Assignment

Chapter 16

Chapter 17

Chapter 18 part a

Chapter 18 part b

CHAPTER 16: MOLECULAR BASIS OF INHERITANCE

1.During what part of the cell cycle is DNA replicated? Why does this happen?

Watson & Crick model

2. What are the three parts of a nucleotide. Draw/depict them and label each.

Five carbon ribose sugar
Phosphate molecule
Nitrogenous bases

3. What type of bond connects nucleotides in the sugar backbone of DNA together?

Phosphates

What type of bonding holds the two DNA strands together?

4. What does it mean that the two strands of a DNA molecule are anti-parallel?

It means forming a double helix

5. Explain the semi-conservative model of DNA replication. Draw/depict it.

6. How is the DNA double helix unwound for replication? What enzymes are involved in this step and what are their functions?

Helicase and Topoisomerase

7. What is an RNA primer and why is it necessary to start DNA replication?

8. In what direction are nucleotides added to the new strand by DNA polymerase?

5′ to 3′ direction

9. What is the difference between the leading strand and the lagging strand?

Leading strand is a strand that copy quickly.
Lagging strand is a strand that copy slowly

10. What are Okazaki fragments? What enzyme joins them together to form a new continuous DNA strand?

They areshort DNA segments. The enzyme DNA ligase

11. How does proof-reading keep the accuracy of DNA replication so high?

By minimizing the chance of incorporating wrong nucleotides

12. What is a telomere? Do prokaryotes have telomeres?

It is the end of a chromosome. They don’t have telomeres

CHAPTER 17: FROM GENE TO PROTEIN

1.What is the central dogma of biology?
             a                            b______DNA_______ ? ____RNA________ ? _______protein_____________

The arrows indicate what processes? a)Transcription

b)Translation

2. Most genes code for the production of what type of organic molecule?

Amino acids

3. Where in the cell does transcription occur for prokaryotes?For eukaryotes?

For prokaryotes: cytoplasm
For eukaryotes: nucleus

4. What is a codon? How do they code for amino acids?

It is a sequence made of 3 bases in the mRNA molecule. They code for amino acids by using a triplet code.

5. What does it mean that the genetic code is universal?

It means that all organisms use same codons for specific amino acid.

6. How is RNA different from DNA?

7. What does RNA polymerase do during transcription?

It takes the ribose into new strand of mRNA.

8. How does RNA polymerase know where to start?

The beginning of gene is called promoter

In what direction are nucleotides added?

They are added to the 3′ direction end of the RNA molecule

9. Explain what occurs in the three stages of transcription: (see pages 341-342)

Initiation: RNA polymerase works initiallyat the beginning of a gene

Elongation: Nucleotides added to the 3′ end of the growing RNA molecule

Termination: in this process, it signals the end of transcription and the pre-mRNA is released for processing

10. Does RNA processing occur in prokaryotes?

No

11. Where does RNA processing occur in the cell?

Eukaryotes

12. What are the three ways that pre-mRNA is processed?

Addition of cap to 5′ end

1) Why are the altered ends important?

To stabilize molecule

2) Addition of long tail made of repeating A’s at the 3′ end

3) Pre-mRNA is spliced

13. Which will be kept and translated, an exon or intron?

Exon

14. Are introns just a waste of space? How might they be helpful?

yes

15. What are the monomers that make up a protein polymer?

How many different types of these monomers exist?

16. A protein polymer is called ____________.

The covalent bond that joins protein monomers is called a ___________.

17. Does translation occur in the nucleus? ______

What cellular structure performs translation?

Do all living organisms have this structure (even prokaryotes)? ___________

18. The DNA strand provided below is the template strand. Fill in the complementary RNA nucleotides, then use the genetic code (Fig17.5) to fill in the amino acids (use 3-letter abbreviations) that the RNA codons specify.

DNA: TAC – TGG – ACA – GCG – TCA – CAT – ATT

RNA:

AMINO ACIDS:

19. What is tRNA? Explain the role of tRNA in translation. How does tRNA bring the correct amino acid (explain the anti-codon)?

20. Draw a ribosome attached to a strand of mRNA. Label the 5` and 3` ends of the mRNA and draw an arrow to show which direction the ribosome will move along the strand.

21. For translation to start, what are all of the things that must come together?

22. How is translation terminated?

23. Where are free ribosomes found in the cell?

Where are attached ribosomes found in the cell?

Attached ribosomes make secreted proteins. Explain what this means.

24. What is a point mutation?

Define: Substitution –

Insertion –

Deletion –

25. Why are insertions and deletions often more serious mutations than a substitution? What is a frame shift?

26. Explain: Silent –

Mis-sense –

Non-sense –

27. What is a mutagen? What are some examples?

28. Do all RNA’s get translated into polypeptides?

We can amend the Central Dogma to DNA ? RNA ? functional product

What are some functional products besides proteins?

CHAPTER 18: REGULATION OF GENE EXPRESSION

1.What is an operon? How are these useful for PROKARYOTES?

2. Fill in the table:

	Trp Operon	Lac Operon
Repressible or Inducible
Default ON or OFF
Is on when…
Is off when…
Catabolic or Anabolic

3. What do the enzymes coded for in the trp operon do?

When trp is present, are the genes in the trp operon transcribed?

4. What is a repressor?

5. What is an operator?

6. What is an inducer?

7. Which operon (trp or lac) is controlled by feedback inhibition?

8. Are operons found in eukaryotes?

9. Explain differential gene expression… different cell types in a multicellular organism are due to what?

10. Chromatin structure:

Does acetylation prevent or allow transcription?

Does DNA methylation prevent or allow transcription?

How does chromatin density affect transcription?

11. In EUKARYOTES, regulation of transcription involves transcription factors.

What is the role of general transcription factors?

What are specific transcription factors called?

*There are DNA segments where transcription factors bind (control elements) that are upstream of the gene:

Enhancers (distal) bind which type of transcription factor?

Proximal control elements bind which type of transcription factor?

12. In all organisms (prokaryotes and eukaryotes), there is a promoter upstream of the gene. What important enzyme for transcription binds here?

Is the promoter a protein or a segment of DNA?

13. Thinking about differential gene expression in EUKARYOTES (of course… proks are single-celled)… explain how activators drive differential gene expression in different types of cells. See Figure 18.11 for help.

14. Alternative RNA splicing is a form of post-transcriptional regulation. Explain how alternative splicing affects gene expression.

15. What 3 processes must occur for a multicellular organism to develop from a fertilized egg: (state & define each one)

16. Besides a haploid nucleus, what else is in an egg that comes from the mother?

17. Early development is directed by: (explain each)

Cytoplasmic determinants –

Induction –

18. What does it mean when a cell becomes determined? Using Figure 18.18 as an example, how does control of gene expression relate to cell determination?

19. Proto-oncogenes code for proteins that function in what process?

Explain 1 way that a proto-oncogene may become an oncogene? (See Fig 18.23)

Cancer can be caused by a mutation in a proto-oncogene that causes there to be too little or too much of the proto-oncogene protein made?

20. Tumor-suppressing genes code for proteins with what function?

Cancer can be caused by a mutation in a tumor-suppressing gene that causes there to be too little or too much of the tumor-suppressing protein made?

21. Explain how mutations that occur over time accumulate and contribute to cancer. Use colon cancer and Figure 18.26 as an example.

22. Individuals can have a genetic predisposition for certain types of cancer, but environment also plays a big role in development of cancer. Explain how genetics and environment (smoking, UV light, chemical exposure, radiation, etc…) can be synergistic in causing cancer.