Chapter 3 Flashcards
Briefly describe the fluid mosaic model.
The fluid mosaic model states that the molecular arrangement of the plasma membrane resembles an ever-moving sea of fluid lipids containing a mosaic of many different proteins.
1) What are the three main parts of a eukaryotic cell?
D) plasma membrane, cytoplasm, nucleus
The three main components of the lipid bilayer portion of a plasma membrane are
phospholipids, cholesterol, and glycolipids
What are the nonpolar parts of phospholipids?
fatty acid tail groups
5) The polar portion of a cholesterol molecule, which forms hydrogen bonds with the polar heads of neighboring phospholipids and glycolipids, consists of a
a) –OH group
6) This type of membrane protein extends across the entire lipid bilayer of the plasma membrane touching both intracellular fluid and the extracellular fluid.
transmembrane protein
Describe five different functions of integral membrane proteins.
Some membrane proteins act as ion channels or carriers that transport substances across the membrane. Other membrane proteins act as receptors that allow the cell to respond to various types of ligands. Other membrane proteins are enzymes that catalyze specific chemical reactions. Still other membrane proteins act as linker proteins that anchor cells to neighboring structures including other cells. Lastly, some membrane proteins serve as cell identity molecules.
8) This type of membrane protein enables cells to catalyze specific chemical reactions at the inner or outer surface of their plasma membrane.
enzymes
9) Which of the following types of membrane proteins function by recognizing and binding to hormones and neurotransmitters?
receptors
10) This type of membrane protein anchors cells to neighboring cells and to protein filaments found outside or inside the cell.
linkers
11) Plasma membranes are _____, which means that some chemicals move easily through plasma membrane while other chemicals do not.
a) selectively permeable
12) Which of the following does NOT influence the rate of diffusion of a chemical across a plasma membrane?
amount of ATP available
13) Briefly describe the driving force for the movement of water across plasma membranes.
Water moves across membranes by osmosis, which is driven by solute concentration differences across the membrane. Water moves from the area of low solute concentration to the area of high solute concentrations.
14) This is a measure of a solution’s ability to change the volume of cells by altering their water content.
tonicity
15) This is the transport process by which gases, like O2 and CO2, move through a membrane.
d) simple diffusion
16) In this type of transport process, a solute (e.g. glucose) binds to a specific carrier protein on one side of the membrane. This binding induces a conformational change in the carrier protein that results in the solute moving down its concentration gradient to the other side of the membrane.
d) facilitated diffusion
17) In this transport process, the energy from hydrolysis of ATP is used to drive substances across the membrane against their own concentration gradients.
primary active transport
18) If the solute concentration is greater inside of the cell than outside the cell, water will move by osmosis
a) into the cell.
19) What transport process uses the energy stored in a Na+ or H+ concentration gradient to drive other substances across the membrane against their own concentration gradients?
secondary active transport
20) Which of the following transport processes uses vesicles that fuse with the plasma membrane to secrete materials into the extracellular fluid?
exocytosis
21) Which of the following transport process uses vesicles formed at the plasma membrane to take up extracellular substances and import them into the cell?
endocytosis
22) List the steps involved in receptor-mediated endocytosis.
The steps involved in receptor-mediated endocytosis include 1)ligand binding, 2)vesicle formation, 3)uncoating of the vesicle, 4)fusion of the vesicle with endosome, 5)recycling of receptors to the plasma membrane, and 6)degradation of the ligand in the lysosome.
23) During phagocytosis, binding of a particle to a plasma membrane receptor triggers formation of _____, which are extensions of the plasma membrane of the phagocyte that eventually surround the particle forming a phagosome.
pseudopods
24) Which of the following is NOT a characteristic of the cytosol?
b) cation of electron transport chain carrier proteins
25) Specialized structures within a cell that have a characteristic shape and perform specific functions in cellular growth, maintenance and reproduction are called
organelles
26) Microfilaments, intermediate filaments and microtubules are all components of a cell’s
cytoskeleton
27) This cellular organelle is comprised of a pair of centrioles and the surrounding pericentriolar material.
c) centrosome
28) Spermatozoa is the only type of human cell that contains a _____, which is a whip-like structure that helps propel the sperm towards an oocyte.
b) flagellum
29) Which of the following membrane-enclosed organelles is the site of synthesis of membrane proteins and secretory proteins?
a) rough endoplasmic reticulum
30) Which of the following membrane-enclosed organelles modifies, sorts, and packages proteins destined for other regions of the cell?
Golgi complex
31) Briefly state the functions of the rough and smooth endoplasmic reticulum.
The rough endoplasmic reticulum synthesizes glycoproteins, phospholipids and digestive enzymes that are transferred to other cellular organelles, inserted into the plasma membrane, secreted during exocytosis or stored in the lysosomes. The smooth endoplasmic reticulum synthesizes fatty acids and steroids, detoxifies harmful substances, removes phosphate groups from glucose-6-phosphate, and stores and releases calcium ions that trigger contractions in muscle fibers.
32) Briefly describe how proteins move through the Golgi complex.
Proteins are packaged into transport vesicles by the rough endoplasmic reticulum membrane. These vesicles enter on the (cis) face of the Golgi complex, and the proteins move through the cisternae, from (cis) face through to exit (trans) face. Proteins will leave from the (trans) face of the Golgi complex in vesicles that will deliver the protein to plasma membrane, secretory vesicles, or to other organelles in the cell.
33) Which of the following membrane-enclosed organelles contains several oxidases that are involved in oxidation of fatty acids and amino acids during normal metabolism and in detoxification of chemicals like alcohol in the liver?
peroxisomes
34) Which of the following membrane-enclosed organelles can engulf a worn-out organelle, digest its chemical components, and recycle those digested components?
lysosomes
35) The major function of mitochondria is to
b) generate ATP.
36) Which of the following protects the contents of the nucleus?
nuclear membrane
37) What is the major function of histones?
c) help organize coiling and folding of the DNA
38) Briefly explain the difference between transcription and translation.
Transcription is making mRNA from DNA and it occurs in the nucleus, while translation is making a protein from the information in mRNA and happens in the cytosol of the cell.
39) This portion of a DNA segment does not code for a protein.
introns
40) Briefly describe alternative splicing
Alternative splicing of mRNA is a process in which the pre-mRNA transcribed from a gene is spliced in different ways to produce several different mRNAs. The different mRNAs are used to make different proteins.
Define homologous chromosomes
Homologous chromosomes contain similar genes arranged in the same (or almost the same) order.
42) During this phase of cell division, organelles duplicate and centrosome replication begins.
interphase
43) During this phase of cell division, the centromeres split leading to separation and subsequent migration of the two members of a chromatid pair to opposite poles of the cells. The cleavage furrow also begins to develop during this phase.
anaphase
44) In the diagram, which organelle is responsible for autophagy and autolysis?
C
54) Compare and contrast primary and secondary active transport
Both are energy requiring transport processes that are capable of moving substances against their concentration gradients. Energy obtained from hydrolysis of ATP drives primary active transport, while energy stored in an ionic concentration gradient drives secondary active transport.
55) Compare mitosis to meiosis.
Mitosis is somatic cell division that produces two identical cells with the same number (diploid) and kinds of chromosomes as the original cell. Meiosis is reproductive cell division that produces cells in which the number of chromosomes in the nucleus is reduced in half (haploid)
60) Most intravenous solutions are _____ with respect to blood cells?
isotonic
64) Which of the following transport processes moves substances through cells using endocytosis on one side of a cell and exocytosis on the opposite side of the cell?
c) transcytosis
65) Which disease below is an inherited condition characterized by the absence of a single lysosomal enzyme called Hex A?
a) Tay-Sachs disease
66) Which organelle is responsible for synthesis of steroids, phospholipids and functions as a reservoir for Ca2+?
c) smooth endoplasmic reticulum
67) What other organelle besides the nucleus contain DNA?
d) mitochondrion
68) This is the site of synthesis of rRNA and assembly of rRNA and proteins into ribosomal subunits.
nucleolus
69) What compound would a cell lacking ribosomes be unable to make?
proteins
70) The following is a particular sequence of base triplet on a DNA molecule: ATG. What is the corresponding codon for the mRNA?
e) UAC
71) The following is a particular sequence of codon on mRNA: ACU. What is the corresponding anti-codon for the tRNA?
a) UGA
72) Describe the difference between the cytoplasm and the cytosol.
The cytoplasm is all the cellular material (organelles and fluid) between the plasma membrane and the nucleus, while the cytosol is only the fluid portion of the cytoplasm.
73) The difference in concentration of a specific chemical, like Na+, on the inside and outside of a plasma is referred as a(n)
concentration gradient
74) An orderly, genetically programmed cell death is referred to as ________, while disorganized pathological cell death is referred to as ________.
b) apoptosis; necrosis
