Mutations overview

• Erwin Chargaff → A = T, C = G

was a biochemist known for formulating Chargaff's rules, which state that in DNA, the amount of adenine equals thymine, and the amount of cytosine equals guanine. This discovery was fundamental in understanding the structure of DNA.

• Rosalind Franklin → X-ray images of DNA

was a chemist and X-ray crystallographer whose work was critical in discovering the double helix structure of DNA. Her famous photo 51 provided key evidence for the helical structure of DNA.

• James Watson & Francis Crick → Double helix model

were molecular biologists who developed the double helix model of DNA structure, building on the work of Chargaff and Franklin. Their model provided insights into how genetic information is stored and replicated.

• Shape: Double helix

is the three-dimensional structure of DNA, consisting of two intertwined strands that coil around each other. This configuration is crucial for the stability of genetic information.

• Made of nucleotides

DNA

• Phosphate

Phosphate is a chemical compound consisting of a phosphorus atom bonded to four oxygen atoms. It plays a crucial role in biological processes as part of DNA and RNA and is involved in energy transfer through ATP.

• Deoxyribose sugar

Deoxyribose sugar is a five-carbon sugar molecule that is an essential component of DNA. It distinguishes DNA from RNA, where ribose is the sugar present. Deoxyribose lacks one oxygen atom compared to ribose, which is reflected in its name.

• Nitrogen base

A C T G in RNA the T’s switched out for U

🔗 Base Pairing

Base pairing refers to the specific hydrogen bonding between the nitrogenous bases of DNA. Adenine (A) pairs with Thymine (T) through two hydrogen bonds, and Cytosine (C) pairs with Guanine (G) through three hydrogen bonds. This pairing is crucial for maintaining the double helix structure and ensures accurate DNA replication

• Held by hydrogen bonds

The bases like A C G T OR U

Sugar

Deoxyribose

Strands in DNA / RNA

Double and single

Bases

A, T, C, G

Function of DNA

Stores info

• Called semi-conservative

DNA replication is referred to as semi-conservative because each new DNA molecule consists of one old strand (parental) and one new strand (daughter). This method of replication helps preserve the original genetic information while producing two identical copies of the DNA.

• Each new DNA =

• 1 old strand + 1 new strand

• Helicase →

• unzips DNA

• Primase →

• adds primer

• DNA polymerase →

• builds new strand

• Ligase →

• connects fragments

• Leading strand →

• continuous

• Lagging strand →

• fragments (Okazaki fragments)

• Antiparallel →

• strands run opposite directions (3' to 5', 5' to 3')

Step 1: protein synthesis is ?

Transcription (DNA → mRNA)

• Where does protein synthesis happen during transcription?

• in nucleus

• Enzyme:

• RNA polymerase

Step 2: protein synthesis

Translation (mRNA → protein)

Where does protein synthesis happen during translation?

• Happens at ribosome

• mRNA → function

• carries code ( messenger )

• tRNA → function

• brings amino acids ( transfer )

• 1 Codon = how many nucleotides ?

• 3 bases on mRNA

• Anticodon =

• matches codon A-T or U G-C

• Made of amino acids

What proteins are made of

• Form polypeptides

Long chains of proteins

A proteins shape determines its …

• function

Changes in DNA sequence

Effect of a mutation

• Point mutation →

• one base change one point n the chain

• Frameshift mutation →

• shifts entire reading frame whole things altered

• Deletion

Where one base is completely deleted and is removed from the chain

• Insertion

Where one base is added in and completely changes the whole chain

• Substitution

Where one thing is removed and is replaced by another still same amount off bases tho

• Duplication

Where a whole chromosome or part of one is duplicated having a copy of that part of DNA

• Translocation

a segment of a chromosome breaks off and attaches to another chromosome. This can lead to genetic diversity but also cause disorders.

• DNA

• stores instructions to make proteins

• Proteins control

• traits

• “Transcription =

• copy, Translation = build”

• “Mutually exclusive =

• cannot happen together”