intro to DNA + The Central Dogma

recall: DNA stands for ___________________ _____, a huge _____________ made of _________ monomers.

deoxyribonucleic acid, polymer, nucleotide

DNA is the ________ form of information concerning _________ ________ of all organisms

storage, protein structure

3 components of a nucleotide

• nitrogenous base (A, G, C, G)

• phosphate group

• deoxyribose sugar

purines are double ringed:

pyrimidines are single ringed:

🖇adenine, guanine

📎thymine, cytosine, uracil

☆ “you can CUT yourself on PYRAMIDS”

The OH group is on the __ end, and the phosphate group is on the __ end

3’, 5’

The “sides” of the DNA molecule are composed of a ___________-charged _______ - __________ backbone, held together by ______________ bonds

negatively, sugar-phosphate, phosphodiester

the two strands of DNA are held together by __________ bonds between ___________ _______

hydrogen, nitrogenous bases

⇨ A=T, C☰G

Chargaff’s Rule

the amount of adenine = to the amount of thymine; and the amount of cytosine = the amount of guanine

ie. complementary pairs are in equal percents

base pairing can occur btn purines and pyrimidines because:

the strands run in opposite directions (antiparallel)

RNA is unique from DNA because (5):

• has a ribose sugar (has an OH on 2’)

• uses the pyramidine Uracil instead of Thymine

• single stranded

• shorter

• less stable than RNA

DNA packaging “order”

double helix → coils around histones → supercoils → condenses into chromosome

what is the central dogma of molecular genetics/biology?

the fundamental principle; states that DNA is transcribed into mRNA which is translated into a polypeptide (which then gets folded into a protein)

____ amino acids exist, which are coded for by a sequence of ___ _____________, called a _______

20, 3 nucleotides, CODON

more than one codon codes for a specific amino acid; this is important/useful because:

it reduces errors, which can cause serious medical conditions

The Genetic Code is _________, so it applies to all ___________ with a few exceptions

UNIVERSAL, organisms

Besides amino acids, which are indicated in the genetic code table, special codons exist that signal for ___________ to either ____ or _____

translation, stop, start

⇨ called stop codons and start codons

the START codon is ____, which also codes for the amino acid ________________

🟢 AUG, methionine

the STOP codons are:

🛑 UAA, UAG, UGA

3 points of the central dogma

1. DNA replicates to conserve DNA (so that every cell gets a copy) 🫧

2. DNA is transcribed ➙ RNA in the nucleus (RNA copies of each gene are made from the DNA templates) 📠

3. RNA leaves nucleus and meets ribosomes, where it’s translated (directs assembly of amino acid chain/polypeptide) 🍖👷

kinds of RNA

📨 Messenger RNA (mRNA)

🍝 Ribosomal RNA (rRNA)

🌳 Transfer RNA (tRNA)

mRNA

• The RNA version of the DNA gene

• Intermediate between the DNA and Ribosome

• Translated into protein by ribosomes

tRNA

Delivers amino acids to ribosomes during translation

rRNA

• non-coding RNA

• binds with proteins to form ribosomes

• primary component of ribosomes

Gene Expression

when the DNA code is used to produce a protein using transcription and translation processes