Biology Notes - A1.2 Nucleic Acids

DNA

Deoxyribonucleic acid, the genetic material of living organisms.

RNA

Ribonucleic acid, a type of nucleic acid involved in protein synthesis.

Nucleotide

The basic building block of DNA and RNA, consisting of a sugar, base, and phosphate.

Deoxyribose

The sugar component in DNA nucleotides.

Ribose

The sugar component in RNA nucleotides.

Adenine (A)

One of the four nitrogenous bases in DNA and RNA; pairs with thymine in DNA and uracil in RNA.

Thymine (T)

One of the four nitrogenous bases in DNA; pairs with adenine.

Cytosine (C)

One of the four nitrogenous bases in DNA and RNA; pairs with guanine.

Guanine (G)

One of the four nitrogenous bases in DNA and RNA; pairs with cytosine.

Uracil (U)

The nitrogenous base in RNA that replaces thymine found in DNA.

Purines

A group of nitrogenous bases that includes adenine and guanine.

Pyrimidines

A group of nitrogenous bases that includes cytosine, thymine (in DNA), and uracil (in RNA).

Double helix

The structure of DNA consisting of two antiparallel strands twisted around each other.

Antiparallel strands

The orientation of the two strands of DNA in opposite directions.

Hydrogen bonding

The attraction between complementary nitrogenous base pairs that stabilizes the DNA structure.

Complementary base pairing

The specific pairing of adenine with thymine and guanine with cytosine in DNA.

Coding strand

The strand of DNA that carries the base sequence that will be read by enzymes.

Codon

A sequence of three nitrogenous bases that codes for a specific amino acid.

Mutation

A change in the base sequence of DNA that can lead to variations in proteins.

Nucleosomes

Structures formed by DNA wrapped around histone proteins to package DNA in eukaryotic cells.

Polymer

A large molecule composed of repeating subunits, such as nucleotides in DNA and RNA.

Polynucleotide strand

A strand of nucleotides linked together to form DNA or RNA.

Transcription

The process of copying the genetic code from DNA to mRNA.

Translation

The process of synthesizing proteins from mRNA at the ribosome.

Genetic code

The sequence of nitrogenous bases in DNA that determines the amino acid sequence in proteins.

Universal genetic code

The theory that almost all organisms use the same genetic code.

Gene

A segment of DNA that contains the instructions for synthesizing a specific protein.

Histones

Proteins that help package DNA into nucleosomes in eukaryotic cells.

Hereditary material

The substance that carries genetic information; proven to be DNA.

Hershey & Chase experiment

An experiment that demonstrated that DNA, not protein, is the genetic material.

Chargaff's rules

The observation that the amount of adenine equals thymine and guanine equals cytosine in DNA.

Phosphodiester bond

The covalent bond formed between the phosphate group of one nucleotide and the sugar of the next.

Sugar-phosphate backbone

The alternating chain of sugar and phosphate groups that forms the structural framework of DNA and RNA.

Replication

The process of copying DNA prior to cell division.

RNA types

Different types of RNA including mRNA, tRNA, and rRNA, each with unique functions.

DNA packaging

The process by which DNA is condensed to fit within the cell nucleus.

Mitochondria

Organelles in eukaryotic cells that contain DNA and are involved in energy production.

Chloroplasts

Organelles in plant cells that contain DNA and are involved in photosynthesis.

Virus

A non-living entity that contains RNA or DNA and requires a host cell for replication.

Bioinformatics

The use of software and algorithms to analyze biological data, including DNA sequences.

Nucleotide structure

A nucleotide consists of a pentose sugar, a nitrogenous base, and a phosphate group.

Single-stranded RNA

RNA molecules that are typically single-stranded and used for protein synthesis.

DNA's information storage

DNA can store vast amounts of genetic information due to its diverse base sequences.

Conserved sequences

Genetic sequences that remain unchanged across different species, indicating common ancestry.

Directionality of DNA

DNA strands have a directionality (5' to 3') that is crucial for replication and transcription.

SARS-CoV-2

A virus that contains RNA as its genetic material and causes COVID-19.

Eukaryotic cell

A type of cell that contains a nucleus and membrane-bound organelles, including DNA.

Prokaryotic DNA

DNA that is naked, lacking histones, typically found in bacteria.

Nucleotide representation

In diagrams, nucleotides can be represented using simple shapes: circles for phosphates, pentagons for sugars, and rectangles for bases.

Protein synthesis

The process through which cells create proteins based on the genetic code.

RNA's role in protein synthesis

mRNA carries the code from DNA to the ribosomes, where proteins are assembled.

Gene expression regulation

The process where certain genes are turned on or off during cellular activity.

Replication fork

The area where the strands of DNA are separated for replication.

Genetic engineering

The manipulation of an organism's genome using biotechnology.

Watson and Crick

The scientists who proposed the double helix model of DNA in 1953.

Histone modification

Chemical changes to histones that can affect gene expression.

Nucleotide comparison

DNA nucleotides differ from RNA nucleotides primarily in their sugar and one nitrogenous base.

Octamer

The core of eight histone proteins around which DNA is wrapped in a nucleosome.

Gene annotations

Tools used in bioinformatics to describe the function of genes and their products.

Nuclear DNA

DNA located within the nucleus of eukaryotic cells, containing the majority of an organism’s genetic information.

Base sequence

The order of nucleotides in a DNA or RNA strand that determines genetic