Cell function quizzes/ answers/ FINAL EXAM REVIEW

The intracellular domain of an interegrin is connected to

Cytoskeleton

Which of the following is NOT a part of the extracellular martix?

Actin

The soft agar assay for cancer cell research is based on which of the following?

Intergrin-based signaling

The type of cellular junction that establishes cell cell polairty is the

Tight junction

The NLS has the following sequence characteristics

Contains a stretch of positively charged residues

The small monomeric G protein that functions in the nuclear import by disscoiating protein cargo from import receptor in the nucleues is

Ran-GTP

An interspecies heterokayron assay to study shutting proteins is based on which of the following?

Cell fusion

The DNA fingerprinting technique is based on which of the following?

All of the above

Which of the following best describes the main enzyme used ina PCR reaction?

A thermostable DNA polymerase which retains its activity at high temepertures

In the sanger method of DNA sequncing, incorpation of nucleotides stops because

The dideoxynucleotide analogs have no 3’-OH group to contiune DNA synthesis

In eukarotic cells, Transccription of mRNA is primarily the function of

RNA polymerase II

Which of the following is NOT associated with mRNA processing in eukaryotes?

Acetylation of histones

Which of the following would correctly represent the number of introns and the number of exons in a gene without any alternative splicing?

1, 2

What's the best explanation for the ability of tRNA to serve as a primer for a reverse transcriptase, which is DNA polymerase?

It has a free 3’-OH

A suppressor tRNA

All the above

Which of the following is NOT a feature of the genetic code?

Each codon represents a different amino acid

In order to examine mRNA transcripts isolated from cells, one needs to convert an RNA template to DNA. Doing this conversion requires which of the following enzymes?

Reverse transcriptase

Modulation of which of the following can contribute to the regulation of protein expression:

All of the above

Kanamycin is an antibiotic that binds to bacterial ribosomes and allows diverse RNAs with any anticodon to bind to the A site. What effects does kanamycin therefore have on bacterial translation?

It causes incorportion of incorrect amino acids into polypeptide

For the wobble theory of translation, the “wobbling” part is at:

3rd position of codon and 1st position of anticodon

Taxol inhibits the disassesmbly of mircotubule filaments

True

All three types of filaments (MT, MF, and IF) are polar filaments

False

Which of the following is a common feature of regulation of muscle contraction in both skeletal and smooth muscles?

Both involve Ca++-based regulation. Increase in Ca++ in cystol leads to contraction

The fundamental contracile unit of skeletal muscle is called a

Sacromere

Critical concentration is

The concentration of tubulin dimers at which assembly is balanced with disassembly

Which of the following would be INCONSISTENT with an inch-worm type of movement for kinesin’s motion on microtubules

Signifcant rotation force generated at the walking heads during movement

In order for a cell to crawl, it must produce a plasma membrane protrusion at the front of the cell, this structure is called a(n)

Lamelipodium

The actin-binding protein cofilin cleaves actin filaments near the minus end. What effect will this likely have on the assembly of actin filaments?

Promoting disassembly

The protein that normally blocks the myosin binding to actin filaments is named

Tropomyosin

The beta tubulin near the minus end of the microtubule would be

GDP form

You wish to obtain a pure nuclei sample from lysed cells. The best way to obtain this sample would be?

Centrifugation

The limit of resolution can be best defined as?

The distance that two objects must be apart to be distinguished as separate objects

When scientist use the scientific method, they use terms to indicate their degree of certainty. Which of the following terms conveys the least degress of certainty?

Hypothesis

Why do polar substances such as NaCl dissolve so readily in water?

The partially charged ends of water surround the salt ions to form a sphere of hydration between the water and ions

Which of the following one-letter symbols represent an amino acid that is polar uncharged?

Q

Which statement of the primary structure of a protein is NOT true?

It is the linear sequence of nucleotides that are linked together by peptide

Which of the following proteins/ domains contains mostly β- strands instead of ⍺helices?

Porin

What of the following is a disaccharide?

lactose

Which of the following is NOT a characteristic of DNA?

Contains ribose

Which of the following is NOT a polymer of numerous monomor units?

Lipids

Which organelle has only a single membrane around it?

Peroxisome

An allosteric inhibtor

Binds at the regulator site

Based on your knowledge of the chemistry of the cell membrane, which of the following compounds would you couple with a new drug to achieve better uptake by the cell

Lipids

Inactivation of a fluorescent dye in a very concentrated spot on a cell so that the fluidity of the membrane is visualized is called

Photobleaching

Many integral membrane proteins have not been analyzed by X-ray crystallography. However, transmembrane segments can be inferred using computer analysis of the protein's amino acid sequence. This techinque is know as

Hydropathic analysis

Which of the following is the smallest?

An amino acid

A negative free energy change indicates that

The reaction is exergonic

Which of the following best describes the special “high energy” bond of ATP?

Phosphoanhydride bond

Which of the following statements best describes the role of NAD+/ NADH in glycolysis?

NAD+ is used to recieve and carry electrons

The chemiosmotic model of ATP synthesis is based on several lines of experimental evidence. Which of the following statements is NOT correct experimental evidence to support the chemiosmotic model?

Oxidative phosphorylation does not require a membrane-enclosed compartment

You are isolating cell fractions using a variety of centrifugation techniques. You have two very similar fractions from liver cells but you don’t know what they are. As a result, you need to test the fractions for unique enzyme activities, if you are looking for the smooth ER fraction, one enzyme activity you can test for is

Glucose-6-phosphatase

The resting potential of a particular nerve cell is -66mV. Depolarization of the membrane will shift the membrane potential toward

0mV

Which of the following is likely mechanism for a protein encoded by an oncogenic virus to cause cancer?

Encoding a version Ras protein that is always on

The Ames test, the first step of which is mixing a chemical with liver homegenate before applying the mixure to a bacterial growth medium, is designed to

Deteremine whether the compound is carinogenic or not

Which of the following is a characteristic of apoptosis?

Cell blebbing

Which of the following statement is NOT true regarding apoptosis?

It is a process that, when enhanced, would contributed to increased oncogenesis

Which of the following is a potential mechanism for activating a protooncogene?

Excessive expression

What is a freeze-fracture experiment?

Splits membrane to study memebrane structure and proteins

What is the DNA laddering assay?

Detects apoptosis by showing fragmented DNA pattern

What is the differentiation of stem cells in vitro?

Turns stem cells into specfic cell types in the lab

What is time-lapse microscopy?

Records cells over time, the study movement and behavior

What is Cryo-Electron Microscopy?

High-resoultion imaging of molecules by freezing samples

What is ultracentrifugation?

Separates molecules by size/density using high-speed spinning

What is therapeutic human cloning?

Creates stem cells genetically identical to a patient for treatment

What is Western Blotting?

Detects specific proteins using antibodies

What is a soft-agar assay?

Tests if cells can grow without attachment (cancer-like behavior)

What is the Ames Test?

Tests if a chemical is mutagenic/carcinogenic

What is the Polymerase Chain Reaction (PCR)

Amplifies (copies DNA)

What is Reverse Transcription?

Converts RNA ——→ DNA

What is the hierarchy analysis of mutant cells?

Determines order of genes in a pathway

What is FRAP (Fluorescence Recovery After Photobleaching)?

Measures movement of molecules in membrane

What is Hypnotherapy plot analysis?

Predicts hydrophobic regions in proteins (like membrane-spanning parts)

Function of Kinase

Adds phosophate group

Function of DNase

Breaks down DNA

Function of RNase

Breaks down RNA

Function Hydrolase

Breaks bonds using water

Function caspase

Cuts proteins during apoptosis

Function Protease/Proteinase

Breaks down proteins

Function of Pepidase

Breaks down peptides (smaller protein pieces)

Function Primase

Make RNA primer for DNA replication

Function of Polymerase

Builds DNA or RNA strand

Function of ligase

Joins DNA fragments together

Function of Exonuclease

Removes nucleotides from the ENDS of DNA

Function of Endonuclease

Cuts INSIDE a DNA strand

Function of Methyltransferase

Adds methyl groups

Function of Separase

Separates sister chromatids during cell divison

Function Aminoacyl-tRNA synthetase

Attaches correct amino acid to tRNA

Function Phosphatase

Removes phosphate group

Function of Histone acetyltransferase (HAT)

Adds acetyl groups to histones ——→ loosens DNA (more gene expression)

Function of Deaminase

Removes amino group

Function of Lipase

Breaks down fats (lipids)

Function of ATPase

Break down ATP ——→ release energy

Function of GTPase

Breaks down GTP (often in signaling like Ras)

Function of Reverse transcriptase

Makes DNA from RNA

How does Sanger sequencing or pyrosequencing work?

Sanger stops the DNA and reads the fragment sizes

Pyrosequencing detects light when bases are added (more bases added = brighter light)

how does PCR work?

1. Denaturation—- DNA is heated so it unzips into TWO strands

2. Annealing (cooling down)—Short DNA pieces called primers stick to target sequences

3. Extension (building DNA): DNA polymerase adds nucleotides and builds a new DNA strand

Familial Hypercholesterolemia

Defects in LDL transport into cells by receptor-mediated endocytosis (feedback regulation of cholesterol synthesis), Genetic mutations in the LDL receptor gene

Common features of GPCR and RTK signaling

Both detect external signals and trigger intracellular signaling cascades that amplify the response and change cell behavior.

Differences of GPCR and RTK signaling

GPCR: uses G proteins+ second messagers ( cAMP and Ca++)

RTK: Kinase activation + phosphorylation signaling

Above critical concentration means

Mictroubles grow