Chapter 3 Flashcards
1
Q
plasma membrane
A
cell membrane
2
Q
nuclear envelope
A
a double membrane with nuclear pores that surround nucleus
3
Q
cytoplasm
A
where most cell activities take place
4
Q
chromatin
A
dispersed, thin strands of DNA and associated proteins in nucleus, which condenses to become visible mitotic chromosomes during cell division
5
Q
nucleolus
A
consists of ribosomal RNA and proteins
6
Q
ribosome
A
site of protein synthesis
7
Q
Rough endoplasmic reticulum
A
synthesizes proteins and transports them to the golgi apparatus
8
Q
Smooth endoplasmic reticulum
A
Manufactures lipids and carbohydrates; detoxifies harmful chemicals; stores calcium
9
Q
golgi apparatus
A
Modifies, packages, and distributes proteins and lipids for secretion or internal use
10
Q
lysosome
A
Membrane-bound vesicle pinched off Golgi apparatus; contains digestive enzymes
11
Q
Peroxisome
A
Serves as one site of lipid and amino acid degradation; breaks down hydrogen peroxide
12
Q
Proteasomes
A
Tubelike protein complexes in the cytoplasm; Break down proteins in the cytoplasm
13
Q
Mitochondria
A
ATP synthesis
14
Q
Centrioles
A
Pair of cylindrical organelles in the centrosome, consisting of triplets of parallel microtubules; Serve as centers for microtubule formation; determine cell polarity during cell division; form the basal bodies of cilia and flagella
15
Q
Flagellum
A
Extension of the plasma membrane; propels spermatozoa
16
Q
Microvilli
A
Extension of the plasma membrane containing microfilaments; Increase surface area of the plasma membrane for absorption and secretion; modified to form sensory receptors
17
Q
membrane potential
A
regulation of ion movement by cells results in a charge difference across the plasma membrane
18
Q
glycocalyx
A
collection of glycolipids, glycoproteins, and carbohydrates on the outer surface of the plasma membrane.
19
Q
Phospholipids
A
assemble to form a lipid bilayer
20
Q
lipid bilayer
A
double layer of phospholipid molecules
21
Q
fluid-mosaic model
A
suggests that the plasma membrane is neither rigid nor static in structure but is highly flexible and can change its shape and composition through time.
22
Q
Cholesterol
A
other major lipid in the plasma membrane; limits the movement of phospholipids, providing stability to the plasma membrane
23
Q
integral proteins (or intrinsic proteins )
A
protein molecules that penetrate deeply into the lipid bilayer, in many cases extending from one surface to the other
24
Q
peripheral proteins (or extrinsic proteins )
A
attached to either the inner or the outer surfaces of the lipid bilayer.
25
marker molecules
cell surface molecules that allow cells to identify other cells or other molecules.
26
glycoproteins
proteins with attached carbohydrates
27
glycolipids
lipids with attached carbohydrates
28
attachment proteins
allow cells to attach to other cells or to extracellular molecules
29
Cadherins
proteins that attach cells to other cells
30
integrins
proteins that attach cells to extracellular molecules.
31
transport proteins
integral proteins that allow ions or molecules to move from one side of the plasma membrane to the other.
32
Channel proteins
one or more integral proteins arranged so that they form a tiny channel through the plasma membrane
33
leak ion channels or non-gated ion channels
channel proteins that are always open and are responsible for the plasma membrane’s permeability to ions when the plasma membrane is at rest.
34
gated ion channels
channel proteins that can be open or closed.
35
ligands
small molecules that bind to the proteins or glycoproteins.
36
ligand-gated ion channels
gated ion channels that open or close in response to
| chemical signals or ligands
37
voltage-gated ion channels
gated ion channels that open or close when there is a change in charge across the plasma membrane
38
Carrier proteins or transporters
integral membrane proteins that move ions or molecules from one side of the plasma membrane to the other.
39
Uniport
the movement of one specific ion or molecule across the membrane.
40
Symport
the movement of two different ions or molecules in the same direction across the plasma membrane
41
antiport
the movement of two different ions or molecules in opposite directions across the plasma membrane.
42
ATP-powered pumps
transport proteins that move specific ions and molecules from one side of the plasma membrane to the other.
43
Receptor proteins
proteins or glycoproteins in the plasma membrane that have an exposed receptor site on the outer cell surface
44
cystic fibrosis
a genetic disorder that affects chloride ion channels.
45
G protein complex
located on the inner surface of the plasma membrane which acts as an intermediary between a receptor and other cellular proteins.
46
selectively permeable
allows only certain substances to pass through it.
47
vesicle
small, membrane-bound sac that can transport large, non-lipid-soluble molecules, small pieces of matter and even whole cells across the plasma membrane
48
Diffusion
the movement of solutes from an area of higher solute concentration to an area of lower solute concentration
49
concentration gradient
The concentration difference between two points, divided by the distance between the two points
50
Viscosity
a measure of how easily a liquid flows
51
Osmosis
the diffusion of water (solvent) across a selectively permeable membrane
52
Selectively permeable
the membrane allows water but not all the solutes dissolved in the water to diffuse through it.
53
Aquaporins or water channel proteins
increase membrane permeability to water in some cell types, such as kidney cells.
54
Osmotic pressure
the force required to prevent water from moving by osmosis across a selectively permeable membrane.
55
isosmotic
Solutions with the same concentration of solute particles that have the same osmotic pressure even if the types of solute particles in the two solutions differ from each other.
56
hyperosmotic
solution that has a greater concentration of solute particles, and therefore a greater osmotic pressure than another solution
57
hyposmotic
when a solution is more dilute, with the lower osmotic pressure compared with the more concentrated solution.
58
isotonic
when a cell placed into a solution neither shrinks nor swells
59
tonicity
the shape of the cell remains constant, maintaining its internal tension or tone
60
hypertonic
when a cell is placed into a solution and water moves out of the cell by osmosis, causing the cell to shrink
61
hypotonic
when a cell is placed into a solution and water moves into the cell by osmosis, causing the cell to swell
62
crenation
in red blood cells, when water moves by osmosis from the cell into the hypertonic solution, causing the cell to shrinks
63
lysis
when a cell swells too much and ruptures
64
Mediated transport
the process by which transport proteins mediate, or assist, the movement of large, water-soluble molecules or electrically charged molecules or ions across the plasma membrane.
65
Specificity
each transport protein binds to and transports only a single type of molecule or ion
66
Competition
the result of similar molecules binding to the transport protein
67
Saturation
the rate of movement of molecules across the membrane
| is limited by the number of available transport proteins
68
Facilitated diffusion
a carrier-mediated or channel-mediated process that moves substances into or out of cells from a higher to a lower concentration
69
Active transport
a mediated transport process that requires energy provided by ATP; can move from lower to higher concentrations
70
sodium-potassium pump; sodium-potassium ATP-ase
active transport system that moves Na + out of cells and K + into cells
71
Secondary active transport
involves the active transport of an ion, such as sodium, out of a cell, establishing a concentration gradient, with a higher concentration of the ions outside the cell.
72
Endocytosis
the uptake of material through the plasma membrane by the formation of a vesicle; phagocytosis and pinocytosis
73
receptor-mediated endocytosis
when the plasma membrane contains specific receptor molecules that recognize certain substances and allow them to be transported into the cell by phagocytosis or pinocytosis.
74
Hypercholesterolemia
common genetic disorder characterized by the reduction in or absence of low-density lipoprotein (LDL) receptors on cell surfaces, which interferes with the receptor-mediated endocytosis of LDL cholesterol; results in too much production of cholestrol
75
exocytosis
when secretions accumulate within vesicles, move to the plasma membrane, and fuse there, then contents are expelled from the cell.
76
Cytosol
fluid portion of the cytoplasm, which contains the cytoskeleton and cytoplasmic inclusions.
77
cytoskeleton
supports the cell and holds the nucleus and other organelles in place.
78
Microtubules
hollow tubes composed primarily of protein units called tubulin; help provide support and structure to the cytoplasm of the cell, much like an internal scaffolding; they are involved in cell division and in the transport of intracellular materials; and they form essential components of certain cell organelles, such as centrioles, spindle fibers,
cilia, and flagella.
79
Actin filaments or microfilaments
small fibrils that form bundles, sheets, or networks in the
cytoplasm; provide structure to the cytoplasm and mechanical support for microvilli, support the plasma membrane, and define the shape of the cell.
80
Intermediate filaments
protein fibers that provide mechanical strength to cells and support the extensions of nerve cells.
81
cytoplasmic inclusions
aggregates of chemicals either produced or taken in by the cell; contained in cytosol
82
lipo-chromes
pigments that increase in amount with age.
83
nuclear pores
At many points on the surface of the nuclear envelope, the
| inner and outer membranes fuse to form porelike structures
84
Deoxyribonucleic acid (DNA)
mostly found within the nucleus with small amounts found within mitochondria; DNA and associated proteins are organized into chromosomes and histones
85
histones
important for the structural organization of DNA
86
chromatin
During most of the cell’s life cycle, the chromosomes are dispersed throughout the nucleus as these delicate filaments; during cell division the dispersed chromatin
becomes densely coiled, forming compact chromosomes.
87
ribonucleic acid (RNA)
can leave the nucleus through nuclear pores;
88
gene
A sequence of nucleotides in a DNA molecule that specifies the structure of a protein or RNA molecule
89
Ribosomes
sites of protein synthesis; consist of ribosomal RNA (rRNA)
| and proteins; produced separately in the nucleolus
90
Free ribosomes
primarily synthesize proteins used inside the cell, whereas ribosomes attached to the endoplasmic reticulum usually produce proteins that are secreted from the cell.
91
cisternae
interior spaces of organelle sacs and tubules that are isolated from the rest of the cytoplasm.
92
smooth endoplasmic reticulum
manufactures lipids, such as phospholipids, cholesterol, and steroid hormones, as well as carbohydrates; phospholipids help form vesicles; enzymes help reduce chemical toxicity
93
rough endoplasmic reticulum
where proteins are produced and modified for secretion and for internal use.
94
Golgi Apparatus
modifies, packages, and distributes proteins and lipids manufactured by the rough and smooth endoplasmic reticula
95
transport vesicles
proteins produced in ribosomes and packaged into transport vesicles that move to the Golgi apparatus, fuse with the Golgi membrane, and release the protein into the Golgi apparatus cisterna.
96
secretory vesicles
membrane-bound; pinch off from the Golgi, move to the surface of the cell, their membranes fuse with the plasma membrane, and the contents of the vesicle are released to the exterior by exocytosis.
97
Lysosomes
membrane-bound vesicles that form at the Golgi; contain a variety of hydrolytic enzymes that function as intracellular digestive systems.
98
autophagia
when lysosomes also digest the organelles of the cell that are no longer functional
99
Peroxisomes
membrane-bound vesicles; smaller than lysosomes; contain enzymes that break down fatty and amino acids; hydrogen peroxide is a byproduct of the breakdown.
100
catalase
enzyme that breaks down hydrogen peroxide to water and oxygen.
101
Pompe disease
rare genetic disorder caused by the inability of lysosomal enzymes to break down glycogen.
102
Familial hyperlipoproteinemia
group of genetic disorders that occur when large amounts of lipids accumulate in phagocytic cells that lack the normal enzymes required to break down the lipid droplets.
103
Mucopolysaccharidoses, such as Hurler syndrome
genetic diseases in which lysosomal enzymes are unable to break down mucopolysaccharides (glycosaminoglycans), so these molecules accumulate in the lysosomes of connective tissue cells and nerve cells.
104
Proteasomes
consist of large protein complexes, including several enzymes that break down and recycle other proteins within the cell.
105
cristae
infoldings that project like shelves into the interior of the mitochondrion.
106
matrix
substance located in the space formed by the inner membrane.
107
mitochondrial diseases
Disorders that result from changes in mitochondrial genes that can lead to disruptions in normal ATP synthesis, reducing the amount of ATP produced by the cells.
108
Leber hereditary optic neuropathy
results in sudden vision loss due to optic nerve degeneration.
109
centrosome
specialized zone of cytoplasm close to the nucleus; center of microtubule formation in the cell.
110
spindle fibers
extend out in all directions from the centrosome; attaches to a chromosome and stops growing or shrinking during cell division.
111
Dynein arms
proteins connecting adjacent pairs of microtubules
112
basal body
modified centriole
113
Flagella
similar structure to cilia, but longer; sperm
114
Genes
functional units of heredity, the transmission of genetic traits from parent to offspring.
115
gene expression
production of proteins from the information stored in DNA; involves transcription and translation
116
transcription
copy of; transcription is the synthesis of mRNA, tRNA, and rRNA based on the nucleotide sequence in DNA
117
translation
changing of something from one form to another
118
transfer RNA (tRNA)
transport molecules that transfer RNA (tRNA) and carry the amino acids to the ribosomes
119
RNA polymerase
enzyme that synthesizes the complementary RNA molecule from DNA.
120
promoter
a DNA nucleotide sequence that RNA polymerase attaches to; the attachment of RNA polymerase to the promoter causes a portion of the DNA molecule to unwind, exposing the nucleotide sequence
121
transcription factors
other proteins that the RNA must first associate with in order to interact with the DNA.
122
terminator
a DNA nucleotide sequence that when RNA polymerase
| encounters it, it detaches from the DNA, releasing the newly formed mRNA.
123
exons
Regions of the mRNA that code for proteins
124
introns
non-protein-coding regions
125
pre-mRNA
An mRNA that contains introns; functional mRNA consists only of exons
126
posttranscriptional processing
modifications made before a pre-mRNA leaves the nucleus, which produces the functional mRNA that is used in translation to produce a protein
127
poly-A tail
added to one end of the mRNA and a 7-methyl guanosine cap is added to the other end; ensure that mRNA travels from the nucleus to the cytoplasm and interacts with ribosomes during translation
128
alternative splicing
when various combinations of exons are incorporated into mRNA
129
genetic code
information contained in mRNA
130
codons
genetic code is carried in these sets of three nucleotide units
131
start codon
signals the beginning of translation
132
stop codons
signal the end of translation
133
ribosomal RNA (rRNA)
The function of tRNA is to match a specific amino acid to a specific codon of mRNA.
134
anticodon
consists of three nucleotides and is complementary to a particular codon of mRNA
135
polyribosome
resulting cluster of ribosomes attached to the mRNA after a ribosome uses the initial part of mRNA, another ribosome can attach to the mRNA and begin to make a protein
136
proproteins
longer when they are first made than in their final, functional state; extra piece of the molecule is cleaved off by enzymes to make the proprotein into a functional protein.
137
proenzymes
the proproteins of the proteins that are enzymes
138
posttranslational processing
various modifications to proteins
139
cell life cycle
the changes a cell undergoes from the time it is formed until it divides to produce two new cells; two stages: interphase and cell division (mitosis and cytokinesis)
140
Interphase
phase between cell divisions; 90% or more of the life cycle of a typical cell is spent in interphase.
141
DNA replication
process by which two new strands of DNA are made, using the two existing strands as templates.
142
DNA polymerase
an enzyme that adds new nucleotides to the 3′ end of the growing strands.
143
leading strand
forms as a continuous strand
144
lagging strand
forms in short segments called Okazaki fragments .
145
DNA ligase
splic Okazaki fragments
146
Mitosis
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.
147
mitotic chromosomes
During mitosis, the chromatin becomes very densely coiled to form these compact chromosomes
148
chromatids
one of the two copies of the original chromosome each mitotic chromosome consists of
149
centromere
where the chromatids are attached
150
kinetochore
protein structure that binds the centromere and provides a point of attachment for microtubules that will move the chromatids during mitosis
151
prophase
chromatin condenses to form mitotic chromosomes; spindle fibers extend from the centrioles to the centromeres of the chromosomes; the centrioles divide and migrate to each pole of the cell; in late prophase, the nucleolus and nuclear envelope disappear.
152
metaphase
chromosomes align near the center of the cell.
153
anaphase
the chromatids separate; at this point, two identical sets of chromosomes are moved by the spindle fibers toward the centrioles at one of the poles of the cell. At the end of anaphase, each set of chromosomes has reached an opposite pole of the cell, and the cytoplasm begins to divide.
154
telophase
nuclear envelopes form around each set of chromosomes to form two separate nuclei; The chromosomes begin to uncoil and resemble the genetic material characteristic of interphase.
155
Cytokinesis
division of the cell’s cytoplasm to produce two new cells.
156
cleavage furrow
an indentation of the plasma membrane that forms midway between the centrioles.
157
Genetics
the study of heredity—that is, the characteristics children inherit from their parents.
158
Mendelian genetics
study of how genetic traits are passed from parent to offspring
159
genomic medicine
genetic approach to the diagnosis and management of disease
160
gametes
sex cells
161
genotype
The genes an organism has for a given trait
162
phenotype
The expression of the genes as a trait
163
alleles
Alternate forms of genes
164
dominant allele
mask the effects of the recessive allele for that trait
165
homozygous
the two alleles for the trait are identical
166
heterozygous
the two alleles for the trait are different
167
polydactyly
has extra fingers or toes; dominant expression
168
Somatic cells
all the cells of the body except the gametes.
169
diploid number
normal number of chromosomes in a somatic cell; 46 chromosomes
170
haploid
normal number of chromosomes in a gamete; 23 chromosomes
171
autosomal chromosomes
all the chromosomes except the sex chromosomes; 22 pairs
172
sex chromosomes
determines the sex of the individual; 1 pair; X or Y chromosomes
173
karyotype
a display of the chromosomes of a somatic cell during metaphase of mitosis.
174
homologous chromosomes
Chromosome pairs; each member of the pair is a homolog; 1 from mother, 1 from father
175
genome
all the genes found in the haploid number of chromosomes from one parent.
176
locus
location, on a chromosome; each gene of the genome occupies a specific locus
177
multiple alleles
alleles can exist in many forms; Differences in alleles arise by mutation
178
allelic variant
different form of an allele, or mutated allele (gene), or a polymorphism (many forms).
179
phenylketonuria (PKU)
autosomal recessive trait with multiple alleles.
180
complete dominance
homozygous dominant and the heterozygote had the same phenotype
181
codominance
two alleles at the same locus are expressed so that separate, distinguishable phenotypes occur at the same time; blood types
182
incomplete dominance
the dominant allele does not completely mask the effects of the recessive allele in the heterozygote; beta, major, and minor thalassemia
183
polygenic traits
result from the interactions of many genes; height, intelligence, eye color, and skin color.
184
Sex-linked traits
traits affected by genes on the sex chromosomes
185
X-linked traits
affected by genes on the X chromosome; most sex-linked traits are X-linked
186
Y-linked traits
affected by genes on the Y chromosome.
187
meiosis
cell division that reduces chromosome number by half; gametes are produced that have one homolog from each of the homologous pairs of chromosomes.
188
carrier
carrier for a recessive trait is a person who is heterozygous for that trait, with one normal allele and one disorder-causing allele. The carrier does not exhibit the disorder
but can pass it on to his or her children.
189
genetic disorder
a failure of structure, function, or both as a result of abnormalities in a person’s genetic makeup- DNA
190
mutagens
Agents that cause mutations
191
point mutation
A mutation involving a single nucleotide change
192
structural mutations
Mutations that change the sequence or number of nucleotides involve changes in chromosome structure
193
nondisjunction
As the chromosomes separate during meiosis, the two members of a homologous pair may not segregate as they normally do. As a result, one of the daughter cells receives both chromosomes, and the other daughter cell receives none.
194
aneuploidy
zygote with 47 chromosomes or 45 chromosomes rather
| than the normal 46
195
Down syndrome or trisomy 21
type of aneuploidy in which three chromosomes 21 are present.
196
syndrome
set of signs and symptoms occurring together as the result of a single cause, such as a single mutation or one extra chromosome
197
Cancer
usually results from a series of somatic mutations that cause uncontrolled cell division and changes in the normal functions of cells.
198
genomic map
depicts the DNA nucleotide sequences of the genes and their locations on the chromosomes
199
gene therapy or genetic engineering
repairs or replaces defective genes or gene products, resulting in cures or treatments for genetic disorders.
