Genetics: DNA Structure, Genomes, Replication, Meiosis, and Molecular Techniques

Fill-in-the-blank practice flashcards covering DNA molecular structure, genome organization, prokaryotic and eukaryotic DNA replication, meiosis, and basic molecular biology techniques.

Purines, which include adenine and guanine, are made up of __________ carbon-nitrogen rings.

two

Hydrogen bonds form between complementary bases: two bonds between an AT pair and __________ between a CG pair.

three

B-DNA is the most common secondary structure of DNA, forming a right-handed double helix with about __________ per turn.

$$10\,bp$$

A genome is defined as a __________ set of DNA molecules present in an organelle, a cell, or an organism.

haploid

Viral genomes usually are the smallest in size, ranging from about __________ to $2\,Mb$.

$$2\,Kb$$

Bacterial genomes are found in the cytoplasm, specifically in a nucleoprotein complex called the __________.

nucleoid

Eukaryotic genomes are the largest among organisms, ranging from $8\,Mb$ to over __________.

$$900\,Gb$$

Regions of eukaryotic genomes that are gene rich and relax throughout most of the cell cycle are called __________.

euchromatin

A nucleosome involves wrapping $145\,bp$ of DNA around an octameric core composed of two of each of the following histones: __________.

H2A, H2B, H3, and H4

A fifth type of histone, __________, binds linker DNA close to the nucleosome forming the chromatosome.

H1

In animals, gametes are haploid cells carrying $n$ chromosomes and a DNA content of __________.

C

In human somatic cells, the 2C value is $6.41\,pg$ for males and __________ for females.

$$6.51\,pg$$

Near the end of G1, passage into S phase is controlled by the __________ checkpoint.

G1/S

Ring-shaped protein complexes called __________ hold sister chromatids together after S phase.

cohesins

The origin of replication in E. coli (OriC) spans __________.

$$245\,bp$$

In E. coli, the initiator protein __________ binds to 9-mer boxes to melt the AT-rich repeats of the DUE.

DnaA

In E. coli, __________, a type II topoisomerase, uses ATP to insert negative supercoils into dsDNA.

Gyrase

Together, helicase (DnaB) and primase (DnaG) form the __________.

primosome

In E. coli, DNA Pol I uses __________ exonuclease activity to remove RNA primers.

5' to 3'

Replication termination in E. coli occurs when the replication terminator protein __________ binds to ter sequences.

TUS

While E. coli's replisome synthesizes DNA at about $1\,Kb$ per second, the eukaryotic replisome moves at about __________.

$1.5\,Kb$ per minute

Eukaryotic cells use three main nuclear replicative polymerases: DNA polymerase __________.

$\alpha$, $\delta$, and $\epsilon$

The enzyme __________ is a reverse transcriptase that synthesizes single-strand telomeric repeats to extend chromosome ends.

telomerase

Prophase I of meiosis occurs in four sequential stages: leptonema, zygonema, __________, and diplonema.

pachynema

An average of 55 chiasmata are observed per cell in human male meiosis, compared to around __________ in female meiosis.

90

Nondividing T lymphocytes can be induced into mitosis using __________, a lectin extracted from red kidney beans.

phytohemagglutinin (PHA)

To arrest dividing cells in metaphase for karyotyping, cells are treated with a spindle-disrupting agent such as __________.

colcemid

In 1983, __________ developed the polymerase chain reaction (PCR) technique.

Kary Mullis

The thermostable Taq polymerase used in PCR was originally isolated from the thermophilic bacterium __________.

Thermus aquaticus

To visualize DNA in agarose gels, __________ is added as an intercalating agent that fluoresces under UV light.

ethidium bromide (EtBr)

Almost all restriction endonucleases require __________ as a cofactor for cleavage activity.

$$Mg^{2+}$$

Type II restriction endonucleases typically recognize palindromic DNA sequences of about __________ in length.

4 to 6 bp

The molecular cytogenetic technique FISH stands for __________.

fluorescence in situ hybridization

A __________ blot is a molecular assay similar to a Southern blot, except that RNA is the target nucleic acid.

northern

In blue-white colony screening, bacterial cells carrying a recombinant plasmid with a disrupted lacZ gene produce __________ colonies.

white

Sanger sequencing relies on chain termination caused by the incorporation of __________.

dideoxynucleotides (ddNTPs)

The CRISPR-Cas9 system consists of a Cas9 nuclease coupled with an engineered __________.

guide RNA (gRNA)

Target recognition by Streptococcus pyogenes Cas9 relies on a 5' PAM motif consisting of the sequence __________.

NGG

The molecular structure shown in this diagram represents the double-helix structure of __________.

DNA

In the cell cycle diagram below, the stage during which DNA synthesis occurs is labeled as the __________.

S-Phase

The image shown below depicts paired metaphase chromosomes organized from largest to smallest, known as a __________.

karyogram

The gene-editing mechanism depicted in the diagram below is known as the __________ system.

CRISPR-Cas9