Bio Unit 6 - Central Dogma and Genes

What is the central dogma?

An important theory in molecular biology that describes the flow of genetic information from DNA to messenger RNA (mRNA) to protein

What is DNA?

deoxyribonucleic acid, that is double helix shape, can't leave the nucleus, contains the genetic information

Building blocks of DNA and RNA

Nucleotides, made of a 5 carbon sugar, phosphate backbone and a nitrogenous base either A,G,C, T (and U instead of T for RNA)

Nucleotides for DNA

Adenine, Thymine, Guanine, Cytosine

A->T

C->G

Nucleotides for RNA

Adenine, Uracil, Guanine, Cytosine

A->U

C->G

3 types of RNA

mRNA, tRNA, rRNA (messenger, transfer, ribosomal)

What are the individual building blocks of proteins

Amino Acids (codon sequence chart)

DNA ➙ mRNA

Transcription (letters)

mRNA➙ amino acid sequence (on codon chart)

Translation (names like Ala)

mRNA

the messenger RNA that attaches to ribosomes in the cytoplasm, has the codons that has the instructions to make a protein

tRNA

transfer RNA: carries amino acids to the ribosomes, has anticodons. Looks like T's

rRNA

ribosomal RNA; type of RNA that makes up part of the ribosome

Codon

Specific sequence of three bases on a strand of mRNA that provides genetic code information for an amino acid

Anticodon

three bases on a tRNA that pairs with the complementary bases on an mRNA molecule during protein synthesis

Ribose

5 carbon sugar in RNA

Polypeptide

A polymer (chain) of many amino acids linked together by peptide bonds.

Where does transcription occur

nucleus of eukaryotes and cytoplasm of prokaryotes

Where does translation occur

At ribosomes in the cytoplasm, or attached to rough ER

Transcription

Synthesis of RNA molecule from DNA template

Translation

mRNA is decoded and a protein is produced

RNA polymerase

Enzyme that links RNA nucleotides together during transcription

Silent mutation

A mutation that changes a single nucleotide but does not change the amino acid created. ex: CUU is changed to CUC

Insertion/deletion

Frameshift mutation that "shifts" the reading frame of the genetic message by inserting or deleting a nucleotide

Frameshift mutation

Genetic mutation that is caused by insertion or deletion

Nonsense mutation

A mutation that changes an amino acid to one of the three stop codons, resulting in a shorter and non-functional protein

Stop codons

UAA, UAG, UGA

Missense mutation

The DNA code is altered so that codes for the wrong amino acid. Ex: sickle cell anemia because the point mutation leads to the addition of valine

Substitution

When one nucleotide (Base pair) replaces another which could result in a silent, missense or nonsense mutation

Gene

DNA sequence that codes for a protein and determines the trait

Trait

A characteristic that an organism can pass on to its offspring through its genes.

Gene mutation

a change in the base sequence of a gene, changes polypeptide structure

Chromosomal Mutation

Large scale changes in number and structure. There is deletion, duplication (doubles which may cause Tay Sachs), inversion and translocation

Mutations that are not inherited

somatic mutations

RNA splicing

In Eukaryotes, cuts out the introns and adds the 5' cap and poly A tail

Introns

part of the mRNA transcription that gets removed in Eukaryotes and isn't coded for proteins

Exons

part of mRNA transcription that remain in the Eukaryotes and will code for protein

Alternative splicing

different mRNA exons are combined in Eukaryotes to make different proteins

spliceosomes

RNA protein complex that catalyzes the removal of introns from pre- mRNA

5' cap and poly A tail

Addition to eukaryote mRNA transcription to protect mRNA from degrading and allow it to leave the nucleus

TATA Box

Promoter sequence crucial for transcription initiation. Where transcription factors bind

Transcription factors

Collection of proteins that mediate the binding of RNA polymerase and the initiation of transcription.