MOLBIO - MT 122 - Lecture 3 - Nucleic Acids and Proteins

DNA replication

The process in which each chromosome is duplicated before cell division.

Mitotic phase (M phase)

The time in which the cell divides to form two daughter cells.

Interphase

The time between two cell divisions or mitoses.

G1 phase

S phase

G2 phase

Interphase is subdivided into what phases?

d. S phase

A phase in which each chromosome has doubled its DNA content and is composed of two identical sister chromatids linked at the centromere?

a. G1 phase

b. M phase

c. G2 phase

d. S phase

e. None of the choices

a. G1 phase

A period of cellular growth preceding DNA synthesis.

a. G1 phase

b. M phase

c. G2 phase

d. S phase

e. None of the choices

b. First statement is incorrect. Second statement is correct.

G2 phase is a A period of cellular growth after DNA synthesis but PRECEDING mitosis.

G2 phase

A period of cellular growth after DNA synthesis and succeeding mitosis. Here, replicated DNA is checked for any errors before cell division.

a. First statement is correct. Second statement is incorrect.

b. First statement is incorrect. Second statement is correct.

c. Both statements are correct.

d. Both statements are incorrect.

d. Both A and B

methotrexate and hydroxyurea which target the S phase; vincristine and vinblastine target the M phase.

Which chemotherapeutic agent/s target/s S phase?

a. Methotrexate

b. Hydroxyuerea

c. Vinblastine

d. Both A and B

e. Both B and C

a. Nucleoside

Nitrogenous base + a 5-carbon sugar

a. Nucleoside

b. Nucleotide

c. Nucleic acid

d. None of the choices

c. Nucleic acid

-Series of nucleotides or polynucleotides

-DNA or RNA (depending on sugar present)

a. Nucleoside

b. Nucleotide

c. Nucleic acid

d. None of the choices

b. Nucleotide

Nitrogenous base + a 5-carbon sugar (nucleoside) + a phosphate residue

a. Nucleoside

b. Nucleotide

c. Nucleic acid

d. None of the choices

d. Both A and C

What are the two nitrogenous bases that are commonly found in nucleic acids both RNA and DNA?

a. Purines

b. Pyrimidines

c. Adenine and Guanine

d. Both A and C

e. Both A and B

dATP

dGTP

dCTP

dTTP

The four nucleotide building blocks of DNA are abbreviated as? (nomenclature)

TRUE

TRUE or FALSE

The base sequence of the nucleic acid is written by convention in the 5′→3′ direction.

10 base pairs

How many are the base pairs per complete turn of the helix?

Recombination

A person's DNA is unique, formed by the process of?

Watson- Crick DNA or B-DNA

The native form of DNA is an energetically favorable secondary structure: a right-handed, double-stranded helix, which is also known as?

c. Both statements are correct.

The hydrophilic sugar-phosphate backbone of each strand is on the outside of the double helix while the hydrogen-bonded base pairs are stacked in the center of the molecule.

a. First statement is correct. Second statement is incorrect.

b. First statement is incorrect. Second statement is correct.

c. Both statements are correct.

d. Both statements are incorrect.

-The two strands or polymers must run in opposite directions (antiparallel) as defined by the free hydroxyl groups at each end (3’-5’ vs. 5’-3’).

-The sequences of each molecule must be such that the two strands are complementary (i.e. “A” always pairs with “T” by two hydrogen bonds, and “G” always pairs with “C” by three hydrogen bonds).

For the two DNA polymers to form the proper hydrogen bonds between the bases, what are the two requirements that must be fulfilled?

pH 4-9

All dsDNA molecules, regardless of base sequence, retain the same shape and size within a pH range of?

TRUE

TRUE OR FALSE

RNA is less stable than DNA

23 chromosome pairs

The vast amount of genetic material is organized into how many homologous chromosome pairs?

b. Nucleosome

It is the basic packaging unit of chromatin is known as?

a. Chromatin

b. Nucleosome

c. Histone

d. 10-NM Chromatin fiber

c. Chromatin

Nuclear DNA in conjunction with its associated structural proteins, including histone and nonhistone proteins. is known as?

a. Histone H1

b. Nucleosome

c. Histone

d. 10-NM Chromatin fiber

d. 10-NM Chromatin fiber

A series of nucleosomes is sometimes called "beads on a string" but is more properly referred to as?

a. Histone H1

b. Nucleosome

c. Histone

d. 10-NM Chromatin fiber

a. Histone H1

It is associated with the linker DNA found between nucleosomes to help package them into a solenoid-like structure, which is a thick 30-nm fiber, is called?

a. Histone H1

b. Nucleosome

c. Histone

d. 10-NM Chromatin fiber

FALSE

It is MORE condensed during interphase

TRUE OR FALSE

Generally, chromatin is much more condensed during interphase, at which time DNA is replicated.

Euchromatin

It is known for its genomic regions rich in genes and less condensed chromatin.

Heterochromatin

It is known for its gene-poor regions and more densely packed and condensed chromatin.

Eukaryote chromosomes

Contain two specialized regions of heterochromatin, namely the centromeres and telomeres.

TELOMERE

CENTROMERE OR TELOMERE

Contain repetitive nucleotide sequences that are located on and protect the ends of chromosomes.

CENTROMERE

CENTROMERE OR TELOMERE

Play a role in directing the movement of chromosomes between daughter cells during cell division.

TRUE

TRUE OR FALSE

For replication to occur, the original double-stranded helix must be unwound by the enzyme Topoisomerase.

Okazaki fragments

One daughter strand is synthesized continuously (leading strand), while the other strand (lagging strand) must be synthesized discontinuously through the formation of short nucleotide sequences called?

Transcription

What is the process called In which involves copying a gene's DNA sequence to make an RNA molecule or template?

DNA Polymerases

Possess an exonuclease or "proofreading" function, this is called

DNA transcription

Involves the process of transferring the sequence of information from the coding regions of DNA to an mRNA (messenger RNA) strand.

Promoter region

RNA polymerase binds to sequences in the regulatory region of the gene called?

21 amino acids

How many amino acids are involves in protein synthesis?

Codon

These 21 amino acids may each be stratified in a three-nucleotide sequence known as a?

UAA, UAG, UGA

What are the three stop codons?

UGA

Which of the stop codons is able to code for the 21st amino acid known as Selenocysteine?

AUG

This is known as the start codon

Methionine

This is always the first amino acid in every protein that is synthesized.

TRUE

TRUE OR FALSE

When the stop codon sequence is reached, the synthesis is complete.

Coding mutations

There are aberrant times when different base pairs cause different codons to be presented. When this occurs, they are known as?

1 - b

2 - d

3 - c

4 - a

Correctly pair the following:

(e.g. 1 - a)

1. The codon encodes for a completely different amino acid (UUA→ GUA)

2. Involves the addition of a base, which will rearrange downstream codons into a completely different set of amino acid encodings.

3. The codon encodes for a stop codon, that causes the synthesis to be prematurely terminated, resulting in an abnormal protein.

4. A mutation changes one base into another, but it still encodes for the same amino acid.

a. Silent mutation

b. Missense mutation

c. Nonsense mutation

d. Frameshift mutation

a. First statement is correct. Second statement is incorrect.

Effective against gram NEGATIVE bacteria

Quinolones or Fluoroquinolones

(-floxacin)

Inhibit the enzyme DNA gyrase, which is the bacterial equivalent of the enzyme topoisomerase II. Effective against gram positive bacteria.

a. First statement is correct. Second statement is incorrect.

b. First statement is incorrect. Second statement is correct.

c. Both statements are correct.

d. Both statements are incorrect.

Reverse transcription

It involves the formation of a DNA strand from an RNA strand which is called?

Chargaff's rule

The rule that in DNA there is always equality in quantity between the bases A and T and between the bases G and C. Name the rule.

Tertiary structure

The structure that undergoes folding.

Secondary structure

The side chains or the R-groups of amino acids start to contort or associate with one another, this structure is called?

Quaternary structure

The structure we refer to as associations between one or more protein sub-unit.

Fibrous Proteins

Globular Proteins

Intermediate Proteins

Proteins can be further classified according to structure which are?

Simple Proteins

Conjugated proteins

Proteins can be also classified into composition which are?

Structural Proteins

Enzymes

Hormones

Pigments

Transport Proteins

Contractile Proteins

Storage proteins

Toxins

Proteins can be also classified into functions which are?

Post-translational Modification

A process in which the translation is done and the polypeptide is released from the ribosome, and the changes done to it after the translation process.