Chapter 3 Flashcards
1
Q
Cell
A
Living structural and functional units enclosed by a membrane
2
Q
Cell Division
A
One cell divides into 2 identical cells
3
Q
Cell Biology/cytology
A
Is the study of cellular structure and function
4
Q
Plasma Membrane
A
Forms the cell’s flexible outer surface separating the cells internal/external environment
5
Q
Internal environment
A
Everything inside the cell
6
Q
External environment
A
Everything outside the cell
7
Q
Cytoplasm
A
Consists of all the cellular contents between the plasma membrane and the nucleus.
8
Q
What compartments does Cytoplasm consist of
A
Cytosol and Organelles
9
Q
Cytosol
A
fluid portion of cytoplasm
10
Q
Organelles
A
Includes cytoskeleton, ribosomes, endoplasmic reticulum, Golgi complex, lysosomes, peroxisomes and mitochondria. Each have specific functions, shape, characteristics
11
Q
Nucleus
A
a large organelle that houses most of a cell’s DNA
12
Q
Chromosomes
A
A single molecule of DNA associated with several proteins
13
Q
Genes
A
Hereditary units that control most aspects of cellular structure and function
14
Q
Plasma Membrane
A
Flexible yet sturdy barrier that surrounds and contains cytoplasm
15
Q
What Structural Model does the Plasma Membrane use and describe it
A
Fluid mosaic model- the molecular arrangement of plasma membrane resembles a continually moving sea of fluid lipids that contains a mosaic of many different proteins.
16
Q
Basic Structural framework of the Plasma Membrane
A
Lipid Bilayer
17
Q
Lipid Bilayer
A
2 back to back layers made up of 3 types of lipid molecules
18
Q
3 types of lipid molecules in the lipid bilayer
A
Phospholipids (75%, contain phosphorus), Cholesterol (20%, a steroid with an attached OH), Glycolipid (5%, lipid with an attached carbohydrate)
19
Q
Amphipathic
A
molecules that have both polar and non-polar parts
20
Q
Membrane Proteins
A
Integral or peripheral according to whether they are firmly embedded in the membrane
21
Q
Integral Protein
A
Extend into or through the lipid bilayer and are firmly embedded into it
22
Q
Transmembrane protein
A
Usually an integral protein. This means that they span the entire lipid bilayer and protrude into both the cytosol and extracellular fluid
23
Q
Peripheral Protein
A
Not as firmly embedded in the membrane. They are attached to the polar heads of membrane lipids or to integral proteins at the inner/outer surface of the membrane
24
Q
Glycoprotein
A
proteins with carbohydrate groups attached to the ends that protrude into the extracellular fluid
25
Glycocalyx
the carbohydrate portions of glycolipids and glycoproteins form an extensive sugary coating
26
4 Functions of Plasma Proteins
1.Act as barrier separating inside and outside of wall
2.Controls the flow of substances in and out of the cell.
3.Helps identify the cell to other cells
4.Participates in intracellular signalling
27
Membrane Protein Functions
Ion Channels, Carriers, Receptors, Enzymes, Linkers, Cell-identity markers
28
Ion Channels
Pores/holes that specific ions, such as K+ can flow through to get into/out of the cell
29
Carriers
Selectively moving a polar substance or ion from 1 side of the membrane to the other; also known as transporters
30
Receptors
Serve as cellular recognition sites; each type of receptor recognizes and binds a specific type of molecule
31
Ligand
a specific molecule that binds to a receptor
32
Enzymes
That catalyze specific chemical reactions at the inside/outside surface of the cell
33
Linkers
the anchor proteins into the plasma membranes of neighbouring cells to 1 another or to a protein filaments inside/outside the cell; peripheral proteins serve as enzymes/linkers
34
Cell-Identity Markers
May enable a cell to recognize other cells or same kind during tissue formation/recognize and respond to potentially dangerous foreign cells
35
Membrane Permeability-Permeable
Permeable means a structure permits passage of substances through it
36
Membrane Permeability-Impermeable
means a structure does not permit the passage of substances through it
37
Selective Permeability
Plasma membranes permit some substances to pass more readily than others through it
38
Concentration Gradient
Is the difference in the concentration of a chemical from one place to another (such as fro inside a cell to outside of a plasma membrane)
39
Electrical Gradient
Typically the inner surface of the plasma membrane is more negatively charged and then outer surface is more positively charged; a difference in the electrical charges between 2 regions
40
Membrane potential
the charge difference, because the electrical gradient occurs across the plasma membrane
41
Electrochemical Gradient
the combined influence of the concentration gradient and the electrical gradient on movement of a particular ion
42
What is essential to the life of a cell
transport across the plasma membrane
43
Passive Processes
when a substance moves down its concentration or electrical gradient to cross membrane using only its own kinetic energy/kinetic energy intrinsic to the particles moving/no input energy from the cell (diffusion)
44
Active Processes
Cellular energy used to drive the substance 'uphill' against its concentration or electrical gradient-usually in the form of ATP
45
Vesicles
another way substances may enter/leave cells- an active process in which tiny spherical membrane sacs are used- Active transport
46
Diffusion
is a passive process in which the random mixing of particles in a solution occurs because of the particles' kinetic energy
47
Solutes and Solvents
Both undergo diffusion
48
Factors that influence diffusion rate
Steepness of concentration gradient, temperature, mass of diffusing substance, surface area, diffusion distance,
49
Simple Diffusion
a passive process in which substances move freely through the lipid bilayer of the plasma membranes of cells w/o the help of membrane transport proteins
50
Facilitated diffusion
solutes are too polar or highly charged to move through the lipid bilayer by simple diffusion can cross the plasma membrane by passive process
51
Channel-mediated facilitated diffusion
a solute moves down its concentration gradient across the lipid bilayer through a membrane channel
52
Ion Channels
Integral transmembrane proteins that allow passage of small inorganic ions that are too hydrophilic to penetrate the nonpolar layer of the lipid bilayer
53
Gated Channel
When part of the channel protein acts as a plug/gate, changing shape in one way to open pore and in another way to close it
54
Carrier/Transport-mediated facilitated diffusion
Moves a solute down its concentration gradient across the plasma membrane
55
Transport Maximum
the # of carriers available in a plasma membrane places an upper limit, on the rate in which facilitated diffusion can occur
56
Osmosis
A type of diffusion in which there is net movement of a solvent through a selectively permeable membrane
57
Aquaporins
Integral membrane protein that functions as water channels
58
Hydrostatic pressure
Forces water molecules to move back into the left arm
59
Osmotic Pressure
The solution with an impermeable solute also exerts a force, the pressure of a solution is proportional to the concentration of the solute particles that can't cross the membrane-->higher solute concentration, higher solute's osmotic pressure
60
Tonicity
Is a measure of the solutions ability to change the volume of cells by altering their water content
61
Isotonic Solution
Any solution in which a cell—for example, a red blood cell (RBC)—
maintains its normal shape and volume
62
Hypotonic Solution
A solution that has a lower concentration of solutes than the cytosol inside the RBCs
63
Hemolysis
To split apart RBC's
64
Lysis
the rupture of other types of
cells due to placement in a hypotonic solution
65
Hypertonic Solution
has a higher concentration of solutes than does the cytosol inside
RBCs
66
Crenation
In a solution water molecules move out of the cells
faster than they enter, causing the cells to shrink. The shrinkage is called crenation
67
Active Transport
an active process because energy is required for carrier
proteins to move solutes across the membrane against a concentration
gradient. Two sources of cellular energy can be used to drive active
transport: (1) Energy obtained from hydrolysis of adenosine triphosphate
(ATP) is the source in primary active transport; (2) energy stored in an ionic
concentration gradient is the source in secondary active transport.
68
Primary Active Transport
energy
derived from hydrolysis of ATP changes the shape of a carrier protein,
which “pumps” a substance across a plasma membrane against its concentration gradient.
69
Pumps
carrier proteins that mediate primary active
transport
70
Na+/K+ Pump or Na+/K+ ATPase
The most prevalent primary active transport mechanism expels
sodium ions (Na+) from cells and brings potassium ions (K+) in. Because of the specific ions it moves, this carrier is called the sodium–
potassium pump. Because a part of the sodium–potassium pump
acts as an ATPase, an enzyme that hydrolyzes ATP, another name for
this pump is Na+–K+ ATPase.
71
Secondary Active Transport
the
energy stored in a Na+ or H+ concentration gradient is used to drive
other substances across the membrane against their own concentration gradients. Because a Na+ or H+ gradient is established by primary active transport, secondary active tr
72
Symporters
Move 2 substances in the same direction
73
Antiporters
move 2 substance in opposite directions across the membrane
74
Transport in vesicles
transport a variety of substances from one structure to another w/n cells
75
Vesicles
A small spherical sac
76
Exocytosis
Materials move out of a cell by the fusion with plasma membrane of vesicles formed inside the cell
77
Endocytosis
Materials move into a cell in a vesicle forms from the plasma membrane
78
Receptor Mediated Endocytosis
is a highly selective type of endocytosis by which cells take up specific ligands
79
Steps in Receptor Mediated Endocytosis
Binding, Vesicle Formation, Uncoating, Fusion with endosome, Recycling of receptors to plasma membrane, Degradation of lysosomes
80
Phagocytosis
Is a form of endocytosis in which the cell engulfs large solid particles
81
Phagocyte
Only a few body cells; macrophages-->located in many body tissues Neutrophils--> type of white blood cellT
82
Two main types of Phagocytes
Macrophages & Neutrophils
83
Pseudopod
Projections of its plasma membrane and cytoplasm. Pseudopods surround the particle outside the cell, and the membranes fuse to form a vesicle called a
phagosome.
84
Phagosome
membranes of the pseudopod fuse to form a vesicle called a
phagosome.
85
Bulk-Phase Endocytosis (Pinocytosis)
a form of endocytosis in which tiny droplets of extracellular fluid are
taken up. The plasma membrane folds inward
and forms a vesicle containing a droplet of extracellular fluid.
86
Exocytosis
releases materials from a cell. (1) secretory cells that liberate digestive enzymes,
hormones, mucus, or other secretions and (2) nerve cells that
release substances called neurotransmitters
87
Transcytosis
vesicles undergo
endocytosis on one side of a cell, move across the cell, and then
undergo exocytosis on the opposite side
88
Cytoplasm
consists of all the cellular contents between the plasma
membrane and the nucleus, and has two components: (1) the cytosol
and (2) organelles
89
Cytosol
is the fluid portion of the cytoplasm
that surrounds organelles (55%). is the site of many chemical reactions required for a
cell’s existence
90
Cytoskeleton
a network of protein filaments that extends
throughout the cytosol
91
3 Parts of Cytoskeleton
microfilaments, intermediate filaments, and
microtubules
92
Microfilament
the thinnest elements of the cytoskeleton. They help generate
movement and provide mechanical support.
93
Microvilli
nonmotile, microscopic fingerlike
projections of the plasma membrane. Greatly increase the surface area of the cell
94
Intermediate Filaments
thicker than microfilaments but
thinner than microtubules. They are found in parts of cells subject to
mechanical stress; they help stabilize the position of organelles
such as the nucleus and help attach cells to one another
95
Microtubule
help determine cell shape. They
also func-tion in the movement of organelles such as secretory vesicles,
of chromosomes during cell division, and of specialized cell projections,
such as cilia and flagella.
96
Organelles
specialized structures within the cell
that have characteristic shapes, and they perform specific functions in
cellular growth, maintenance, and reproduction.
97
Centrosome
Located near the nucleus, contains 2 components (centriole and Pericentriolar)
98
Centriole
cylindrical structures composed of 9 clusters of 3 microtubules arranged in a circular pattern
99
Pericentriolar Material
contains hundreds of ring shaped complexes composed of the protein tubulin
100
Tubulin
complexes are the organizing centres for growth of the mitotic spindle; which plays a critical role in cell division for microtubule formation in non-dividing cells
101
Tubules
complexes composed of the protein
102
Cilium
numerous short hair-like projections that extend from the surface of the cell
103
Flagellum
Similar in structure to cilia but are typically much longer, usually move an entire cell
104
Ribosome
Are the sites of protein synthesis; these tiny structures reflect their high content of one type of RNA, each one includes more than 50 proteins.
105
Endoplasmic Reticulum (ER)
A network of membranes in the form of flattened sacs or tubules; extends from nuclear envelope to which its connected and projects throughout the cytoplasm
106
Two Types or ER
Rough and Smooth
107
Rough ER
continuous with the nuclear membrane and usually is folded into a series of flattened sacs. The outer surface of rough ER is studded with ribosomes, the sites of protein synthesis. Proteins
synthesized by ribosomes attached to rough ER enter spaces within the ER for processing and sorting.
108
Smooth ER
extends from the rough ER to form a network of
membrane tubules. synthesize fatty acids and steroids
109
Golgi Complex
The first step in the transport pathway of the proteins synthesized.
110
Cisterns
small, flattened membranous sacs with bulging edges (in Golgi Complex)
111
Medial Cisterns
Sacs between the entry and
exit faces in the golgi complex
112
Functions of the Golgi Complex
1. Modifies, sorts, packages, and transports proteins received from the rough ER.
2. Forms secretory vesicles that discharge processed proteins via exocytosis into extracellular fluid; forms membrane vesicles that ferry new molecules to the plasma membrane; forms transport vesicles that carry molecules to other organelles, such as lysosomes.
113
Proteins arriving at, passing through, and exiting the Golgi
complex do so through
maturation of the cisternae and
exchanges that occur via transfer vesicles
114
Lysosomes
Form from the golgi complex. can contain as many as 60 kinds
of powerful digestive and hydrolytic enzymes that can break down a
wide variety of molecules once lysosomes fuse with vesicles formed
during endocytosis.
115
Autophagy
The process by which entire worn-out
organelles are digested
116
Autophagome
the organelle to be digested is enclosed by a membrane derived from the ER to create a vesicle.
117
Peroxisome
contain several oxidases, enzymes that can
oxidize (remove hydrogen atoms from) various organic substances.
118
Functions of Lysosomes
1. Digest substances that enter a cell via endocytosis and transport final
products of digestion into cytosol.
2. Carry out autophagy, the digestion of worn-out organelles.
3. Implement autolysis, the digestion of an entire cell.
4. Accomplish extracellular digestion.
119
Proteasomes
Continuous destruction of unneeded, damaged, or faulty proteins is the function of tiny barrelshaped structures consisting of four stacked rings of proteins around
a central core
120
Mitochondria
referred to as the “powerhouses” of the cell.
121
What does a Mitochondria consist of
external mitochondrial
membrane and an internal mitochondrial membrane
122
Mitochondrial Cristae
The internal mitochondrial membrane that contains a series of folds
123
Functions of Mitochondria
1. Generate ATP through reactions of aerobic cellular respiration.
2. Play an important early role in apoptosis.
124
Mitochondrial Matrix
The central fluid-filled cavity of a mitochondrion, enclosed by the internal mitochondrial membrane.
125
Apoptosis
the orderly, genetically programmed death of a cell.
126
Nucleus
is a spherical or oval-shaped structure that usually is the
most prominent feature of a cell
127
nuclear envelope
separates the nucleus from the cytoplasm. Both layers of the nuclear
envelope are lipid bilayers similar to the plasma membrane.
128
Nuclear Pores
control the movement of substances between the
nucleus and the cytoplasm.
129
Nucleoli
function in producing ribosomes.
130
Genes
control cellular structure and direct cellular
activities.
131
Chromatin
Each chromosome is a long molecule of DNA that is coiled
together with several proteins
132
Genome
The
total genetic information carried in a cell or an organism.
133
Nucleosome
Electron micrographs reveal that chromatin has
a beads-on-a-string structure. The bead is a nucleosome
134
Histones
Each nucleosome bead consists double-stranded DNA wrapped twice around
a core of eight proteins. Help organize the coiling and folding of DNA.
135
Linker DNA
string between the
beads
136
Chromatin Fiber
In cells that are not dividing, another histone promotes
coiling of nucleosomes into a larger-diameter chromatin fiber,
which then folds into large loops.
137
Chromatids
Just before cell division takes
place, however, the DNA replicates (duplicates) and the loops condense even more, forming a pair of chromatids
138
Functions of Nucleus
Controls Cellular structure, Directs cellular activties, Produces ribosomes in nucleoli
139
Two Main Steps of Protein Synthesis
Transcription and Translation
140
Proteome
refers
to all of an organism’s proteins
141
Gene expression
a gene’s DNA is used as a template for synthesis of a specific protein.
142
Base triplet
A sequence of three such nucleotides in DNA.
143
Codon
Each DNA base triplet is transcribed as a complementary sequence of three nucleotides
144
Genetic Code
is the set of rules that relate
the base triplet sequence of DNA to the corresponding codons of RNA
and the amino acids they specify
145
First step in Protein Synthesis: Transcription
occurs in the nucleus, the genetic information represented by the sequence of base triplets in DNA serves as atemplate for copying the information into a complementary sequence of codons.
146
Which three types of RNA are made from the DNA template:
Messenger RNA (mRNA), Ribosomal RNA (rRNA), Transfer RNA (tRNA)
147
Messenger RNA
directs the synthesis of a protein.
148
Ribosomal RNA
joins with ribosomal proteins to make
ribosomes.
149
Transfer RNA
binds to an amino acid and holds it in place
on a ribosome until it is incorporated into a protein during translation. One end of the tRNA carries a specific amino acid, and the opposite end consists of a triplet of nucleotides called an anticodon.
By pairing between complementary bases, the tRNA anticodon attaches to the mRNA codon.
150
Anitcodon
a triplet of nucleotides
151
RNA Polymerase
An enzyme that catalyzes transcription of DNA.
152
Promoter
The segment of
DNA where transcription begins, a special nucleotide sequence
153
Terminator
Transcription of the DNA strand ends at another special nucleotide sequence. specifies the end of the gene
154
Introns
do not code for parts of proteins.
155
Extrons
do code for segments of a protein.
156
Translation
the nucleotide sequence in an mRNA
molecule specifies the amino acid sequence of a protein. Ribosomes
in the cytoplasm carry out translation.
157
Steps of Translation
The nucleotide sequence in an mRNA molecule specifies the amino acid sequence of a protein-->Ribosomes in cytoplasm carry out translation-->Small subunit of a ribosome has a binding site for mRNA-->larger subunit of a ribosome has a binding site for mRNA-->larger subunit has 3 binding sites for tRNA molecules; a P site, a A site and an E site--> P site binds to tRNA carrying next amino acid to be added to growing polypeptide, E binds to tRNA just before its released from the ribosome
158
Polyribosome
Several ribosomes attached to the same mRNA
159
Cell Division
the process by
which cells reproduce themselves.
160
2 types of cell division
somatic cell division and reproductive cell division
161
Somatic Cell
any cell of the body
other than a germ cell.
162
Germ Cell
is a gamete (sperm or oocyte) or any precursor cell destined to become a gamete
163
Somatic Cell Division
a cell undergoes a nuclear division called mitosis and a cytoplasmic division called cytokinesis. to produce two genetically identical cells. replaces dead or
injured cells and adds new ones during tissue growth.
164
Reproductive Cell Division
the mechanism that produces
gametes.
165
Meiosis
The 2 step process of reproductive cell division in which the number of chromosomes in the
nucleus is reduced by half.
166
Cell Cycle in Somatic Cell Division
is an orderly sequence of events in which a somatic cell
duplicates its contents and divides in two.
167
homologous chromosomes
The two chromosomes that
make up each pair of inherited chromosome from each parent
168
Sex Chromosomes
designated X and Y. In females the homologous pair
of sex chromosomes consists of two large X chromosomes; in males
the pair consists of an X and a much smaller Y chromosome.
169
diploid
(2n) cells
somatic cells contain two sets of chromosomes
170
When a cell reproduces, it must replicate (duplicate) all its chromosomes to pass its genes to the next generation of cells. The cell
cycle consists of two major periods:
Interphase (when cell is not dividing) and Mitotic phase (When cell is dividing)
171
Interphase
the cell replicates its
DNA, It also produces
additional organelles and cytosolic components in anticipation
of cell division. Interphase is a state of high metabolic activity; it is during this time that the cell does most of its growing.
172
During which time does a cell does most of its growing.
Interphase
173
3 Stages of Interphase
G1, S and G2
174
G1 phase
the cell is metabolically active; it replicates most
of its organelles and cytosolic components but not its DNA; centromes replications also beings; total cell cycle time is 24 hours; lasts 8-10 hours
175
G0 Stage
Cells that remain in G1 for a very
long time, perhaps destined never to divide again
176
S Phase
the interval between G1 and G2, lasts about 8 hours. DNA replication occurs. As a result of DNA replication, the two identical cells formed during cell division later in the cell
cycle will have the same genetic material.
177
G2 Phase
interval
between the S phase and the mitotic phase. It lasts 4 to 6 hours. During
G2, cell growth continues, enzymes and other proteins are synthesized
in preparation for cell division, and replication of centrosomes is completed.
178
Mitotic Phase
results in the formation of two identical cells, consists of a nuclear
division (mitosis) and a cytoplasmic division (cytokinesis) to form two
identical cells.
179
Stages of Mitosis or Mitotic Phase
Prophase, Metaphase, Anaphase, Telophase
180
Prophase
During early prophase, the chromatin fibers
condense and shorten into chromosomes that are visible under the
light microscope. The condensation process may prevent entangling of the long DNA strands as they move during mitosis.
181
Centromere
holds the chromatid pair together
182
Mitotic Spindle
a football-shaped assembly of microtubules that
attach to the kinetochore
183
Metaphase
the microtubules of the mitotic spindle align the centromeres of the chromatid pairs at the exact
center of the mitotic spindle.
184
Anaphase
the centromeres split,
separating the two members of each chromatid pair, which move toward opposite poles of the cell. Once separated, the chromatids are termed chromosomes. As the chromosomes are pulled by the microtubules of the mitotic spindle during anaphase, they appear V-shaped because the centromeres lead the way, dragging the trailing arms of the chromosomes toward the pole.
185
Telophase
begins after chromosomal movement stops. The identical sets of chromosomes, now at opposite poles of the cell, uncoil and revert to the threadlike chromatin form. A nuclear envelope forms
around each chromatin mass, nucleoli reappear in the identical nuclei, and the mitotic spindle breaks up.
186
Events of Somatic Cell Division
G1, S phase, G2 phase, mitosis, cytokinesis
187
Cell's Three Possible Destinies
(1) to remain alive and functioning
without dividing, (2) to grow and divide, or (3) to die.
188
Aptosis
a normal type of cell death
189
Necrosis
a pathological type of cell death that results
from tissue injury
190
Meiosis
the reproductive cell division that occurs in the gonads (ovaries
and testes), produces gametes in which the number of chromosomes
is reduced by half
191
haploid (n) cells
gametes that contain a single set of 23
chromosomes.
192
2 Stages of Meiosis
meiosis I and meiosis II.
193
Meiosis I and II
, meiosis I begins with a diploid starting cell and ends
with two cells, each with the haploid number of chromosomes.
During meiosis II, each of the two haploid cells formed during meiosis
I divides; the net result is four haploid gametes that are genetically
diff erent from the original diploid starting cell.
194
The sizes of cells are measured what units
micrometers
195
