Biology: 2.6-2.7 Quest

Mutation

-A change in a gene or chromosome due to a change in the amino acid sequence -deletion: a base is lost, frameshift -insertion: an extra base is added, frameshift -substitution: one base is substituted for another, if aa changes-missense, if aa does not change-silent, if it makes the aa stop-nonsense

DNA replication and the enzymes involved

-it is described as "Semiconservative" bc after this process the two resulting DNA contains one strand of the original DNA and one newly made strand of DNA. -Complementary base pairing ensures that the two DNA molecules that result from replication will be identical in their base sequences and identical to the parent molecule. -Helicase is an enzyme that "unzips" the DNA strand. It breaks the hydrogen bonds between the complementary bases and separates the double helix. -After the strands are separated, DNA polymerase comes in and adds nucleotides onto the exposed bases to form a new strand on the preexisting one.

If a polypeptide consists of 240 amino acids, what is the minimum number of nucleotides needed on the sense strand of a gene to code for it?

720

What type of bond occurs between the nitrogenous bases?

The bond that occurs between complementary bases are hydrogen bonds. These hydrogen bonds are easily broken making the replication process for DNA to be much more efficient. Also, because these hydrogen bonds are so easily put together and broken, RNA is capable of being temporarily double stranded when it needs to.

How has insulin production for diabetics changed over time?

Insulin would be extracted from the pancreases of pigs and cattle but this process was not as efficient and some patients would develop allergic reactions to the animal insulin. Now, diabetes are treated with human insulin. This process was discovered when the human gene for insulin was transferred to E. coli, resulting in the production of human insulin.

sickle cell anemia

a genetic disorder due to missense that causes abnormal hemoglobin, resulting in some red blood cells assuming an abnormal sickle shape

Which are the correct directions of the following processes? Each refers to the direction that the new product is synthesised. Replication Transcription Translation i. 5' to 3' 3' to 5' 3' to 5' ii. 3' to 5' 5' to 3' 5' to 3' iii. 5' to 3' 5' to 3' 5' to 3' iv. 3' to 5' 3' to 5' 3' to 5'

iii.

which type of mutation results in abnormal amino acid sequence?

insertion/deletion

leading and lagging strands

leading is the strand that has an exposed 3' is added continuously in the 5'-->3' direction by DNA polymerase . lagging strand has an exposed 5'. It still is made in 5'-->3' direction but discontinuous in okazaki fragments that require ligase to stitch back together

Anticodon

located on the tRNA molecules and they are a three base sequence that is complementary to and bonds to the mRNA. The tRNA bind to the amino acid and carry it to that corresponding codon. There can only be two tRNA's bonding at the same time. There are 20 tRNA's

Name the enzyme used in the polymerase chain reaction.

taq polymerase

Translation

the process by which polypeptides are synthesized on ribosomes according to the genetic code. This occurs in the cytoplasm. The mRNA containing the codons runs through the ribosome and the tRNA brings the corresponded amino acids to the ribosome to be translated into a protein/polypeptide chain.

Differences between DNA and RNA

-DNA has deoyribose, thymine, is double-stranded -RNA has ribose, uracil, is single-stranded, and is used

How does the polymerase differ in replication and transcription?

-In replication, DNA polymerase creates a complementary copy of the DNA sequence using DNA nucleotides. -In transcription, RNA polymerase is used and it connects RNA nucleotides with the complementary bases of the original strand to create mRNA.

What do 3' and 5' refer to?

3' and 5' refer to the carbon on the sugar which is part of the nucleotide. They mark the two ends of the polymer strands.

Which of the following statements about DNA is true?

DNA normally forms a double helix, and the two strands are anti-parallel.

Which enzyme is responsible for joining together the nucleotides of the new DNA strand during DNA replication?

DNA polymerase

PCR (polymerase chain reaction)

PCR is used to make many copies of a selected DNA sequence. Taq DNA Polymerase is an enzyme that can withstand higher temperatures without being denatured.With Taq DNA polymerase, PCR is able to produce large numbers of selected base sequence copies in a short amount of time. -Denaturation: addition of heat to separate the two sides of the DNA Annealing: Cools off the DNA by being pulled apart and then the primers are added DNA synthesis: make more copies of DNA so the DNA polymerase will begin to build the DNA and the DNA gets warmer again

Which molecule is found in both DNA and RNA?

Phosphate

Which base replaces thymine in RNA?

Uracil

which type of mutation is responsible for new variations of a trait?

missense substitution

monomers of DNA and RNA

-nucleotides, which are made up of a phosphate group, a five-carbon sugar and a nitrogenous base

To which end of a DNA strand are new nucleotides added?

3'- DNA replication goes in the 5' to 3' direction because DNA polymerase acts only on the -OH (3') end of the existing strand for adding free nucleotides.

If 15% of a sample of DNA is thymine, what percentage of the DNA is guanine?

35%

What type of bond occurs within the nucleotide?

Covalent bonds are formed within the nucleotide and these bonds will not easily break. The sugar- phosphate backbone benefits DNA and RNA by being a strong and reliable structure of alternating sugar and phosphate groups that a base can link to.

Which of the following are directly involved in both replication and transcription?

DNA

The base ratios in the DNA and RNA for an onion (Allium cepa) are given below. Bases A / % G / % C / % T / % DNA 31.8 18.4 18.2 31.3 Bases A / % G / % C / % U / % RNA 24.9 29.8 24.7 20.6 What is the reason for the difference between these figures?

DNA is made entirely of double helix but RNA is not.(DNA is a double helix with complementary base pairing. So the percentage A and T should be equal because they pair up (same is true for G and C). RNA however is usually single stranded so the percentages do not need to match.)

Which of the following is true about DNA replication?

DNA replication happens during the S phase of the cell cycle.

Meselson and Stahl

Determined that DNA replication is semiconservative using the isotope 15N

Watson and Crick

Developed the double helix model of DNA with help from other scientists who competed and collaborated with them along the way -Franklin confirmed the helix structure -Chargaff discovered base pairings

Which of the following happens the earliest during DNA replication?

Free nucleotides base pair to original polynucleotide

What type of bond connects two DNA strands?

Hydrogen bonds

Which of the following best defines the term "nucleic acid backbone"?

Nucleic acids are composed of a backbone of sugar molecules and phosphate groups. The nitrogen bases are attached to the sugars.

What are the three main components of a DNA nucleotide?

Phosphate, Deoxyribose sugar, Nitrogenous Base

sense and antisense strands

The antisense strand contains the gene and is used as a template (ACGT). The sense strand is complementary to the antisense strand and is the same as the mRNA except the mRNA will contain uracil and not thymine.

In a DNA deoxyribose sugar of a single nucleotide, which carbon is connected to the base?

The first carbon

Which carbon(s) in a DNA deoxyribose sugar of a single nucleotide is/are part of the link to an adjacent nucleotide?

The third and fifth carbon

How would the following DNA sequence, ACGTTGCATGGCA, be transcribed?

UGCAACGUACCGU

What is meant by the term "antiparallel" in describing the DNA strands?

When describing DNA strands, antiparallel means that the strands still run parallel, but in the opposite directions

Which enzyme is responsible for unwinding the DNA double helix in preparation for DNA replication?

helicase

label of diagram of DNA nucleotides

nucleotide diagram

Which of these features correctly describes a similarity between DNA and RNA?

Both nucleic acids have covalent bonds between molecules within a nucleotide.

A fragment of the DNA has been transcribed into RNA. What would be the sequence of RNA for the following DNA sense strand? CCAGATATAC

CCAGAUAUAC

A fragment of the DNA has been transcribed into RNA. What would be the sequence of RNA for the following DNA sense strand? - CCAGATATAC

CCAGAUAUAC

If the mRNA sequence is GCU CCU GAG UUG, then the corresponding anti-sense strand DNA sequence must be:

CGA GGA CTC AAC

wobble effect

The last or 3rd nitrogenous base can change but the amino acid it codes for stays the same

What does complementary base pairing mean ?

This means that specific bases only link with other specific bases. In DNA, adenine and thymine bases pair together and cytosine and guanine bases pair. In RNA, the base pairings are the same except uracil replaces thymine.

How does insulin evolution support the universal nature of the genetic code?

This transferring of genes for the use of human insulin is possible because E. coli use the same genetic code as humans. This is because all organisms read this code the same way. The insulin produced has the same amino acid sequence as a gene that is to be transcribed and translated into a human cell.

What base does Adenine pair with?

Thymine

How is the polymerase chain reaction (PCR) used?

To make many copies of a DNA molecule.

Transcription

occurs in the nucleus of a eukaryotic cell. This is when the RNA polymerase creates a copy of the DNA code by creating the complementary base pairing of the DNA sequence and transcribing them into the messenger RNA

Codon

sequence of three bases on the mRNA that correspond to one amino acid in a polypeptide. There are 64 possible codons. Codons only code for one specific amino acid, but multiple codons can code for the same amino acid

Which of the following is not a component of the PCR reaction?

tRNA