Protein Synthesis, DNA Replication, and RNA

Purine

An organic Molecule that has a double ring of carbon and nitrogen atoms; adenine and guanine are purines.

Pyrimidine

An organic molecule that has a single ring of carbon and nitrogen atoms; cytosine, thymine, and uracil are pyrimidines.

What is the name of the building blocks or sub units that compare the DNA molecule?

Nucleotide

What is the primary function of DNA?

The DNA is the storage area for the protein building instructions of the cell

Define "complimentary base pair" and give an example.

The DNA nucleotide always pair in this way: adenine pairs with thymine and cytosine pairs with guanine. These are referred to as complimentary base pairs.

Across the center of the DNA helix, a purine must always bond to a pyrimidine

True

The chromosomes that are found in prokaryotes are different from those found in eukaryotes. Which of the following describes prokaryotic DNA? (1) It is a single, circular chromosome. (2) It is linear. (3) Prokaryotes have many, separate chromosomes in each cell, just as the eukaryotes do. (4) There is no difference between a prokaryotic and a eukaryotic chromosome.

1

Alternating sugar and phosphate molecules form the sides or "backbone" of the DNA molecule. Why are the alternating sugars and phosphates referred to as a "backbone"?

The genetic information is contained in the series of nitrogen bases that form the center of the DNA helix. These bases must remain in the correct order, or the "language" will be pure gibberish. The sugars and phosphates are referred to as the "backbone" because they provide the structure and support of the molecule, keeping these bases in the correct order.

When a DNA molecule is replicated, what is the relationship between the original strand and the newly formed strands of DNA?

The newly formed strands are identical to the original, parental strands

Nitrogen bases are bonded together across the center of the helix with hydrogen bonds.

True

There are five nitrogen bases

True

If the DNA from one cell were stretched out, it would extend about 6 feet

True

What are two functions of DNA polymer during replication?

DNA polymerase(3) is the principle enzyme involved in DNA replication. These enzymes add the new nucleotides to the newly forming strands of DNA. DNA polymerases(1) also proofread the new strands as they are being made and will correct any errors that are found.

What does DNA stand for?

Deoxyribo Nucleic Acid

A double helix is shaped like a straight, untwisted ladder.

False

Adenine always bonds to thymine, but occasionally it can also bond to cytosine

False

Phosphates are bonded to sugars and sugars are bonded to nitrogen bases with covalent bonds.

False

The process of DNA replication produces an identical copy of the original DNA strand

true

There are five nitrogen bases in the DNA molecule.

False

How can an enormous amount of DNA fit inside one cell?

The DNA is wrapped tightly around proteins called histones. DNA is wrapped twice around a group of 8 histones forming a bead like structure called a nucleosome. The nucleosomes are coiled and supercoiled to form a chromosome

Ribose

The five carbon sugar found in RNA

Each strand of the DNA molecule can be used to make another strand during replication. This is because the two sides are ______ to each other. (1) homologous (2) complimentary (3) identical (4) translatable.

2

What is the function of DNA in cells? (1) It serves as a filler material to keep the nucleus from collapsing. (2) It stores the information that directs the ribosomes in protein synthesis. (3) It is the storage area for carbohydrates and other macromolecules. (4) It is a storage area for unused nucleotides.

2

Which of the following does not describe the structure of DNA? (1) It is a double helix. (2) It contains the 5-carbon sugar, ribose. (3) It has a sugar/phosphate backbone. (4) It is composed of nucleotides.

2

The main enzyme of replication whose function is to link together individual nucleotides along a template strand is called: (1) RNA polymerase (2) ligase (3) DNA polymerase (4) nuclease

3

Which of the following would not be found in a nucleotide? (1) a 5-carbon sugar (2) a nitrogen base (3) DNA polymerase (4) a phosphate group

3

When replication is complete, two _____ copies of the DNA molecule have been produced and the cell is ready to begin _____. (1) different; growing (2) identical; growing (3) different; transcription (4) identical; cell division

4

Which of the following might cause accidental damage or changes in existing DNA? (1) exposure to chemicals (2) radioactivity (3) x-rays (4) excessive exposure to ultraviolet light (5) all of the above.

5

What is meant by the "base-pairing" rules?

Adenine always pairs with thymine. Cytosine always pairs with guanine. These are referred to as the base pairing rules.

Using letters to symbolize the nitrogen bases, indicate which bases always pair together. How many bonds hold each pair together?

Adenine bonds with thymine; two hydrogen bonds are formed between them. Guanine bonds with cytosine; three hydrogen bonds form between them

How did Chargaff's rules help Watson and Crick develop their model of the DNA molecule?

From Char gaff's work, Watson and Crick knew that the amount of cytosine was equal to the amount of guanine; and that the amount of adenine was equal to the amount of thymine. Watson and Crick realized that the reason this was true was because A was always bonded to T and that C was always bonded to G.

If 20% of the nucleotide in a DNA molecule are adenine, what percentage of each of the other three bases would be found in this molecule? This is known as _______________________ rules.

If 20% of the nucleotide are adenine, then 20% of the nucleotide are thymine. The remaining 60% is divided equally between cytosine and guanine; each would compose 30% of the molecule. This is known as Char gaff's rules.

Deoxyribose

The five carbon sugar that is found in DNA

What is the advantage to the multiple sites of replication along the DNA molecule?

The replication of DNA begins at many origins of replication along the DNA molecule. This speeds up the process of replication. If replication started at one end and proceeded until it reached the other end, the process would be much slower.

What three critical things must genes be able to do?

The three critical roles of genes: a) Genes must be able to store and carry the genetic information. b) Genes must be able to put this information to work to produce the traits of the organism. c) There must be a mechanism of copying this information so that new cells formed by mitosis and gametes formed by meiosis will have a complete set of the genetic information.

What is the name of the structure seen to the right? Label the three parts composing this structure. How are the three parts held together

This is a drawing of a single nucleotide. The PO4 in the yellow circle is the phosphate group. The green, 5-sided shape is the sugar, deoxyribose. The orange, 6-sided shape is a nitrogen base. The sugar is held to the nitrogen base on one side and to the phosphate group on the other side by covalent bonds.

There is no difference between the sugar found in DNA and the sugar found in RNA

True

Why did Watson and Crick refer to the DNA molecule as a "double helix"?

Watson and Crick called the DNA structure a double helix. "Double" refers to the fact that the molecule is double stranded or is composed of two sides. "Helix" refers to the spiraling nature of the molecule; the two sides are twisted around one another.

Why is it so important that the DNA molecule be able to make copies of itself?

Whenever cells are preparing for mitosis or meiosis, The DNA must be copied exactly so that each new cell will receive an identical copy of the complete genome.

Replication results in two copies of the DNA molecule.

true