Unit 6 Gene expression and regulation

DNA

Anti-parallel double helix structure with a Deoxyribose sugar

→ Adenine = Thymine

→ Guanine = Cytosine

Purines

Double ringed structure of nucleotides

(Opposites)

Adenine & Guanine

Pyrimidines

Single ringed structure of nucleotides

Cytosine, Thymine, and Uracil

RNA

Single Stranded, uses Uracil instead of thymine and has a ribose sugar

Used in protein synthesis

Central Dogma

DNA → RNA → Proteins

Transcription→ translation → proteins

Helicase

Unwinds DNA strands

Topoisomerase

Goes Infront of Helicase weakening hydrogen bonds preventing supercoiling when DNA is un-winded

RNA Primer

Short RNA strand that initiates DNA synthesis, by preparing DNA strands for new nucleotides

DNA Polymerase

Goes in the 5’ → 3’ direction continuously (leading strand) and lagging in 3’ → 5’ strand because it cannot go in both directions and synthesizes DNA by adding complementary nucleotides. ALSO PROOF READS

Ligase

Pieces together Okazaki fragments in the 3’ → 5’ Direction

RNA Polymerase

Reads the template strand in the 3’ → 5’ direction and makes complimentary MRNA strand in the 5’ → 3’ direction

MRNA modification

before leaving the nucleus MRNA is modified to prevent errors, these modifications include

→ adding a guanine cap and a Poly-A tail

Introns

Non-coding sections of DNA that are removed from MRNA

Exons

Remaining nucleotides not taken out by MRNA modification that are expressed as part of the final mRNA transcript.

Translation

Process of turning RNA → Proteins

Happens in 3 stages:

→ Initiation

→ Elongation

→ Termination

Transcription

DNA → RNA Copy (MRNA)

Initiation

Ribosome attaches to MRNA cap and TRNA binds start codon (meth)

Elongation

Ribosome moves along MRNA strand in 5’ → 3’ direction, as it does that tRNA binds complimentary anti-codons to MRNA codons to form a polypeptide chain

Termination

When a Stop codon is released in the ribosome it triggers the release of a stop codon and the protein is completed

Upstream

DNA Sequencing placed before the start of transcription so it can be affected by regulatory proteins and gene expression can be controlled

Downstream

Sequence following the transcriptions start site

Operons

A group of genes in bacteria that operate together allowing coordinated regulation of gene expression.

Either Inducible: are activated by the presence of another molecule

Ex) Lac Operon

Or can be repressive: Are always on and only turned off in the presence of another molecule

Transcription factors

Eukaryotic proteins that help regulate the transcription of genes by binding to nearby DNA.

Silent mutations

Mutations that do not change the amino acid sequence of a protein, often occurring in the coding region of a gene.

Frameshift mutations

Insertions or deletions of nucleotides that shift the reading frame of the genetic code, potentially altering the entire amino acid sequence downstream.

Horizontal gene transfer

The process by which an organism transfers genetic material to another organism in the environment.

Transduction

Viral transmission of genetic info during infection

Conjugation

The transfer of genetic material between bacteria through direct cell-to-cell contact, often via a pilus.

Transposition

The movement of DNA segments within and between DNA molecules, often resulting in genetic variability.

Gel Electrophoresis

A laboratory method used to separate DNA, RNA, or proteins based on their size and charge, allowing for analysis and comparison.

PCR

A molecular biology technique used to amplify specific DNA sequences, making millions of copies for analysis.

Bacterial Transformation

The process by which bacteria take up foreign DNA from their environment, resulting in genetic changes.