transcription & translation

Flashcards about transcription and translation.

Central Dogma

A theory stating genetic material flows from DNA to RNA to a protein (transcription & translation).

Reverse Transcription

The synthesis of DNA from an RNA template, this process is driven by RNA-dependant DNA polymerases (also known as reverse transcriptase).

Semi-conservative replication

DNA synthesis occurs using semi-conservative replication resulting in 2 new DNA strands, each containing one original strand and one new strand.

DNA

Double-stranded, contains a deoxyribose sugar, contains adenine, guanine, thymine, and cytosine, and is found in the nucleus and mitochondria.

RNA

Single-stranded, contains a ribose sugar, contains adenine, guanine, uracil, and cytosine, and is found in the cytoplasm, nucleus, and ribosomes.

Purines

Two-carbon nitrogen ring bases [adenine & guanine] which are also constituents of ATP, GTP, cAMP, NADH, and coenzyme A.

Pyrimidines

One-carbon nitrogen ring bases [thymine, uracil & cytosine] found in vitamins such as vitamin B1 and riboflavin.

Complementary Base Pairing

Adenine will always form 2 hydrogen bonds with thymine or uracil, and guanine will form 3 hydrogen bonds with cytosine.

Phosphodiester Bonds

Hold together the sugar-phosphate backbone of DNA which gives the molecule support.

Transcription

The process of converting the template strand of DNA into mRNA.

DNA Helicase

Unzips the strand of DNA to expose the bases by breaking the hydrogen bonds, creating transcription bubbles.

RNA Primase

Creates RNA primers to tag a certain area from which RNA polymerase begins.

Single-Stranded Binding (SSB) Proteins

Bind to the DNA strands to prevent the two strands from binding to another again.

Topoisomerase

Makes sure the rest of the DNA strand doesn’t supercoil.

RNA Polymerase II

Elongates RNA by adding nucleotide triphosphates complementary to a DNA template.

Hairpin Loop

An unpaired loop of mRNA that is created when a mRNA strand folds and forms base pairs with another section of the same strand; it contains a GC-rich hairpin and a U-rich tract.

Promoter

A region of DNA upstream of a gene, where proteins bind to initiate transcription of that gene (not the same as RNA primase).

Transcription Factors

Proteins involved in the process of transcribing DNA into RNA, they regulate the transcription of genes.

Gene Activators

Proteins that turn on genes by increasing the likelihood that RNA polymerase will bind to DNA.

Transcription Repressor

A protein that binds to DNA to prevent RNA polymerase from transcribing genes, e.g., thyroid hormones, oestrogen, growth hormone, and cAMP.

5’ Cap

Added to the beginning of the mRNA strand and protects the mRNA strand from degradation.

3’ Poly-A Tail

Added to the end of the mRNA strand and protects the mRNA strand from degradation + helps the strand swim to the ribosome.

Introns

Non-coding bits that are spliced and removed during post-translational modification.

Exons

Coding bits that are joined together during post-translational modification to form the mature mRNA strand.

Translation

mRNA travels from the nucleus to the ribosome to translation

tRNA

Transfer RNA molecules that carry the complementary anti-codon and binds to the start codon of mRNA and carries the amino acid methionine (Met).

A Site (Aminoacyl)

Accepts the incoming aminoacylated tRNA during Translation.

P Site (Peptidyl)

Holds the tRNA strand during Translation.

Release Factors

Proteins that enter the ribosome once a stop codon is reached, resulting in the disassembly of the ribosome.

Epigenetics

The process with how our behaviours and environment can cause changes in our genetics.

Silent Mutation

A mutation that doesn't significantly change the amino acid, so the protein remains functional

Missense Mutation

A mutation that can be either conservative (substitutes similar amino acid) or non-conservative (substitutes amino acids that aren’t similar)

Nonsense Mutation

A mutation resulting in a change in DNA base that results in a stop codon and causes the cell to stop building a protein prematurely.

Frameshift Mutation

Caused by a deletion or insertion in the DNA sequence that shifts the way the mutation is read.