EOC REVIEW
DNA, RNA, Replication, Transcription and Translation
DNA/RNA
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Carry genetic information
All organisms share the same genetic code (nitrogenous bases)
Made of a chain of nucleotides
Nucleotides contain a sugar, phosphate, and a nitrogen base
The sugars and phosphates link to make the sugar phosphate backbone and the Nitrogen bases are held in the
middle by hydrogen bonds
DNA
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Double stranded/helix
Sugar is deoxyribose
Remains in the nucleus
Codes for proteins/RNA
Four Base Pairs: ATCG
o Adenine
o Thymine
o Guanine
o Cytosine
RNA
Single stranded/helix
Sugar is ribose
Can leave the nucleus
Copy of DNA information
Four Base Pairs: AUCG
Adenine
Uracil
Cytosine
Guanine
Review Questions
1. In DNA, what does Adenine pair with? Thymine
2. In DNA, what does Cytosine pair with? Guanine
3. What three things do nucleotides contain? Sugar, Phosphate and nitrogen base
4. What is the sugar called in RNA? Ribose
5. What is the sugar called in DNA? Deoxyribose
Replication
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Occurs in Interphase’s s phase
Replication occurs in both directions
The process used by cells to copy DNA, making an identical strand of DNA
Enzyme unzips DNA and each side of the ladder, and acts as a template for the building of the complementary
strand
o Use the Nitrogen Base Pairing Rules
 A-T, C-G
 TACGGAC (old strand)
 ATGCCTG (new strand)
Codon
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Sequence of three mRNA nucleotides that code for an amino acid
EOC REVIEW
Transcription
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The process of making RNA from DNA
DNA> mRNA (occurs in the nucleus)
o TACGGAC (template DNA strand)
o AUGCCUG (RNA Built)
1. RNA polymerase binds to and separates the DNA strands at promoter sites
o Promoter- 3 base sequence that serves as a starting and ending points for RNA to be made.
2. RNA polymerase uses one strand of DNA as a template to make the complementary strand of DNA
Three types of RNA have a role in protein synthesis
o 1. mRNA- messenger: blueprint for how to build protein
o 2. tRNA-transfer: carries amino acids from the cytoplasm to the ribosomes
o 3. rRNA-ribosomal: makes up a ribosome, where protein is made
Review Questions
1. What does semi conservative mean?
The replicated copy of DNA has one new side
and one Old side
2. How many nucleotides code for an amino acid?
3
3. What is the process of making RNA from DNA?
Transcription
Translation
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The process of building a protein by matching
codons in mRNA to anticodons of tRNA (use codon chart)
o mRNA>protein (occurs on ribosomes)
1. mRNA attaches to a ribosome
2. Starting at codon “AUG”, ribosome reads each codon
o Codon= 3 nucleotides
3. For each codon, an amino acid is brought into the ribosome by tRNA
o Each tRNA molecule carries only one kind of amino acid
o Each tRNA has the anticodon, that is complementary to one mRNa codon
4. A peptide bond forms between each amino acid as it is brought into the ribosome> polypeptide chain
5. tRNA is released
6. Polypeptide chain stops growing when the ribosome reaches a stop codon on the mRNA
Polypeptide (protein) & mRNA are released from the ribosome
Reminders:
o 3 nucleotides= 1 codon=1 amino acid
o 20 different amino acids
o Proteins are determined by the sequence of amino acids
Review Questions
1. What are the segments of DNA that code for proteins or traits?
Exons, codons, genes
EOC REVIEW
1.
2.
3.
4.
5.
2. What is the process of making RNA from DNA?
transcription
3. How many different amino acids are there?
20
What is the 1st step in protein synthesis?
transcription
What is the 2nd step in protein synthesis?
translation
What is mRNA>proteins at the ribosome?
translation
What is converting DNA>mRNA in the nucleus?
Transcription
Which of these changes to the DNA triplet TCG will affect a protein produced?
a. AGT
b. TCA
c. TCC
d. AGA
EOC REVIEW
Cell Division General
Haploid – having one set of chromosomes (n) – gametes – sperm/egg
Diploid – having two sets of chromosomes (2n) – body cells – one set is maternal and one is paternal
Plants cells do not have centrioles to do cell division
Steps to cell Division
Interphase
Cell spends most of its time = resting phase
Steps
1. G1- cell grows
2. S – DNA is synthesized
3. G2- all other organelles are copied
Steps of Mitosis
1. Prophase- nuclear membrane breaks down
2. Metaphase chromatids line up in the middle
3. Anaphase- sister chromatids are pulled apart
4. Telophase- plants = cell plate
animals = cleavage furrow
Cytokinesis- separation of cell (not a step of mitosis)
*** asexual reproduction – a type of reproduction that only involves one parent cell. Daughter cells look identical to the
parent cell. Examples include: Mitosis, Binary fission in bacteria, cloning, regeneration, and budding.
Advantage – quicker, requires less energy, mass production
EOC REVIEW
Disadvantage – less variation, no genetic diversity, more difficult to evolve
REVIEW QUESTIONS
1. When does the replication of DNA occur? What is this phase called?
S phase of Interphase
2. What happens during G1 and G2?
G1- cell grows
G2- organelles are copied and the nucleus prepares to divide
3. What stage does the cell spend most of its life in? _______Interphase____________
4. What does the cell do during this time?
G1- cell grows
G2- organelles are copied and the nucleus prepares to divide
S- DNA replicates
Mitosis Overview
Produces two identical diploid daughter cells
Occurs in body cells to grow and repair
DNA coils to form chromosomes during cell division
Cancer / mutations
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Caused when mitosis/cell cycle cannot be stopped
Mass accumulation of cells none as a tumor
There is an error somewhere in replication, transcription, translation
Cannot be passed from parent to offspring unless located on the gametes (egg or sperm)
5. Put the following stages of mitosis (cell division)
in order. Then Name them.
1st: ___C________ called ____Interphase_______
2nd: ___B________ called ____Prophase
3rd: ___E________ called _____Metaphase
4th: ___A________ called _____Anaphase
5th: ____D_______ called Telophase/ Cytokinesis
6. How many chromosomes do humans have in their… Body cells? ___46_____
EOC REVIEW
Goal 3: Learner will develop an understanding of the continuity of life and the changes of organisms
over time. 30-35%
3.01: Analyze the molecular basis of heredity including: DNA replication, Protein Synthesis (transcription and
translation), and gene regulation.
1. Below is a strand of DNA. (Chapter 12) DNA in the cells exists as a
double helix – what needs to be added to it to make it a double helix?
Give the complementary nucleotide sequence. __C___ _T____G_
__G____ _C_____T ______ ______
2. Describe the structure of DNA. What are the black pentagons?
_Deoxyrobose, a 5 carbon sugar__________ What are the nitrogen
bases? __adenine, thymine cytosine and guanine__________ What
weak bonds hold the complementary bases together?
__hydrogen_Bonds____
3. If the strand of DNA above undergoes transcription, what will the sequence of the mRNA be? __GUGGCU
4. After translation, what would the amino acid sequence be for this section of mRNA? (read from right to left)
___valine, alanine_______________________________________________________
EOC REVIEW
5. What is a codon? A triplet of RNA nucleotides that codes for a specific amino acid
6. Compare RNA and DNA in the following table.
RNA
DNA
Sugars
ribose
deoxyribose
Bases
Guanine, cytosine, adenine
and uracil
Guanine, cytosine, adenine
and thymine
Strands
single
double
Where
cytoplasm
nucleus
Codes for proteins
Carries all genetic
information
In Cell
Function
7. What kind of bond holds the amino acids together in the protein that is formed? ___peptide___
8. What are the three types of RNA and what are their functions?
1) ___messenger RNA carries code from DNA to ribosomes__________________________________
2) ___transfer RNA transfers amino acids to the ribosomes_________________________________
3) _____site of translation , it IS the ribosome_____________________
9. What kind of weak bonds hold the two strands of DNA together? ______hydrogen__________________
10. Why is it important that these bonds be weak? So that they can “unzip” for replication and making mRNA
EOC REVIEW
11. Describe the process of DNA replication. What enzyme breaks apart the hydrogen bonds between bases?
________DNA Helicase__________________
How many pieces of DNA are made? ___2_____ What does semi-conservative mean? One side of copied strand is the
original and the other side is a new strand
12. Describe the process of protein synthesis:
What is transcription? DNA copies its code
onto mRNA
13. What is translation? Coding for specific
amino acids
14. What happens to DNA when a mutation occurs? A base sequence changes
15. How does this affect the mRNA? mRNA will also change accordingly
EOC REVIEW
16. How can this affect translation? It might code for a different amino acid OR it might not
17. How does this affect the structure and shape of the resulting protein? _
it might change the protein or shorten the amino acid chain___________
Cell Cycle
Look at the diagram of the cell cycle.
18. When does the replication of DNA occur? What is this phase called?
S phase of interphase
19. What do GI and G2 represent?
Growth phases
20. What stage does the cell spend most of its life in? ___interphase________________
What does the cell do during this time? Grows, replicates and goes about the general cell business
21. Does mitosis include cytokinesis (division of the cytoplasm)? (Y/N?)
no
Gene Expression and Regulation
22. In the diagram to the left, what is the role of the RNA polymerase?
Causes the RNA to attach to DNA
23. What is the role of the repressor? Stop RNA polymerase from attaching RNA to DNA
EOC REVIEW
24. The gene codes for lactase, an enzyme that digests milk sugar (lactose).
25. When lactose is present what happens to the repressor?
Stops working
26. When the repressor does not attach to the repressor region of the gene, what happens to gene expression?
Lactase is formed
27. If all the cells in an organism (cells with nuclei) have the same DNA, explain, in terms of genes, how a nerve cell
functions differently from a muscle cell. Nerve cells are coded genetically to be long and sensitive to electrical stimuli in
order to carry messages
28. Why do pancreas cells produce insulin in great amounts but blood cells does not? Blood cells have other jobs and
are genetically coded for them
29. What is cancer? What are some causes of cancer? Rapidly growing cells. The cell cycle is not checked
3.02 Compare and contrast the characteristics of asexual and sexual reproduction.
30-31. Complete the following Chart of Mitosis and Meiosis.
MITOSIS
Type of reproduction
MEIOSIS
Asexual
Sexual
Diploid
Diploid
(Asexual or sexual)
Chromosome number of mother
EOC REVIEW
cell (1N=haploid or 2N=diploid)
Chromosome number of daughter
cells (1N=haploid or 2N=diploid)
Diploid
Haploid
Number of cell divisions
One
Two
Number of cells produced
Two
Four
When does replication happen?
Growing and developing or repair
Reproduction only
SOURCES OF VARIATION
Mutations only
Crossing over
Crossing over
No
Yes
33. How many chromosomes do humans have in their…
Body cells? _46_______ Sex cells? ____23______
34. What does Diploid mean? 2n number of chromosomes
35. What does Haploid mean?1n number of chromosomes
36. When does crossing over occur during Meiosis? _____prophase I________________________
37. What is the major focus of Meiosis I? ______________Crossing Over___________________________________
38. What is the major focus of Meiosis II? ________________Cell division into gametes__________________________