Biology Nucleic Acids Chapter 1

Nucleic acids

Constitute the genetic material of living organisms.

Two types of nucleic acids

DNA (deoxyribonucleic acid) and RNA (ribonucleic acid).

Where are nucleic acids found?

In the nucleus of eukaryotic cells, mitochondria, chloroplasts, and prokaryotic cells.

DNA

Deoxyribonucleic acid; nucleic acid that carries genetic information.

RNA

Ribonucleic acid; nucleic acid primarily involved in protein synthesis.

Genome

The entire genetic content of a cell.

What does DNA code for?

The genome of the cell and thousands of genes.

Gene

A section of DNA containing instructions for producing proteins or various forms of RNA.

How does DNA control cellular activities?

By turning genes on or off.

Chromatin

A complex of DNA and histone proteins.

Chromosome

A threadlike structure containing tightly wound and packed chromatin around nucleosomes.

Nucleosome

DNA associated with 8 histone proteins.

Histones

Proteins associated with DNA that help package it into chromatin and chromosomes.

Main role of RNA in the cell

Protein synthesis.

mRNA

Messenger RNA; an intermediary nucleic acid that leaves the nucleus and carries the blueprint for protein synthesis to the ribosome.

Transcription

The process associated with mRNA in which information from DNA is used to produce RNA.

tRNA

Transfer RNA; serves as a bridge between nucleotides and amino acids during translation.

Translation

The process of using information to make a protein; tRNA helps connect nucleotides and amino acids.

rRNA

Ribosomal RNA; assists in protein synthesis and contributes to ribosome structure.

Nucleotide

The monomer of DNA and RNA.

Three parts of a nucleotide

Nitrogenous base, pentose sugar, and one or more phosphate groups.

Nitrogenous base

A component of a nucleotide; can be a purine or pyrimidine.

Pentose sugar

A five-carbon sugar found in nucleotides.

Phosphate group

A component of a nucleotide attached to the pentose sugar.

Pyrimidines

Nitrogenous bases with one ring: cytosine, thymine, and uracil (C, T, U).

Purines

Nitrogenous bases with two rings: adenine and guanine (A, G).

Pyrimidine bases

Cytosine (C), thymine (T), and uracil (U).

Purine bases

Adenine (A) and guanine (G).

Deoxyribose

The pentose sugar found in DNA.

Ribose

The pentose sugar found in RNA.

DNA structure

A double helix structure.

Where are the sugar and phosphate groups in DNA?

On the outside of the double helix.

Where are the nitrogenous bases in DNA?

Stacked in the interior of the double helix.

Antiparallel orientation

The two DNA strands run in opposite directions.

DNA strand directions

One strand runs 5′ to 3′ and the other runs 3′ to 5′.

Hydrogen bonding

In DNA, hydrogen bonds connect complementary nitrogenous bases on opposing strands.

Complementary base pairing

The specific pairing of nitrogenous bases between two DNA strands.

DNA base pairing

Adenine pairs with thymine (A-T), and guanine pairs with cytosine (G-C).

Adenine (A)

Forms a base pair with thymine (T) in DNA and uracil (U) in RNA.

Thymine (T)

A DNA pyrimidine that pairs with adenine.

Guanine (G)

A purine that pairs with cytosine.

Cytosine (C)

A pyrimidine that pairs with guanine.

Uracil (U)

An RNA pyrimidine that replaces thymine and pairs with adenine.

RNA base pairing

A pairs with U, and G pairs with C.

RNA structure

RNA is often single stranded and is more variable in form than DNA.

Difference between DNA and RNA structure

DNA always exists as a double helix, while RNA molecules are more variable in form and are often single stranded.

DNA function

Carries genetic information.

RNA function

Is involved in protein synthesis.

DNA location

Remains in the nucleus.

RNA location

Leaves the nucleus.

DNA sugar

Deoxyribose.

RNA sugar

Ribose.

DNA pyrimidines

Cytosine (C) and thymine (T).

RNA pyrimidines

Cytosine (C) and uracil (U).

DNA purines

Adenine (A) and guanine (G).

RNA purines

Adenine (A) and guanine (G).

ATP

Adenosine triphosphate; the energy currency of the cell.

Role of ATP

Stores and provides usable energy for cellular activities; cells use energy released by breaking down food molecules to synthesize ATP.

NAD+

Nicotinamide adenine dinucleotide; carries electrons.

FAD

Flavin adenine dinucleotide; carries electrons.

Other roles of nucleotides

Nucleotides are involved in molecules such as ATP, NAD+, and FAD.

Key nucleic acid terms

DNA, RNA, nucleotides, ATCG, ATP, complementary base pairing, purines, pyrimidines, chromatin, and nucleosome.

Key concept for nucleic acids

Describe the composition, structure, and function of nucleic acids.

Purine memory trick

"Purines = two rings"; adenine and guanine are purines.

Pyrimidine memory trick

"C.U.T. the pyramid": cytosine, uracil, and thymine are pyrimidines.

DNA vs. RNA base difference

DNA uses thymine (T), while RNA uses uracil (U).

DNA vs. RNA strand difference

DNA is a double helix, while RNA is often single stranded.

DNA vs. RNA sugar difference

DNA contains deoxyribose, while RNA contains ribose.

DNA vs. RNA function difference

DNA carries genetic information, while RNA is involved in protein synthesis.

DNA vs. RNA location difference

DNA remains in the nucleus, while RNA leaves the nucleus.