Chapter 3 A&P Cell Biology
If an mRNA molecule is 1800 nucleotides (bases) in length, this molecule will contain _____ codons.
600
What is a secretory vesicle?
A small vesicle that moves substances through the cell to the cell surface
Which of the following is an example of posttranslational processing?
Adding polysaccharide side chains to a protein
Imagine a cell membrane that contacts a chemical agent that deforms any proteins present. Which of the following molecules will not be able to cross the membrane?
Glucose
Stacks of flattened membranes; modifies, packages, and distributes proteins and lipids
Golgi apparatus
The __________ functions to chemically modify cellular products such as proteins and package them in vesicles?
Golgi apparatus
Vesicles that contain digestive enzymes
Lysosomes
Able to spread and become worse
Malignant
The process by which cancer spreads to distant sites
Metastasis
Increase surface area of the plasma membrane for absorption of substances
Microvilli
Major sites of ATP synthesis by the process of respiration
Mitochondria
When a person trains for running long distances, which of the following organelles is likely to increase in number to help provide increased amounts of energy available to skeletal muscle?
Mitochondria
Largest organelle of the cell; contains DNA
Nucleus
The outer boundary of cells; controls the entry and exit of substances
Plasma membrane
A cell is exposed to cyanide, a toxic molecule that blocks mitochondrial ATP synthesis. Which of the following processes will be most directly affected?
Sodium-potassium pump transporting sodium and potassium ions
All cells contain the same genes, but some genes may be turned on or off depending on the specific functions of each cell.
TRUE
Cells in the G1 phase of the cell cycle contain half as much DNA as cells in the G2 phase.
TRUE
DNA replication is the process by which two new strands of DNA are made using the two existing strands as templates.
TRUE
Due to alternative splicing, there are likely more protein varieties in the body than there are genes in the human genome.
TRUE
Mitochondria contain their own DNA.
TRUE
Most pre-mRNAs are larger than the mRNAs formed from them.
TRUE
The enzyme DNA ligase splices Okazaki fragments of the lagging strand after they are formed.
TRUE
Cytotoxic T lymphocytes are immune cells that can detect the presence of virus-infected body cells. Once contact is made, the T lymphocyte releases substances that cause the infected cell to remove itself through a programmed self destruction process. What is this process called?
Apoptosis
System of microtubules and microfilaments that gives cells support, shape, and movement
Cytoskeleton
Which of the following statements about microtubules during anaphase is true?
Those attached to chromosomes shorten, while those that are unattached elongate.
_____________ RNA has the function of bringing amino acids to the ribosome during translation.
Transfer
1. The outermost component of a cell is the plasma membrane.
True
3. The plasma membrane encloses and supports the cell contents.
True
4. The plasma membrane determines what moves into and out of cells.
True
5. The plasma membrane can be used to attach cells to other cells.
True
Swellings that involve neoplastic tissue
Tumor
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
Ion movement across the plasma membrane creates an electrical charge difference known as ______.
a membrane potential
A DNA nucleotide sequence to which RNA polymerase first binds is called __________.
a promoter
The plasma membrane molecule that provides stability to the membrane and determines the fluid nature of the membrane is __________.
cholesterol
In the nucleus, DNA is wrapped around and also covered with many proteins. A single structure comprised of DNA and all of its associated proteins is called a/an __________.
chromosome
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
White blood cells that phagocytize and digest other cells would be expected to
contain large numbers of lysosomes.
The division of the cytoplasm is called __________.
cytokinesis
Genetic translation occurs at ribosomes located in the _____________ of the cell.
cytoplasm
Most cellular activities take place in the __________.
cytoplasm
Microtubules and microfilaments are the primary components of the __________.
cytoskeleton
Plasma membrane phospholipids are arranged as a ________.
double layer with hydrophobic tails facing inward toward each other
The environment outside the plasma membrane is most appropriately referred to as __________.
extracellular
The observation that the plasma membrane of the cell is not static or rigid, but highly flexible and changing has been referred to as the ______.
fluid-mosaic membrane model
The collection of carbohydrates, glycolipids, and glycoproteins of the plasma membrane is called the __________.
glycocalyx
DNA replication results in two new DNA molecules. Each of these new molecules
has one strand of nucleotides from the parent DNA and one newly synthesized strand of nucleotides.
Some hormone receptors can be found associated with the cell membrane of a target cell. These receptors are proteins that have a portion exposed to the extracellular environment (where the hormone will be found) and a portion exposed to the cytoplasmic environment of the cell (where the cellular change begins to take place). Based on this information, these hormone receptors are _________.
integral proteins
Membrane proteins that penetrate deeply into the lipid bilayer and can possibly extend from one surface to the other are called __________ proteins, whereas other proteins that are attached to either the inner or the outer surface of the lipid bilayer are called __________ proteins.
integral; peripheral
The time between cell divisions is called __________.
interphase
Pre-mRNA contains noncoding regions called
introns.
Any chemical signal molecule used by cells to communicate with each other, is called a(n)
ligand.
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 _______ function in the destruction of nonfunctional organelles.
lysosomes
Large molecules move across cell membrane with the help or assistance of protein carriers. This type of transport is generically called _______.
mediated transport
In general, water-soluble molecules diffuse through the __________, and lipid-soluble molecules diffuse through the ____________.
membrane channels; lipid bilayer
The nucleotide sequence of ________ determines the amino acid sequence of a protein.
messenger (mRNA)
Chromosomes align along the equator during __________.
metaphase
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
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
osmosis
Cytoplasm is found
outside the nucleus but inside the plasma membrane.
If a membrane protein only contains hydrophilic amino acids, it is most likely a ________ membrane protein.
peripheral
An organ like the liver contains cells that are active in detoxification. These cells contain a large number of _______.
peroxisomes
Organelles called __________ contain catalase and are active in detoxification.
peroxisomes
To prevent the entry of toxic substances or pathogens into the bloodstream, the liver screens everything that the digestive system takes in. Because this organ's cells are actively involved in the detoxification of chemicals, many liver cells contain large quantities of __________.
peroxisomes
White blood cells engulf foreign particles by means of __________.
phagocytosis
The predominant lipid in the cell membrane is a __________.
phospholipid
An inactive protein that can be converted to an active enzyme is called a __________.
proenzyme
Which of the following represents the correct order of the phases of mitosis?
prophase -> metaphase -> anaphase -> telophase
Proteins typically have only a short life span, and are molecularly "tagged" or earmarked for hydrolysis into small polypeptide fragments. Cellular structures dedicated to the routine digestion of proteins within the cytosol are __________.
proteosomes
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
Skeletal muscle cells need large numbers of _______ to make the many proteins they contain.
ribosomes
The organelles that are composed of small and large subunits and are responsible for protein synthesis are __________.
ribosomes
The adrenal glands manufacture and release steroid hormones such as cortisol and androgens. Cells of the adrenal gland are therefore likely to contain large amounts of _________, used to synthesize the lipids involved in steroid synthesis.
smooth endoplasmic reticulum
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
Ribosomes are most closely associated with
synthesis of molecules.
Cytokinesis is completed at the end of __________.
telophase
DNA replication occurs during __________.
the S phase of interphase
The membrane potential is due to
the difference in numbers of electric charges between the intracellular and extracellular sides of the plasma membrane.
Check all that occur at the cellular level as a result of aging.
1. The risk for unsuccessful completion of sex cell division and maturation decreases. 2. Cells experience increased metabolic functions.
There is a concentration difference for Na+ into intestinal epithelial cells. This gradient provides the energy for the symport of glucose and in some cells, the antiport of H+. This secondary active transport in the intestine works by the following. (Check all that apply.)
1.Active transport of sodium into the cell 2.Active transport of potassium out of the cell
Check all of the major theories of aging.
1.Damage to lysosomes
Which of the following events occurs in the secondary active transport of glucose?
1.Na+ ions and glucose are cotransported by the same carrier molecule. 2.The Na+-K+ pump maintains a Na+ concentration gradient across the plasma membrane. 3.Energy comes from diffusion of Na+ ions down their concentration gradient. 4.Glucose is moved against its concentration gradient into the cell. ALL THESE ANSWERS
Which of the following may happen after a G protein-type receptor binds its ligand?
1.The cell may be stimulated to open ion channels in the plasma membrane. 2.The cell may be stimulated to activate one or more intracellular signal pathways. 3.The cell may be stimulated to activating enzymes associated with the plasma membrane. ALL THESE Choices are correct
Cytoplasm contains
1.the cytosol. 2.organelles bound by membranes, such as mitochondria and the Golgi. 3.organelles not bound by membranes, such as ribosomes and centrioles. ALL THESE
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
Not inclined to spread and not likely to become worse
Benign
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
Cancer cells are often associated with losing the ability to attach to neighboring cells. Which of these protein types might cancer cells stop producing?
Cadherins
A malignant, spreading tumor
Cancer
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?
Catalase
Used in formation of microtubules found in cilia and flagella
Centrioles
Which molecule determines the fluidity of the plasma membrane?
Cholesterol
Which of the following events does not occur in prophase of mitosis?
Chromosomes are replicated.
Move materials over the surfaces of cells
Cilia
DNA replication occurs during mitosis.
FALSE
During anaphase, DNA and its associated proteins appear as dispersed chromatin threads within the nucleus.
FALSE
RNA polymerase binds to a start codon on DNA.
FALSE
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.
FALSE
2. The substances outside of the plasma membrane are intracellular.
False
6. The intracellular contents of the cell are similar to the extracellular contents.
False
Propels spermatozoa in humans
Flagella
Which stage of the cell cycle immediately precedes the S phase?
G1
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.
In one form of endocytosis, a molecule binds to a specific protein on the cell surface and triggers vesicle formation and endocytosis. What type of transport is this?
Receptor-mediated endocytosis
The structures upon which protein synthesis directly takes place
Ribosome
Extensive membrane system upon which protein synthesis takes place
Rough endoplasmic reticulum
What is the term used to describe a small generic membrane-bound structure that transports substances to the plasma membrane for release by exocytosis?
Secretory vesicle
What is a membrane potential?
The electrical charge difference across the membrane caused by ion movement
What is mediated transport?
The movement of molecules across a membrane by means of a protein carrier
Nonmotile cell extensions called microvilli contain cytoskeletal support filaments largely made of __________. Those of cilia and flagellae contain structures largely made of __________.
actin; tubulin
The protein-mediated movement of substances across a membrane that requires energy, such as the ATP, is called __________ transport.
active
The presence of a cellular clock, presence of "death genes," and damage to DNA or mitochondria are all theories of __________.
aging
The term organelle is best defined as
all structures within the cell that are specialized for particular functions.
The rate of diffusion can be increased with ________.
an increase in the viscosity of the solvent
Chromosomes begin migrating towards poles of the cell during __________.
anaphase
The process by which there is programmed cellular death is __________.
apoptosis
The process of controlled cell death is referred to as __________.
apoptosis
Insulin hormone is a protein made up of 110 amino acids. Cells in the pancreas are stimulated to secrete insulin when blood glucose levels are increased. Based on this information, ribosomes engaging in insulin synthesis
are attached to the endoplasmic reticulum.
At the base of each cilium is a structure called the __________.
basal body
Glycolipids consist of lipids and __________.
carbohydrates
Receptor proteins are most closely associated with
cell communication.
Mitotic spindle fibers are most closely associated with
cell reproduction.
Mitochondria are most closely associated with
cellular energy use.
Match the event with the appropriate step of processing.
this step occurs in the nucleus. Posttranscriptional processing This step involves the placement of a cap and tail to the mRNA molecule. Posttranscriptional processing This step involves the joining of two or more amino acid chains with one another. Posttranslational processing This step involves the incorporation of exons and the removal of introns from the resultant molecule. Posttranscriptional processing This step occurs in the cytoplasm. Posttranslational processing
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
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.
A symporter will transport __________ across the cell membrane.
two different ions or molecules in the same direction
If 0.9% NaCl (saline) solution is isotonic to a cell, then a 0.5% saline solution
will cause crenation of the cell.
