DNA Replication…Notes

Steps: 1. A section of the DNA molecule unwinds and becomes a ___________________ladder.

2. The 2 nucleotide chains are separated by __________________enzymes, which break the hydrogen bonds between the bases.

3. DNA polymerases bind to the 2 sides of DNA moving along in opposite directions, attaching free ___________________to the existing DNA chain.

4. Covalent bonds join sugars and phosphates, __________________bonds join base pairs.

• The process of replication happens at many different locations along the DNA ________________________, not just from one end to the other.

• Result: 2 new strands of DNA that are exact copies of the original, and the cell is ready to undergo cell division (_______________!).

Picture: (see in your book 12-2, pages 333-334)

Let’s watch an animation of how this happens!

Mutations…

• • • • When the bases mis-match themselves in base-pairing, this is one type of ____________.

There is about one error in every 10,000 paired nucleotides but DNA can proof-read itself and repair the mutation, helping keep the error rate to about one error per 1

__________nucleotides.

This has serious effects in new ___________.

Mutations can be bad or good…

• • •

Good and Bad…

Mutations drive _______________to happen!

Good mutations – help the organism survive longer so that their ___________can be passed down – Examples: camouflage, drug resistant bacteria (good for them, bad for us!) Bad mutations – cause the organism to __________and not allow those genes to be passed down – Examples: genetic disorders that cause early death, cancer

Transcription and Translation

Protein Synthesis

•

What is it?

– Transcription happens when DNA is transcribed (making a ________________) into RNA – Translation is when the information is translated into a ________________

Transcription: the process by which genetic information is copied from DNA to _______.

Steps: 1. RNA transcription starts on the DNA strand (the template) at the “____________” (initiator or start) gene.

2. RNA polymerase binds to the promoter gene and travels down one side of the ____________________(original DNA) attaching complementary RNA bases and nucleotides.

3. The base pairing rules are the same except U replaces T on the _________strand.

4. This continues until it reaches a DNA region called the “termination signal” (or _________). 5. The RNA polymerase _________________both the DNA molecule and the newly formed RNA molecule (travels to cytoplasm). 6. DNA _______________back up!

This newly formed strand is called mRNA or messenger RNA.

After mRNA is formed

• • We are able to make a protein in the cytoplasm. (______________________) Remember… – The amount and kind of ___________that are produced in a cell determine the structure and function of the cell. – In other words, proteins carry out the genetic __________________________(genes) encoded in our DNA.

• • mRNA is now grouped into letters of ______ (a group of 3 letters is called a codon).

– Each codon will code for one amino acid (AA).

– AAs are the __________________blocks of proteins.

– A few codons do not code for an AA, instead they signal for translation of an mRNA to ______________(initiator/start codon/promoter) or stop (stop codon/ termination signal).

mRNA is ready to be “_____________” by 2 other types of RNA…

rRNA or ________________RNA • • • When the mRNA gets to the cytoplasm, rRNA (which is in __________________form) will attach itself over the strand.

It helps attach the __________to the mRNA This is where ribosomes are made!

__________ or Transfer RNA

• tRNA will locate the start ___________on the mRNA strand and will form the appropriate AA for that codon • • tRNA travels down the mRNA to the next codon and forms the appropriate ________ for that codon The second AA attaches to the 1 st & the tRNA molecule ________________from the 1 st mRNA codon • This continues until a string/chain of AA are formed = a _________________is made!