Cell and Molecular Biology Review

Comprehensive fill-in-the-blank practice flashcards covering cell biology, molecular genetics, organelles, cell cycle regulation, and experimental techniques based on lecture notes.

The primary structure of a protein consists of a linear sequence of amino acids read from the __________ terminus to the C terminus.

N

In protein secondary structure, alpha helices and beta sheets are stabilized by __________ bonds.

hydrogen

During post-translational glycosylation, carbohydrate chains are typically added to Ser, Thr, or __________ side chains.

Asn

Ubiquitination is the post-translational attachment of ubiquitin to __________ side chains to target proteins for degradation.

lysine

Unsaturated fatty acids increase membrane fluidity because their double bonds introduce a __________, preventing tight lipid packing.

kink

Microtubules are composed of α-tubulin and β-tubulin forming hollow cylindrical tubes with an outer diameter of __________.

$$25\,nm$$

The diameter of intermediate filaments ranges from $10\,nm$ to __________, placing them between microfilaments and microtubules.

$$12\,nm$$

Actin filaments are dynamic polymers of ATP-actin monomers that exhibit __________, where polymerization at one end coincides with depolymerization at the other.

treadmilling

While kinesin moves anterograde toward the plus end of microtubules, the motor protein __________ moves retrograde toward the minus end.

dynein

Functions of the smooth endoplasmic reticulum (SER) include steroid hormone synthesis, liver detoxification, and the sequestration of __________ ions in muscle cells.

calcium

When DNA wraps around the histone octamer to form a nucleosome, it achieves a compaction factor of __________ times relative to its initial linear state.

$$7$$

During chromosome condensation, the $30\,nm$ chromatin fiber loops onto a nonhistone protein scaffold to form the __________ extended chromosome section.

$$300\,nm$$

The FISH technique, which stands for __________, uses sequence-specific fluorescent probes to identify complementary nucleic acid sequences.

Fluorescent in situ hybridization

In the Watson-Crick model of DNA, the double helix makes one complete helical turn every __________ base residues.

$$10$$

During cytosine deamination, uracil is formed and pairs with adenine, causing an original GC base pair to mutate to a __________ base pair after two rounds of replication.

AT

The DNA repair enzyme photolyase reverses pyrimidine dimers using energy absorbed exclusively from __________ light.

blue

In the prokaryotic lac operon, the inducer that binds to and inactivates the lac repressor is __________.

allolactose

The non-coding RNA species termed __________ functions in nuclear processes including the splicing of pre-mRNA.

snRNAs

The small nucleolar RNAs known as __________ function to process and chemically modify ribosomal RNAs.

snoRNAs

Eukaryotic RNA polymerase __________ is responsible for synthesizing the 5.8S, 18S, and 28S rRNA genes.

I

A bacterial $70S$ ribosome is assembled from a large $50S$ subunit and a small __________ subunit.

$$30S$$

Peptide bond formation between adjacent amino acids during translation elongation is catalyzed by __________.

peptidyl transferase

The $26S$ proteasome consists of a central catalytic $20S$ core unit capped at each end by a __________ regulatory unit.

$$19S$$

Wee1 kinase phosphorylates inhibitory sites on Cdks, suppressing the activity of __________ prior to mitosis.

Cdk1

The phosphatase __________ triggers Cdk1 activation at the onset of mitosis by removing inhibitory phosphates.

Cdc25

The anaphase-promoting complex (APC/C) initiates sister chromatid separation by targeting __________ for destruction, releasing active separase.

securin

In vertebrates, the $G_1\text{-Cdk}$ complex is composed of Cyclin D paired with Cdk4 or __________.

Cdk6

According to the Baltimore classification, Group VI viruses have a single-stranded RNA genome that replicates via a DNA intermediate using __________.

reverse transcriptase

Vesicles coated with __________ transport cargo in an anterograde direction from the endoplasmic reticulum to the Golgi complex.

COPII

Proteins targeted for transport to lysosomes carry the specific sorting tag __________.

Mannose 6 Phosphate

In the illustrated DNA double helix, the vertical distance separating adjacent stacked base pairs is __________.

$$0.34\,nm$$

In the tRNA structure shown, the invariant trinucleotide sequence found at the $3'$ amino acid attachment site is __________.

CCA

In the centrosome diagram shown, each centriole barrel is composed of nine microtubule triplets consisting of an A tubule, a B tubule, and a __________ tubule.

C

In the chemical reaction shown, condensation between the carboxyl group of one amino acid and the amino group of another creates a __________ bond.

Peptide

As shown in the mRNA structure comparison, eukaryotic mRNA contains a $3'$ poly-A tail containing __________ adenine nucleotides.

$$150\text{--}250$$

In the mitochondrial electron transport chain shown, electrons from NADH are transferred into the chain by the protein complex __________.

NADH dehydrogenase

The mammalian Cdk inhibitor protein that suppresses $G_1\text{/S-Cdk}$ and $S\text{-Cdk}$ activities specifically following DNA damage is __________.

p21

Repetitive satellite DNA sequences are typically $100\text{--}200\text{ base pairs}$ in length and are predominantly located within the __________ of chromosomes.

centromere

Semiconservative replication of DNA was experimentally demonstrated in E. coli using isotope density centrifugation by __________ and Stahl.

Meselson

Biological experiments carried out via computer simulations or modeling software are designated in __________.

silico

Evidence supporting the endosymbiotic origin of mitochondria includes their double membrane and their own circular __________.

genome

Stem cells that can differentiate into all three primary germ layers and gonadic cells, but cannot form extraembryonic tissues, are termed __________.

pluripotent