Chp 8 From DNA to Proteins Study Guide Set

What is a nucleotide?

-The smaller units, or monomers, that make up DNA. -Nitrogen base + sugar (ribose or deoxyribose) and phosphate group

Summarize the three key steps of transcription.

1. A large transcription complex, including RNA polymersase and other proteins, assembles at the start of a gene and begins to unwind the DNA. 2. Using one strand of the DNA as a template, RNA polymerase strings together a complementary strand of RNA. 3. The RNA strand detaches from the DNA as it is transcribed, and the DNA zips back together.

List two ways that the process of transcription and replication are similar.

1. Both occur within the nucleus of eukaryotic cells 2. are catalyzed by large enzymes, involve in unwinding of the DNA double helix 3. involve complementary base pairing of the DNA strand 4. are highly regulated by the cell.

How do DNA and RNA differ?

1. DNA and RNA have different sugars molecules. 2. DNA is typically double-stranded and is made up of nucleotides with bases C, G, A, and T. 3. RNA is single-stranded and made up of nucleotides with bases C, G, A, and U.

Summarize the steps of DNA replication.

1. Enzymes unzip the double helix by breaking the hydrogen bonds. 2. Each parental strand acts as a "template" for DNA polymerase to bind nucleotides together to form new strands that are complementary to the original strands. 3.DNA Ligase" seals the sugar-phosphate backbone of the new strands. 4. Two identical DNA molecules result.

List two ways that the end results of transcription and replication differ.

1. Replication occurs only once during each round of the cell cycle and makes a double-stranded copy of all the DNA in a cell 2. Transcription occurs repeatedly throughout the cell cycle to make proteins, rRNAs, and tRNAs as needed by a cell 3. Transcription makes a single-stranded complement of only a particular DNA sequence

What are 3 ways that DNA and RNA are similar?

1. both made of nucleotides 2. same nitrogenous bases - A,G,C 3. Both carry genetic information

What are 3 ways that DNA and RNA are different?

1. nucleotides have different sugars (deoxyribose vs. ribose) 2. different nitrogenous bases (U vs.T) 3. DNA is double-stranded, RNA is single- stranded/RNA can leave the nucleus, DNA can't

How many amino acids are there?

20 amino acids

Which nucleotide pairs with T?

A

Why was the bacteriophage an excellent choice for research to determine whether genes are made of DNA or proteins?

A bacteriophage consists of little more than a protein coat surrounding DNA. The protein coat is left behind when the viral DNA enters a bacterium.

Explain the connection between a codon and an amino acid.

A codon is a sequence of three nucleotides that specifies a particular amino acid. Each tRNA molecule binds to a specific amino acid and has an anticodon that binds to a specific codon.

What is a bacteriophage?

A virus that infects bacteria and takes over a bacterium's genetic machinery and directs it to make more viruses.

What four bases are found in DNA?

A- Adenine, T- Thymine, C - Cytosine, G - Guanine

Which sequence of bases would pair with the sequence TGACTA?

ACTGAT

If one stand of DNA had the sequence TAGGTAC, what would be the sequence of the complementary DNA strand?

ATCCATG

What is the start codon?

AUG (Met)

What four bases are found in RNA?

Adenine, Uracil, Cytosine, Guanine

What is DNA ligase?

An enzyme that seals the sugar-phosphate backbone of the new strands.

Using the Genetic code chart from your notes, or textbook Fig. 8.13 pg. 244. What amino acid is coded by CGA?

Arginine (Arg)

Summarize the key steps in the process that Avery's team used to identify the transforming principle.

Avery and his team purified transforming factor and then performed three tests: for the presence of DNA versus protein, for the relative proportion of nitrogen to phosphorous, and for the interaction with specific enzymes.

How are the base-pairing rules related to Chargaff's research on DNA?

Because A pairs only with T, and C pairs only with G, DNA will always have approximately the same proportion of A and T and the same proportion of C and G.

How does DNA serve as its own template during replication?

Both stands act as a template. Because base pairing is specific, the sequence of one strand dictates what the sequence of the other strand will be.

How did Watson and Crick determine the three-dimensional shape of DNA?

By building models

What is the purpose of transcription?

DNA can't leave the nucleus, so it gives the genetic code to mRNA to be taken to the ribosome for protein synthesis

DNA contains ____________________ but no __________________.

DNA contains phosphorous but no sulfur.

Avery and his team isolated Griffith's transforming principle. What type of molecule did they conclude the transforming principle contained?

DNA is present but protein is not.

How do cells help ensure that DNA replication is accurate?

DNA polymerase has a built-in proofreading function that corrects most mispaired nucleotides.

What is DNA polymerase?

DNA polymerases bond nucleotides together and proofreads to ensure accuracy

What is Chargaff's rule?

DNA should have a 1:1 ratio (G=C, A=T)

How do the base pairing rules explain how a strand of DNA acts as a template during DNA replication?

During DNA replication, nucleotide T always pairs with A, and C with G. The nucleotides on one strand are complementary to those on the other.

Why is it important that human chromosomes have many origins of replication?

Each chromosome in a eukaryotic cell is very long. If replication started at only one place, it would take a very long time to finish. multiple origins of replication let the process happen more quickly.

Why is DNA replication called semi-conservative?

Each daughter DNA molecule is composed of one parental strand and one new strand

What does each tRNA carry?

Each tRNA carries an amino acid

Avery and his team isolated Griffith's transforming principle. Which type of enzyme destroys the ability of the transforming principle to function?

Enzymes that destroy DNA

Which nucleotide pairs with C?

G

Using the Genetic code chart from your notes, or textbook Fig. 8.13 pg. 244. What amino acid is coded by GGA?

Glycine

What conclusions did Griffith make based on his experimental results?

Griffith concluded that a transforming principle had been transferred from the heat-killed S bacteria to the live R bacteria.

Summarize Griffith's experiment.

Griffith experimented with different strains of pneumonia bacteria, S (lethal) and R (harmless). When he injected mice with S strain bacteria, the mice died. When he injected mice with R strain bacteria, they lived. However, when he injected mice with heat-killed S strain bacteria (not lethal anymore), they lived. But now for the double whammy. When he injected mice with heat-killed S strain bacteria and live R strain bacteria, the mice died.

What was "transformed" in Griffith's experiment?

Harmless R bacteria were transformed into pathogenic S bacteria.

Based on the first three results of Griffith's experiment, what should have happened in the fourth experiment? Reference textbook. pg. 226 Fig. 8.1

In the fourth experiment the mouse should have lived because the S bacteria were dead, along with whatever caused the bacteria to be deadly.

What are introns?

Introns are pre-mRNA molecules that have bits and pieces cut out of them before they go into action.

How does DNA replication ensure that cells have complete sets of DNA?

It doubles the amount of DNA so that both of the daughter cells resulting from mitosis have their own complete set of DNA.

What is the central dogma?

It is a statement that summarizes how information flows in one direction from DNA to RNA to proteins.

How is each new replication DNA molecule related to the original molecule?

It is identical to the original DNA molecule.

Using the Genetic code chart from your notes, or textbook Fig. 8.13 pg. 244. What happens when a ribosome reads the codon AUG?

It produces methionine (which is also the start codon)

What is the function of Transfer RNA (tRNA)?

Matches m-RNA codon to add correct amino acids during protein synthesis

Why does a cell need to replicate its DNA quickly?

Our cells have large mounts of DNA. It must be copied quickly enough to keep up with the demand for cell division and to enable the cell to carry out its normal functions.

Proteins contain _________________ but very little ___________________.

Proteins contain sulfur but very little phosphorous.

What roles do proteins play in DNA replication?

Proteins help unzip the DNA strand, hold the strands apart, and bond nucleotides together.

What evidence suggested that there was a transforming principle in Griffith's experiment?

R bacteria in the presence of dead S bacteria became pathogenic (caused disease).

What enzyme helps a cell to make a strand of RNA?

RNA polymerase

What is the function of Ribosomal RNA (rRNA)?

Ribosomal RNA is found in the ribosomes and is used to bind the mRNA and the tRNA to the ribosome during translation to make proteins.

When is DNA replicated during the cell cycle?

S phase (synthesis)

What is the template?

Something that serves as a pattern

What did Franklin's data reveal about the structure of DNA?

That it was of uniform width

Using the Genetic code chart from your notes, or textbook Fig. 8.13 pg. 244. Suppose a tRNA molecule had the anticodon AGU. What amino acid would it carry?

That tRNA molecule would recognize the mRNA codon UCA, so it would carry the amino acid Serine.

Which part of a DNA molecule carries the genetic instructions that are unique for each individual: the sugar-phosphate backbone or the nitrogen-containing bases? Explain.

The backbone is the same in all DNA. The nitrogen-containing bases provide the unique instructions.

Why can the mRNA strand made during transcription be though have as a mirror image of the DNA strand from which it was made?

The mRNA chain is complementary to the DNA molecule. Like a mirror image, the mRNA chain has a distinct relationship to the DNA molecule, but is not identical to it.

Avery and his team isolated Griffith's transforming principle. What is the chemical makeup of the transforming principle?

The ratio of nitrogen to phosphorus in the transforming principle is similar to the ratio found in DNA.

What are exons?

The remaining pieces of pre-mRNA that are spliced together to form the final mRNA.

Briefly describe how the process of translation is started.

The small ribosomal subunit binds to the mRNA strand at the start codon, which binds the first tRNA molecule. This complex signals the large ribosomal subunit to bind, forming a functional ribosome, which can then continue accepting tRNA molecules and forming bonds between amino acids.

How does DNA base pairing result in a molecule that has a uniform width?

The sugar-phosphate backbone is on the outside. Inside the structure, a base with two rings always pairs with a base with only one ring.

What is a codon?

The three nitrogenous bases on mRNA

What is an anticodon?

The three nitrogenous bases on tRNA

How many stop codons are there? What are they?

There are 3, UAA UAG and UGA

Summarize how Hershey and Chase confirmed that DNA is the genetic material.

They labeled the protein of bacteriophages with radioactive sulfur and their DNA with radioactive phosphorous. The bacteriophages were allowed to infect bacteria. Hershey and Chase separated the phages from the infected bacteria and showed that phosphorous, a component of DNA, not sulfur, had entered the bacteria.

How did Avery and his group identify the transforming principle?

They purified the component of S bacteria that caused R bacteria to transform into S bacteria. This extract was tested for the presence of DNA or protein, its chemical composition, and its reaction to enzymes.

Why does DNA replication need to occur?

To make a copy of all the DNA in a cell so that it can be passes on to a new cell

Using the Genetic code chart from your notes, or textbook Fig. 8.13 pg. 244. What happens when a ribosome reads the codon UGA?

Translation stops

Using the Genetic code chart from your notes, or textbook Fig. 8.13 pg. 244. What amino acid is coded by UGG?

Tryptophan

If a DNA segment has the nucleotides AGCCTAA, what would be the nucleotide sequence of the complementary RNA strand?

UCGGAUU

What is DNA replication?

When DNA makes a copy of itself during the cell cycle

Each codon on the mRNA codes for what?

a specific amino acid (or to start/stop translation)

What does transfer RNA (tRNA) do?

brings amino acids from the cytoplasm to a ribosome to help make the growing proteins during translation

What is the function of Messenger RNA (mRNA)?

carries code from DNA to ribosomes

What does messenger RNA (mRNA) do?

copies the coded message from DNA in the nucleus and carries it into the cytoplasm

What are the two types of Nucleic Acids?

deoxyribonucleic acid (DNA) and ribonucleic acid (RNA)

What is a purine?

double-ringed nitrogenous base; adenine and guanine

How many types of nucleotides are present in DNA?

four

What holds the two strands of DNA together?

hydrogen bonds

What must be broken for the DNA strand to separate?

hydrogen bonds connecting base pairs

Explain how the interaction between mRNA codons and tRNA anticodons codes for a specific amino acid.

mRNA codons are the three-nucleotide sequences that code for specific amino acids. Anticodons are the tRNA sequences complementary to the mRNA codons that bring the specific amino acid into the growing polypeptide (protein).

Once mRNA is created, where does it go?

mRNA leaves the nucleus & attaches to a ribosome in the cytoplasm.

What does ribosomal RNA (rRNA) do?

makes up ribosomes

Where does DNA replication take place?

nucleus of a cell

Which parts are the same in all nucleotides?

phosphate group and deoxyribose

Why might a cell make lots of rRNA but only one copy of DNA?

rRNA is a component of ribosomes, and many ribosomes are needed to keep up with the level of protein synthesis needed by a cell. In contrast, each cell needs only one set of DNA, so it is copied only in preparation for cell division.

What is RNA?

ribonucleic acid, is a chain of nucleotides, each made of a sugar, a phosphate group, and a nitrogen-containing base.

What is a pyrimidine?

single-ringed nitrogenous base; cytosine and thymine

What is RNA?

single-stranded nucleic acid that contains the sugar ribose; made of nucleotides

What is translation?

the decoding of an mRNA message into a protein

Which parts are different in all nucleotides?

the nitrogen containing base

Where does transcription occurs?

the nucleus (DNA can't leave the nucleus)

What is transcription?

the process of copying a sequence of DNA to produce a complementary strand of RNA

Where does translation take place?

the ribosome (in the cytoplasm)

What is a double helix?

two strands of DNA wind around each other like a twisted ladder

A ________ must always bond with a _________________.

•A purine must always bond with a pyrimidine.

How does RNA Polymerase know where a gene starts & stops?

•RNA polymerase binds to places on the DNA called promoter •Promoters tell RNA polymerase where to start •Signals at the end of the gene code cause transcription to stop