DNA (DeoxyriboNucleic Acid)

DNA Acronym

DeoxyriboNucleic Acid

DNA

The carrier of genetic information

Cell

The building blocks of all living organisms

Gene

A unit of heredity which is transferred from a parent to offspring and is able to determine some characteristic of the offspring. It codes for amino acids which make up proteins.

Simplified: It makes specific code for specific trait

Chromosome 

A threadlike structure of DNA coiled around a histone found in the nucleus of most living cells, carrying genetic information in the form of genes

Types of Chromosomes

Autosomes and Sex Chromosomes

Male Sex Chromosomes

XY

Female Sex Chromosomes

XX

Types of Sex Chromosomes 

X and Y 

Gamete Types

Sperm (from male) and Ovem (from female)

Gamete 

A reproductive or sex cell that unites with another of the opposite sex during sexual reproduction to form a new organism 

Homologous

Similar in position, structure or evolutionary origin but not necessarily in function

Zygote

A diploid cell which is the fusion of two gametes from a fertilised ovum

Nucleotide

The basic building block of nucleic acids like DNA and RNA

Chargaff’s Rule 

The rule which states that in any DNA sample, the amount of adenine (A) is roughly equal to the amount of thymine (T), and the amount of guanine (G) is roughly equal to the amount of cytosine (C)

Monomers

Molecules which are the building blocks of polymers

Polymers

Molecules of repeating monomers

Codon

Group of 3 nitrogenous bases which code for a particular amino acid

RNA Acronym 

RiboNucleic Acid 

RNA

Nucleic acid present in all living cells which acts as a messenger carrying instructions from DNA for controlling the synthesis of proteins

Fun Fact: In some viruses RNA rather than DNA carries the genetic information

mRNA (Messenger RNA)

A single-stranded molecule that carries genetic instructions from DNA to the ribosome, where it serves as a template for building proteins

tRNA (Transfer RNA)

A small RNA molecule that functions as an adaptor in protein synthesis, linking the codons on messenger RNA (mRNA) to the correct amino acids

Transcription

1. DNA is unzipped

2. Complementary strand is built and transmitted as RNA

Translation

1. mRNA enters ribosomes and codons are read

2. tRNA brings corresponding amino acid

3. Repeat until STOP amino acid found

Anti-codons

Complementary to codons

Protein Functions

• Form cells

• Can be hormones

• Can be antibodies

Mutation 

Change or error to DNA 

Spontaneous mutation

Genetic changes that occur naturally due to factors like DNA replication errors or internal cellular processes, in the absence of external mutagens

Induced Mutation

Changes to an organism's DNA caused by external environmental factors, known as mutagens, such as chemicals or radiation

Point Mutation

One nitrogenous base in has a mutation affecting a nucleotide or more

Mutagen 

Agent or factors that induces mutation (heighten the likelihood of mutation) 

Mutagen Examples

• Radiation

• Infectious Disease

• Chemical Substances

Types of Substitution

• Missense

• Silent

• Nonsense

Missense

A type of point mutation where a single DNA base pair change results in a codon that codes for a different amino acid, leading to a change in the resulting protein

Silent 

A point mutation (changes in a single nucleotide) that does not result in a change in the amino acid sequence of the protein

Nonsense

A type of point mutation where a nucleotide substitution changes a codon (a sequence of three nucleotides) into a stop codon (UAG, UAA, or UGA)

Insertion

Genetic mutation where one or more nucleotide bases are inserted into the DNA sequence

Deletion

Genetic mutation where a portion of DNA (like nitrogenous bases) is removed or lost

Inversion 

Two genetic pieces of information are switched 

or

When a segment of a chromosome breaks, flips 180 degrees, and reattaches in the reversed order

Chromosomal Mutation

Changes to the structure or number of whole chromosomes, which can involve large segments of DNA

Genome

Complete set of genes and DNA in a cell or organism

Genome Maps

Order of genes and spacing between then on chromosomes

Epigenetics

Study of environmental influences on how genes work
Example: Genes turning ‘on’ and ‘off’

Diploids

Two sets or copies

Haploids

One copy or set

Maternal Chromosomes

Chromosomes from mother from ovum

Parental Chromosomes

Chromosomes from father from sperm

Allele

One of two or more variations of a gene found on the same location on a chromosomes

Enzyme

A biological catalyst that speeds up chemical reactions in living things

DNA Replication Process

1. Helicase unzips DNA

2. Single stranded binding proteins (not an enzyme) holds DNA apart 

3. Primer are added by the primase enzyme. Primers are starting points for the polymerase enzyme

4. Polymerase enzyme adds complementary bases by binding to proteins and adding matching nucleotides 

5. Exonuclease enzymes remove junk like primers while polymerase enzyme fills the gaps which the exonuclease enzymes leave

6. Another polymerase enzyme rechecks the DNA

7. Ligase enzyme makes a backbone for the new strand

8. The DNA twists into two new strands. Topoisomerase assists. 

Semi-conservation

The principle that during DNA replication, each new double-stranded DNA molecule is composed of one original "parent" strand and one newly synthesized "daughter" strand

Helicase 

A class of enzymes that are unwind and separate the two strands of a DNA or RNA double helix

Single Stranded Binding Protein 

A class of proteins that bind to and stabilize single-stranded DNA (ssDNA) to protect it from damage and holds the strands apart 

Primase

A type of enzyme that synthesizes short RNA primers, which are necessary for DNA polymerases to begin synthesizing a new DNA strand

Primer

A short, single-stranded nucleic acid (RNA or DNA) that provides a starting point for DNA synthesis to the polymerase 

Polymerase

An enzyme that synthesizes long chains of polymers, most commonly nucleic acids like DNA and RNA

Ligase

An enzyme that acts as a "molecular glue" to join DNA or RNA fragments by creating a bond between them which creates a backbone helping to seal the DNA

Type of Sugar in DNA

Deoxyribose

Type of Sugar in RNA

Ribose

Polypeptide Chain

A long sequence of amino acids linked together by peptide bonds, forming the fundamental structure of proteins

Transcription

The process of copying a gene's DNA sequence into messenger RNA (mRNA), which happens in the nucleus of a cell

Translation

The process of using the mRNA sequence as a template to assemble a specific chain of amino acids, which fold into a protein, and this takes place in the cytoplasm on a ribosome

Ribosome

An organelle which consists of RNA and is the binding of messenger RNA and transfer RNA to synthesize polypeptides and proteins.

Frameshift Mutation

A type of genetic mutation caused by the insertion or deletion of nucleotides in DNA in a number that is not a multiple of three

Coding Strand 

The DNA strand that has the same base sequence as the resulting mRNA molecule, with the exception of having thymine (T) instead of uracil (U)

Template Strand

A single strand of DNA that serves as a pattern for synthesizing a complementary strand of RNA during transcription or a new DNA strand during replication

Amino Acid

Organic compounds that serve as the building blocks of proteins

Autosomal

Chromosomes (numbered 1-22) that are not sex chromosomes

Nucleotide Components

Sugar, phosphate and nitrogenous base

Complementary Base Pairing

Adenine – Thymine

Guanine – Cytosine

Bond in DNA

Hydrogen Bond