Chapter 3 Quiz

What is a secretory vesicle?

A small vesicle that moves substances through the cell to the cell surface

Which of the following may happen after a G protein-type receptor binds its ligand?

All of the choices are correct.

Which of the following statements about receptor-mediated endocytosis is true?

It involves clathrin-coated pits.

DNA replication occurs during mitosis.

DNA replication occurs during __________.

Which of the following statements about microtubules during anaphase is true?

Those attached to chromosomes shorten, while those that are unattached elongate.

Due to alternative splicing, there are likely more protein varieties in the body than there are genes in the human genome.

True

Ion movement across the plasma membrane creates an electrical charge difference known as ______.

a membrane potential

The plasma membrane molecule that provides stability to the membrane and determines the fluid nature of the membrane is __________.

cholesterol

Genetic translation occurs at ribosomes located in the _____________ of the cell.

cytoplasm

Pre-mRNA contains noncoding regions called

introns.

The glucose transport protein, GLUT1, is used to transport glucose from blood and extracellular fluid into cells. It does not require ATP, and its function is unaffected in cells that can't make much ATP. Based on this information, we can predict that the intracellular concentration of glucose is __________ that in blood

lower than

Organelles called __________ contain catalase and are active in detoxification.

peroxisomes

The segment of the DNA molecule where messenger RNA synthesis begins is called the __________.

promoter

Which of the following represents the correct order of the phases of mitosis?

prophase -> metaphase -> anaphase -> telophase

Skeletal muscle cells need large numbers of _______ to make the many proteins they contain.

ribosomes

Thyroid hormone (TH) can cause some cells to produce more proteins, such as sodium-potassium pumps, to help increase metabolic rate and heat production. Which of the following best describes how TH accomplishes this?

Genes are activated in the target cell, increasing transcription of specific mRNAs.

The membrane potential is due to

the difference in numbers of electric charges between the intracellular and extracellular sides of the plasma membrane.

As the ribosome shifts down the mRNA by a distance of one codon, _________.

the tRNA that was in the A site moves into the P site

During gene expression, __________ is the process of making an RNA copy of a portion of the DNA, and __________ is the process of directing the synthesis of a protein based off the sequence of the RNA.

transcription; translation

1. A solution consists of one or more substances, called solvents, dissolved in a liquid or gas, which is called the solute. 2. Diffusion is the movement of solutes from an area of higher solvent concentration to an area of lower solvent concentration. 3. Diffusion is a property resulting from the constant, random motion of all atoms, molecules, or ions in a solution. 4. At equilibrium, the net movement of solutes stops, although random molecular motion continues, and the movement of solutes in any one direction is balanced by equal movement in the opposite direction.

1. False 2. False 3. True 4. True

1. Proteasomes consist of several enzymes that break down and recycle lipids within the cell. 2. Proteasomes are tunnel-like structures with protein subunits at their ends that regulate which proteins are taken in for digestion.

1. False 2. True

1. The information contained in rRNA is "read" by a ribosome in sets of three nucleotides. These sets are called codons. 2. Each codon codes for an amino acid during translation. 3. There are 64 possible codons but only 20 amino acids. Therefore, amino acids can have more than one codon. 4. There are three start codons and one stop codon within the genetic code.

1. False 2. True 3. True 4. False

1. DNA replication is the process by which two new strands of DNA are made using the two existing strands as templates. 2. During anaphase, DNA and its associated proteins appear as dispersed chromatin threads within the nucleus. 3. The enzyme DNA ligase splices Okazaki fragments of the lagging strand after they are formed. 4. The production of new nucleotide strands is conducted by DNA polymerase, an enzyme that adds new nucleotides to the 5' end of the growing strands.

1. True 2. False 3. True 4. False

Imagine a polypeptide that is 100 amino acids in length. During translation of this polypeptide, how many codons (including those coding for amino acids and those that do not code for amino acids) were involved in the translation process?

101

Correctly arrange the following steps describing synthesis of a secretory or plasma membrane protein.(1) The protein moves through ER and then is carried in vesicles to the Golgi apparatus.(2) A vesicle pinches off from the Golgi apparatus and carries the product to the plasma membrane.(3) The Golgi apparatus modifies the protein and then packages it into a vesicle.(4) A protein is made by ribosomes on the rough ER.

4, 1, 3, 2

Which of the following characteristics of a molecule prevents it from diffusing through a cell membrane without assistance?

Being polar

Cells maintain a charge difference across their plasma membranes. This charge difference is used in processes such as signaling by the nervous system, and for stimulating coordinated contraction in muscle cells. Select which of the following statements is correct about the plasma membrane.

Both "The region just outside of the plasma membrane contains a greater number of positively charged ions and molecule than found in the corresponding region inside the membrane" and "The extracellular fluid contains more positively charged ions than the intracellular fluid" are correct.

The anticodon sequence GUA pairs with which of the following codons?

CAU

Given its reactive nature, oxygen is essential to cellular metabolic reactions. Peroxisomes use oxygen to break down fatty acids. In doing so, they use oxygen to remove hydrogens from fatty acid chains, yielding hydrogen peroxide (H2O2). Cells also routinely release potentially destructive molecules, such as superoxide (O2) in signaling, self-defense, or as a metabolic side product. Superoxide combines with hydrogen peroxide to make an even more destructive molecule called a hydroxyl radical. Therefore, the removal of these two reactants is a routine "housekeeping" chore within the cell. Which enzyme is used to prevent hydrogen peroxide accumulation in the peroxisome?

Catalse

________ affect(s) the fluidity of the cell membrane by limiting the movement of phospholipids.

Cholesterol

Which of the following events does not occur in prophase of mitosis?

Chromosomes are replicated.

A DNA base sequence is A T G C C G. The sequence of bases in a strand of mRNA transcribed from this sequence of bases in DNA would be __________.

U A C G G C

The protein-mediated movement of substances across a membrane that requires energy, such as the ATP, is called __________ transport.

active

The rate of diffusion can be increased with ________.

an increase in the temperature

The process by which there is programmed cellular death is __________.

apoptosis

At the base of each cilium is a structure called the __________.

basal body

Glycolipids consist of lipids and __________.

carbohydrates

The _____________ of the messenger RNA is recognized by the _____________ of the transfer RNA.

codon; anticodon

Chemical signal molecules such as hormones, and nervous system cells best represent the cellular activity of __________

communication

The division of the cytoplasm is called __________.

cytokinesis

Plasma membrane phospholipids are arranged as a ________

double layer with hydrophobic tails facing inward toward each other

If 0.9% NaCl (saline) solution is isotonic to a cell, then a 0.5% saline solution

is hypotonic to the cell.

Any chemical signal molecule used by cells to communicate with each other, is called a(n)

ligand

Large molecules move across cell membrane with the help or assistance of protein carriers. This type of transport is generically called _______.

mediated transport

The result of __________ is the division of a cell's chromosomes into two new nuclei, each of which has the same amount and type of DNA as the original nucleus. The division of the cells cytoplasm is called __________and occurs with the production of two new cells.

mitosis; cytokinesis

Proteins and mRNA exit the nucleus via __________.

nuclear pores

Internal structures of a cell that carry out specialized metabolic tasks are called __________.

organelles

Specialized, functional structures found within cells are called ______. There are a number of these in each cell, and they are generally visible under the electron microscope.

organelles

If a membrane protein only contains hydrophilic amino acids, it is most likely a ________ membrane protein

peripheral

The __________ endoplasmic reticulum manufactures lipids and carbohydrates whereas the __________ endoplasmic reticulum supports the synthesis of proteins that will eventually be sent to the Golgi apparatus.

smooth; rough

The name of the structure that causes the synthesis of RNA to cease is called the __________.

transcription terminator

A type of microscopy called __________ involves electrons passing through a thin section of a specimen.

transmission electron microscopy

Mitosis forms

two daughter cells with the same amount of DNA as the mother cell.

Osmosis is best defined as the movement of

water molecules across a membrane from an area of high water concentration to an area of lower concentration.

What is a membrane potential?

The electrical charge difference across the membrane caused by ion movement

Which stage of the cell cycle immediately precedes the S phase?

G1

The complimentary messenger RNA strand that would be synthesized from the DNA base sequence of CTGAC would be __________.

GACUG

Elongation of the polypeptide chain is terminated when a stop codon enters the P site of the ribosome.

False

RNA polymerase binds to a start codon on DNA.

False

Most cellular activities take place in the __________.

cytoplasm

1. Mitochondria make energy available to the cell by generating ATP. 2. The mitochondrion has a smooth inner membrane, but the outer membrane has numerous infoldings called cristae to increase surface area. 3. The enzymes of the citric acid (or Krebs) cycle are embedded within the inner membrane. 4. Cells with greater energy requirement have more mitochondria than cells with lower energy requirements. 5. Increases in the number of mitochondria result from the division of the preexisting mitochondria.

1. True 2. False 3. False 4. True 5. True

Which of the following events occurs in the secondary active transport of glucose?

All of these choices are correct.

What is mediated transport?

The movement of molecules across a membrane by means of a protein carrier

All cells contain the same genes, but some genes may be turned on or off depending on the specific functions of each cell.

True

The term organelle is best defined as

all structures within the cell that are specialized for particular functions.

Lungs serve the purpose of gas exchange. We inhale air, drawing in oxygen (O2) and exhale air, expelling carbon dioxide (CO2). Both of these molecules are small and nonpolar, and therefore freely pass though membrane bilayers of cells in the lungs. Based on this information, the movement of O2 from the alveoli of the lungs into the bloodstream is an example of

diffusion

The mitotic spindle fibers attach to chromosomes via special structures termed __________.

kinetochores

Cytoplasm is found

outside the nucleus but inside the plasma membrane.

An organ like the liver contains cells that are active in detoxification. These cells contain a large number of _______.

peroxisomes

The centrosome is a/an ______ in the cell containing two centrioles that appear to serve as a template for the formation of the ______ contained by cilia and flagellae.

region; microtubules

Exocytosis is a process by which cells

release substances from the cell via vesicles.