1. Chapter 12
Molecular Genetics

2. The structure of DNA and DNA replication

3. DNA - Deoxyribonucleic Acid
To understand genetics, scientists had to learn the chemical makeup of the _______.
Scientists discovered that genes are made of ____
Scientists also found that DNA stores and transmits the genetic information from one ____________ to of an organism to the next.
Scientists began studying DNA structure to find out how it carries info, decides traits, and replicates itself.

4. DNA – The structure
DNA is a long molecule made up of units called _________________.
Each nucleotide contains a 5-carbon ________, a __________ group, and a nitrogen-containing _________.
There are four kinds of bases in DNA:
Adenine (___)
Guanine (___)
Cytosine (___)
Thymine (___)

5. The Nucleotides
Green = 5-C sugar
Peach = phosphate

6. Watson and Crick Watson and Crick made a 3-D model of DNA.
Their model was a ______________, in which two strands are wound around each other.
A double helix is like a twisted ___________
____________ and phosphates make up the side of the ladder
________________ bonds between the bases hold the strands together (the rungs)

7. DNA

8. ___ always pairs with ___
Chargaff’s rule
Aka the “base pairing rule”
Chargaff’s rule states that bonds only form between certain base pairs
___ always pairs with ___
You must memorize this!!!!

9. Base-pairing

10. Where can you find dna?
Most prokaryotes have one large DNA molecule floating in the _____________.
Eukaryotes have DNA in the _____________.
Amazing fact:
The nucleus of a human cell contains more than 1 meter of DNA!

11. Chromosomes
Contain both DNA and protein, which are tightly packed together to form ____________.
Chromatin consists of DNA that is tightly coiled around proteins called ______________.
This forms a beadlike structure called a ______________.
Nucleosomes pack with one another to form a thick fiber, which is shortened by a system of loops and coils.
Nucleosomes allow enormous amounts of DNA to fit into such a small region.

14. DNA Replication
Before a cell divides, it copies its DNA in a process called ______________.
During replication:
The DNA molecule ____________into 2 strands – each strand of the DNA molecule serves as a model for the new strand.
Following the rules for _________________, new bases are added to each strand.
The end result is two ______________strands.

15. How does replication occur?
It’s carried out by a series of enzymes
Some enzymes “unzip” the molecule of DNA – the hydrogen bonds between bases are broken
The two strands unwind and serve as templates to create two new strands
The key enzyme is called DNA __________ – joins individual nucleotides to produce a DNA molecule
DNA polymerase is also involved in “_____________” each of the new DNA strands to minimize errors.

16. DNA Replication

17. Let’s Replicate!
Original Strand = T A C G T T New Strand = ______________ Original Strand = ATCGGCAATCACGAT New Stand = __________________

18. RNA and Protein Synthesis

19. RNA – The basics
For a gene to work, the genetic instructions in the DNA molecule must be ___________.
The first step is to copy the DNA sequence into ___________.
RNA is a molecule which contains instructions for making ______________.

20. RNA – The structure RNA is similar to DNA, except for:
RNA contains the sugar ______________
DNA has deoxyribose
RNA is _____________-stranded
DNA is double stranded
RNA has __________in place of thymine – A, U, C, G
DNA has A, T, C, G

21. RNA Molecules – what do they do?
There are 3 kinds of RNA –
Messenger RNA (______)
What is this in the story? ______________
Has the instructions for joining amino acids to protein
Ribosomal RNA (______)
Assembles the proteins
Transfer RNA (______)
What is this in the story? ______________
Carries each amino acid to the ribosome according to the coded message in mRNA
Contains an anticodon to pair up with mRNA

23. Transcription Process of making (or __________) RNA from DNA
Occurs in the ____________
During transcription:
DNA strands are separated
RNA strand is built using one DNA strand as a template
DNA is transcribed (written) into RNA following base-pairing rules except that U binds to A
DNA Strand = TACGCTACGCCTAATACT
New mRNA Strand = ____________________

24. Transcription to translation
The directions for making proteins are in the order of the four nitrogenous _________
This code is read _____ letters at a time
Each grouping of 3 letters is called a _________
AUG/CGA/UGC/GGA/UUA/UGA
Each codon stands for one _______________
There is one “start” codon and 3 “stop” codons
Start = AUG
Stop = UGA, UAA, UAG

25. Translation
Process in which the cell uses info from mRNA to make ___________
Takes place in the _______________
How does it work?
mRNA moves into the cytoplasm and attaches to ______________
As each codon of the mRNA moves through the ribosome, the proper amino acid is brought into the ribosome by _________.
The ribosome joins together each amino acid and the protein chain grows.
When the ribosome reaches a stop codon, the polypeptide chain is ___________.

26. How do we figure out the amino acids?
Use a Codon Chart

27. Let’s do an example! DNA Strand = TACGCTACGCCTAATACT
mRNA Strand = ______________________
Split into codons = ______________________
Create Protein = ______________________________ ______________________________

28. Mutations Mutations are ___________made when cells copy their own DNA.
Mutations are ___________in the genetic material of a cell.
There are two types of mutations:
Gene mutations – changes in a ___________gene
Chromosomal mutations – change in the number of structure of ___________________and affect multiple genes

29. Gene Mutations __________mutations (substitution)–
Occur at a single point in the DNA sequence
Causes one base to replace another, which only affects one amino acid
___________mutations (insertion, deletion) –
A base is added or removed
All the codons are affected/changed resulting in a completely different protein

30. Chromosome mutations Change in structure of chromosomes Four types:
Deletions = ABC-DEF  ___________
Duplications = ABC-DEF  ____________
Inversions = ABC-DEF  ___________
Translocations = ABC-DEF  ___________ GH-IJKL ___________