Biochemistry L7 Nucleic Acids

What are the two main types of nucleic acids?

DNA and RNA

What are the monomers of nucleic acids called?

Nucleotides

What three components make up a nucleotide?

Phosphate, sugar (pentose), and nitrogenous base

What is the sugar in DNA called, and how does it differ from RNA's sugar?

Deoxyribose (missing oxygen at carbon 2) vs. ribose (has oxygen at carbon 2)

What are the two categories of nitrogenous bases?

Purines (double-ring) and pyrimidines (single-ring)

List the purine bases.

Adenine and guanine

List the pyrimidine bases.

Thymine, cytosine, and uracil

Which bases are found in DNA but not RNA?

Thymine

Which base is found in RNA but not DNA?

Uracil

How are nucleotides linked to form polynucleotides?

Through phosphodiester linkages (dehydration/condensation reactions)

What is released during the formation of a phosphodiester bond?

One molecule of water

What is the repeating pattern in a polynucleotide's backbone?

Sugar-phosphate backbone

What type of bond connects the sugar of one nucleotide to the phosphate of another?

Ester bond (in phosphodiester linkage)

Which carbons are involved in phosphodiester bonds?

5’ carbon of one nucleotide and 3’ carbon of the next

What is the structure of DNA?

Double helix

What type of sugar is in DNA?

Deoxyribose

How do DNA strands run relative to each other?

Antiparallel (reverse direction)

Which bases pair together in DNA?

Adenine-Thymine, Guanine-Cytosine

What type of bonds hold DNA base pairs together?

Hydrogen bonds

Why is complementary base pairing important for DNA?

Allows accurate replication and carries coded information

What are the key features of DNA's double helix structure?

"Long Books Stay United Creating Stories"

Each letter stands for:

• L – Long molecule stores lots of information

• B – Backbone (sugar-phosphate) makes it stable

• S – Stable double helix keeps bases protected

• U – Unzips easily due to weak hydrogen bonds

• C – Complementary base pairing enables accurate replication

• S – Sequence of bases holds coded instructions for proteins

What is the function of DNA?

Stores genetic information and helps make proteins

What is the structure of RNA?

Single-stranded

What type of sugar is in RNA?

Ribose

Which bases are found in RNA?

Adenine, Uracil, Guanine, Cytosine

What are the three types of RNA?

mRNA, tRNA, rRNA

What is the role of mRNA?

Messenger RNA carries genetic information from DNA to ribosomes

What is the role of tRNA?

Transfer RNA brings amino acids to ribosomes during protein synthesis

What is the role of rRNA?

Ribosomal RNA forms part of the ribosome's structure

What elements are nucleic acids composed of?

Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorus (CHONP)

What is the central dogma of biology?

DNA → RNA → Protein

How does DNA's structure aid in replication?

Weak hydrogen bonds allow unzipping; complementary bases ensure accuracy

Why is DNA's double helix stable?

Sugar-phosphate backbone protects bases inside the helix

What is the mnemonic for DNA bases?

ATGC (Adenine, Thymine, Guanine, Cytosine)

What is the mnemonic for RNA bases?

AUGC (Adenine, Uracil, Guanine, Cytosine)

What does "PyCUT" stand for in nucleic acids?

Pyrimidines: Cytosine, Uracil, Thymine

What does "PuGA" stand for in nucleic acids?

Purines: Guanine, Adenine

How does RNA differ from DNA in strand structure?

RNA is single-stranded; DNA is double-stranded

What is the directionality of DNA strands?

5’ to 3’ and 3’ to 5’ (antiparallel)

What is the role of the sugar-phosphate backbone?

Provides structural stability to nucleic acids

Why are nucleic acids considered polymers?

They are made of repeating nucleotide monomers (polynucleotides)

What type of reaction forms polynucleotides?

Dehydration/condensation reaction

Where is the phosphate group attached in a nucleotide?

To the 5’ carbon of the sugar

What is the significance of DNA's long length?

Stores large amounts of genetic information

How does RNA participate in protein synthesis?

mRNA, tRNA, and rRNA work together to translate DNA code into proteins

Which RNA type is part of the ribosome?

rRNA (ribosomal RNA)

Which RNA type carries amino acids?

tRNA (transfer RNA)

What is the function of nucleic acids in cells?

Store and transmit genetic information, direct protein synthesis

How many hydrogen bonds form between A-T and G-C pairs?

A-T: 2 bonds; G-C: 3 bonds

What is the term for the linkage between nucleotides?

Phosphodiester linkage