1. Chapter 12
DNA & RNA

2. Interest Grabber Order! Order!
Section 12-1
Order! Order!
Genes are made of DNA, a large, complex molecule. DNA is composed of individual units called nucleotides. Three of these units form a code. The order, or sequence, of a code and the type of code determine the meaning of the message.
1. On a sheet of paper, write the word cats. List the letters or units that make up the word cats.
2. Try rearranging the units to form other words. Remember that each new word can have only three units. Write each word on your paper, and then add a definition for each word.
3. Did any of the codes you formed have the same meaning?
4. How do you think changing the order of the nucleotides in the DNA codon changes the codon’s message?

3. Interest Grabber A Perfect Copy
Section 12-2
A Perfect Copy
When a cell divides, each daughter cell receives a complete set of chromosomes. This means that each new cell has a complete set of the DNA code. Before a cell can divide, the DNA must be copied so that there are two sets ready to be distributed to the new cells.

4. I
Section 12-2
1. On a sheet of paper, draw a curving or zig-zagging line that divides the paper into two halves. Vary the bends in the line as you draw it. Without tracing, copy the line on a second sheet of paper.
2. Hold the papers side by side, and compare the lines. Do they look the same?
3. Now, stack the papers, one on top of the other, and hold the papers up to the light. Are the lines the same?
4. How could you use the original paper to draw exact copies of the line without tracing it?
5. Why is it important that the copies of DNA that are given to new daughter cells be exact copies of the original?

5. II. Chromosomes & DNA Replication
A-DNA & Chromosomes
In cytoplasm in prokaryotes
In _______________________found in cell nucleus in the form of a number of chromosomes(46 humans,8 Drosophilia and 22 Sequoia trees)
eukaryotes

6. 1--DNA length
1.6 mm in E.coli(has 4,639,221 base pairs)---obviously it must be tightly folded

7. 2-Chromosome Structure
Eukaryotic cells have about 1000 times as many base pairs of DNA than a bacterium
Humans cells have ~ 1 m DNA
Eukaryotic chromosomes contain DNA and a protein ,which together make _____________________-consisting of DNA tightly packed around proteins called histones
chromatin

8. DNA and histone together make beadlike_____________________________
Nucleosomes pack together to make thick fibers,drawn together during mitosis…also separating
Role of nucleosomes-fold great lengths of DNA into tiny spaces
nucleosomes

13. Prokaryotic Chromosome Structure
Section 12-2
Chromosome
E. coli bacterium
Bases on the chromosome

14. Figure 12-10 Chromosome Structure of Eukaryotes
Section 12-2
Nucleosome
Chromosome
DNA
double
helix
Coils
Supercoils
Histones

15. B. DNA Replication
Each strand of DNA double helix has all the info to___________________________by base pairing
Strands are complementary
In prokaryotes,this point and proceeds-often in 2 directions
In Eukaryotes,DNA replication 100’s of places,going both directions until complete
__________________________is where replication occurs
Reconstruct the other half
Replication fork

16. 1-Duplicating DNA
__________________________or duplication of DNA happens before cell division---ensuring each cell has a complete set of DNA molecules
Each strand of a double helix serves as a _____________________or model for new strand
A pairs w/ T and C w/ G
template
replication

17. 2-How Replication Occurs
Carried out by a series of enzymes that unzip a molecule
____________________________________ joins individual nucleotides to make a DNA molecule….also proof reads the new strands
DNA polymerase

19. Figure 12–11 DNA Replication
Section 12-2
Original strand
DNA polymerase
New strand
Growth
DNA polymerase
Growth
Replication fork
Replication fork
Nitrogenous bases
New strand
Original strand

20. III. RNA & Protein Synthesis
The double helix structure explains how DNA is copied,but not how a gene works-_______________are coded DNA instructions that control the production of protein in the cell.
A) The structure of RNA
Long chain of nucleotides
3 main differences between DNA & RNA:
1--Sugar is _________________
2---Generally single-stranded
3---RNA contains ________________(U) in place of thymine (T)
ribose
uracil
genes

21. B. Types of RNA Protein synthesis messenger ribosomal Transfer
Main job=_________________-ie the assembly of amino acids into proteins
3 Types:
____________________(mRNA)-carry copies for instructions from DNA to rest of cell
____________________(rRNA)-type of RNA that helps make up ribosomes,where proteins assembled
________________(tRNA)transfers each amino acid to the ribosome as it is coded for on mRNA.
messenger
ribosomal
Transfer

22. Bring amino acids to ribosome
Concept Map
Section 12-3
RNA
can be
Messenger RNA
Ribosomal RNA
Transfer RNA
also called
which functions to
also called
which functions to
also called
which functions to
mRNA
Carry instructions
rRNA
Combine
with proteins
tRNA
Bring amino acids to ribosome
from to
to make up
DNA
Ribosome
Ribosomes

23. C. Transcription-produces RNA molecules by copying part of nucleotide sequence of DNA into a complementary sequence in RNA
Requires enzyme known as _______________________________________-binds to DNA and separates DNA strands.Then uses one strand as template to make RNA
The enzyme only binds to areas known as promoters-signals that indicate where to make RNA.Similar signals tell where to stop
RNA-polymerase

24. Figure 12–14 Transcription
Section 12-3
Adenine (DNA and RNA)
Cystosine (DNA and RNA)
Guanine(DNA and RNA)
Thymine (DNA only)
Uracil (RNA only)
RNA polymerase
DNA
RNA

25. D. RNA editing
________________________ in eukaryotic genes ,sequences of nucleotides that ARE NOT involved in coding for proteins
_______________________-DNA sequence that does code for protein
exons
introns

26. E. Genetic Code polypeptide
______________________-chain of amino acids=proteins
_________________-3 consecutive nucleotides that specify a specific amino acid
Example –UCGCACGGU reads UCG_CAC_GGU and codes for Serine-Histidine-Glycine
codon

27.  The Genetic Code
Section 12-3

29. Universal code
64 possible 3 base codons
AUG can specify methionine or start codon
3 stop codons that do not code for an amino acid

30. F. Translation ribosome
______________________reads the instructions for the order in which amino acids should be joined by reading mRNA
____________________________is the decoding of an mRNA message into a polypeptide(protein)
Before translation occurs,mRNA is transcribed from DNA and released into __________________________.
Translation begins when mRNA molecule in cytoplasm attaches to a _____________________.
translation
cytoplasm
ribosome

31. Each tRNA carries one kind of amino acid
As each codon of the mRNA moves through the moves through the ribosome,_____________brings in the proper,indicated amino acid and transferred to polypeptide chain
Each tRNA carries one kind of amino acid
__________________ is a group of 3 bases on a tRNA that are complementary to a mRNA codon
Ribosome forms a _________________bond between amino acids and breaks tRNA bond releasing it
Protein keeps growing until ribosome reaches stop codon on mRNA
tRNA
peptide
anticodon

32. Figure 12–18 Translation
Section 12-3

33. Figure 12–18 Translation (continued)
Section 12-3

34. IV.Mutations=________________________
Changes in genetic material
Gene mutation
A.---Kinds of Mutations 1)
________________________________-changes in a single gene
_____________________________________-changes in 1 or a few a single point in DNA-includes substitutions,insertions and deletions
Substitutions usually affect no more than 1 amino acid
____________________________________-insertions or deletions where the reading frame of the codon message is changed-can VERY much alter or even stop the function of a protein
Point mutation
Frameshift mutation

35. 2)Chromosomal Mutations-change in the # or structure of chromosomes-can change the location of genes on chromosomes and /or number of copies of some genes.
4 types-1)Deletions-loss of all or part of a chromosome
2)__________________-extra copies of a part of a chromosome
3)________________reverse directions of parts of chromosomes
4)____________-part of one chromosome breaks off and attaches to another
translocations
duplication
inversions

36. Gene Mutations: Substitution, Insertion, and Deletion
Section 12-4
Deletion
Substitution
Insertion

37. Figure 12–20 Chromosomal Mutations
Section 12-4
Deletion
Duplication
Inversion
Translocation

38. B. Significance of Mutations
Many have no effect
Harmful effects include genetic disorders and cancer
________________________-contains extra set of chromosomes-bad in most cases but often helpful in PLANTS.
polyploidy

39. V. Gene Regulation
operon
Only a fraction of a gene expressed at one time
___________________-group of genes that operate together
________________-where repressor binds operon (when it)is turned off
Operons not usually found in eukaryotes-these genes are usually controlled individually and regulation more complex---mainly because of cell specialization
Hox genes-control differentiation of cells and tissues in the embryo
operator

40. Typical Gene Structure
Section 12-5
Promoter (RNA polymerase binding site)
Regulatory sites
DNA strand
Start transcription
Stop transcription

41. Karyotypes