1. Protein Synthesis

2. RNA
Ribonucleic acid(RNA) consists of a single strand of nucleotides instead of the 2 strands found in DNA
RNA nucleotides contain ribose isntead of deoxyribose. Ribose has an OH on the 2nd carbon
RNA uses the nitrogenous base uracil instead of thymine. Uracil attaches to adenine

4. Protein Synthesis
Step 1 – Transcription is the transfer of the information from DNA to RNA
Step 2- Translation is the process of reading the information on DNA and converting it into the amino acid sequences of the protein
The specific sequence of genes (bases) on DNA directly determine the sequence of RNA, and therefore the types of proteins made

6. Transcription
Transcription is the synthesis of messenger RNA (mRNA) from DNA
Occurs in the cytoplasm in prokaryotes and the nucleus in eukaryotes
Three key steps: Initiation, Elongation, Termination

7. Transcription Initiation
Promoter- a specific sequence of DNA that signals the start of transcription, like the starting line in a race
RNA polymerase finds to the promoter on DNA
RNA polymerase then separates the 2 DNA strands by breaking the hydrogen bonds

8. Transcription Elongation
As RNA polymerase moves along DNA, it untwists the double helix and separates the strands
RNA polymerase then adds nucleotides to the 3’ end of mRNA
Follows the base-pair ruling, but now pairing U with A

9. Transcription Termination
Termination signal- sequence of bases in DNA that tell RNA polymerase to stop transcription
Most common terminal signal is AATAAAA
RNA polymerase is released from DNA and DNA will re-anneal

11. RNA Modifications
In eukaryotes, mRNA is modified before it’s sent out of the nucleus
2 major types of modifications
Alterations of mRNA ends and RNA splicing

12. RNA Modifications 5’ end received a guanine cap
3’ end received a poly-A tail, adenine nucleotides
These help protect mRNA from breaking down

13. RNA Modifications
Genes have stretches of nucleotides that don’t code for anything, called “junk DNA” (pre-mature mRNA)
These regions are called introns or intervening sequences
Coding regions = exons
An enzyme called a spliceosome removes the introns and join the exons together (mature mRNA)

14. Snurps small nuclear ribonucleic particles

15. Translation The building of a polypeptide (protein) from mRNA
Uses transfer RNA (tRNA) to help
Occurs in the cytoplasm on the ribosome

16. Translation tRNA – cloverleaf shape 3 bases needed per 1 amino acid
Contains anticodon – triplet of bases complementary to the bases (codon) on mRNA
Carries corresponding amino acid on the other end that can detach
3 bases needed per 1 amino acid
Codons are 3 nucleotide sequences for an amino acid, found on mRNA
The codons bind to the anticodons on tRNA, which will then bring the corresponding amino acid to form a protein

18. Translation Ribosomes
Made up of 2 subunits, large and small made of ribosomal RNA (rRNA)
Have special binding sites
P site holds tRNA with amino acid chain
A site hold the next tRNA

19. Translation 3 stages: Initiation, Elongation, Termination Initiation
mRNA and tRNA join
Anticodon + complementary codon
mRNA start codon is AUG
tRNA is UAC and brings the “start” amino acid methianine
Large and small subunits join, forming a functional ribosome around the RNA

20. Translation Elongation
Amino acids are added one by one by the following process
mRNA codon binds with anticodon on tRNA
Peptide bond is formed between the new amino acid and the last one
tRNA moves over from A site to P site

22. Translation Termination
Elongation continues until a stop codon is reached (UAA, UAG, UGA)
Polypeptide (protein) is released from ribosome and ribosome falls apart into the 2 subunits

25. Gene Regulation
Mutations- change in the DNA (gene) and only passed onto offspring if in the sex cells

26. Gene Regulation
Gene rearrangements- mutation that moves an entire set (of bases) to a new spot
Transposition- gene moves
Chromosomal- chromosome rearranges

27. Gene Regulation Gene alteration- mutations that change a gene
Point mutation- a single base is changed
Base pair substitution- changes one base for another
Silent- base pair substitution that gives the same amino acid, allowing for the protein to form
Insertion- bases are added
Deletion- bases are deleted
Frameshift- an insertion or deletion that alters the codon reading, always occurs with insertion/deletions

29. Prokaryotic Gene Regulation
Prokaryotes only have ~2,000 genes
The operator is the on/off switch
The operon is a set of genes that code for enzymes involved in the same function
RNA polymerase attached to DNA at the promoter and begins to transcribe
It will continue until it reaches the repressor, a protein that binds the operator and blocks RNA polymerase

31. Eukaryotic Gene Regulation
Eukaryotes have 30,000 genes and the process is more complicated
They have a promoter, enhancer, and activator
The enhancer is a sequence of DNA that can be bound by transcription factors (TF, a protein that controls transcription)

32. Eukaryotic Gene Regulation
The activator attaches to the enhancer and causes a loop to form bringing the enhancer close to the promoter by being in contact with the TF
RNA polymerase attaches to the promoter and beings transcription