What are the two groups the bases are split into?
- Purine bases
- Pyrimidine bases
What does A Base stand for?
Adenine
What does G Base stand for?
Guanine
What does T Base stand for?
Thymine
What does C Base stand for?
Cytosine
What does U Base stand for?
Uracil
What bases are grouped in Purine Bases?
- adenine (A)
- guanine (G)
What bases are in Pyrimidine Bases?
- Thymine (T)
- Cytosine (C)
- Uracil (U)
What bases does DNA contain?
- A
- G
- T
- C
What bases does RNA contain?
- G
- C
- U
- A
What is the bond present between two polynucleotide strands? Where is this bond?
Hydrogen bond between bases
What is the complementary base pairing?
- A-T
- G-C
How many Hydrogen bonds are there between A-T?
2
How many Hydrogen bonds are there between C-G?
3
What does RNA do?
RNA transfer genetic info from DNA to ribosomes for protein synthesis
What is the Structure of RNA? (Include components) [5]
- Ribose sugar (still pentose)
- Phosphate group
- One of the nitrogen containing bases A, C, G, U
- Nucleotides form a single polynucleotide strand
- RNA strands are much shorter than most DNA polynucleotides (single, short chain)
What are the three types of RNA molecules?
- mRNA (messenger RNA)
- rRNA (ribosomal RNA)
- tRNA (transfer RNA)
What does mRNA do?
Transfers genetic info from DNA to ribosomes
What are ribosomes made of?
- rRNA
- proteins
What is the Structure of DNA? Include components. [6]
- DNA Nucleotide is made from phosphate group
- Deoxyribose (pentose sugar)
- A nitrogen containing organic base - A, T, C, G
- Double Helix Structure
- 2 seperate polynucleotide strands form a spiral - antiparallel
- They’re joined together by Hydrogen bonds between complementary bases
How can genetic information fit into a small space in cell nucleus?
Because DNA molecules are long and coiled up tightly
What does Antiparallel mean?
- The two DNA strands run in opposite directions
What do two antiparallel strands twist to form?
A DNA double helix
What is the differences between DNA and RNA? [8]
- DNA - Double stranded, twsited into a double helix and held together by hydrogen bonds
- RNA - Single stranded
- DNA - Deoxyribose Sugar
- RNA - Ribose Sugar
- DNA Base - A, T, G, C
- RNA Base - A, U, G, C
- DNA Size - Long
- RNA Size - Short
How is DNA stable? [4]
- Phosphodiester backbone protects more chemically reactive organic bases inside double helix
- Hydrogen bonds link organic bases forming bridges
- There are three H-bonds between G-C, rather than two for A-T
- A higher proportion of C-G pairings make DNA more stable
What is function of DNA?
Hold genetic information
In every DNA molecule which components remain same?
- Phosphate group
- Deoxyribose
In eukaryotic cells, how is DNA packaged?
They’re packaged as chromosomes inside the nucleus
How is 2m of DNA put in a cell?
It’s tightly coiled and folded
What is Eukaryotic DNA associated with?
Histones
What is making up Histones?
Protein
What can histones form in a nucleus?
Chromatin - the substance from which chromosmes can be made
In prokaryotic cells, what is DNA like?
It’s loose in cytoplasm
Use your knowledge of enzyme action to explain why new jnucleotides can only be added in a 5’ to 3’ direction.
[4]
- DNA is antiparallel
- shape of nucleotide is different
- enzyme has active sites with specific shape
- only substrates with complementray shape
